Chemistry Exam 2

For a process at constant volume,

w = 0 and ΔE = q.

Acetic acid (CH3CO2H), formic acid (HCO2H), hydrofluoric acid (HF), aqueous ammonia (NH3), and aqueous methylamine (CH3NH2) are commonly classified as

weak electrolytes.

An ideal gas expands into a vacuum (external pressure = 0) without gaining or losing heat. For this expansion

ΔE does not change.

For a process at constant pressure,

ΔH = q.

For the reaction I2(g) → I2(s), ΔH° = -62.4 kJ at 25°C. Based on these data, at 25°C

ΔH°sub = 62.4 kJ/mol.

In which case is the work done on the system always positive?

ΔV < 0

The enthalpy of fusion, or heat of fusion (ΔHfusion), of water is positive and corresponds to which physical change?

H2O(s) → H2O(l)

Which of the following gases has the lowest average speed at 25°C?

H2S

Write a net ionic equation for the neutralization reaction of HCN(aq) with NaOH(aq).

HCN(aq) + OH-(aq) → CN-(aq) + H2O(l)

What is the total pressure in a 10.0 L flask which contains 0.127 mol of H2(g) and 0.288 mol of N2(g) at 20.0°C?

0.998 atm

How many H+ ions can the acid CH3CO2H donate per molecule?

1

What is the molar concentration of sodium ions in a 0.350 M Na3PO4 solution?

1.05 M

A steel bottle contains argon gas at STP. What is the final pressure if the temperature is changed to 115°C?

1.42 atm

It takes 11.2 kJ of energy to raise the temperature of 145 g of benzene from 25.0°C to 70.0°C. What is the specific heat of benzene?

1.72 J/(g ∙ °C)

Which of the following is not equivalent to 1 atm pressure?

10 cm Hg

A balloon contains 0.76 mol N2, 0.18 mol O2, 0.031 mol He and 0.026 mol H2 at 739 mm Hg. What is the partial pressure of O2?

130mm

How many H+ ions can the acid, H2CO3, donate per molecule?

2

Write a balanced net ionic equation for the reaction of H2SO4(aq) with Ba(OH)2(aq).

2 H+(aq) + SO42-(aq) + Ba2+(aq) + 2 OH-(aq) → BaSO4(s) + 2 H2O(l)

Write a net ionic equation for the neutralization reaction of H3PO4(aq) with Ba(OH)2(aq).

2 H3PO4(aq) + 3 Ba2+(aq) + 6 OH-(aq) → Ba3(PO4)2(s) + 6 H2O(l)

A 1.00 L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

2.01 atm

An "empty" aerosol can at 25°C still contains gas at 1.00 atmosphere pressure. If an "empty" can is thrown into a 475°C fire, what is the final pressure in the heated can?

2.51 atm

Write a balanced net ionic equation for the reaction of AgNO3(aq) with Cu(s).

2Ag+(aq) + Cu(s) → 2 Ag(s) + Cu2+(aq)

How many H+ ions can the acid H3PO4 donate per molecule?

3

How many grams of O2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?

34.7 g

At STP how many liters of NH3 can be produced from the reaction of 6.00 L of N2 with 6.00 L of H2? N2(g) + 3 H2(g) → 2 NH3(g)

89.6 L

How many molecules of N2 are in a 500.0 mL container at 780 mm Hg and 135°C?

9.23 × 1021

Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain diffusion of a gas?

A gas consist of tiny particles moving in random straight line motion.

Which pair of compounds is soluble in water?

A) AgBr and AgI B) CdS and (NH4)2S *C) KI and Ba(NO3)2 D) NaNO3 and CuCO3

Which pair of compounds is insoluble in water?

A) AgNO3 and KNO3 B) Na2S and CuS C) (NH4)2SO4 and AgI *D) PbSO4 and Pb3(PO4)2

Predict the products of a reaction between AgNO3(aq) and KBr(aq).

*C) AgBr(s) and KNO3(aq)

What is the oxidation number of the chromium atom in K2Cr2O7?

+6

What is the oxidation number of the sulfur atom in H2SO4?

+6

What is the oxidation number of the oxygen atom in H2O2?

-1

When 0.250 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical equation shown below, 177 kJ of heat are released. Calculate the value of ΔH for this reaction, as written. 2 CH4(g) + 3 Cl2(g) → 2 CHCl3(l) + 3 H2(g) ΔH = ?

-1420 kJ

The volume of 350. mL of gas at 25°C is decreased to 125 mL at constant pressure. What is the final temperature of the gas?

