What number of atoms of phosphorus are present in 1.00g of each of the compounds in exercise 48?

Answers

Answer 1

Answer:

Explanation:

The compounds in exercise 48 are:

a) P4O6,

b) Ca3 (PO4)2, and

c) Na2 H PO4

So, proceed with the calculus for each compound.

a) Molecular formula: P4O6

Molar mass: 4 * 31 g/mol + 6* 16g/mol = 220 g/mol

Number of moles in 1.00 grams of compound = mass in grams / molar mass =

= 1.00 g / 220 g/mol = 0.004545 mol

0.004545 mol of P4O6 contains 4 * 0.004545 =  0.01818moles of atoms of P.

=> 0.01818 moles * 6.022 * 10^23 atoms / mol = 1.095 * 10^ 22 atoms of P.

Answer: 1.095 * 10^22 atoms of P.

b) Ca3 (PO4)2

molar mass = 3 * 40.1 g/mol + 2 * 31.0 g/mol + 8 * 16 g/mol = 310.3 g/mol

number of moles in 1.00 g of Ca3 (PO4)2 = 1.00 g / 310.3 g/mol = 0.00322 mol

0.00322 mol of compound * 2 mol P / mol of compound = 0.00644 mol P

0.00644 mol P * 6.022 * 10^23 atom / mol = 3.878 * 10 ^ 21 atoms P

Answer: 3.878 * 10^21 atoms P

c) Na2 H PO4

molar mass = 2 * 23.0 g/mol + 1 g/mol + 31.0 g/mol + 4 * 16g/mol = 142.0 g/mol

number of moles = 1.00 g / 142.0 g/mol = 0.0070 moles Na2HPO4

=> 0.0070 moles P

=> 0.0070 * 6.022 * 10^23 = 4.215 * 10^21 atoms of P

Answer: 4.215 * 10^21 atoms P

Answer 2

Final answer:

To determine the number of atoms of phosphorus in a compound, you need to use the molar mass and Avogadro's number. Convert the mass of the compound to moles and then multiply by Avogadro's number to get the number of atoms.

Explanation:

The number of atoms of phosphorus present in a compound can be determined using the molar mass and Avogadro's number. We need to convert the mass of the compound to moles using its molar mass, and then multiply by Avogadro's number to get the number of atoms.

For example, if we have 1.00g of phosphorus pentoxide (P2O5), we can calculate the number of atoms of phosphorus by:

Calculating the moles of P2O5 using its molar mass (141.94 g/mol) Converting the moles of P2O5 to moles of phosphorus using the ratio in the balanced equation (2 moles of P per 1 mole of P2O5) Multiplying the moles of phosphorus by Avogadro's number (6.022 x 1023 atoms/mol)

The result will be the number of atoms of phosphorus in 1.00g of P2O5.


Related Questions

A salt sample is placed into some water and nearly all of it dissolve without stirring and heating. the resulting solution is

Answers

In the concept of dissolving a soluble compound in water to form an aqueous solution, there are three types of solution: unsaturated, saturated and supersaturated/

Saturated solution is the limiting boundary among the three. This solution is made when the maximum amount of salt is added to the water. This can be manifested when you add another pinch of salt but does not dissolve even if you dissolve it. This is because it has reached its limit. Below this is the unsaturated solution where it dissolves all of the solute. Supersaturated solution is when you force the solution to dissolve the additional salt even if it saturated already. This can be possible if you heat the solution.

Therefore, since the solution still dissolves the salt without heating and even without stirring, the resulting solution is still an unsaturated solution.

_____ are soluble complement fragments that mediate localized and systemic inflammatory responses.

Answers

Anaphylatoxins are soluble complement fragments that mediate localized and systemic inflammatory responses. They are also called as complement peptides. They are produced to be a part of the complement system's activation. These are the fragments C3a, C4a and C5a which plays an important role in host defense and immune response. 

What substance is needed to reverse a condensation reaction?

Answers

Like we can use steam,300C temperature,60-70 atm and phosphoric acid which convert the ethene to alcohol which hydration reaction reverse of condensation reaction

Calculate the total pressure (in atm) of a mixture of .0200 mol of helium and .0100 mol of hydrogen in a 2.5 l flask at 10c

Answers

To determine the total pressure of the gas mixture, we need to assume that the gases are ideal so we use the equation PV = nRT where P is the pressure, V is the volume, n is the number of moles, T is the temperature of the system and R is the universal gas constant. We assume that the temperature of the system would be at 25 degrees Celsius. The pressure is calculated as follows:

PV = nRT
P = nRT / V
P = (0.02 + 0.01) (0.08205) (25 + 273.15) / 2.5
P = 0.2936 atm

Therefore, the pressure in the gas system would be 0.2936 atm

Write the empirical formula of at least four binary ionic compounds that could be formed from the following ions: ,
V+5
,
Cl−
,
O−2

Answers

Bynari means that the compound is formed by two kind of elements.

