Answers
2.g
3.e
4.f
5.h
6.d
7.c
8.a
Related Questions
What is the molarity of a 1.50 L solution containing 14 g of HCl
Answers
Molar mass HCl = 1 + 35.5 => 36.5 g/mol
* Number of moles :
n = m / mm
n = 14 / 36.5
n = 0.383 moles of HCl
Therefore :
M = n / V
M = 0.383 / 1.50
= 0.255 M
hope this helps!
Calculate the energy difference for a transition in the paschen series for a transition from the higher energy shell n=4. express your answer to four significant figures and include the appropriate units.
Answers
The energy difference for a transition in the Paschen series from the higher energy shell n=4 is approximately 13.6 eV.
Explanation:The energy difference for a transition in the Paschen series can be calculated using the equation:
AE = E1 - E2 = 2.179 × 10-18 J
To express the answer in eV, we can use the conversion factor: 1 eV = 1.6022 × 10-19 J
Therefore, the energy difference for the transition in the Paschen series from the higher energy shell n=4 is approximately 13.6 eV.
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For hydrogen, what is the wavelength of the photon emitted when an electron drops from a 4p orbital to a 2s orbital in a hydrogen atom?
Answers
When electrons transfer from orbital to orbital, they may release (high to low) or absorb (low to high) energy in the form of light which can be measuredin wavelength. The formula to be used is Rydberg's formula:
1/λ = R(1/n₁² - 1/n₂²), where
λ is wavelength measured in meters
n₁ and n₂ are the energy levels such that n₂>n₁
R is the Rydberg constant equal to 1.097×10⁷ m⁻¹
1/λ =1.097×10⁷ m⁻¹ (1/2² - 1/4²)
λ = 4.86×10⁻⁷ or 4.86 pm
What is true about the solution process involved in an instant cold pack?
The process is endothermic and has a negative enthalpy of solution.
The process is exothermic and has a negative enthalpy of solution.
The process is endothermic and has a positive enthalpy of solution.
The process is exothermic and has a positive enthalpy of solution.
Answers
Answer:
c
Explanation:
Which describes the volume of 1 mol of gas at standard temperature and pressure? The volume is greater for a larger mass of gas.
The volume is the same for any gas.
The volume depends on the size of the container.
The volume varies with the pressure.
Answers
PV = nRT
V = nRT / P
V = (1 mol ) (0.08205 L-atm / mol K) (273.15 K ) / 1 atm
V = 22.4 L
Determine whether or not each mixture is a buffer. check all that apply. check all that apply. koh and nh3 hbr and nacl hcl and hbr hcho2 and nacho2
Answers
- a weak base combined with its conjugate acid, or
- a weak acid combined with its conjugate base
Now, examining each of the choices:
1- KOH and NH3: since they are both bases, thus this mixture is not a buffer
2- HBr and NaCl: since HBr is a strong acid while NaCl is the salt of another different acid, thus this mixture is not a buffer
3- HCl and HBr: these are both considered to be strong acid, thus this mixture is not a buffer
4- HCHO2 and NaCHO2: as for HCH02, it is considered a weak base while NaCHO2 is considered its conjugate base, thus this mixture is a buffer
HCHO2 and NaCHO2, and CH3NH2 and CH3NH3Cl can make buffer solutions. HCl and NaCl, and NH3 and NaOH cannot make buffer solutions.
Explanation:1. HCHO2 is formic acid, a weak acid, while NaCHO2 is the salt made from the anion of the weak acid (the formate ion [CHO2]). The combination of these two solutes would make a buffer solution.
2. HCl is a strong acid, not a weak acid, so the combination of these two solutes would not make a buffer solution.
3. CH3NH2 is methylamine, which is like NH3 with one of its H atoms substituted with a CH3 group. Because it is not listed in Table 12.8.1, we can assume that it is a weak base. The compound CH3NH3Cl is a salt made from that weak base, so the combination of these two solutes would make a buffer solution.
4. NH3 is a weak base, but NaOH is a strong base. The combination of these two solutes would not make a buffer solution.
What is the Celsius temperature of 1 mole of a gas that has an average kinetic energy of 4,265 joules?
69°C
96°C
369°C
435°C
Answers
Answer:
Explanation:
Kinetic energy is the energy possessed by an object by virtue of its motion.
Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is determined by the equation:
[tex]K=\frac{3nRT}{2}[/tex]
K= kinetic energy
n= number of moles
R= gas constant
T= temperature
[tex]4265J=\frac{3\times 1\times\times 8.314\times T}{2}[/tex]
[tex]T=342K[/tex]
[tex]tK=(t-273)^0C[/tex]
[tex]T=342K=(342-273)^0C=69^0C[/tex]
Thus temperature will be [tex]69^0C[/tex]
If 4.0 g of hydrogen and 10.0 g of oxygen are mixed according to the equation 2 h2 + o2 → 2 h2o, which is the limiting reagent?
Answers
2 : 1
Next, we determine the moles of hydrogen and oxygen that are actually present using:
moles = mass / Mr
Hydrogen:
moles = 4 / 2 = 2
Oxygen:
10/32 = 0.3125
Therefore, it is evident that the moles of oxygen present, 0.3125, are less than those that are required for 2 moles of hydrogen, which is 1. This makes oxygen the limiting reactant, which is the one that limits the completion of a reaction.
Final answer:
To find the limiting reagent between hydrogen and oxygen, we convert their masses to moles and use the stoichiometry of the balanced chemical reaction 2 H2 + O2 → 2 H2O. Oxygen is the limiting reagent because there are not enough moles of O2 to fully react with the available moles of H2.
Explanation:
To determine the limiting reagent when 4.0 g of hydrogen (H2) and 10.0 g of oxygen (O2) are mixed to react according to the equation 2 H2 + O2 → 2 H2O, we need to perform mass-mole calculations for both reactants and compare the stoichiometry of the balanced equation.
First, convert the mass of each reactant to moles:
For H2: Molecular weight is approximately 2.02 g/mol. Thus, 4.0 g H2 ÷ 2.02 g/mol = 1.98 moles of H2.
For O2: Molecular weight is approximately 32.00 g/mol. Thus, 10.0 g O2 ÷ 32.00 g/mol = 0.3125 moles of O2.
According to the balanced equation, 2 moles of H2 react with 1 mole of O2. Therefore, to fully react with 1.98 moles of H2, we would need 0.99 moles of O2. However, we only have 0.3125 moles of O2, which is insufficient to react with all the H2. Therefore, O2 is the limiting reagent.
How many kPa are in 2,150 mmHg?
2.83 kPa
287 kPa
1.61 ´* 104 kPa
2.18 ´* 105 kPa
Answers
2150 mmHg ( 1 atm / 760 mmHg ) ( 101.325 kPa / 1 atm ) = 286.643 kPa
Therefore, the closest value from the choices is the second one which has the value of 287, this would be answer.
To convert 2,150 mmHg to kPa, divide by the conversion factor 7.5 mmHg, resulting in approximately 286 kPa.
Explanation:A conversion factor is a mathematical ratio that allows you to convert from one unit of measurement to another. It is often used to change units within the same system (e.g., converting inches to centimeters) or between different systems (e.g., converting miles to kilometers) by multiplying or dividing by the appropriate factor.
To convert from millimetres of mercury (mmHg) to kilopascals (kPa), you can use the conversion factor:
1 kPa = 7.5 mmHg
First, divide 2,150 mmHg by the conversion factor:
= 2,150 mmHg / 7.5 mmHg
= 286.67 kPa
Rounding to the nearest hundredth, the answer is approximately 286 kPa.
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To sterilize a 50.0-g glass baby bottle, we must raise its temperature from 22.0ºc to 95.0ºc . how much heat transfer is required?
Answers
Heat absorbed = Heat to be supplied = Heat transferred m C (T2 - T1)
Heat transferred = 50.0 g (0.84 J/ g C) (95 C - 22 C) = 3066 J
Calculate the total percentage of oxygen in magnesium nitrate crystals, Mg(NO3)2.6H2O
Answers
soaps feel slippery on our hands because they dissolve the oil on our skin, decreasing friction. this is because soap contains
Answers
Soaps are made by the process saponification. Soaps contains long chain fatty acids and glycerol. The oily nature of soaps are due the presence of fatty acids.
What is saponification?Saponification is the process, making of soaps from glycerol and fatty acids. Therea are different types of soaps based on the ionic nature of the long chain fatty acids.
There are alkaline soaps in which the acidic chain possess a negatively charged group and acidic soaps are those bearing positively charged ions. The nature of sopas can be varied as per the use also.