-167°C

Calculate the work energy, w, gained or lost by the system when a gas expands from 15 L to 35 L against a constant external pressure of 1.5 atm. [1 L ∙ atm = 101 J]

-3.0 kJ

At constant pressure, the combustion of 5.00 g of C2H6(g) releases 259 kJ of heat. What is ΔH for the reaction given below? 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(l).

-3120 kJ

At STP how many grams of Mg are required to produce 35 mL of H2 in the reaction shown below? Mg(s) + 2 HCl(aq) → H2(g) + MgCl2(aq)

0.038g

A gas occupies 22.4 L at STP and 14.5 L at 100°C and 2.00 atm pressure. How many moles of gas did the system gain or lose?

0.05 moles lost

A balloon filled with helium gas at 20°C occupies 2.91 L at 1.00 atm. The balloon is immersed in liquid nitrogen at -196°C, raising the pressure to 5.20 atm. What is the volume of the balloon in the liquid nitrogen?

0.15 L

What is the molar concentration of sulfate ions in a 0.150 M Na2SO4 solution?

0.150 M

The approximate normal melting point of this substance is *diagram

190k

The approximate normal boiling point of this substance is *diagram

300k

The specific heat of copper is 0.385 J/(g ∙ °C). If 34.2 g of copper, initially at 25°C, absorbs 4.689 kJ, what will be the final temperature of the copper?

381°C

A 10.0-L flask containing He, 2.00 mole of Ar, and 3.00 mole of Ne has a total pressure of 24.5 atm at 25°C. How many moles of He are in the flask?

5.00 mol

The action of some commercial drain cleaners is based on the following reaction: 2 NaOH(s) + 2 Al(s) + 6 H2O(l) → 2 NaAl(OH)4(s) + 3 H2(g) What is the volume of H2 gas formed at STP when 4.32 g of Al reacts with excess NaOH?

5.38 L

Given: 4 NO2(g) + O2(g) → 2 N2O5(g) ΔH° = -110.2 kJ find ΔH° for N2O5(g) → 2 NO2(g) + 1/2 O2(g).

55.1 kJ

How many liters of oxygen are needed to exactly react with 27.8 g of methane at STP? CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)

77.6 L

Which one of the following compounds is soluble in water?

A) Ag3PO4 B) CuS *C) Pb(NO3)2 D) ZnCO3

Which of the following compounds exhibits hydrogen bonding?

A) CH3Cl B) HI C) H3C-O-CH3 *D) NH3

Which is expected to have the largest dispersion forces?

C8H18

Write a net ionic equation for the neutralization reaction of CH3CO2H(aq) with CsOH(aq).

CH3CO2H(aq) + OH-(aq) → CH3CO2-(aq) + H2O(l)

In liquid methanol, CH3OH which intermolecular forces are present?

Dispersion, hydrogen bonding and dipole-dipole forces are present.

In the reaction AgNO3(aq) + HI(aq) → AgI(s) + HNO3(aq) the spectator ions are

H+ and NO3-

Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions?

HBr

Which has the smallest dipole-dipole forces?

N2

Which one of the following gases will have the highest rate of effusion?

N2O

Which of the following exhibits ion-dipole forces?

NaCl(aq)

An approximation of absolute zero was made from an extrapolation of

V vs. T

The mixing of different gases by random molecular motion with frequent collisions is called

diffusion.

A process by which gas molecules escape through a tiny hole in a membrane into a vacuum without collisions is called

effusion.

Pressure is defined as

force divided by unit area.

Which of the following is not a state function?

heat

An aqueous solution of HI is named

hydriodic acid.

When pressure-volume measurements are made on 1.0 mol of gas at constant temperature , a plot V versus P results in a

hyperbola.

The first law of thermodynamics

is a statement of conservation of energy.

If the number of moles of gas is doubled at constant temperature and volume, the pressure of the gas

is doubled.

According to the diagram, the solid phase of this substance *diagram

is more dense than the liquid phase.

Water (H2O), methyl alcohol (CH3OH), ethyl alcohol (CH3CH2OH), ethylene glycol (HOCH2CH2OH), and sucrose (C12H22O11) are commonly classified as

nonelectrolytes.

The SI unit for pressure is the

pascal.

The reaction Na3PO4(aq) + 3 AgNO3(aq) → Ag3PO4(s) + 3 NaNO3(aq) is best classified as a(n)

precipitation reaction.

Water has an unusually high

specific heat

When temperature-volume measurements are made on 1.0 mol of gas at 1.0 atm, a plot V versus T results in a

straight line.