You have listed three ions, V 5+, Cl - and O 2-.

Binary ionic compounds are formed by a positive ion and a negative ion, so the possible ionic compound formed by the listed ions are:

1) VCl5, where the number 5 next to Cl is a subscript.

2) V2O5, where the number 2 next to V and the number 5 next to O are subscripts.

Subscripts are used to indicate the number of atoms of each element in the formula.

So, the empirical formula searched are VCl5 and V2O5.

I can give you other examples with more ions.

Ca (2+) and S(2-) => Ca2S2 => CaS

Na(+) and F(-) => NaF

Cs(+) and Br(-) => CsBr


A patient requires 36 mmol of phosphate and 90 meq of potassium in their pn. the pharmacy has stock solutions of potassium phosphate (3 mmol of phosphate and 4.4 meq potassium per ml) and potassium chloride (2 meq potassium/ml). how many milliliters of potassium chloride are required?

Answers

First, we need to calculate for the volume of potassium phosphate required to meet the desired phosphate level of 36 mmol.

V potassium phosphate = 36 mmol / (3 mmol / mL)

V potassium phosphate = 12 mL

This also contains potassium in the amounts of:

V potassium in potassium phosphate = (4.4 meq / mL) * 12 mL

V potassium in potassium phosphate = 52.8 meq

Therefore the lacking amount of potassium is 90 – 52.8 = 37.2 meq

This lacking potassium must be supplied by the potassium chloride. Calculating for volume of potassium chloride:

V potassium chloride = 37.2 meq / (2 meq / mL)

V potassium chloride = 18.6 mL             (ANSWER)

To meet the patient's potassium requirement, 18.6 ml of potassium chloride solution is needed after considering potassium provided by the potassium phosphate solution. The total potassium needs are 90 meq, with 52.8 meq provided by 12 ml of potassium phosphate. The remaining 37.2 meq is met by administering 18.6 ml of potassium chloride.

To determine how many milliliters of potassium chloride (KCl) are needed, we first need to calculate the total potassium (K) requirement not met by the potassium phosphate (K₃PO₄) solution.

Step-by-Step Solution:

The patient needs 90 meq of potassium (K) in total.The potassium phosphate solution provides both potassium and phosphate, with 3 mmol of phosphate and 4.4 meq of potassium per ml.We need 36 mmol of phosphate, so we calculate the required volume of potassium phosphate solution:
(36 mmol PO₄ / 3 mmol PO₄ per ml) = 12 ml of K₃PO₄ solution.This 12 ml of potassium phosphate solution provides:
(12 ml x 4.4 meq K per ml) = 52.8 meq of K.Subtract the potassium provided by the phosphate solution from the total potassium requirement:
(90 meq K - 52.8 meq K) = 37.2 meq of K required from potassium chloride.The potassium chloride solution concentration is 2 meq K per ml. Therefore, we calculate the required volume of potassium chloride solution:
(37.2 meq K / 2 meq K per ml) = 18.6 ml of KCl solution.

Thus, 18.6 ml of potassium chloride are required to meet the patient’s potassium needs.

0 ml of 0.212 m naoh is neutralized by 13.6 ml of an hcl solution. the molarity of the naoh solution is

Answers

I believe the correct volume of 0.212 M NaOH is 25.0 mL and not 0 mL.

Since the reactants are strong base and a strong acid then this is an example of neutralization reaction. The balance chemical reaction is:

NaOH + HCl ---> NaCl + H2O

We can see from the reaction above that the ratio of NaOH to HCl is 1:1. Therefore,

number of moles HCl = (0.212 mol NaOH / L) * 0.025 L * (1 mol HCl / 1 mol NaOH)

number of moles HCl = 0.0053 mol HCl

 

Molarity is number of moles divided by volume in Liters, therefore the molarity of HCl solution is:

Molarity HCl = 0.0053 mol HCl / 0.0136 L

Molarity HCl = 0.390 M

The solubility of barium chromate, bacro4, is 2.81 × 10−3 g/l. calculate the solubility product of this compound.

Answers

Solubility product constants are values to describe the saturation of ionic compounds with low solubility. A saturated solution is when there is a dynamic equilibrium between the solute dissolved, the dissociated ions, the undissolved and the compound. It is calculated from the product of the ion concentration in the solution. For barium chromate, the dissociation would  be as follows:

BaCrO4 = Ba^2+ + (CrO4)^2-

So, the expression for the solubility product would be:

Ksp = [Ba^2+] [(CrO4)^2-]

we let x = [BaCrO4] = [Ba2+] = [(CrO4)2-] = 2.81x10^-3 g/L ( 1 mol / 253.35 g ) = 1.11x10^-5

Ksp = x(x)
Ksp= x^2
Ksp = (1.11x10^-5)^2
Ksp = 1.23x10^-10

The Ksp of Barium chromate at that same temperature for the solubility would be 1.23x10^-10.