Fatty acids are long chain hydrocarbons formed by the combination of simple hydrocarbons and they will reacts easily with alcohols forming esters of fatty acids that are soaps.
Hence, the presence of fatty acids make the soaps oily in nature and move gains friction in our hand.
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1. When an ionic bond forms between magnesium (Mg) and bromine (Br), which of the following occurs?
A. Mg loses one electron.
B. Mg loses two electrons.
C. Mg gains two electrons.
D. Mg and Br share electrons.
2. Which of the following must occur in order for an ionic bond to form?
A. Two ions must be close enough to each other to share electrons.
B. Uncharged atoms must remain electrically neutral and combine.
C. Two ions must belong to the same group to be attracted to each other.
D. An atom that gains electrons must be attracted to an atom that loses electrons.
Answers
The correct answers are:
1. B. Mg loses two electrons.
When Mg and Br combine, 2 atoms of Br attaches itself to Mg. The chemical reaction is:
Mg + Br ---> MgBr2
Since Br is more electronegative than Mg, then Mg loses an electron per Br therefore losing 2 electrons.
2. D. An atom that gains electrons must be attracted to an atom that loses electrons.
An ionic bond is formed when one molecule is more electronegative than the other molecule which results in gaining and losing of electrons. The more electronegative molecule gains electron while the less electronegative loses electron.
In the formation of an ionic bond between magnesium and bromine, magnesium loses two electrons to become a Mg₂ + ion, and these oppositely charged ions attract each other to form the bond.
Explanation:Understanding Ionic Bonds between Magnesium and Bromine:
1. When an ionic bond forms between magnesium (Mg) and bromine (Br), the process involves a transfer of electrons. Specifically, Mg loses two electrons (Option B) to achieve a stable electron configuration similar to the nearest noble gas. As a result, magnesium becomes a Mg₂+ ion.
2. For an ionic bond to form, there must be a transfer of electrons from one atom to another, leading to the formation of ions with opposite charges, which are then attracted to each other (Option D). An atom with a lower electronegativity, like magnesium, will lose electrons and become a positively charged cation. Conversely, an atom with higher electronegativity will gain electrons and become a negatively charged anion, such as bromine becoming Br-.
What formula can be used to calculate [H30+]?
A. [H3O+] = log(OH-)
B. [H3O+] = 1 x 10 [-OH-]
C. [H3O+] = antilog(–pH)
D. [H3O+] = [H3O+][ OH-]
Answers
pH = -log [H3O+]
-pH = log [H3O+]
10^-pH = 10^log [H3O+]
10^-pH = [H3O+]
where 10^x is the same as antilog of x.
[H3O+] = antilog (-pH)
The principal ingredient of glass is ______________________.
Answers
In aqueous solution, globules of up to several thousand amphiphilic molecules arranged with the hydrophilic groups on the surface and the hydrophobic groups buried in the center are called _____.
Answers
CH4(g) + H2O(g) mc004-1.jpg CO(g) + 3H2(g) What will happen to the equilibrium of this reaction if CO is added to the system?
Answers
How does electronegativity cause the polarity in water and, ultimately, enable water to form hydrogen bonds between other water molecules?
Answers
So . . .
When the two form covalent bonds, oxygen pulls the electrons closer and farther from hydrogen
So . . .
The water molecule is polar, with oxygen more negative and hydrogen more positive.
So . . .
Since opposites attract, the more negative oxygens attract the more positive hydrogens of other water molecules, forming the hydrogen bonds.
Electronegativity in water creates partial charges, causing polarity. This polarity allows hydrogen bonding between water molecules, enhancing interactions.
In a water molecule (H₂O), oxygen is more electronegative than hydrogen. This means that oxygen attracts the shared electrons in the O-H bonds more strongly than hydrogen does.
As a result, the electrons spend more time closer to the oxygen atom, giving it a partial negative charge (δ−), while the hydrogen atoms acquire a partial positive charge (δ+). This uneven distribution of charge creates a dipole moment, making water a polar molecule.
The polarity of water molecules causes them to be attracted to each other. The partial positive charge of one water molecule is attracted to the partial negative charge of another, forming hydrogen bonds.
These bonds are relatively weak compared to covalent bonds but are crucial for water’s unique properties, such as its high boiling point and surface tension.
Rank these compounds by highest boiling point to lowest boiling point? Pentane, neopentane, isopentane
Answers
The compounds ranked by boiling point from highest to lowest are: Pentane > Isopentane > Neopentane.