HBr, HCl, HClO4, KBr, and NaCl are all classified as

strong electrolytes.

Which of the following is not a type of energy or energy transfer?

temperature

According to the kinetic molecular theory, the pressure of a gas in a container will decrease if the

temperature of the gas decreases.

Write a balanced net ionic equation for the reaction of CdCl2(aq) with Na2S(aq).

Cd2+(aq) + S2-(aq) → CdS(s)

Which species functions as the oxidizing agent in the following reduction-oxidation reaction: Zn(s) + Cu2+(aq) → Cu(s) + Zn2+(aq).

Cu2+(aq)

Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain Charles' law?

The average kinetic energy of gas particles is proportional to the Kelvin temperature.

Some assumptions from the kinetic molecular theory are listed below. Which one is most frequently cited to explain compressibility of a gas?

The volume of the particles is negligible compared to the volume of the gas.

What is expected when the reaction shown below takes place in a thermally-insulated container outfitted with a movable piston at a constant atmospheric pressure of 1 atm? 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(g)

Volume will increase and work will be done by the system.

The reaction 2 HNO3(aq) + Ba(OH)2(aq) → Ba(NO3)2(aq) + 2 H2O(l) is best classified as a(n)

acid-base neutralization reaction.

The reaction HNO3(aq) + KOH(aq) → KNO3(aq) + H2O(l) is best classified as a(n)

acid-base neutralization reaction.

In which compound is the oxidation state of hydrogen not +1?

A) H2O B) H2O2 *C) NaH D) Na2HSO4

Which pair of reactants will produce a precipitate when mixed together?

A) HCl(aq) and NaOH(aq) B) HCl(aq) and Na2CO3(aq) C) HCl(aq) and Na2S(aq) *D) HCl(aq) and Pb(NO3)2(aq)

Which one of the following compounds is insoluble in water?

A) K2SO4 B) NaNO3 *C) PbSO4 D) Rb2CO3

In which compound is the oxidation state of oxygen not -2?

A) MgO B) Li2O *C) Na2O2 D) Al2O3

Which covalent bond is the most polar?

A) N-F *B) C-F C) Cl-F D) F-F

Write a balanced net ionic equation for the reaction of AgNO3(aq) with KBr(aq).

Ag+(aq) + Br-(aq) → AgBr(s)

Three identical flasks contain three different gases at standard temperature and pressure. Flask A contains CH4, flask B contains CO2, flask C contains N2. Which flask contains the largest number of molecules?

All flasks contain the same number of molecules.

One mole of which gas has the greatest density at STP?

Ar

Which law does the equation V/n, = k represent?

Avogadro's law

"Equal volumes of different gases at the same temperature and pressure contain the same molar amounts" is another way of stating

Avogadro's law.

Predict the products of a reaction between Ba(NO3)2(aq) and K2SO4(aq).

BaSO4(s) and KNO3(aq)

In a solution prepared by mixing CH3OH with H2O the major species present are

CH3OH and H2O

Which of the following gases has the highest average speed at 400K?

CO2

Which is a measure of the sum of the kinetic and potential energies of each particle in the system?

E, the internal energy

10.0 g of a metal, initially at 25°C, are placed into 10.0 g of water, initially at 100°C. Which metal will have the highest final temperature? Shown after each metal is its specific heat in J/(g∙°C).

Gold (0.129)

Write a balanced net ionic equation for the reaction of Na2CO3(s) and HCl(aq).

Na2CO3(s) + 2 H+(aq) → 2 Na+(aq) + H2O(l) + CO2(g)

Write a balanced net ionic equation for the reaction of NiBr2(aq) with (NH4)2S(aq).

Ni2+(aq) + S2-(aq) → NiS(s)

Which of the following equations represents "Boyle's law"?

PV = k

Write a balanced net ionic equation for the reaction of Pb(NO3)2(aq) with NaI(aq).

Pb2+(aq) + 2 I-(aq) → PbI2(s)

When K2SO4(aq) and Pb(NO3)2(aq) are mixed, a white colored precipitate forms which is

PbSO4.

The combustion reaction CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) can be classified as a(n)

oxidation-reduction reaction.

The reaction C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(l) is best classified as a(n)

oxidation-reduction reaction.

The reaction Cu(s) + 2 AgNO3(aq) → Cu(NO3)2(aq) + 2 Ag(s) is best classified as a(n)

oxidation-reduction reaction.

The reaction Pb(NO3)2(aq) + K2SO4(aq) → PbSO4(s) + 2 KNO3(aq) is best classified as a(n)

precipitation reaction.

Which depends only on the initial and final state?

q + w