The solubility product (Ksp) of barium chromate (BaCrO₄) is approximately 1.227 × 10⁻¹⁰.

Given information,

Solubility of barium chromate = 2.81 × 10⁻³ g/l

The molar solubility (S) is the number of moles of the compound that dissolve per liter of solution.

Molar mass of BaCrO₄ = (atomic mass of Ba) + (atomic mass of Cr) + 4 (atomic mass of O)

Molar mass of BaCrO₄ = 137.33 + 51.996 + 4 × 16.00

Molar mass of BaCrO₄= 137.33 + 51.996 + 64.00

Molar mass of BaCrO₄= 253.326 g/mol

Molar solubility (S) = (mass of BaCrO₄/ molar mass of BaCrO₄)

S = (2.81 × 10⁻³)/(253.326 )

S = 1.108 × 10⁻⁵ mol/L

Since the stoichiometric coefficients of BaCrO₄ are 1 for both barium ions (Ba²⁺) and chromate ions (CrO₄²⁻), the solubility product can be calculated as:

Ksp = [Ba²⁺][CrO₄²⁻]

Ksp ≈ 1.108 × 10⁻⁵  × 1.108 × 10⁻⁵

Ksp = 1.227 × 10⁻¹⁰

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How many equivalents of pyruvate are needed to generate 1 equivalent of glucose?

Answers

Gluconeogenesis is the process by which the body produce glucose from non-carbohydrate substrates such as pyruvate. To produce glucose from pyruvate, two moleucules of pyruvate is needed. The reaction for the gluconeogenesis reaction is as follow:
2 pyruvate + 4 ATP + 2 GTP + 2 NADH = Glucose + 4 ADP + 2 GDP + 2 NAD + 6Pi. 

Potassium forms an oxide containing 1 oxygen atom for every 2 atoms of potassium. what is the coefficient of oxygen in the balanced equation for the reaction of potassium with oxygen to form this oxide?

Answers

Final answer:

The balanced equation for the reaction of potassium with oxygen to form potassium oxide is 4 K(s) + O2(g) → 2 K2O(s), so the coefficient of oxygen (O2) is 1.

Explanation:

The student is asking about the reaction of potassium with oxygen to form potassium oxide, which contains 1 oxygen atom for every 2 atoms of potassium. To balance the chemical equation for this reaction, it is important to recognize that oxygen is diatomic (O2) and potassium forms an oxide where potassium has a 1+ charge, and oxide has a 2- charge. The formula for potassium oxide using the crisscross method becomes K2O.

The balanced equation for the reaction will be:

4 K(s) + O2(g) → 2 K2O(s)

Thus, the coefficient of oxygen (O2) in the balanced equation is 1.

How many different 3d states does the hydrogen atom have?

Answers

An electron in a hydrogen atom would have 10 states for a 3d orbital, like any other element.

n = 3, l = 2, in one of ml = 2, 1, 0, -1, -2 each with ms = -½ or +½ or a total of 10 possible states.

None of these are a ground state of an electron in the hydrogen atom.

Enjoy :)

Different 3d states that does the hydrogen atom have are 10.

What are energy states of atom?

The energy state is also familiarly known as the energy level plays a vital role in explaining the atomic structure. The energy levels or the energy state is any discrete (definite) value from a set of values of total energy for a subatomic particle confined by a force to limited space or for a system of such particles, for example like an atom or a nucleus.

The energy level is an old name used with the electron orbits of the Bohr model before quantum mechanics. In the quantum mechanical treatment and because of the uncertainty principle, thus we can not have orbits and hence the term energy states are used instead, thus technically there is not much of a difference between energy levels and energy states.

An electron in a hydrogen atom would have 10 states for a 3d orbital, like any other element.

n = 3, l = 2, in one of ml = 2, 1, 0, -1, -2 each with ms = -½ or +½ or a total of 10 possible states.

None of these are a ground state of an electron in the hydrogen atom.

Therefore, Different 3d states that does the hydrogen atom have are 10.

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0 ml of a 6.0 m hno3 stock solution is diluted using water to 100 ml. how many moles of hno3 are present in the dilute solution? 25.0 ml of a 6.0 m stock solution is diluted using water to 100 ml. how many moles of are present in the dilute solution? 6.0 moles 0.6 moles 0.15 moles 1.5 moles

Answers

When you are dealing with mixtures that are non-reactive such as HNO3 or nitric acid and water, you do a process of dilution. All you did was decrease the concentration of the HNO3 solution, but it still contains the same amount of moles for the solute. In the concept of law of conservation of mass, the amount of mass or moles (if non-reactive) are additive, no more no less. The final moles would then be the original moles of solute and the added water. 

