CHEM 2 MIDTERM

The Henry's law constant for helium gas in water at 30°C is 3.70 × 10-4 M/atm. When the partial pressure of helium above a sample of water is 0.300 atm, the concentration of helium in the water is ________ M.

1.11 × 10-4

The rate constant for a first-order reaction is 0.54 s-1. What is the half-life of this reaction if the initial concentration is 0.33 M?

1.3 s

What are the units of k in the following rate law?Rate = k[X]2[Y]

1/ m^2s

What are the units of k in the following rate law? Rate = k[X]2[Y]2

1/(m^3s)

A solution is 2.25% by weight CsF . How many grams of CsF are in 450.0 g of solution?

10.1 g

The fluorocarbon C2Cl3F3 has a normal boiling point of 47.6°C. The specific heats of and C2Cl3F3(g) are 0.91 J/gK and 0.67 J/gK, respectively. The heat of vaporization of the compound is 27.49 kJ/mol. The heat required to convert 50.0 g of the compound from the liquid at to the gas at 80.0°C is ________ kJ.

10.36

The enthalpy change for converting 1.00 mol of ice at -25.0°C to water at 60.0°C is The specific heats of ice, water, and steam are and respectively. For H2O, = 6.01 kJ/mol, and .

11.46

Ethyl chloride, C2H5Cl, is used as a local anesthetic. It works by cooling tissue as it vaporizes; its heat of vaporization is 26.4 kJ/mol. How much heat could be removed by 30.0 g of ethyl chloride?

12.3 kJ

Copper has a face-centered cubic structure and has a density of 8.96 g/cm3. What is its atomic radius?

128 rpm

What mass of SrBr2 is contained in 80.85 g of a 22.4% by mass solution of SrBr2 in water?

18.1 g

The heat of vaporization of water at 100°C is 40.66 kJ/mol. Calculate the quantity of heat that is absorbed/released when 8.00 g of steam condenses to liquid water at 100°C.

18.1 kJ of heat are released

How many half-lives are required for the concentration of reactant to decrease to 25% of its original value?

2

In DNA, adenine and thymine have ________ hydrogen bonds between them.

2

The decomposition of dinitrogen pentoxide is described by the following chemical equation2 N2O5(g) → 4 NO2(g) + O2(g)If the rate of disappearance of N2O5 is equal to 1.20mol/min at a particular moment, what is the rate of appearance of NO2 at that moment?

2.40 mol/min

The isomerization of methylisonitrile to acetonitrileCH3NC(g) → CH3CN(g)is first order in CH3NC. The rate constant for the reaction is 2.57 × 10-5 s-1 at 463 K. The of the reaction when the initial [CH3NC] is 0.030 M is ________ s.

2.7 x 10^4

Assign the appropriate labels to the phase diagram shown below.

A = gas, B = solid, C = liquid, D = triple point

The Henry's Law constant of methyl bromide, CH3Br, is k= 0.159 mol/(L ∙ atm) at 25°C. What is the solubility of methyl bromide in water at 25°C and at a partial pressure of 300. mm Hg?

0.0628 mol/L

Determine the solubility of CO2 in soda water at 25°C if the pressure of CO2 is 6.0 atm. The Henry's law constant for carbon dioxide in water at this temperature is 3.4 × 10-2 M/atm.

0.20 M

The decomposition of dinitrogen pentoxide is described by the following chemical equation2 N2O5(g) → 4 NO2(g) + O2(g)If the rate of appearance of NO2 is equal to 0.960 mol/min at a particular moment, what is the rate of appearance of O2 at that moment?

0.240 mol/min

Calculate the molality of a solution formed by dissolving 31.3 g of LiI in 500.0 mL of water.

0.468 m

A solution is prepared by dissolving 19.9 g of benzene (C6H6) in 282 g of carbon tetrachloride The concentration of benzene in this solution is ________ molal. The molar masses of and CCl4 are and respectively.

0.904

A solution is prepared by adding 0.880 mol of KCl to 889 g of water. The concentration of KCl is ________ molal.

0.990

To make a 0.125 m solution, one could take 0.125 moles of solute and add

1 kg of solvent

What are the units of k in a second-order reaction?

1 m/s

Which of the following forms an ionic solid?

