exam 3

A 35.6 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rose from 35.0 to 76.0°C and the heat capacity of the calorimeter is 23.3 kJ/°C, what is the value of DH°rxn? The molar mass of ethanol is 46.07 g/mol. C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g)ΔH°rxn = ?

-1.24 × 103 kJ/mol

Using the following equation for the combustion of octane, calculate the heat of reaction for 50.00 g of octane. The molar mass of octane is 114.33 g/mole. 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ

-2410 kJ

Use the information provided to determine ΔH°rxn for the following reaction: ΔH°f (kJ/mol)CH4(g) + 4 Cl2(g) → CCl4(g) + 4 HCl(g)ΔH°rxn = ? CH4(g)-75 CCl4(g)-96 HCl(g)-92

-389 kJ

In the presence of excess oxygen, methane gas burns in a constant-pressure system to yield carbon dioxide and water: CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)ΔH = -890.0 kJ Calculate the value of q (kJ) in this exothermic reaction when 1.10 g of methane is combusted at constant pressure.

-61.2 kJ

Calculate the change internal energy (ΔE) for a system that is giving off 65.0 kJ of heat and is performing 855 J of work on the surroundings.

-65.9 kJ

How many moles of CO are contained in a 5.71 L tank at 155°C and 2.80 atm?

0.455 moles

A mixture of 10.0 g of Ne and 10.0 g Ar have a total pressure of 1.6 atm. What is the partial pressure of Ar?

0.54 atm

In the laboratory, hydrogen gas is usually made by the following reaction: Zn(s) + 2 HCl(aq) → H2(g) + ZnCl2(aq) How many liters of H2 gas, collected over water at an atmospheric pressure of 752 mm Hg and a temperature of 21.0°C, can be made from 1.566 g of Zn and excess HCl? The partial pressure of water vapor is 18.65 mm Hg at 21.0°C.

0.599 L

Zinc reacts with aqueous sulfuric acid to form hydrogen gas: Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) In an experiment, 125 mL of wet H2 is collected over water at 27°C and a barometric pressure of 753 torr. The vapor pressure of water at 27°C is 26.74 torr. The partial pressure of hydrogen in this experiment is ________ atm.

0.955

Give the temperature and pressure at STP.

0°C and 1.00 atm

A basketball is inflated to a pressure of 1.80 atm in a 23.0°C garage. What is the pressure of the basketball outside where the temperature is -2.00°C?

1.65 atm

How much heat is absorbed when 40.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to the following chemical equation? 5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g)ΔH° = 239.9 kJ

159.8 kJ

What volume will 0.875 moles of Kr occupy at STP?

19.6 L

How many liters of oxygen gas can be produced at STP from the decomposition of 0.0625 L of 3.00 M H2O2 in the reaction according to the chemical equation shown below? 2 H2O2(l) → 2 H2O(l) + O2(g)

2.10 L

What volume will 5.91 × 1022 atoms of Ne occupy at STP?

2.20 L

A sample of copper absorbs 43.6 kJ of heat, resulting in a temperature rise of 50.0°C, determine the mass (in kg) of the copper sample if the specific heat capacity of copper is 0.385 J/g°C.

2.26 kg

The mole fraction of krypton in dry air near sea level is 0.00000114. The concentration of krypton is ________ molecules per liter, assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

2.68 × 1016

According to the following reaction, how much energy is required to decompose 56.0 kg of Fe3O4? The molar mass of Fe3O4 is 231.55 g/mol. Fe3O4(s) → 3 Fe(s) + 2 O2(g)ΔH°rxn = +1118 kJ

2.70 × 105 kJ

What pressure will 2.6 × 1023 molecules of Rn exert in a 3.9 L container at 45°C?

2.9 atm

The mole fraction of oxygen in dry air near sea level is 0.20948, where the molar mass of oxygen is 31.998. The partial pressure of oxygen when the total atmospheric pressure (dry air) is 97.5 kPa is ________ kPa.

20.7

Which of the following (with specific heat capacity provided) would show the largest temperature change upon gaining 200.0 J of heat?

25.0 g Pb, CPb = 0.128 J/g°C

A piece of iron (mass = 25.0 g) at 398 K is placed in a styrofoam coffee cup containing 25.0 mL of water at 298 K. Assuming that no heat is lost to the cup or the surroundings, what will the final temperature of the water be? The specific heat capacity of iron = 0.449 J/g°C and water = 4.18 J/g°C.

308 K

A gas is at 35.0°C and 2.50 L. What is the temperature of the gas if the volume is increased to 5.00 L?

343°C

Wind power produces nearly ________ percent of U.S. electricity.

5

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT (C3H5(NO3)3, d = 1.60 g/mL, molar mass = 227.10 g/mol) reacts according to the following reaction. 4 C3H5(NO3)3(l) → 6 N2(g) + O2(g) + 12 CO2(g) + 10 H2O(g)

57.2 L

A syringe initially holds a sample of gas with a volume of 285 mL at 355 K and 1.88 atm. To what temperature must the gas in the syringe be heated/cooled in order to have a volume of 345 mL at 2.50 atm?

572 K

What volume will a balloon occupy at 1.5 atm, if the balloon has a volume of 4.4 L at 2.2 atm?

6.5 L

What volume (in mL) will a sample of F2 gas occupy in a syringe at 5.5 atm, if the F2 has a volume of 30.0 mL at 1.2 atm?

6.5 mL

Calculate the temperature, in K, of 2.20 moles of gas occupying 3.70 L at 3.12 atm.

64.0 K

How many liters ofoxygen gas are needed to produce 110.0 grams of water at 25.0°C and 1.00 atm pressure according to the chemical equation shown below? 2 H2(g) + O2(g) → 2 H2O(l)

74.7 L

To what temperature must a balloon, initially at 25°C and 2.00 L, be heated in order to have a volume of 6.00 L?

894 K

Which of the following statements is TRUE?

All of the above are true.

Which of the following samples will have the greatest average speed at 355 K?

CH4

Identify the gas particle that travels the fastest.

H2

Identify a substance that is NOT in its standard state.

HCl

Which of the following gas samples would be most likely to behave ideally under the stated conditions?

He at STP

In weather, high-pressure systems and low-pressure systems typically go from west to east in the United States. What type of weather does this indicate?

High pressure usually indicates clear weather and low pressure usually indicates unstable weather.

Give the units of specific heat capacity.

J/g °C

Choose the reaction that illustrates ΔH°f for KHCO3.

K(s) + 1/2 H2(g) + C(s) + 3/2 O2(g) → KHCO3(s)

Give the gas that is the highest percent by volume in dry air.

N2

Identify the element or molecule that has the lowest diffusion rate.

Xe

Identify the element or molecule that has the lowest effusion rate.

Xe

A scuba diver experiences ________ as she descends into the ocean water.

increase of 1 atm for each 10 m of depth

Energy that is associated with the motion of an object is called

kinetic energy

An instrument used to measure the pressure of a gas in a laboratory is called a

manometer.

Which of the following signs on q and w represent the surroundings that is doing work on the system, as well as gaining heat from the surroundings?

q = +, w = +

Define energy.

the capacity to do work

Define heat.

the flow of energy caused by a temperature difference

A 1.43-g sample of an unknown pure gas occupies a volume of 0.333 L at a pressure of 1.00 atm and a temperature of 100.0°C. The unknown gas is

xenon

For a particular process that is carried out at constant pressure, q = 140 kJ and w = -30 kJ. Therefore,

ΔE = 110 kJ and ΔH = 140 kJ.