You can solve this by multiplying the concentration in molarity with the volume. Molarity is moles of solute per liter solution. Since the volume is 100 mL or 0.1 L, then

6 moles/L * 0.1 L = 0.6 moles nitric acid

[tex]\boxed{{\text{0}}{\text{.15 mol}}}[/tex] of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] is present in the dilute solution.

Further Explanation:

The proportion of substance in the mixture is called concentration. The most commonly used concentration terms are as follows:

1. Molarity (M)

2. Molality (m)

3. Mole fraction (X)

4. Parts per million (ppm)

5. Mass percent ((w/w) %)

6. Volume percent ((v/v) %)

Molarity is a concentration term that is defined as the number of moles of solute dissolved in one litre of the solution. It is denoted by M and its unit is mol/L.

The formula to calculate the molarity of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] solution is as follows:

[tex]{\text{Molarity of HN}}{{\text{O}}_3}\;{\text{solution}} = \frac{{{\text{Moles}}\;{\text{of}}\;{\text{HN}}{{\text{O}}_3}}}{{{\text{Volume }}\left( {\text{L}} \right){\text{ of}}\;{\text{HN}}{{\text{O}}_3}\;{\text{solution}}}}[/tex]            …… (1)

Rearrange equation (1) to calculate the moles of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex].

[tex]{\text{Moles}}\;{\text{of}}\;{\text{HN}}{{\text{O}}_3} = \left( {{\text{Molarity of HN}}{{\text{O}}_3}\;{\text{solution}}} \right)\left( {{\text{Volume of}}\;{\text{HN}}{{\text{O}}_3}\;{\text{solution}}} \right)[/tex]    …… (2)

The volume of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] solution is to be converted into L. The conversion factor for this is,

[tex]{\text{1 mL}} = {10^{ - 3}}\;{\text{L}}[/tex]  

So the volume of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] solution is calculated as follows:

[tex]\begin{aligned}{\text{Volume of HN}}{{\text{O}}_{\text{3}}}\;{\text{solution}}&=\left( {{\text{25 mL}}}\right)\left({\frac{{{{10}^{ - 3}}\;{\text{L}}}}{{{\text{1 mL}}}}} \right)\\&=0.02{\text{5 L}}\\\end{aligned}[/tex]

The molarity of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] solution is 6M.

The volume of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] solution is 0.025 L.

Substitute these values in equation (2).

[tex]\begin{aligned}{\text{Moles}}\;{\text{of}}\;{\text{HN}}{{\text{O}}_3}&=\left( {{\text{6 M}}} \right)\left( {0.02{\text{5 L}}} \right)\\&=0.1{\text{5 mol}} \\ \end{aligned}[/tex]

The number of moles of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] in 25 mL solution is 0.15 mol.

Dilution is the conversion of a concentrated solution into a dilute solution with the addition of extra solvent but the amount of solute is unaltered. The change that arises is an increase in the volume of the solution.

In the given solution, dilution is done and the concentration of solution decreases during the process. But the number of moles of solute remains unaltered. Therefore the number of [tex]{\text{HN}}{{\text{O}}_{\text{3}}}[/tex] in the dilute solution is also 0.15 mol.

Learn more:

1. Calculation of volume of gas: https://brainly.com/question/3636135

2. Determine the moles of water produced: https://brainly.com/question/1405182

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Concentration terms

Keywords: molarity, HNO3, dilution, moles of HNO3, volume, solution, 0.15 mol, concentration, 25 mL, 6 M, concentrated solution, dilute solution.

How much heat is released when 75 g of octane is burned completely if the enthalpy of combustion is -5,500 kJ/mol C8H18

Answers

Answer : The heat released during the reaction is [tex]-8.4\times 10^3kJ[/tex]

Explanation :

First we have to calculate the number of moles of octane [tex](C_8H_{18})[/tex].

[tex]\text{Moles of }C_8H_{18}=\frac{\text{Mass of }C_8H_{18}}{\text{Molar mass of }C_8H_{18}}[/tex]

Molar mass of [tex]C_8H_{18}[/tex] = 114 g/mole

[tex]\text{Moles of }C_8H_{18}=\frac{75g}{114g/mole}=0.658mole[/tex]

Now we have to calculate the heat released during the reaction.

[tex]\Delta H=\frac{q}{n}[/tex]

or,

[tex]q=\Delta H\times n[/tex]

where,

[tex]\Delta H[/tex] = enthalpy change = -5500 kJ/mol

q = heat released = ?

n = number of moles of [tex]C_8H_{18}[/tex] = 0.658 mol

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

[tex]q=(-5500kJ/mol)\times (0.658mol)=-8358.66kJ=-8.4\times 10^3kJ[/tex]

Therefore, the heat released during the reaction is [tex]-8.4\times 10^3kJ[/tex]

The quantity of heat released when the octane is burned completely is -3,613.5 Joules.