CuSO4

Which of the following statements is true?

a. Intermolecular forces hold the atoms in molecules together b. dispersion forces stronger than dipole-dipole c. hydrogen bonds stronger than covalent d. vapor pressure increases with temperature e. none are true D

Which of the following statements is FALSE?

a. The half-life of a first-order reaction is dependent on the initial concentration of reactant. b. It is not possible to determine the rate of a reaction from its balanced equation. c. None of the statements is FALSE. d. The average rate of a reaction decreases during a reaction. e. The rate of zero-order reactions is not dependent on concentration. A

Which of the following statements is FALSE?

a. The rate of a first-order reaction is dependent on concentration. b. None of the statements is FALSE. c. The rate of second-order reactions is dependent on concentration. d. The half-life of a second-order reaction is not dependent on concentration. e. The half-life of a zero-order reaction is dependent on concentration. D

Which of the following statements is generally TRUE?

a. The solubility of a solid is highly dependent on temperature. b. The solubility of a solid is not dependent on either temperature or pressure. c. The solubility of a solid is highly dependent on both pressure and temperature. d. None of the above. e. The solubility of a solid is highly dependent on pressure. A!

A solution is formed at room temperature by vigorously dissolving enough of the solid solute so that some solid remains at the bottom of the solution. Which statement below is TRUE?

a. The solution is considered saturated. b. The solution would be considered unsaturated if it were cooled a bit to increase the solubility of the solid. c. The solution is considered supersaturated. d. None of the above is true. e. The solution is considered unsaturated.a. A

Capillary action occurs because

adhesive forces are greater than cohesive forces

Identify the characteristics of a body-centered cubic cell.

edge length = 4r/, 68% packing efficiency

To make a 4.00 M solution, one could take 4.00 moles of solute and add

enough solvent to make 1.00 L of solution.

Which of the following compounds will be most soluble in ethanol (CH3CH2OH)?

ethylene glycol (HOCH2CH2OH)

Consider the phase diagram below. If the dashed line at 1 atm of pressure is followed from 90 to 450°C, what phase changes will occur (in order of increasing temperature)?

fusion, followed by vaporization

An allotrope of carbon that consists of flat sheets of carbon atoms covalently bonded together as interconnected hexagonal rings is called

graphite

Solutions having osmotic pressures less than those of body fluids are called

hyposmotic

For a reaction that follows the general rate law, Rate = k[A][B]2, what will happen to the rate of reaction if the concentration of A is increased by a factor of 2.00? The rate will

increase by factor of 2.00

Characteristics of liquid

indefinite shape and definite volume

Identify the characteristics of a liquid.

indefinite shape but definite volume

Which of the following represents the integrated rate law for a first-order reaction?

ln[A]/[A]0 = -Kt

What data should be plotted to show that experimental concentration data fits a first-order reaction?

ln[reactant] vs. time

If two substances are soluble in all proportions then they are ________ in each other.

miscible

Give the term for the amount of solute in moles per liter of solution.

molarity

Identify the type of solid for ice.

molecular solid

Identify the addition polymer.

polypropylene

Identify the condensation polymer.

polyurethane

Identify the compound that has the zinc blende structure

silver iodide

Identify the rate-determining step.

slowest step

Identify the shape for SiO4.

tetrahedral

Define solubility.

the amount of a substance that will dissolve in a given amount of solvent

define critical point

the temperature and pressure above which a supercritical fluid exists

Identify the type of interaction between atoms in a nonbonding atomic solid.

weak dispersion forces

Choose the situation below that would result in an endothermic ΔHsolution.

when delta H solute > delta H hydration

Choose the situation below that would result in a ΔHsolution near 0.

when delta H solute is close to delta H hydration

Identify the technique that determines the arrangement of atoms and measures the distance between them.

x-ray diffraction

Which of the following substances should have the highest melting point?

MgO

Determine the rate law and the value of k for the following reaction using the data provided.2 N2O5(g) → 4 NO2(g) + O2(g) [N2O5]i (M) Initial Rate (M-1s-1)0.123 6.40 × 10-40.174 9.05 × 10-40.224 1.16 × 10-3

Rate = 5.2 × 10⁻3 s-1[N2O5]

Which rate law has a molecularity of three?

Rate = k[A][B][C]

Place the following substances in order of increasing vapor pressure at a given temperature.SF6 SiH4 SF4

SF4 < SF6 < SiH4

capillary action

The ability of a liquid to flow against gravity up a narrow tube

Define condensation

The change from a gas to a liquid

Given the following rate law, how does the rate of reaction change if the concentration of Y is doubled?Rate = k[X][Y]2

The rate of reaction will increase by a factor of 4.

Give the characteristic of a first-order reaction having only one reactant.

The rate of the reaction is directly proportional to the concentration of the reactant.

Give the characteristic of a zero-order reaction having only one reactant.

The rate of the reaction is not proportional to the concentration of the reactant.

Give the characteristic of a second-order reaction having only one reactant.

The rate of the reaction is proportional to the square of the concentration of the reactant.

Consider the phase diagram shown. Choose the statement below that is TRUE.

The solid phase of this substance is higher in density than the liquid phase.

