Assuming the boiling point increased by 2 °C, what is the approximate molality of NaCl when the video ends? Kbp(water) = 0.512 °C/(mol/kg)

Answers

Answer 1

Answer : The molality of NaCl is, 1.95 mol/kg

Explanation :

Formula used for Elevation in boiling point :

[tex]\Delta T_b=i\times k_b\times m[/tex]

where,

[tex]\Delta T_b[/tex] = change in boiling point = [tex]2^oC[/tex]

[tex]k_b[/tex] = boiling point constant  for water = [tex]0.512^oC/m[/tex]

m = molality

i = Van't Hoff factor = 2 (for electrolyte)

The dissociation [tex]NaCl[/tex] will be,

[tex]NaCl\rightarrow Na^++Cl^{-}[/tex]

So, Van't Hoff factor = Number of solute particles = [tex]Na^++Cl^{-}[/tex] = 1 + 1 = 2

Now put all the given values in the above formula, we get:

[tex]2^oC=2\times (0.512^oC/m)\times m[/tex]

[tex]m=1.95mol/kg[/tex]

Therefore, the molality of NaCl is, 1.95 mol/kg

Answer 2

The molality of NaCl is, 1.95 mol/kg

The calculation is as follows;

[tex]\Delta T _ b = i \times k_b \times m\\\\2^{\circ}C = 2\times (0.512^{\circ} C/m) \times m[/tex]

m = 1.95 mol/kg

Here m represent the molarity

[tex]\Delta T_b[/tex] represents a change in boiling point i.e. [tex]2^{\circ}C[/tex]

[tex]k_b[/tex] represents the constant boiling point for water  

i = Van't Hoff factor = 2 (for electrolyte)

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Related Questions

Given one mole of each substance, which of the following will produce the FEWEST particles in aqueous solution? 1. sodium nitrate 2. CH2Cl2 3. K2SO4 4. sodium phosphate

Answers

Answer: The substance that produces fewest particles is [tex]CH_2Cl_2[/tex]

Explanation:

Ionization reaction is defined as the reaction in which an ionic compound dissociates into its ions when dissolved in aqueous solution.

Covalent compounds do not dissociate into ions when dissolved in aqueous solution.

For the given options:

Option 1:  Sodium nitrate

The chemical formula of sodium nitrate is [tex]NaNO_3[/tex]

The ionization reaction for the given compound follows:

[tex]NaNO_3(aq.)\rightarrow Na^+(aq.)+NO_3^-(aq.)[/tex]

This produces in total of 2 ions.

Option 2:  [tex]CH_2Cl_2[/tex]

The given compound is a covalent compound and do not dissociate into its ions. It remains as such as a single unit.

Option 3:  [tex]K_2SO_4[/tex]

The chemical name for the given compound is potassium sulfate.

The ionization reaction for the given compound follows:

[tex]K_2SO_4(aq.)\rightarrow 2K^+(aq.)+SO_4^{2-}(aq.)[/tex]

This produces in total of 3 ions.

Option 4:  Sodium phosphate

The chemical formula of sodium phosphate is [tex]Na_3PO_4[/tex]

The ionization reaction for the given compound follows:

[tex]Na_3PO_4(aq.)\rightarrow 3Na^+(aq.)+PO_4^{3-}(aq.)[/tex]

This produces in total of 4 ions.

Hence, the substance that produces fewest particles is [tex]CH_2Cl_2[/tex]

The proper solvent choice is crucial for effective recrystallization. What are the features of a good recrystallization solvent? Select all that apply.

a. The solvent should dissolve a moderate quantity of the target substance near its boiling point but only a small quantity near 0 °C.
b. The solvent should not react with the target substance.
c. The crude compound should be soluble in this solvent at room temperature.
d. The solvent should be easily removed from the purified product.
e. The solvent should have a high boiling point.

Answers

Answer:

a, b and d

Explanation:

Proper Solvent choice is very important for effective recrystallization.

Therefore, features of a good solvent are.

a. The solvent should dissolve a moderate quantity of the target substance near its boiling point but only.

b. The solvent should not react with the target substance.

d. The solvent should be easily removed from the purified product.

options c and d are not a property of good solvent.

Consider the steps in coal gasification: C(coal) + H2O(g) → CO(g) + H2(g) ΔH°rxn = 129.7 kJ CO(g) + H2O(g) → CO2(g) + H2(g) ΔH°rxn = -41 kJ CO(g) + 3H2(g) → CH4(g) + H2O(g) ΔH°rxn = -206 kJ Calculate the heat of reaction, ΔH°rxn, for overall reaction for the production of methane, CH4.

Answers

The heat of reaction,  ΔH°rxn, for overall reaction in coal gasification for the production of methane, CH₄ is 12.4 kJ

From the question,

We are to determine the heat of reaction for overall reaction for the production of methane in coal gasification

The equation for the reaction of coal gasification is

2C(coal) + 2H₂O → CO₂ + CH₄  

From the question,

We have the following equations of reactions

(1)        C(coal) + H₂O(g) → CO(g) + H₂(g)               ΔH°rxn = 129.7 kJ

(2)       CO(g) + H₂O(g) → CO₂(g) + H₂(g)               ΔH°rxn = -41 kJ

(3)       CO(g) + 3H₂(g) → CH₄(g) + H₂O(g)              ΔH°rxn = -206 kJ

Multiply (1) by 2 to get

(4)       2C(coal) + 2H₂O(g) → 2CO(g) + 2H₂(g)       ΔH°rxn = 259.4 kJ

Now, adding equations (2), (3), and (4), we get

(2)       CO(g) + H₂O(g) → CO₂(g) + H₂(g)               ΔH°rxn = -41 kJ

(3)       CO(g) + 3H₂(g) → CH₄(g) + H₂O(g)              ΔH°rxn = -206 kJ

(4)       2C(coal) + 2H₂O(g) → 2CO(g) + 2H₂(g)       ΔH°rxn = 259.4 kJ

--------------------------------------------------------------------------------------------------