Given the following data:

Mass of octane = 75 gramsEnthalpy of combustion = -5,500 kJ/mol

To find the quantity of heat released when the octane is burned completely:

First of all, we would determine the number of moles of octane in this chemical reaction.

[tex]Number\;of\;moles \;(C_8H_{18})= \frac{Mass\; of\;octane}{Molar\;mass\;of\;octane}[/tex]

Substituting the values into the formula, we have;

[tex]Number\;of\;moles \;(C_8H_{18})= \frac{75}{114.23}[/tex]

Number of moles ([tex]C_8H_{18}[/tex]) = 0.657 moles.

Now, we can find the quantity of heat released when the octane is burned completely:

1 mole of octane = -5,500 kJ/mol

0.657 mole of octane = X kJ/mol

Cross-multiplying, we have:

[tex]X = -5500[/tex] × [tex]0.657[/tex]

X = -3,613.5 Joules.

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Tina conducted an experiment to test her hypothesis. Her hypothesis was that by crushing aspirin and putting it into potting soil increases the growth rate of tomato plants. The results of the experiment show that there was no significant difference in the growth rates between the control and the experimental groups. What should Tina do with the results of this experiment?

Answers

run the test atleast 3 times and then determin the outcome of the expiriment 

A 92.0 ml volume of 0.25 m hbr is titrated with 0.50 m koh. calculate the ph after addition of 46.0 ml of koh at 25 ∘c.

Answers

In neutralization reactions, a base and an acid react to form an ionic salt and water. There is a rule that when a strong base and a strong acid react, the pH of their salt is always neutral which is at pH 7. However, this is only true if equal amounts of acid and base are consumed and that there is no excess. Otherwise, the excess acidity or basicity will adjust the total pH.

Strong acids are the following: HCl, HBr, HI, HClO4, HClO3, HNO3 and H2SO4. Strong bases are KOH, LiOH, NaOH, Ca(OH)2, Sr(OH)2 and Ba(OH)2. Therefore, we can already establish that both of the reactants are strong. The complete reaction is

HBr + KOH ⇒ KBr + H₂O

So, 1 mole of HBr would require 1 mol of KOH, and vice versa. Let'scompute the amount of the initial reactants:

mol HBr: (0.25 mol/L)*(0.92 L) = 0.23 mol HBr
mol KOH: (0.5 mol/L)*(0.46 L) = 0.23 mol KOH

There are equal amounts of acid and base. Thus, pH of the KBr solution is neutral at pH 7.

After adding 46.0 mL of 0.50 M KOH to 92.0 mL of 0.25 M HBr, the solution is neutral and has a pH of approximately 7.

To determine the pH of the solution when 46.0 mL of 0.50 M KOH is added to 92.0 mL of 0.25 M HBr at 25°C, follow these steps:

Calculate the moles of HBr and KOH:

Moles of HBr: 0.25 M × 0.092 L = 0.023 moles

Moles of KOH: 0.50 M × 0.046 L = 0.023 moles

Determine the reaction completeness:

KOH completely neutralizes an equivalent amount of HBr (1:1 ratio):

0.023 moles of HBr neutralized by 0.023 moles of KOH.

Calculate the pH:

After the neutralization, there are no excess moles of acid (H+) or base (OH-), resulting in neutral pH.

The pH of the resulting solution is therefore approximately 7.

In summary, after adding 46.0 mL of 0.50 M KOH to 92.0 mL of 0.25 M HBr, the solution is neutral, with a pH of approximately 7

Give the set of four quantum numbers that could represent the electron lost to form the k ion from the k atom

Answers

Final answer:

The electron lost to form a potassium ion from a potassium atom is from the 4s orbital. Its set of quantum numbers, which describe its state, are (4,0,0,±1/2).

Explanation:

The electron lost to form the potassium (K) ion from the K atom would be the electron in the highest energy level, or the outermost shell, of the atom. This shell, also called the valence shell, contains only one electron for Potassium. This electron can be characterized by its four quantum numbers: the principal quantum number (n), the azimuthal quantum number (l), the magnetic quantum number (m), and the spin quantum number (ms).

For potassium, this electron resides in the 4s orbital. So the set of quantum numbers for this electron would be: n=4 (fourth energy level), l=0 (s orbital), m=0 (orientation of the orbital), and ms=±1/2 (two possible spin states). Thus, the set of quantum numbers for the electron lost to form the K ion from the K atom is (4,0,0,±1/2).

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In a controlled experiment, the factor tested is called the A. constant. B. independent variable. C. dependent variable. D. control.