Define colloid.

a mixture in which a dispersed substance is finely divided in a dispersing medium

A solution in which the dissolved solute is in dynamic equilibrium with the solid solute is called

a saturated solution

Choose the statement below that is TRUE.

a. A solution will form between two substances only if the solvent-solvent interactions are weak enough to overcome the solute-solvent interactions. b. None of the above is true. c. A solution will form between two substances if the solute-solvent interactions are small enough to be overcome by the solute-solute and solvent-solvent interactions. d. A solution will form between two substances if the solute-solvent interactions are of comparable strength to the solute-solute and solvent-solvent interactions. e. A solution will form between two substances if the solute-solute interactions are strong enough to overcome the solvent-solvent interactions. D!

Given the following balanced equation, determine the rate of reaction with respect to [Cl2]. If the rate of Cl2 loss is 4.44 × 10-2 M/s, what is the rate of formation of NOCl?2 NO(g) + Cl2(g) → 2 NOCl(g)

8.88 × 10-2 M/s

A solution is prepared by dissolving 70.0 g of sucrose, C12H22O11, in 250. g of water at 25°C. What is the vapor pressure of the solution if the vapor pressure of water at 25°C is 23.76 mm Hg?

23.4 mm Hg

What is the overall order of the following reaction, given the rate law?X + 2Y → 4Z Rate = k[X][Y]

2nd order

Nickel crystallizes in a face-centered cubic structure. What is the edge length of the unit cell if the atomic radius of nickel is 125 pm?

354 pm

If the concentration of a reactant is 6.25%, how many half-lives has it gone through?

4

MgO crystallizes in a cubic unit cell with O2- ions on each corner and each face. How many Mg2+ and O2- ions are in each unit cell of MgO?

4 Mg2+ ions and 4 O2- ions

How many moles of NaI are contained in 244 mL of 0.135 m NaI solution? The density of the solution is 1.22 g/mL.

4.02 x 10^-2 mol NaI

Ethanol (C2H5OH) melts at -114°C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/gK and 2.3 J/gK, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -125°C to liquid ethanol at -80°C?

4.95 kJ

What is the edge length of a face-centered cubic unit cell made up of atoms having a radius of 175 pm?

495 rpm

The decomposition of dinitrogen pentoxide is described by the following chemical equation2 N2O5(g) → 4 NO2(g) + O2(g)If the rate of appearance of O2 is equal to 2.60 mol/min at a particular moment, what is the rate of disappearance of N2O5 at that moment?

5.20 mol/min

Calculate the total quantity of heat required to convert 25.0 g of liquid CCl4(l) from 45.0°C to gaseous CCl4 at 76.8°C (the normal boiling point for CCl4). The specific heat of CCl4(l) is 0.857 j/g, its heat of fusion is 3.27 kJ/mol, and its heat of vaporization is 29.82 kJ/mol

5.53 kJ

Determine the solubility of N2 in water exposed to air at 25°C if the atmospheric pressure is 1.2 atm. Assume that the mole fraction of nitrogen is 0.78 in air and the Henry's law constant for nitrogen in water at this temperature is 6.1 × 10-4 M/atm.

5.7 x 10^-4 M

Barium has a radius of 224 pm and crystallizes in a body-centered cubic structure. What is the edge length of the unit cell?

517 pm

Coordination number of simple cubic cell

6

Give the coordination number for a simple cubic cell.

6

How many moles of NaI are contained in 3470 g of water in a 0.0175 m NaIsolution?

6.07 × 10-2 mol NaI

The enthalpy change for converting 10.0 g of ice at -50.0°C to water at 70.0°C is ________ kJ. The specific heats of ice, water, and steam are and respectively. For H2O, = 6.01 kJ/mol, and .

7.31

For a reaction, what generally happens if the temperature is increased?

An increase in k occurs, which results in a faster rate.

Identify the CFC with the longest atmospheric lifetime.

CFC-115

Which of the following forms a molecular solid?

CO2

Place the following compounds in order of decreasing strength of intermolecular forces. I. CH3CH2CH2CH2CH2CH3 II. (CH3)3CCH3 III. (CH3)3CCH2CH3

I. > III > II

Identify the element that is the best insulator.

carbon

Identify the element with the largest band gap.

carbon

________ is the gas dissolved in carbonated drinks.

carbon dioxide

When two waves interact with their crests and troughs in alignment is called

constructive interference

To increase solubility of a gas into a liquid the most, then

decrease the temperature and raise the pressure.

In the hydrogenation of double bonds, a catalyst is needed. In the last step, the reactants must escape from the surface into the gas phase. This step is known as

desorption

When two waves interact with the crests of one aligning with the troughs of the other is called

destructive interference.

Give the major force between acetone and chloroform.

dipole-dipole

Identify the major force between molecules of pentane.

dispersion