CHEM 102 Exam 3

Calculate the reaction enthalpy for the formation of anhydrous aluminum chloride:

2Al(s) + 3Cl₂(g) ---> 2AlCl₃(s)

• −1049 kJ

• −448.8 kJ

• −1406.8 k

• −703.4 kJ

Given the following data:

Find the ΔH of the following reaction:

C(s, gr) + O₂(g) ---> CO₂(g)

• −394 kJ

• +234 kJ

• +592 kJ

• −1220 kJ

How much energy in kJ is needed to heat 5.00 g of ice from −10.0 °C to 30.0 °C? The heat of fusion of water is 6.02 kJ/mol, and the molar heat capacity is 36.6 J/mol K for ice and 75.3 J/mol K for liquid water

• 2.40 kJ

• 1.67 kJ

• 55 kJ

• -2.40 kJ

How many grams of ice at −17.0 °C must be added to 741 grams of water that is initially at a temperature of 70.0 °C to produce water at a final temperature of 12.0 °C? The specific heat of liquid water is 4.184 J/g °C and of ice is 2. J/g °C. For water the normal melting point is 0.0 °C and the heat of fusion is 334 J/g.

• 415 g

• 0.415 g

• 4.15g

• 173619.264 J

Which statements are true for cup calorimetry when 32.2 g of water at 14.9 °C mixes with 32.2 grams of water at 46.8 °C.

I. The colder water will warm up (heat energy "flows" into it). The warmer water will cool down (heat energy "flows" out of it).

II. The whole mixture will wind up at the SAME temperature.

III. The energy which "flowed" out (of the warmer water) equals the energy which "flowed" in (to the colder water)

• I

• I, III

• none of these statements

• all of these statements

1.85 L of a gas is collected over water at 98.0 kPa and 22.0 °C. What is the volume of the dry gas at STP? P_H2O at 22.0 °C. is 2.6447 kPa

• 1.61 L

• .161 L

• 1.61 mL

• .161 mL

Determine the enthalpy of reaction for the following:

H₂(g) + ¹⁄₂O₂(g) ---> H₂O(g)

Using the following bond enthalpies (in kJ/mol): H−H (432); O=O (496); H−O (463)

• ΔH = 432 kJ

• ΔH = 680 kJ

• ΔH = -926 kJ

• ΔH = −246 kJ

A spray can is used until it is empty except for the propellant gas, which has a pressure of 1344 torr at 23 °C. If the can is thrown into a fire (T = 475 °C), what will be the pressure in the hot can

• 3.40 × 10³ torr

• 3.40 torr

• 13.44 × 10³ torr

• 7.60 × 10³ torr

What is the molar mass of a compound that takes 2.65 times as long to effuse through a porous plug as it did for the same amount of XeF₂ at the same temperature and pressure?

• 1188.8 g/mol

• 1195.6 g/mol

• 1178.6 g/mol

• 1088.8 g/mol

A container with two gases, helium and argon, is 30.0% by volume helium. Calculate the partial pressure of helium and argon if the total pressure inside the container is 4.00 atm.

• He: 1.20 atm, Ar=2.80 atm

• He and Ar are 0.300 atm

• Unable to calculate it.

• He: 2.80 atm, Ar: 1.20 atm,