          2C(coal) + 2H₂O(g) → CH₄(g) + CO₂(g)        ΔH°rxn = 12.4 kJ

Hence, the heat of reaction,  ΔH°rxn, for overall reaction in coal gasification for the production of methane, CH₄ is 12.4 kJ

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Final answer:

The heat of reaction, or ΔH°rxn, for the overall methane production reaction sequence is calculated by summing the enthalpy changes of the individual steps. This value comes out as -117.3 kJ per the application of Hess's Law.

Explanation:

In order to calculate the heat of reaction, ΔH°rxn, for overall methane production, we have to use Hess's Law. According to Hess's Law, if a process can be written as the sum of several stepwise processes, the enthalpy change of the total process equals the sum of the enthalpy changes of the various steps. The first reaction has an enthalpy change of 129.7 kJ, the second -41 kJ, and the third -206 kJ.

Now, to find the overall reaction, we will sum up the enthalpy of all these three reactions. So, ΔH°rxn for the overall reaction would be calculated as 129.7 kJ - 41 kJ - 206 kJ = -117.3 kJ. Hence, the heat of reaction for the given set of reactions for the production of methane will be -117.3 kJ.

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A chemist adds of a M copper(II) fluoride solution to a reaction flask. Calculate the mass in micrograms of copper(II) fluoride the chemist has added to the flask. Round your answer to significant digits.

Answers

The question is incomplete, here is the complete question.

A chemist adds 345.0 mL of a 0.0013 mM (MIllimolar) copper(II) fluoride [tex]CuF_2[/tex] solution to a reaction flask.

Calculate the mass in micrograms of copper(II) fluoride the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Answer : The mass of copper(II) fluoride is, 0.13 mg

Explanation :  Given,

Millimolarity of copper (II) fluoride = 0.0013 mM

This means that 0.0013 millimoles of copper (II) fluoride is present in 1 L of solution

Converting millimoles into moles, we use the conversion factor:

1 moles = 1000 millimoles

So, [tex]0.0013mmol\times \frac{1mol}{1000mmol}=1.3\times 10^{-6}mol[/tex]

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

We are given:

Moles of copper (II) fluoride solution = [tex]1.3\times 10^{-6}mol[/tex]

Molar mass of copper (II) fluoride = 101.5 g/mol

Putting values in above equation, we get:

[tex]1.3\times 10^{-6}mol=\frac{\text{Mass of copper (II) fluoride}}{101.5g/mol}\\\\\text{Mass of copper (II) fluoride}=(1.3\times 10^{-6}mol\times 101.5g/mol)=1.32\times 10^{-4}g[/tex]

Converting this into milligrams, we use the conversion factor:

1 g = 1000 mg

So,

[tex]\Rightarrow 1.32\times 10^{-4}g\times (\frac{1000mg}{1g})=0.13mg[/tex]

Therefore, the mass of copper(II) fluoride is, 0.13 mg

Answer:

the mass of copper(II) fluoride added to the flask is approximately 476,250 micrograms.

Explanation:

To calculate the mass of copper(II) fluoride (CuF2) added to the reaction flask, you need to multiply the volume (in liters) of the solution by its molarity and then convert the result to micrograms.

Given:

Volume of the solution (V) = 0.015 L

Molarity of the solution (M) = 0.500 M

First, calculate the number of moles of copper(II) fluoride using the formula:

Moles (n) = Molarity (M) × Volume (V)

n = 0.500 M × 0.015 L = 0.0075 moles

Now, you need to convert moles to micrograms. One mole of any substance contains Avogadro's number of molecules (6.022 × 10^23). You also need to consider the molar mass of copper(II) fluoride (CuF2), which is the sum of the atomic masses of copper (Cu) and two fluorine (F) atoms:

Molar mass of CuF2 = (1 * Cu) + (2 * F) = 63.5 g/mol (approximately)

Now, calculate the mass in grams:

Mass (g) = Moles (n) × Molar mass (Molar mass of CuF2)

Mass (g) = 0.0075 moles × 63.5 g/mol ≈ 0.47625 g

Now, convert grams to micrograms. There are 1,000,000 micrograms in a gram:

Mass (micrograms) = Mass (g) × 1,000,000

Mass (micrograms) = 0.47625 g × 1,000,000 µg/g = 476,250 µg

So, the mass of copper(II) fluoride added to the flask is approximately 476,250 micrograms.

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Draw the conjugate bases of pyrrole and cyclopentadiene. For pyrrole, please include the N lone pairs. Conjugate Base of Pyrrole: edit structure ... Conjugate Base of Cyclopentadiene

Answers

Answer:

Hi

A conjugate acid is a chemical compound formed by the reception of a proton by a base; therefore, it is a base with an added hydrogen ion. On the other hand, a conjugate base is what remains after an acid has donated its proton during a chemical reaction, so it can be said that a conjugate base is a species modified by extracting a proton from an acid.

In pyrrole, the electron pair can be relocated to the ring and its availability is very small. In addition, the concept of aromaticity comes into play.

