Chapter 13 Test Review
1. State each of the following laws (don’t just write the formulas): a) Boyle’s law: volume and pressure are inversely related when temp. is held constant. b) Charles’s law: volume and Kelvin temperature are directly related when pressure is held constant c) Gay-Lussac’s law: pressure and Kelvin temperature are directly related when temperature is held constant d) Avogadro’s Principal: gases of the same volume at the same temperature and pressure will contain the same number of particles. 2) If you increase the volume of a gas but keep the temperature constant, what will happen to the pressure of the gas? decrease 3) If you increase the temperature of a gas but keep the volume constant, what will happen to the pressure of the gas? increase 4) If you increase the pressure on a gas but keep the volume constant, what will happen to the temperature of the gas? increase 5) You have a 5.0 L of gas at 450 mmHg. If the pressure of the gas is increased to 760 mmHg, what will the volume of the gas be? Law used:
Solution: (450 mmHg)(5.0L) = (760 mmHg) (V2) V2 = 3.0 L
6) A gas is confined in an expandable container of 6.0 L at a temperature of 54oC. If the gases is heated to a temperature of 65oC, what will the volume of the container expand to? Law used:
6.0L = V2 327 K 338 K V2 = 6.2 L
7) A gas is under a pressure of 1 atm and a temperature of 19oC. What will the pressure of the gas have be if the temperature reaches 232oC? Law Used:
1 atm = P2 292 K 505 K P2 = 2 atm
8) A gas is under a pressure of 7 atm in a 4.00 L container. Its temperature is 35oC. What will the volume have to be reduced to change the gas’s pressure to 14 atm and 27oC? Law used:
Combined Gas Law
(7 atm)(4.00 L) = (14 atm)(V2) 308 K 300 K V2 = 2 L
9) How many moles of nitrogen can be contained in a 10.0 L container at a pressure of 5.4 atm, a temperature of 25oC? Law used:
Ideal Gas Law
Solution: (5.4 atm)(10.0 L) = n (.0821 L atm)(298 K) mol K n = 2.2 mol
10) What pressure will 4.5 moles of hydrogen gas be under in a 3.00 L container at 37oC? Law used:
Ideal Gas Law
P(3.00 L) = (4.5 mol)(.0821 L atm) (310 K) mol K P = 38 atm
13) How are ideal gases different than real gases?
Ideal gases have perfectly elastic conditions and have no attractive forces between the particles. Also, their individual particles do not have any volume.
14) How many liters of gas do you have if you have 4.9 moles of gas? 4.9 mol x 22.4 L = 110 L 1 mol 15) Convert 29oC to Kelvin. K = 29 + 273 = 302 K 16) What is the value of R when pressure is measured in atmospheres? 0.0821 L atm mol K 16) Why is a tire blowout more likely on a hot summer day than a cold winter day? (think in terms of volume and pressure) On a hot day, the air in the tire will also rise in temperature which will increase the pressure of the gas inside the tire. Since the volume of the tire cannot expand much, there is more chance the tire will blow out if it is driven on. 17) What is the density of O2 at STP?
Density = 32.00 g = 1.43 g/L 22.4 L
18) A gas with a density of 0. 179 g/L has what molar mass at STP? Molar mass = 0.179 g/L x 22.4 L = 4.01 g 19) What is the density of SF4 at 0.855 atm and 100oC? D = (108.06 g )(0.855 atm ) = 3.02 g/L (0.0821 L atm )(373 K) mol K 20) What is the molar mass of a gas that has a density of 1.25 g/L at 25oC and 0.955 atm? Molar mass = (1.25 g/L)(0.0821 Latm/mol K)(298 K) = 32.0 g 0.955 atm 22) In the reaction 2H2 + O2 â†’ 2H2O, how many Liters of oxygen would react completely with 6.4 L H2 at STP? 6.4 L H2 x 1 L O2 = 3.2 L O2 2 L H2
23) Using the same equation in # 22, how many grams of water would be produced from 3.00 L of oxygen at 25oC and 1.5 atm? (1.5 atm)(3.00 L) = n (0.0821 Latm/molk)(298 K) n = 0.18 mol O2 0.18 mole O2 x 2 mole H2O x 18.02 H2O = 6.5 g H2O 1 mol O2 1mol H2O