The boiling point of a compound is influenced by its intermolecular forces.
Compounds with stronger intermolecular forces tend to have higher boiling points because more energy is required to overcome those forces and convert the substance from a liquid to a gas.
Generally, the strength of intermolecular forces increases with increasing molecular size and surface area.
Pentane is a linear hydrocarbon with five carbon atoms in a row. It has the highest boiling point among the three compounds because it has the greatest molecular size and surface area.
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The light intensity of a source is 100 candelas. The illuminance on a surface is 4 lux. How far is the surface from the source?
A. 7 meters
B. 6 meters
C. 4 meters
D. 5 meters
Answers
To find the luminous intensity this formula is used;
Luminous intensity = illuminance × [tex]radius ^{2}[/tex]
∴ Lv = Ev × [tex] r^{2}[/tex]
We know the luminous intensity is 100 candelas and the illuminance is 4 lux.
∴ 100 = 4 x [tex] r^{2}[/tex]
∴ 100/4 = [tex] r^{2}[/tex]
∴ 25 = [tex] r^{2}[/tex]
∴ r =√25 = 5 meters
Therefore, the surface will be at a distance of 5 meters from the source.
A technician has been given 250 ml of 15% acetic acid solution. the pharmacist has asked the tech to dilute the solution to 500 ml with sterile water and to label the solution. what percentage should appear on the label
Answers
The problem is about diluting a 15% acetic acid solution to a larger volume. After diluting the solution from 250 ml to 500 ml, the new percentage concentration of the acetic acid solution is 7.5%. Hence, the label should read 7.5% acetic acid.
Explanation:The problem you presented is a typical one in chemistry, which involves the concept of percentage concentration and dilutions. Initially, we have 250 ml of a 15% acetic acid solution. The amount of acetic acid in the solution is therefore 0.15 * 250 = 37.5 g.
The technician adds enough water to the solution to make the total volume 500 ml. However, the amount of acetic acid doesn't change; it remains 37.5g. To find the new percentage of the acetic acid solution, we take the total mass of the acetic acid (37.5g) and divide it by the total volume of the solution (500 ml), then multiply by 100% to get the percentage:
(37.5g / 500ml) * 100% = 7.5%.
So, the label on the solution should say 7.5% acetic acid.
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The central atom in the clf4 ion has ________ nonbonded electron pair(s) and ________ bonded electron pair(s) in its valence shell.
Answers
The central atom in the ClF4 ion has three nonbonded electron pairs and one bonded electron pair in its valence shell.
Explanation:The central atom in the ClF4 ion has three nonbonded electron pairs and one bonded electron pair in its valence shell. The Cl atom has a total of seven valence electrons and forms four covalent bonds with the four fluorine atoms. This leaves three lone pairs of electrons around the central Cl atom, which are not involved in bonding.
An acid has an acid dissociation constant of 2.8x10^-9. What is the base dissociation constant of its conjugate base?
2.8x 10^-23
3.6x10^-6
2.8x10^5
3.6 x10^22
Answers
pH=-lg(2.8×10⁻⁹)=8.553
pOH=14-pH
pOH=14-8.553=5.447
[OH⁻]=10^(-pOH)
[OH⁻]=10⁻⁵·⁴⁴⁷=3.6×10⁻⁶
Answer: The correct answer is [tex]3.6\times 10^{-6}[/tex]
Explanation:
We are given:
Acid dissociation constant [tex](k_a)=2.8\times 10^{-9}[/tex]
Water dissociation constant [tex](k_w)=1\times 10^{-14}[/tex]
To calculate the base dissociation constant for the conjugate base, we use the equation:
[tex]k_w=k_a\times k_b[/tex]
where,
[tex]k_b[/tex] = base dissociation constant
Putting values in above equation, we get:
[tex]10^{-14}=2.8\times 10^-9}\times k_b\\\\k_b=3.6\times 10^{-6}[/tex]
Hence, the correct answer is [tex]3.6\times 10^{-6}[/tex]
If a large leak of refrigerant occurs such as from a filled cylinder in an enclosed area what action should be taken when no self-contained breathing apparatus is available?
Answers
If a large leak of refrigerant occurs in an enclosed area and no self-contained breathing apparatus is available, the immediate action should be to evacuate the area to fresh air, shut off the source of the leak if possible, and seek medical attention if experiencing symptoms.