Answers

C. Dependent Variable

In a controlled experiment, the factor tested is called the [tex]\boxed{{\text{B}}{\text{. independent variable}}}[/tex].

Further Explanation:

A procedure that is performed in order to support, disprove or validate a hypothesis is known as an experiment. A hypothesis is an idea or thought that needs to be tested with the help of experiments.

Types of experiments:

1. Controlled experiments

The type of experiment that is used for comparing the results of experimental samples with the control samples is called a controlled experiment. Such experiments involve a drug trial. The experimental group will be the one that receives the drug and the other one receiving regular treatment will be the controlled group. The experimental group is also known as the treatment group. Another example of controlled experiments is the protein assay.

2. Natural experiments

These are also called quasi-experiments. These are performed by exposing individuals to the conditions that are governed by nature. Experiments involving weather changes and natural disasters are examples of natural experiments.

3. Field experiments

These are quite different from the experiments performed in the laboratory. Such experiments are usually performed in social studies. These have higher external validity as compared to normal lab experiments. Economic analysis of health and education are some examples of such experiments.

The variable that can be changed by the investigator is called the independent variable while the variable is the one that is affected by the changes in experimental conditions. All the variables in a controlled experiment are kept constant; except for the factor that is to be tested. Such a factor is called the independent variable or the experimental variable.

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Answer Details:

Grade: Senior School

Chapter: Keys to studying chemistry

Subject: Chemistry

Keywords: experiment, hypothesis, controlled experiment, natural experiment, field experiments, dependent variable, independent variable, quasi-experiments.

A volume of 90.0 ml of aqueous potassium hydroxide (koh) was titrated against a standard solution of sulfuric acid (h2so4). what was the molarity of the koh solution if 13.7 ml of 1.50 m h2so4 was needed? the equation is

Answers

2KOH + H₂SO₄ → K₂SO₄ + 2H₂O

v₁=90.0 mL
c₁-?
v₂=13.7 mL
c₂=1.50 mol/L=1.50 mmol/mL

n(KOH)=v₁c₁
n(H₂SO₄)=v₂c₂
n(KOH)=2n(H₂SO₄)

v₁c₁=2v₂c₂

c₁=2v₂c₂/v₁

c₁=2*13.7*1.50/90.0=0.457 mol/L

0.457 M KOH

Henry's law of partial pressures states that when a gas is in contact with a liquid, that gas will dissolve in the liquid in proportion to its partial pressure. henry's law of partial pressures states that when a gas is in contact with a liquid, that gas will dissolve in the liquid in proportion to its partial pressure.
a. True
b. False

Answers

True! Though simplified:
Henry's law is one of the gas laws and was formulated by the British chemist, William Henry, in 1803. It states that: At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

3cu(s) + 8hno3(aq) ——> 3cu(no3)2(aq) + 2no(g) + h2o(l) whichr eactan is the reducing agent?

Answers

...0.............I..V.-II..............II...V.-II...........II..-II.......I...-II
3Cu(s) + 8HNO3 ---> 3Cu(NO3)2 + 2NO + 4H2O

V.....................II
N + 3e -----> N >> reduction
HNO3 - oxidizing agent

..0...........II
Cu ----> Cu + 2e >> oxidation
Cu - reducing agent

Answer:

I think it’s CU

Explanation:

explain the idea that the greek philosopher democritus proposed

Answers

Democritus was a Greek philosopher who studied natural phenomena and concluded together with his mentor, that all matter is made up of tiny particles he called atoms. The basic tenets of this theory are that atoms are invisible, indestructible, are homogeneous, are solid and differ in shape, mass, size arrangement and postion.

Final answer:

Democritus, a Greek philosopher, proposed the idea of atomos or atomon - tiny, indivisible, solid objects - as the building blocks of all matter in the universe. His atomic theory challenged the prevailing belief of the time and laid the foundation for modern understanding of matter.

Explanation:

About 2,500 years ago, Democritus, a Greek philosopher, proposed the idea that all matter in the universe is made up of tiny, indivisible, solid units called atomos or atomon. He believed that these atoms were the building blocks of all substances and that they cannot be further divided. This theory challenged the prevailing belief of the time that the universe was a single, unchangeable entity. Democritus' atomic theory laid the foundation for modern understanding of matter and influenced later scientists such as John Dalton and Albert Einstein.

Consider the redox reaction below.

2Al(s) + 6HCl(aq) ----> 2AlCl3(aq) + 3H2(g)

Which statement correctly describes a half-reaction that is taking place?

A) Hydrogen is oxidized from +1 to 0.
B) Chlorine is reduced from –1 to 0.
C) Aluminum is oxidized from 0 to +3.
D) Hydrogen is reduced from 0 to –1.

Answers

Answer:

The right answer is C.