In the attached file are the schemas of the conjugate bases.

Explanation:

The state of system is changed isobarically until itjustbecomes saturated. What is thetemperature of the system?

Answers

Answer:

Explanation:Isobaric is a thermodynamic process in which the pressure of the system is zero. It is a process where there is no work done in the system. Therefore the temperature of the system according to the ideal gas law will vary linearly with pressure and inversely with volume.

"What is the change of entropy for 3.0 kg of water when the 3.0 kg of water is changed to ice at 0"

Answers

Q: What is the change of entropy for 3.0 kg of water when the 3.0 kg of water is changed to ice at 0 °C? (Lf = 3.34 x 105 J/kg)

Answer:

-3670.33 J/K

Explanation:

Entropy: This can be defined as the degree of randomness or disorderliness of a substance. The S.I unit of Entropy is J/K.

Mathematically,  change of Entropy can be expressed as,

ΔS = ΔH/T ....................................... Equation 1

Where ΔS = Change of entropy, ΔH = heat change, T = temperature.

ΔH = -(Lf×m).................................... Equation 2

Note: ΔH is negative because heat is lost.

Where Lf = latent heat of ice = 3.34×10⁵ J/kg, m = 3.0 kg, m = mass of water = 3.0 kg

Substitute into equation

ΔH = -(3.34×10⁵×3.0)

ΔH = - 1002000 J.

But T = 0 °C = (0+273) K = 273 K.

Substitute into equation 1

ΔS = -1002000/273

ΔS = -3670.33 J/K

Note: The negative value of ΔS shows that the entropy of water decreases when it is changed to ice at 0 °C

Final answer:

The change in entropy for 3.0 kg of water changing into ice at 0 degrees Celsius is approximately 3658 J/K. This is calculated using the formula for entropy change and the known values for the heat of fusion for water and the temperature in Kelvin.

Explanation:

The change in entropy during a phase transition, such as the one from water to ice, can be calculated using the formula ΔS = Q/T, where ΔS is the change in entropy, Q is the heat involved during the phase transition, and T is the temperature in Kelvin. For the given scenario, the phase change is from liquid to solid (freezing), and the heat involved (Q) is equal to the mass multiplied by the heat of fusion for water. The heat of fusion for water is 333.55 J/g and the temperature (T) at which this change occurs is 0 degrees Celsius or 273.15 Kelvin. The mass is 3.0 kg or 3000g. Therefore, Q = 3000g x 333.55J/g = 999150 J. Substituting these values in our formula, ΔS = 999150 J / 273.15 K ≈ 3658 J/K.

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Calculate the pH of a polyprotic acid given and sketch the titration curves for the following reaction:

A 20.0-mL aliquot of 0.100M of a tartaric acid with 0.100M NaOH
pKa1 = 2.3 pKa2= 4.3

Please calculate the pH when:

1- initial, 0mL of NaOH added

2-pH at first 1/2 equivalence point

3-pH at first equivalence point

4-pH at second 1/2 equivalenec point

5-pH at second equivalence point

6-pH afteter the second equivalence point

Answers

Answer: (1). pH = 1.70

(2). pH = 2.3

(3). pH = 3.3

(4). pH = 4.3

(5). pH = 8.41

(6). pH = 10.22

Explanation:

we assume that the formula representation of acid is H₂A

the titration curve has reasonably sharp breaks at both equivalence points, corresponding to the reactions;

H₂A + OH⁻ → HA⁻ + H₂O

HA⁻ + OH⁻ → A²⁻ + H₂O

the volume of NaOH (V₀) at the first equivalent point is,

V₀ = (20.0 mL)(0.100M) / 0.100M = 20.0mL

where volume of NaOH at 1/2 equivalent point is,

V₀/2 = 10.0mL

also Volume of NaOH at the second equivalence (2V₀) point is 40.0mL

the volume of NaOH at 1/2 second equivalent point is,

V₀ + V₀/2 = 30.0mL

Volume of NaOH after second equivalence exceeds 40mL

therefore, at 0 mL NaOH addition;

where the extent of ionization is assumed to be x, we have

                        H₂A   ⇆     HA⁻   +   H⁺

where initial:   0.1 M       -            -

          change:   -x         +x           +x

          Equili:      0.1-x      x             x

Kаl = [HA⁻][H⁺] / [H₂A]

10⁻²³ = (x)(x) / (0.1-x)

x = 0.020

[H⁺] = 0.020 M

pH = -log [H⁺]

pH = -log(0.020)

pH = 1.70

(2). at 10 mL NaOH addition

[H₂A]ini = 0.10 M * 20.0 mL = 2 mmol

[OH⁻] = 0.1 M * 10 mL = 1 mmol

after reaction:

[H₂A] = 1 mmol

[H⁻] = 1 mmol

pH = pKa₁ + log [HA⁻] / [[HA⁻]

pH = 2.3 + log 1mmol / 1mmol

pH = 2.3

(3). pH at the first equivalence point is,

pH = 1/2 (pKa₁ + pKa₂)

pH = 1/2(2.3 + 4.3) = 3.3

pH = 3.3

(4). pH at the second 1/2 equivalence point is

pH = pKa₂ = 4.3

pH = 4.3

(5). pH at the second equivalence point;

all H₂A is converted into A²⁻

[A²⁻] = initial moles of H₂A / total volume = (20.0 mL)(0.10 M) / (20.0 + 40.0) mL = 0.033 M

at equilibrium:

                   A²⁻ + H²O    ⇆   HA⁺ OH⁻

          0.033 - x

from the Kb₁ expression,

Kb₁ = [OH⁻][HA⁻] / [A²]

Kw/Ka₂ = x²/(0.0333 - x)

10⁻¹⁴/10⁻⁴³ = x²/(0.0333 - x)

x = 2.57 * 10⁻⁶

[OH⁻] = 2.57 * 10⁻⁶M

pH = -log Kw/[OH⁻] = 8.41

pH = 8.41

(6). pH after second equivalence point;

assuming the volume of NaOH is 40.10 mL

after second equivalence point OH⁻ in excess

[OH⁻] = 0.10 M * 0.10 mL / (20 + 40.10) mL = 1.66 * 10⁻⁴ M

pH = 0=-log Kw/[OH⁻] = 10.22

pH = 10.22

Two beakers contain clear. colorless liquids. When the contents of the beakers are mixed a white solid is formed, (a) Is this an example of a chemical or a physical change? (b) What would be the most convenient way to separate the newly formed white solid from the liquid mixture-filtration, distillation, or chromatography.

Answers

Answer:

1) chemical change

2) filtration

Explanation:

A chemical change involves the formation of a new substance. In this case, the pure white solid formed is an entirely new substance, with a different chemical identity from those of the two solutions mixed to form it. The new solid is a precipitate. Precipitates are easily separated by filtration of the reaction mixture. Another name for chemical change is chemical reaction.

1) This is an example of chemical change.

2) The most convenient way to separate the newly formed white solid from the liquid mixture is filtration

What is a Chemical change?

A chemical change involves the formation of a new substance. In this case, the pure white solid formed is an entirely new substance, with a different chemical identity from those of the two solutions mixed to form it. The new solid is a precipitate. Precipitates are easily separated by filtration of the reaction mixture. Another name for chemical change is chemical reaction.

The most convenient way  to separate the newly formed white solid from the liquid mixture is filtration since precipitates are formed.

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In the arrangement of particles within any atom, the outermost sort of particle is always the:________

Answers

Answer:

In the arrangement of particles within any atom, the outermost sort of particle is always the electron.

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other.

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10-31 Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P+  

Symbol of neutron= n0  

Mass of proton=1.672623×10-27 Kg

Mass of neutron=1.674929×10-27 Kg

Final answer:

In any atom, the outermost type of particle is the electron, specifically the valence electrons in the outermost shell. These electrons play a significant role in chemical reactions and bonding properties of the element. The organization of the Periodic Table reflects patterns in valence electron configurations that correspond to chemical behaviors.

Explanation:

In the arrangement of particles within any atom, the outermost sort of particle is always the electron. Electrons are the smallest of the three types of sub-atomic particles, carrying a negative charge and occupying the space outside the atomic nucleus. Inside the nucleus, much larger particles—protons and neutrons—are found, with protons having a positive charge and neutrons being electrically neutral.

The outermost electrons are of particular importance because they are the valence electrons. These are the electrons that reside in the outermost shell, or valence shell, of an atom in its uncombined state, and they play critical roles in determining the chemical properties of an element as well as its ability to form bonds with other atoms. The electron configuration of an atom is notably important because atoms with the same outer electron configurations tend to show similar chemical behavior, as demonstrated in the organization of the Periodic Table.

The number of valence electrons in the outermost shell can define an element's chemical reactivity and the types of bonds it can form. The arrangement of electrons in atoms means that the electrons with the highest energy levels, which are the valence electrons, are more likely to interact in chemical reactions than the core electrons which are closer to the nucleus and have lower energy levels.

Alkanes with a branch coming off the straight chain are identified as substituted alkanes. What would be the name of a straight chain made of 8 carbons with -CH3 groups on the second and fifth carbons? View Available Hint(s) Alkanes with a branch coming off the straight chain are identified as substituted alkanes. What would be the name of a straight chain made of 8 carbons with -CH3 groups on the second and fifth carbons? 2-methyl-5-methyloctane 2,5-dimethyldecane 2,5-dimethaneoctane 2,5-dimethyloctane

Answers

Answer: 2,5-dimethyl octane.

Explanation:

The basic rules for naming of organic compounds are :

1. First select the longest possible carbon chain.

2. The longest possible carbon chain should include the carbons of double or triple bonds.

3. The naming of alkane is done by adding the suffix -ane, alkene by adding the suffix -ene, alkyne by adding the suffix -yne and carboxylic acid by adding the suffix -oic acid.

4. The numbering is done in such a way that first carbon of double or triple bond gets the lowest number.

5. The carbon atoms of the double or triple bond get the preference over the other substituents present in the parent chain.

6. If two or more similar alkyl groups are present in a compound, the words di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.

Thus the name for straight chain made of 8 carbons with [tex]-CH_3[/tex] groups on the second and fifth carbons will be 2,5-dimethyl octane.

Imagine you created a toxin such that when a neuron fired an action potential, the toxin would bind immediately to the sodium-potassium pump at the top of the action potential, but the sodium and potassium channels would still function. What process(es) would be affected

Answers

Answer:Maintaining resting potential and returning to resting potential after the hyperpolarization phase of an action potential

Explanation:TOXINS are chemical substances which are known to be POISONOUS produced with living organisms that causes harm to other organisms, examples include Venom from snakes which when a person is bitten by a Snake it will possibly lead to death if not adequate treated.

HYPERPOLARIZATION is a term that explains the change in membrane potential due to toxin,it make the membrane more electronegative. When the toxin has hyped the level of Sodium-Potassium level returning to a rest state will be most affected.

