Name: ______________________

**Gas Laws**

**Background**

In this investigation you will examine three gas laws including Boyle’s Law, Charles’ Law and Gay-Lussac’s Law. You will explore how manipulating the variables of volume (L), pressure (atm) and temperature (K) can affect a sample of gas. The formula for each of the gas laws are:

Boyle’s Law:

P1V1 = P2V2

Gay-Lussac’s Law:

P1 = P2

T1 T2

Charles’ Law:

V1 = V2

T1 T2

**Prelab Question**

1. Briefly describe, in your own words the meaning of each of the following variables, and common units of measurement associated with each:

a. Volume

b. Pressure

c. Temperature

**Procedure**

Visit http://www.teachchemistry.org/gaslaws. Make sure that you select the “Boyle’s Law” tab to begin; it will be shown in white. You should see the picture below on your screen.

**Boyle’s Law**

1. Which one of the three variables: Pressure, Volume or Temperature cannot be changed in Boyle’s Law? This variable is considered a constant.

2. Using the volume control arrows, reduce the volume of the gas to 1.70L.

a. In the space below record your observations regarding the behavior of the particles in the gas sample as the volume is reduced. Make certain to discuss *collisions* in your comments.

b. Calculate the new pressure value for the gas, showing all of your work.

c. Check your final answer for part b by clicking the *calculate* button next to P2.

a. Observations when Volume is reduced: | b. Calculation |

P1V1 = P2V2 |

3. Press the *reset* button at the top right of the screen.

Using the pressure control arrows, reduce the pressure of the gas to 0.700atm.

a. In the space below record your observations regarding the behavior of the particles in the gas sample as the pressure is reduced.

b. In the space below calculate the new volume value for the gas.

c. Check your final answer for part b by clicking the *calculate* button next to V2.

a. Observations when Pressure is reduced: | b. Calculation |

P1V1 = P2V2 |

*Important Terms*

**Direct relationship or directly proportional**: A relationship between two variables, where a change in one variable results in the same change in the other variable. For example, if one variable is increased, then the other variable will also increase.

**Indirect relationship or inversely proportional**: A relationship between two variables, where a change in one variable results in the opposite change in the other variable. For example, if one variable is increased, then the other variable will decrease.

4. Considering the terms described above, do the variables of pressure and volume have a *direct* or an *indirect* relationship in Boyle’s Law? Justify your answer with data.

**Charles’ Law**

Change the simulation to “Charles’ Law” by clicking the tab at the top of the screen it will be shown in white. You should see the picture below on your screen.

1. Which one of the three variables: Pressure, Volume or Temperature cannot be changed in Charles’ Law? This variable is considered a constant.

2. Using the volume control arrows, reduce the volume of the gas to 1.80L.

a. In the space below record your observations regarding the behavior of the particles in the gas sample as the volume is reduced.

b. In the space below calculate the new temperature value for the gas.

c. Check your final answer for part b by clicking the *calculate* button next to T2.

a. Observations when Volume is reduced: | b. Calculation |

V1 = V2 T1 T2 |

3. Using the Temperature controls, increase the temperature of the gas. What changes do you observe in the behavior of the particles of the gas while the temperature is increased?

b. Continue to increase the temperature value until T2 = 443K. Using the equation for Charles’ law, calculate the volume of the gas at this increased temperature. Check your final answer for part b by clicking the *calculate* button next to V2:

V1 = V2

T1 T2

c. Based on the final value calculated in part b) is Charles’ law considered a direct or an indirect relationship between the variables? Explain your choice with reasoning.

**Gay-Lussac’s Law**

Change the simulation to “Gay-Lussac’s Law” by clicking the tab at the top of the screen it will be shown in white. You should see the picture below on your screen.

P1 = P2

T1 T2

2. a. The equation for Gay-Lussac’s law is does it look most similar to the equation for Boyle’s Law or the equation for Charles’ law?

b. What variable is held constant in Gay Lussac’s law?

c. Based on your answer to part a) what prediction can you make about the relationship between the variables of Pressure and Temperature of a gas?

3. a. Using the pressure control arrows, increase the pressure value to 1.50atm, and

fill in the corresponding T2 value in the data table below.

b. Press the *Add Data* button. Using the pressure control arrows, increase the pressure to 2.00atm and fill in the corresponding T3 value in the data table below.

c. Repeat step b for pressure values of 2.50atm and 2.90atm.

P1 = 1.00atm | P2 = 1.50atm | P3 = 2.00atm | P4 = 2.50atm | P5 = 2.90atm |

T1 = | T2 = | T3 = | T4 = | T5 = |

d. Based on the data collected in the table above, what trend can be observed for temperature of a gas when the pressure of the gas is increased? Is this considered a direct or an indirect relationship between the variables?

4. Press the *reset* button at the top right of the screen.

Using the temperature control arrows, reduce the temperature of the gas to 158K.

a. In the space below record your observations regarding the behavior of the particles in the gas sample as the temperature is reduced. Make certain to discuss *collisions* in your comments.

b. In the space below calculate the new pressure value for the gas.

c. Check your final answer for part b by clicking the *calculate* button next to P2.

a. Observations when Temperature is reduced: | b. Calculation |

P1 = P2 T1 T2 |

American Association of Chemistry Teachers

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