Gas Laws homework 1 Name ______
Part I. Reviewing concepts
1. Rank the following gases in order of fastest rate of diffusion (1) to the slowest rate of diffusion (3).
a) Oxygen (O2) ______
b) methane (CH4) ______
c) propane (C3H8) ______
2. Rank the following substances in order from the least dense (1) to the most dense (3) assuming you have 1 mole of each of the following gases @ STP.
Radon ______
Oxygen ______
Carbon dioxide ______
Part II. Understanding Gases conceptually
1. One of the common methods used to collect a gas is to create the gas and bubble the gas into a gas collecting apparatus (like a jar or test tube) that has been filled with water. Because the gas is less dense than the water, it rises up and displaces the water in the jar or test tube. If you use this technique, is the pressure of the gas in the jar the pressure of the gas you just collected? ______Explain why it is or is not the pressure of the gas you just collected.
2. A gas @ STP means it is as standard temperature and standard pressure. What is the standard temperature of a gas in Kelvin? ______
What is standard pressure of a gas in atmospheres? ______
in mmHg? ______in kPa? ______
3. Convert the following (show work for pressure conversions below)
0.89 atm. = ______mmHg = ______KPa
120 oC = ______K 295.15 K = ______oC
For questions 4 & 5, fill in the blank with the correct answer. If there is a pair of words bolded, circle the correct choice.
4. If you have a gas in a sealed, rigid container (______and ______are constant), then increasing the temperature causes the gas molecules to move (faster or slower), therefore causes (more or less) collisions, therefore (increasing or decreasing) the pressure. This is an example of ______Law and illustrates the (direct or inverse relationship) relationship between pressure and temperature.
5. If you have a gas in a sealed balloon and you do not change the temperature of the gas, then squeezing the balloon (increases or decreases) the amount of space the molecules have to move, therefore (increasing or decreasing) volume. This change in volume causes the molecules to collide (more often or less often), which results in a(n) (increase or decrease) in pressure. This is an example of ______Law and illustrates the (direct or inverse) relationship between pressure and volume.
Part III. Problem Solving – Report your answer to the correct number of significant figures)
1. Use the appropriate gas law to find the missing value in each of the following (Show the work at the right)
a) P1 = 300.0 torr, V1 = 200.0 mL,
P2 = 800.0 torr, V2 = ???
b) P1 = 98.5 KPa, T1 = 50.00 oC ,
P2 = 695 mmHg, T2 = ???
c) V1 = 3.20 m3, T1 = 25.0 oC ,
V2 = 1.60 m3, T2 = ???
2. A gas is collected OVER WATER at a temperature of 25oC. If the gas has a volume of 345 ml and the air pressure is 0.85 atm,
a) What is the pressure of the DRY GAS?
b) What would be the volume of the gas if the pressure exerted by the gas were changed to standard pressure?
3. The initial volume of a gas is 350 ml. What would the new volume of the gas be if the pressure of the gas was tripled and the temperature of the gas was held constant?
4. You have 0.36 moles of carbon dioxide in a 76 cm3, sealed balloon. If you squeeze the balloon to a size that is ½ of its original size, what would be the new pressure exerted by the gas inside the balloon?
5. The pressure on a gas at -50.0 oC is doubled, but its volume is held constant. What will be the final temperature in degrees Celcius?
Part IV. Graphing
For each of the following, draw the appropriate graph showing the correct relationship between variables.