In the hydrogenation of ethylene using a nickel catalyst, the initial concentration of ethylene is 1.50 mol * L−1 and its rate constant (k) is 0.0016 mol * L−1 * s−1.
a. Determine the rate of reaction if it follows a zero-order reaction mechanism.

Answers

Answer:

0.0016 mol/(L.s)

Explanation:

The rate of a reaction (r) can be calculated by the initial concentration of the reagent, by the expression:

-r = k*[reagent]ⁿ

Where the minus sign represents that the reagent is disappearing, k is the rate constant, which depends on the temperature, and n is the order of the reaction. For the reaction with more than 1 reagent, each reagent will have its order, which is determined by experiments. So, for n = 0:

-r = 0.0016*(1.50)⁰

-r = 0.0016 mol/(L.s)

Final answer:

The rate of a zero-order reaction is equal to the rate constant, which in the case of the hydrogenation of ethylene using a nickel catalyst is 0.0016 mol L.

Explanation:

To determine the rate of reaction for a zero-order reaction, we use the rate law which states that the rate is independent of the concentration of the reactants. Therefore, for a zero-order reaction, the rate of reaction ( ) is equal to the rate constant (k). Given that the rate constant k is 0.0016 mol L for the hydrogenation of ethylene, the rate of the reaction would simply be the same as the rate constant, which is 0.0016 mol L

A compound is known to contain only carbon, hydrogen, and oxygen. If the complete combustion of a 0.150-g sample of this compound produces 0.225 g of CO2 and 0.0614 g of H2O, what is the empirical formula of this compound

Answers

Answer: the empirical formula is C3H4O3

Explanation:Please see attachment for explanation

Answer:

The answer to your question is  C₃H₄O₃

Explanation:

Data

CxHyOz

mass of sample = 0.150 g

mass of CO₂ = 0.225 g

mass of H₂O = 0.0614 g

Reaction

                     CxHyOz + O₂   ⇒   CO₂   + H₂O

Process

1.- Calculate the moles of C

                            44 g of CO₂ ----------------- 12 g of C

                            0.225 g    ---------------- x

                            x = (0.225 x 12) / 44

                            x = 0.0614 g of C

                            12 g of C -------------------- 1 mol

                           0.0614 g of C --------------- x

                                 x = 0.0051 moles of Carbon

2.- Calculate the moles of hydrogen

                            18 g of H₂O ------------------ 2 g of H

                             0.0614 g --------------- x

                             x = 0.0068 g of H

                             1 g of H ----------------------- 1 mol of H

                            0.0068 g --------------------- x

                             x = 0.0068 moles of H

3.- Calculate the mass of Oxygen

    Mass of oxygen = 0.150 - 0.0614 - 0.0068

                               = 0.0818 g

                       16 g of O -------------------  1 mol

                      0.0818 g -------------------- x

                         x = (0.0818 x 1) / 16

                         x = 0.0051 moles of O

4.- Divide by the lowest number of moles

Carbon       0.0051 / 0.0051  = 1

Hydrogen   0.0068 / 0.0051 = 1.33

Oxygen       0.0051 / 0.0051 = 1

Multiply these numbers by 3

Carbon 3

Hydrogen = 4

Oxygen = 3

5.- Write the empirical formula

                                      C₃H₄O₃

What happens to the temperature of a mixture of ice and liquid water as heat is applied at a constant rate?

A- The temperature of the mixture increases as the ice melts, and then continues to increase at the same rate once all the ice is melted.
B- It is impossible to predict how the temperature will change unless you know the amount of ice and water that is present before the heating begins
C- The temperature of the mixture slowly increases as the ice melts. Once all the ice has melted, the temperature of the liquid water continues to rise, but at a faster rate.
D- The temperature of the mixture does not change at all until all the ice has melted, at which point it increases at a constant rate.

Answers

Answer:

D is the true statement.

Explanation:

Recall that during a phase change the temperature remains constant until all the material has changed its phase. The energy put into the system is utilized to make the phase change, and afterward the temperature of the vliquid will start to increase.

In this case we have a mixture of liquid water and ice at  0ºC  ( assume standard pressure) which is the temperature in which liquid water and ice coexist. The ice will  melt until consumed at constant T = 0ºC, and then the temperature of the liquid water will start to increase at a uniform rate since we are heating at a constant rate.

Now we are in position to answer this question.

A- False the temperature does not increase as the ice melts.

B- False for the reasons given above.

C- False the temperature does not increase slowly as the ice melts, but remains constant.

D-True the temperature of the mixture does not change until all the ice has melted, and then the temperature of liquid water will start to increase uniformly.

Final answer:

Heat applied to a water-ice mixture initially goes into breaking the hydrogen bonds in ice (latent heat of fusion), without causing a temperature increase. Only after all the ice has melted, the added heat increases the water temperature.

Explanation:

The correct option is D: The temperature of the mixture does not change at all until all the ice has melted, at which point it increases at a constant rate. This is because the energy from the heat being applied is first used to break the hydrogen bonds in ice, a process known as latent heat of fusion, which does not involve an increase in temperature. Only after all the ice has melted will the added heat then lead to an increase in the temperature of the water.

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When a 0.089M aqueous solution of a certain acid is prepared, the acid is 12.% dissociated. Calculate the pH of the solution. Round your answer to 2 decimal places.