Oxidation is the loss of electrons. A loss of electrons will appear as an increase in the positive charge of the element as it is converted to an ion. Here we have aluminum have an oxidation state equals zero as a reactant because it is in the element state. After reacting, it combines with three atoms chlorine where each chlorine atom usually has an oxidation state equals -1, therefore, we have -3 charges which have to be neutralized with the 3+ charges of aluminum.

The statement which correctly describe a half-reaction is option C, i.e., Al is oxidized from 0 to +3. At elemental stage as Al, it possess no charge but, when combined with an electronegative atom aluminum gets positively charged.

What is a redox reaction ?

A redox reaction is the combination of oxidation and reduction reaction. Oxidation is the losing electrons and gets into higher oxidation state whereas, reduction is just the opposite where, one species reduces to its lower oxidation state.

All species in their elemental state carries no charge and thus assume an oxidation state of 0. Thus  Al and H₂ have no charge. Hydrogen is in +1 oxidation state in HCl and Al is in +3 oxidation state in AlCl₃ since, Cl has a negative charge hence, 3 Cl possess 3 unit of negative charge.

In the overall reaction, Al is thus oxidised from 0 to +3 oxidation state, whereas, H is reduced from +1 to 0. Hence, option A is correct.

To learn more about redox reactions, please refer the below link:

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One of the most common causes of inaccurate melting points is too rapid heating of the melting point bath. under these circumstances, how ill the observed melting point compare to the true melting point.

Answers

the observed melting point will be higher than the true point

How many moles of NaCl are required to prepare 0.80 L of 6.4 M NaCl

Answers

Hey there! 

Solution :

Volume of solution = 0.80 L

Molarity of solution = 6.4 M

Therefore :

n = M * V

n = 6.4 * 0.80

n = 5.12 moles of NaCl

hope this helps!

1. Which processes are taking place in the system represented by the following equation?
2CO(g) + O2(g) →← 2CO2(g)

2. Consider the reaction represented by the equation 2HI(g) →← H2(g) + I2(g). At a temperature of 520 °C, the equilibrium concentration of HI is 0.80 M, of H2 is 0.010 M, and of I2 is 0.010 M. What is the K for the reaction?

Answers

Final answer:

The equilibrium constant indicates the ratio of product and reactant concentrations at equilibrium. The processes in the first equation involve the formation and decomposition of gases. The K value for the second equation is calculated using given equilibrium concentrations.

Explanation:

The equilibrium constant (K) for a chemical reaction indicates the ratio of the concentrations of the products to the concentrations of the reactants at equilibrium. In the first equation, 2CO(g) + O2(g) → 2CO2(g), the forward reaction is the formation of CO2 from CO(g) and O2(g), while the reverse reaction is the decomposition of CO2(g) into CO(g) and O2(g).

To find the value of K for the reaction 2HI(g) → H2(g) + I2(g), we need to use the given equilibrium concentrations. Using the equation K = [H2][I2]/[HI]^2, we plug in the values to get K = (0.010)(0.010)/(0.80)^2 = 0.00015625.

Final answer:

The reaction represented by the equation 2CO(g) + O2(g) ↔ 2CO2(g) involves the formation and decomposition of carbon dioxide. The equilibrium constant (K) for the reaction 2HI(g) ↔ H2(g) + I2(g) at 520°C is 0.00015625.

Explanation:

The reaction represented by the equation 2CO(g) + O2(g) ↔ 2CO2(g) is an equilibrium reaction. It involves two processes: the formation of carbon dioxide from carbon monoxide and oxygen, and the reverse process where carbon dioxide decomposes to form carbon monoxide and oxygen.

At a temperature of 520°C, we are given the equilibrium concentrations of HI (0.80 M), H2 (0.010 M), and I2 (0.010 M). To find the equilibrium constant (K) for the reaction, we can use the formula:

K = [H2][I2]/[tex][HI]^2[/tex]

Substituting the given concentrations into the formula:

K = (0.010)(0.010)/[tex](0.80)^2[/tex] = 0.00015625

Zinc reacts with hydrochloric acid according to this reaction: Zn(s) + 2HCl (aq) → ZnCl2(aq) + H2(g) Which of the following will react the fastest? a. 2.0 gram lump of zinc in 0.10 M hydrochloric acid b. 2.0 gram sample of powdered zinc in 0.10 M hydrochloric acid c. 2.0 gram lump of zinc in 0.50 M hydrochloric acid d. 2.0 gram sample of powdered zinc in 0.50 M hydrochloric acid

Answers

To evaluate which system would be able to react faster, we look at the factor that could affect the reaction rate of the reaction of zinc and hydrochloric acid. First, we look at the concentrations or the amounts of the reactants. More reactant would mean that reaction rate is higher since collisions of the reactant molecules are likely to happen. We can disregard the amount of zinc since all choices have equal amount of zinc. Looking at the concentration of the hydrochloric acid, we have 0.10 M and 0.50 M. The latter would likely to have higher rate of reaction. Next, we look at the surface areas of the reactants. We neglect the effect of hydrochloric acid since they are all aqueous solution. Greater surface area would lead to higher rate since it would encourage more collisions. Powdered samples would have greater surface areas than lump samples. From the choices, most likely it would be 2.0 gram sample of powdered zinc in 0.50 M hydrochloric acid would have the higher reaction rate. Therefore, the answer is option D.

