# Gas Laws

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## Gas Laws Answer Key

**Instructions:**
Read each question carefully. Choose the answer that best fits the question. For any calculation questions, you must show all your math work.

1.

A large truck passes a car on the highway. According to Bernoulli's principle, which of the following should occur?

- Pressure decreases between the vehicles, so the car and truck move slightly apart.
- Pressure decreases between the vehicles, so the car and truck move slightly together.
- Pressure increases between the vehicles, so the car and truck move slightly apart.
- Pressure increases between the vehicles, so the car and truck move slightly together.

2.

The particles in a ideal gas interact with each other only by perfectly elastic collisions that exchange energy and momentum.

- True
- False

3.

Using the Ideal Gas Law equation, [math]PV=N*k_b*T[/math], determine the number of particles of air contained in one cubic meter at an atmospheric pressure of 101,325Pa and a temperature of [math]293degK[/math].

- [math]N=(P*V)/(k_b*T)[/math]

[math]N=(101,325Pa*1m^3)/(1.38*10^-23*293degK)[/math]

[math]N=2.5*10^25[/math] molecules

4.

A real gas most closely approaches the behavior of an ideal gas under conditions of

- low P and T.
- STP.
- high P and low T.
- high P and T.
- low P and high T.

5.

Suppose a car tire were inflated to a gauge pressure of 32 psi (absolute pressure is therefore 46.7 psi) at [math]30degC[/math]. The car is parked in the street as a cold front hits over night, and the temperature drops to [math]5degC[/math]. What is the new gauge pressure in the tire?

- [math]P_1T_2=P_2T_1[/math]

[math]46.7"psi"*278degK=P_2*303degK[/math]

[math]P_2=[(12982.6"psi"degK)]/(303degK)[/math]

[math]P_2=42.84"psi"[/math]

[math]P_2" of the gauge"=42.84"psi"-14.7"psi"=28.1"psi"[/math]

6.

Gay-Lussac's Law states that the pressure of a gas is directly proportional to the absolute temperature for a fixed mass of gas held at a constant volume.

- True
- False

7.

The ideal gas law predicts that the molar volume (volume of one mole) of gas equals

- (MW)P/RT.
- gRT/PV.
- RT/P.
- 1/2ms-2.
- 22.4 L at any temperature and pressure.

8.

According to Boyle's Law, in a gas at a constant temperature, the change in pressure is inversely proportional to to the change in volume. This relationship can be expressed as an equation, [math]P_1//P_2=V_2//V_1[/math]. If 250mL of a gas, at a pressure of 214mmHg and a constant temperature, is forced into a 105mL rigid container, what will the final pressure be in mmHg?

- [math]P_1V_1=P_2V_2[/math]

[math]214mmHg*0.250L=P_2*0.105L[/math]

[math]P_2=(53.5L*mmHg)/(0.105L)[/math]

[math]P_2=509.52mmHg[/math]

9.

Which property of fluids accounts for why a gas will expand to fill any container, thereby changing the pressure and temperature?

- viscosity
- compressibility
- expandabilty
- hydrostatics

10.

Under conditions of fixed volume and amount of gas, Gay-Lussac's law requires that

I. [math]P_1T_2=P_2T_1[/math].

II. PT = constant.

III. [math]P_1/T_1=P_2/T_2[/math].

I. [math]P_1T_2=P_2T_1[/math].

II. PT = constant.

III. [math]P_1/T_1=P_2/T_2[/math].

- I only
- II only
- III only
- I and III
- I, II, and III

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