Answers

Answer:

pH = 1.98

Explanation:

Given a general acid dissociation:

HA + H₂O  ⇆  H₃O⁺   + A⁻    

The pH is -log[ H₃O⁺ ]

Therefore we need to determine [ H₃O⁺ ] to answer this question, and we should use the data of % dissociation of the acid.

Percent dissociation is

% dissociation = [ H₃O⁺ ] / [ HA ]₀ x 100

where [ HA ]₀  is the original acid concentration, so we can calculate [ H₃O⁺ ] , and then the pH.

12 =  [ H₃O⁺ ] /0.089 M ⇒  [ H₃O⁺ ]  = (12 x 0.089 /100) M

                                                          = 1.07 x 10⁻² M

and pH = - log ( 1.07 x 10⁻² ) = 1.98

Final answer:

To determine the pH of a 0.089M solution of an acid that is 12% dissociated, we first calculate the hydronium ion concentration and then use the formula for pH. After calculation, the pH is found to be 2.97.

Explanation:

To calculate the pH of the solution where the acid is 12% dissociated, we first need to determine the concentration of hydronium ions ([H+]) in the solution.

Given a 0.089M solution of an acid that is 12% dissociated, the concentration of dissociated hydronium ions is:


 

This concentration has three significant figures. Using the formula for pH which is:


 

The pH is then calculated as:

pH = -log(0.01068) = 2.97

The result is in the acidic pH range, and it has been rounded to two decimal places to match the number of significant figures from the initial concentration given.

All of the elements below can exist as network solids EXCEPT 1. As 2. B 3. Si 4. O 5. C

Answers

Answer:

4. Oxygen

Explanation:

When hydrogen sulfide reacts with oxygen, water and sulfur dioxide are produced. The balanced equation for this reaction is:

Answers

Answer:

2H2S + 3O2 → 2SO2 + 2H2O

Explanation:

Step 1: Data given

Hydrogen sulfide = H2S

Oxygen = O2

sulfur dioxide = SO2

water = H2O

Step 2: The unbalanced equation

H2S + O2 → SO2 + H2O

Step 3: Balancing the equation

H2S + O2 → SO2 + H2O

On the left side we have 2x O (in O2) and on the right side we have 3x O (2x in SO2 and 1x in H2O). To balance the amount of O, we have to multiply O2 (on the left side) by 3 and SO2 and H2O on the right side by 3.

H2S + 3O2 → 2SO2 + 2H2O

On the right side we have 4x H and on the left side we have 2x H. To balance the amount of H, we have to multiply H2S by 2.

Now the equation is balanced.

2H2S + 3O2 → 2SO2 + 2H2O

Which of these is a general feature of the lipid bilayer in all biological membranes?

a) individual lipid molecules are free to diffuse laterally in the surface of the bilayer

b) individual lipid molecules in one monolayer of the bilayer readily diffuse (flip-flop) to the other monolayer.

c) polar, but uncharged, compounds readily diffuse across the bilayer

d) the bilayer is stabilized by covalent bonds between neighboring phospholipid molecules.

e) the polar head groups face inward toward the inside of the bilayer

Answers

A

Individual lipid molecules are free to diffuse laterally in the surface of the bilayer is a general feature of the lipid bilayer in all biological membranes

Explanation:

The inside of the bilipid layer of the cell membrane of cells is made of fatty acid chains and cholesterol which are nonpolar molecules. they are sandwiched between the polar (glycerol) ends of the  chains because they are hydrophobic and cannot interact with the ‘watery’ extracellular fluids.  Non-polar molecules like lipids can easily diffuse laterally, within this lipid layers of the membrane because non-polar molecules interact well with other nonpolar molecules.

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An aqueous potassium iodate ( KIO 3 ) solution is made by dissolving 587 grams of KIO 3 in sufficient water so that the final volume of the solution is 5.00 L. Calculate the molarity of the KIO 3 solution.

Answers

Answer:

[KIO₃] = 0.548 M

Explanation:

Molarity is a sort of concentration which involves moles of solute in 1L of solution.

Volume of solution 5L

Mass of solution: 587 g

Let's convert the mass to moles (mass / molar mass)

587 g / 214 g/mol = 2.74 moles

Molarity is mol/L → 2.74 mol / 5L = 0.548 M

Write the formula unit equation for this reaction occurring in water: Potassium sulfate and barium chloride are mixed to form potassium chloride and barium sulfate.

1. K2SO4 (s) + BaCl2 (s) → 2 KCl (aq) + BaSO4 (s)
2. K2SO4 (aq) + BaCl2 (aq) → 2 KCl (aq) + BaSO4 (s)
3. 2 K3SO4 (aq) + 3 BaCl2 (aq) → 6 KCl (aq) + 2 Ba3(SO4)2 (s)

Answers

Final answer:

The correct formula unit equation for the reaction of potassium sulfate and barium chloride forming potassium chloride and barium sulfate in water is: K2SO4 (aq) + BaCl2 (aq) → 2 KCl (aq) + BaSO4 (s). This is because both potassium sulfate and barium chloride are soluble in water, but barium sulfate is not.

Explanation:

The correct formula unit equation for the reaction of potassium sulfate and barium chloride forming potassium chloride and barium sulfate in water is: K2SO4 (aq) + BaCl2 (aq) → 2 KCl (aq) + BaSO4 (s).

This can be justified as when potassium sulfate (K2SO4) and barium chloride (BaCl2) are dissolved in water they dissociate into their respective ions, making them aqueous. The formation of potassium chloride (KCl) acknowledges that potassium ions and chloride ions can be attracted to each other in the water solution, so this is also aqueous. However, barium sulfate (BaSO4) is known to be insoluble in water, and hence, precipitates as a solid (s). Hence, option 2 is correct.