Final answer:

The fastest reaction will be option d: a 2.0 gram sample of powdered zinc in 0.50 M hydrochloric acid, due to the greater surface area of the powdered zinc and the higher concentration of the acid.

Explanation:

When zinc metal is submerged into aqueous hydrochloric acid, a chemical reaction occurs that produces zinc chloride and hydrogen gas. The balanced equation for this reaction is:

Zn(s) + 2HCl(aq) → H₂(g) + ZnCl₂(aq)

This reaction is faster when the surface area of the zinc is increased and the concentration of hydrochloric acid is higher. Thus, option d, a 2.0 gram sample of powdered zinc in 0.50 M hydrochloric acid, will react the fastest because the powdered form of zinc has a larger surface area than a lump, allowing more acid to react with it at the same time. Additionally, a higher concentration of hydrochloric acid, such as 0.50 M compared to 0.10 M, will provide more acid particles in the solution to react with the zinc, thus speeding up the reaction.

The system that shows a decrease in entropy (disorder) is

Answers

There is no definite definition of entropy. In books, entropy is usually introduced through differential equations relating enthalpy and Gibb's free energy. However, that is an advanced explanation. For simplicity, entropy is the state of disorder. So, when the system shows a decrease in entropy, the system's molecules gets in order. For example, freezing water puts it in order because liquid water molecules are compacted into solid crystals. In relation, for a decrease in entropy, the reaction is more non-spontaneous.

Answer: water freezing.

Explanation:

If we dissolve 25 grams of salt in 251 grams of water, what is the mass of the resulting solution?

Answers

If we dissolve 25 grams of salt in 251 grams of water, then the mass of the resulting solution would be 276 grams. This is in accordance to the Law of Conservation of mass which states that mass cannot be created or destroyed. So, the total mass that goes in a certain process should be the same that would would go out the process. In this case, we have two streams that goes in and one stream going out which would be the solution. The two streams going in should be equal to the stream going out.

Overall mass balance:
25 grams salt + 251 grams water = mass of solution
mass of solution = 276 grams

Determine the number of atoms in 1.85 ml of mercury. (the density of mercury is 13.5 g/ml.)

Answers

First step is to get the mass of the mercury:
Pressure = mass/volume
mass = pressure x volume = 13.5 x 1.85 = 24.975 gm

Second step is to calculate the number of moles in 24.975 gm:
From the periodic table, the molar mass of mercury is 200.59
mass = number of moles x molar mass
number of moles = 24.975 / 200.59 = 0.1245 mole

Last step is to get the number of atoms:
Each mole contains 6.02 x 10^23 atoms
number of atoms = 0.1245 x 6.02 x 10^23 = 7.4949 x 10^22 atoms
Final answer:

To determine the number of atoms in 1.85 ml of mercury, convert the volume to mass using the density of mercury. Then, calculate the number of moles of mercury using its atomic mass. Finally, use Avogadro's number to calculate the number of atoms in the given amount of mercury.

Explanation:

To determine the number of atoms in 1.85 ml of mercury, we need to convert the volume to mass using the density of mercury. The density of mercury is 13.5 g/ml. So, the mass of 1.85 ml of mercury is 1.85 ml x 13.5 g/ml = 24.975 g.

Next, we need to calculate the number of moles of mercury using its atomic mass. The atomic mass of mercury is 200.59 g/mol. To find the number of moles, we divide the mass (in grams) by the molar mass: 24.975 g / 200.59 g/mol = 0.1245 mol.

Finally, we can calculate the number of atoms in 0.1245 mol of mercury. Avogadro's number tells us that there are 6.022 x 10^23 atoms in 1 mol of any substance. So, the number of atoms in 0.1245 mol of mercury is 0.1245 mol x 6.022 x 10^23 atoms/mol = 7.49 x 10^22 atoms.

Which of the following is not a correct chemical equation for a double replacement reaction?
2 HNO3 + Mg(OH)2 yields 2 H2O + Mg(NO3)2
H3PO4 + 3 NaF yields 3 HF + Na3PO4
2 KNO2 + BaSO4 yields K2SO4 + Ba(NO2)2
Ca + 2H2O yields Ca(OH)2 + H2

Answers

Ca + 2H2O --> CA(OH)2+H2
it is not a double displacement reaction.
because only Hydrogen is displaced.
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