Gas laws (MS) 2013 Spring

* Your name

* Your teacher

* Block

* Today's date

* 1. Which of the following describes the motion of the gas molecules in a sealed container of gas?

(a) The gas molecules are not moving.

(b) The gas molecules are all moving at the same speed.

(c) The gas molecules move only when the container of the gas is moving.

(d) The gas molecules are moving at different speeds.

* 2. Compared to molecules of cold air, molecules of hot air...

(a) are larger in size.

(b) have more mass.

(c) have more heat molecules mixed with them.

(d) move faster.

* 3. An air mattress can hold weight because the air inside exerts pressure onto the walls of the mattress. Air is made of gas molecules, so how do the gas molecules cause pressure? Please explain.

* 4. Two steel tanks of the same size are filled with gas and stored in the same room. Tank A has more gas molecules than tank B. Which tank has higher internal pressure? Please explain your answer by describing gas molecules’ behaviors.

* 5. A scientist filled a steel tank with air and sealed it so that no air would leak out. She measured the pressure inside the tank in the morning when it was cold and then in the afternoon when it was hot. She found that the pressure increased a lot. Please explain what happened to the gas molecules causing the pressure to increase. Feel free to draw on the drawing sheet to help you explain.

* 6.

When you pump your bicycle tires, the air pump feels harder and harder to push as you push in. Please explain what happen to the gas molecules inside the pump and how they make it harder to push.

* 7A. A steel tank is filled with hydrogen gas at a temperature of 20°C and a pressure of 3 atm (atmospheres). In the following diagram, the circle represents the tank, and the dots represent the distribution of hydrogen molecules.

If the tank is cooled to 5°C, hydrogen still remains a gas. Which of the following diagrams illustrates the distribution of hydrogen molecules at 5°C?

(a)

(b)

(c)

(d)

* Please explain your choice for question 7A.

* 7B. After being cooled to 5°C, the pressure inside the steel tank described in question 7A will be:

(a) 0 atm

(b) In-between 0 atm and 3 atm

(c) 3 atm

(d) Greater than 3 atm

* Please explain your choice for question 7B.

* 8. The evening before a birthday party, you fill several balloons with helium gas. The birthday party occurs on a hot summer day. The next day (the same hot temperature) the latex balloons are noticeably smaller. Which of the following explains this observation?

(a) Some of the helium molecules escaped through pores in the latex.

(b) The helium molecules became smaller than before.

(c) The helium molecules lost their strength.

(d) The molecules moved closer to each other.

* Please explain your choice for question 8.

* 9. Joe pumped his car tires on a cold day and recorded the gas pressure inside the perfectly sealed tires. He checked the pressure again on a hot day but found that the pressure increased a lot. Please explain why the tire pressure increased by describing what happened to the gas molecules inside the tire from the cold day to the hot day.