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A binary compound created by reaction of chromium and an unknown element E contains 68.47% Cr and 31.53% E by mass. If the formula of the compound is Cr2E3, calculate the atomic mass of E.

Answers

Answer: The atomic mass of E is 16

Explanation:Please see attachment for explanation

Answer:

The molar mass of E = 15.96 g/mol

Explanation:

Step 1: Data given

The compound Cr2E3 contains 68.47 % Cr and 31.53 % E

The molar mass of Cr = 52 g/mol

⇒ 2*52 = 104 g/mol

The molar mass of Cr2E3 = 2*52 g/mol + 3X

Step 2: Calculate mass of Cr2E3

Cr is 68.47 %

Mass of Cr = 104 grams

Cr2E3 is 100%

Mass of Cr2E3 = 151.89 grams

Molar mass of Cr2E3 = 151.89 g/mol

Step 3: Calculate mass of E

Mass of E3 = mass of Cr2E3 - mass of Cr

Mass of E3 = 151.89 grams - 104 grams

Mass of E3= 47.89 grams

Mass of E = 15.96 grams

The molar mass of E = 15.96 g/mol

A certain ionic compound X has a solubility in water of 40.3 g/L at 20. degrees C. Calculate the mass X of required to prepare 500. mL of a saturated solution of X in water at this temperature. Be sure your answer has the correct unit symbol and 3 significant digits.

Answers

Answer:

20.1 g

Explanation:

The solubility indicates how much of the solute the solvent can dissolve. A solution is saturated when the solvent dissolved the maximum that it can do, so, if more solute is added, it will precipitate. The solubility varies with the temperature. Generally, it increases when the temperature increases.

So, if the solubility is 40.3 g/L, and the volume is 500 mL = 0.5 L, the mass of the solute is:

40.3 g/L = m/V

40.3 g/L = m/0.5L

m = 40.3 g/L * 0.5L

m = 20.1 g

Final answer:

The solubility value indicates how much of compound X can be dissolved in water at 20°C. Considering we need a 500 mL solution, we require half the solubility of X in grams. Therefore, to calculate the required mass of X, we multiply solubility by volume, yielding a result of 20.15 g.

Explanation:

To calculate the mass of compound X required to prepare a saturated solution of 500 mL, we first need to understand the solubility value provided. The solubility of X is given as 40.3 g/L at 20°C, meaning that 1 L of water can dissolve 40.3 g of X at this temperature.

Since we need only 500 mL (or 0.5 L) of the solution, we will require half of the solubility value in grams of X. Therefore, by simple multiplication, we get:

X mass = Solubility * Volume

= 40.3 g/L * 0.5 L = 20.15 g

So, 20.15 g of compound X is needed for a saturated solution of 500 mL at 20°C.

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Calculate the extinction coefficient where the concentration is in mg/ml and the path length is 1 cm. What dilutions of the stock are each of the prepared solutions (i.e., 1/x)?
The molecular weight of A is 290 g/mole.
Re-calculate the extinction coefficient with the concentration in mM. Note that the newly calculated extinction coefficient will contain an mM-1 term.

Answers

Complete Question

The complete question is show on the first uploaded image

Answer:

This is shown on the second,third , fourth and fifth image

Explanation:

This is shown on the second,third , fourth and fifth image

If a substance has a density of 2.82 g/mL, what will be the volume (in mL) of a 5.71 g sample

Answers

Answer: 2.02mL

Explanation:

Density = 2.82 g/mL

Mass = 5.71 g

Volume =?

Density = Mass /volume

2.82 = 5.71 / Volume

Volume = 5.71 / 2.82

Volume = 2.02mL

A nucleotide is composed of a(n) _____.

a. phosphate group,
b. a nitrogen-containing base, and
c. a hydrocarbon glycerol,

Answers

Answer : A nucleotide is composed of a phosphate group and a nitrogen-containing base.

Explanation :

Nucleotide : It is a building block of nucleic acids or we can say that it is building block of DNA and RNA.

It is composed of three sub-unit molecules which are a nitrogenous base, a five-carbon sugar and one phosphate group.

Nucleotide forms covalent bonds with other nucleotide for the formation of the nucleic acid strand.

Hence, a nucleotide is composed of a phosphate group and a nitrogen-containing base.

Final answer:

A nucleotide is composed of a a. phosphate group, a nitrogen-containing base, and a hydrocarbon glycerol.

Explanation:

A nucleotide is a fundamental building block of nucleic acids, such as DNA and RNA. It consists of three essential components: a phosphate group, a nitrogen-containing base, and a sugar molecule, not a hydrocarbon glycerol. The phosphate group provides a negatively charged backbone, linking individual nucleotides together through phosphodiester bonds, forming the nucleic acid's backbone.

The nitrogen-containing base can be adenine (A), thymine (T), cytosine (C), guanine (G) in DNA, or uracil (U) instead of thymine in RNA. The sugar molecule, deoxyribose in DNA and ribose in RNA, forms the structural framework to which the phosphate group and nitrogenous base are attached.

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On a 12 day wilderness expedition you'll need to heat 5.0kg of water to the boiling point each day. The air temperature will average 25°C. You have available canisters of compressed propane C3H8 fuel, which you'll burn to heat the water. Each canister has 25.g of propane in it. What is the minimum number of fuel canisters you must bring? The standard heat of formation of propane at 25°C is −103.85/kJmol.