Explanation:If a large leak of refrigerant occurs in an enclosed area and no self-contained breathing apparatus is available, there are several actions that should be taken to ensure safety:
Immediately evacuate the area to fresh air.If possible, shut off the source of the leak and prevent any additional release of refrigerant.Seek medical attention if experiencing any symptoms, such as difficulty breathing or irritation of the eyes, throat, or skin.It is important to prioritize personal safety and seek professional assistance when encountering such incidents.
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How many subshells are there in the shell with n = 6?
Answers
"l" is given values from zero till (n-1)
So, for n=6
l is given the following values: 0,1,2,3,4,5
Counting the number of subshells, we will find that the shell with n=6 has 6 subshells
Answer:
5 subshells
Explanation:
What would be the formula of the precipitate that forms when pb(no3)2 (aq) and k2so4 (aq) are mixed? pbk2 pbso4 h2o none of the above k(no3)2?
Answers
When lead ll nitrate react with potassium sulphate, one of the product formed is lead sulphate. The reaction is a double decomposition precipitation reaction; PbSO4 is the precipitate formed.
Answer:
[tex]\rm PbSO_4[/tex] will precipitate in the given reaction.
Explanation:
The reaction takes place between lead nitrate [tex]\rm Pb(NO_3)_2[/tex] and potassium sulphate [tex]\rm K_2SO_4[/tex].
Now, the reaction will be a double displacement reaction in which the ions will exchange between lead nitrate [tex]\rm Pb(NO_3)_2[/tex] and potassium sulphate [tex]\rm K_2SO_4[/tex].
So, the chemical reaction can be written as,
[tex]\rm {Pb(NO_3)_2+K_2SO_4}\rightarrow PbSO_4+2KNO_3[/tex]
In the above equation, [tex]\rm PbSO_4[/tex] is a precipitate which will be settled down in the bottom and [tex]\rm KNO_3[/tex] will form an aqueous solution.
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Question 3(Multiple Choice Worth 2 points)
A 20 gram piece of metal is added to a sample of 100 grams of water inside a calorimeter. If the metal is at a temperature of -5° Celsius and the water is at 20° Celsius, which of the following best describes what will occur inside the calorimeter?
The final temperature of the water will be 15° Celsius.
The energy gained by the metal equals the energy lost by the water.
The final temperature of the water will be higher than the initial temperature.
The temperature lost by the water will equal the temperature gained by the metal.
Answers
It is phrased this way because the focus is on the energy entering the system, more than it leaving the surroundings.
This is a problem based on concept of first law of thermodynamics
if a body is giving heat it will be absorbed by some other body or surrounding.
Now we have taken metal at low temperature and water at high temperature
So water will lose some energy and the same amount of energy will be gained by metal. The exchange will continue untill both reach the same temperature.
So answer is
The energy gained by the metal equals the energy lost by the water.
(6.21×10^3)(0.1050)
(Scientific Notation)
Answers
6210
6210 (0.1050)
652.05
Calculate the freezing point and melting point of a solution containing 10.0g of naphthalene
Answers
The freezing point of the solution is 0.88°C
The melting point of a substance which is also the same as the freezing point is the temperature at which it changes from a solid state to a liquid state at a specific pressure. At the melting point, the substance absorbs heat energy, increasing its temperature and causing the solid structure to break down
We have that;
Number of moles of naphthalene = 10 g/128 g/mol
= 0.078 moles
Mass of benzene = Density * volume
= 0.877 g/cm3 * 100.0 mL
= 87.7 g or 0.0877 Kg
Where;
ΔT = K m i
ΔT = 5.12 * 0.078 moles/ 0.0877 Kg * 1
= 4.6°C
ΔT = Freezing point of pure solvent - Freezing point of solution
Freezing point of solution = 5.48°C - 4.6°C
= 0.88°C
Missing parts
Calculate the freezing point and melting point of a solution containing 10.0 g of naphthalene (C10H8) in 100.0 mL of benzene. Benzene has a density of 0.877 g/cm3
Explain and give examples of theories and laws (big bang molecular clock etc.)
Answers
2. Newton's 1st Law- says that objects in rest will stay in rest and objects in motion will stay in motion. The most important lesson here is that an object in rest may not be in rest position.
3. Ohms law- says the current passing through an area is directly proportional to the voltage