CHEM 1100
Answers to Practice Test 4

Note: Answers given in red


1. A sample of nitrogen gas has a volume of 32.4 L at 20 ^oC. The gas is heated to 220 ^oC at constant pressure. What is the volme of nitrogen?

a. 2.94 L
b. 19.3 L
c. 31.4 L
d. 54.5 L
e. 356 L


2. At what temperature will a fixed mass of gas with a volume of 125 Liters at 15 ^oC and 750 mm Hg occupy a volume of 101 Liters at a pressure of 645 mm Hg?

a. - 73 ^oC
b. 10.4 ^oC
c. 2 ^oC
d. 34 ^oC
e. 200 ^oC


3. Calculate the density of CO₂ (g) at 100 ^oC and 10.0 atm pressure.

a. 1.44 g/L
b. 134 g/L
c. 44.0 g/L
d. 53.6 g/L
e. 14.4 g/L


4. Calculate the volume occupied by 35.2 g of methane gas (CH₄) at 25 ^oC and 1.0 atm.    Given: R= 0.0821 L.atm/K.mol

a. 0.0186 L
b. 4.5 L
c. 11.2 L
d. 29.9 L
e. 53.7 L


5. How many liters of chlorine gas at 650 mm Hg and 25 ^oC can be produced by the reaction of 2.0 L of 2.5 M HCl solution with excess MnO₂?

MnO₂ (s) + 4 HCl (aq) ---> MnCl₂ (aq) + 2 H₂O (l) + Cl₂ (g)
a. 1.25 L
b. 24.2 L
c. 35.7 L
d. 88.6 L
e. 143 L


6. An exothermic reaction causes the surroundings to:

a. warm up
b. become acidic
c. expand
d. decrease in temperature
e. release CO₂


7. How much heat is required to raise the temperature of 2.0 kg of water from 10 ^oC to 80 ^oC.  Given: specific heat of water = 4.18 J/g.^oC

a. 33 kJ
b. 0.585 kJ
c. 585 kJ
d. 585 J
e. 240 kJ


8. Find the standard enthalpy of formation of ethylene, C₂H₄ (g), given the following data:

C₂H₄ (g) + 3 O₂ (g) ---> 2 CO₂ (g) + 2 H₂O (l)        DH_f^o = - 1411 kJ/mol

C (s) + O₂ (g) ---> CO₂                                               DH_f^o = - 393.5 kJ/mol

H₂ (g) + ½ O₂ (g) ---> H₂O                                        DH_f^o = - 241.8 kJ/mol

a. 52 kJ
b. 140 kJ
c. 731 kJ
d. 1.41 x 10³ kJ
e. 2.77 x 10³ kJ


9. Use the following equation to determin how many grams of CaO must react in order to release 525 kJ of heat:

CaO (g) + H₂O (l) ---> Ca(OH)₂ (s)        DH^o = - 64.8 kJ/mol

a. 6.92 g
b. 56.1 g
c. 455 g
d. 606 g
e. 34,000 g


10. Given that:

2 H₂ (g) + O₂ (g) ---> 2 H₂O (l)                                   DH^o = - 571 kJ/mol

C₃H₄ (g) + 4 O₂ (g) ---> 3 CO₂ (g) + 2 H₂O (l)          DH^o = - 1941 kJ/mol

C₃H₈ (g) + 5 O₂ (g) ---> 3 CO₂ (g) + 4 H₂O (l)          DH^o = - 2220 kJ/mol

Calculate DH^o for the reaction:    C₃H₄ (g) + 2 H₂ (g) ---> C₃H₈ (g)

a. - 292 kJ/mol
b. + 292 kJ/mol
c. +850 kJ/mol
d. - 850 kJ/mol
e. none of the above


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