Answers

Final answer:

To find the minimum number of fuel canisters needed to heat the water to boiling point, calculate the heat required to heat the water and compare it to the heat released from burning one canister of propane.

Explanation:

To find the minimum number of fuel canisters needed to heat the water to boiling point each day, we can calculate the heat required to heat 5.0kg of water from 25°C to its boiling point and compare it to the heat released from burning one canister of propane.

The heat required to heat the water is given by the equation Q = mCΔT, where m is the mass of the water, C is the specific heat capacity of water, and ΔT is the temperature change. The specific heat capacity of water is approximately 4.184 J/g°C.

We can use the equation Q = nΔH, where n is the number of moles of fuel burned and ΔH is the heat of combustion, to calculate the heat released from burning one canister of propane. The heat of combustion of propane is given as -2219.2 kJ/mol.

By equating the two equations and solving for n, we can find the number of moles of fuel burned by one canister of propane. Then, we can use the molar mass of propane (44.1 g/mol) to find the mass of propane burned by one canister. Finally, by dividing the total mass of water to be heated by the mass of propane burned by one canister, we can find the minimum number of fuel canisters needed.

By following these calculations, the minimum number of fuel canisters required to heat the water to boiling point each day will be: {number of canisters}.

Using the Bohr model, determine the energy, in joules, necessary to ionize a ground-state hydrogen atom. Show your calculations.

Answers

Answer:

The energy required to ionize the ground-state hydrogen atom is 2.18 x 10^-18 J or 13.6 eV.

Explanation:

To find the energy required to ionize ground-state hydrogen atom first we calculate the wavelength of photon required for this operation.

It is given by Bohr's Theory as:

1/λ = Rh (1/n1² - 1/n2²)

where,

λ = wavelength of photon

n1 = initial state = 1 (ground-state of hydrogen)

n2 = final state = ∞ (since, electron goes far away from atom after ionization)

Rh = Rhydberg's Constant = 1.097 x 10^7 /m

Therefore,

1/λ = (1.097 x 10^7 /m)(1/1² - 1/∞²)

λ = 9.115 x 10^-8 m = 91.15 nm

Now, for energy (E) we know that:

E = hc/λ

where,

h = Plank's Constant = 6.625 x 10^-34 J.s

c = speed of light = 3 x 10^8 m/s

Therefore,

E = (6.625 x 10^-34 J.s)(3 x 10^8 m/s)/(9.115 x 10^-8 m)

E = 2.18 x 10^-18 J

E = (2.18 x 10^-18 J)(1 eV/1.6 x 10^-19 J)

E = 13.6 eV

Consider this reaction occurring at 298 K:

N2O(g) + NO2(g) ⇆ 3 NO(g)

If a reaction mixture contains only N2O and NO2 at partial pressures of 1.0 atm each, the reaction will be spontaneous until some NO forms in the mixture.
What maximum partial pressure of NO builds up before the reaction ceases to be spontaneous?

Answers

The question is incomplete, here is the complete question:

Consider this reaction occurring at 298 K:

[tex]N_2O(g)+NO_2(g)\rightleftharpoons 3NO(g)[/tex]

If a reaction mixture contains only [tex]N_2O\text{ and }NO_2[/tex] at partial pressures of 1.0 atm each, the reaction will be spontaneous until some NO forms in the mixture.

What maximum partial pressure of NO builds up before the reaction ceases to be spontaneous. Given that: [tex]\Delta G^o_{rxn}=107.8kJ/mol[/tex]

Answer: The maximum partial pressure of NO will be [tex]5.01\times 10^{-7}atm[/tex]

Explanation:

For the given chemical equation:

[tex]N_2O(g)+NO_2(g)\rightleftharpoons 3NO(g)[/tex]

The expression of [tex]K_p[/tex] for above equation follows:

[tex]K_p=\frac{p_{NO}^3}{p_{N_2O}\times p_{NO_2}}[/tex]

When the reaction ceases to be spontaneous, the [tex]\Delta G=0[/tex] (at equilibrium)

Relation between standard Gibbs free energy and equilibrium constant follows:

[tex]\Delta G=\Delta G^o+2.303RT\log K_p[/tex]

where,

[tex]\Delta G^o[/tex] = Standard Gibbs free energy = 107.8 kJ/mol = 107800  J/mol  (Conversion factor: 1 kJ = 1000 J )

R = Gas constant = [tex]8.314J/K mol[/tex]

T = temperature = 298 K

[tex]p_{N_2O}=1.00atm[/tex]

[tex]p_{NO_2}=1.00atm[/tex]

Putting values in above equation, we get:

[tex]0=107800J/mol+(2.303\times 8.314J/Kmol)\times 298K\times \log (\frac{p_{NO}^3}{1.00\times 1.00})[/tex]

[tex]-107800=5705.85\times \log (\frac{p_{NO}^3}{1.00\times 1.00})\\\\-18.893=\log (p_{NO}^3)-\log (1.00)\\\\-18.893=3\log (p_{NO})\\\\\log (p_{NO})=-6.30\\\\p_{NO}=10^{-6.30}=5.01\times 10^{-7}atm[/tex]

Hence, the maximum partial pressure of NO will be [tex]5.01\times 10^{-7}atm[/tex]

cortisol is a steroid hormone involved in protein synthesis. what is its molecular formula

Answers

Answer:

C21H30O5

Explanation:

Cortisol with molecular formula C21H30O5 is a steroid hormone released by adrenal glands, it is involved in protein synthesis and can also help to control blood sugar level .

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