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Gas Laws. Advanced Problem Solving. Dalton’s Law.

Gas Laws

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Gas Laws

Advanced Problem Solving

- An apparatus consists of a 4.0L flask containing nitrogen gas at 25 C and 803 kPa joined by a valve to a 10.0L flask containing argon gas at 25 C and 47.2 kPa. The valve is opened and the gases mix. (a) what is the partial pressure of each gas after mixing? B) what is the total pressure of the gas mixture.

Hint 1: Dalton’s law says that you can treat each gas individually.

Hint 2: Treat as two different problems, one for each gas.

Hint 3: Then add to get total pressure.

10.0L

25 C

47 kPa

4.0L

25 C

803 kPa

What is the partial pressure of Nitrogen?

A) 321kPa B) 850 kpa C) 47 kPa D) 229 kPa E) none of the above

4.0L

25 C

803 kPa

10.0L

25 C

47.2 kPa

- An apparatus consists of a 4.0L flask containing nitrogen gas at 25 C and 803 kPa joined by a valve to a 10.0L flask containing argon gas at 25 C and 47.2 kPa. The valve is opened and the gases mix. (a) what is the partial pressure of each gas after mixing? B) what is the total pressure of the gas mixture.

- Dinitrogen oxide gas was generated from the thermal decomposition of ammonium nitrate and collected over water. The wet gas occupied 126 mL at 21 C when the atmospheric pressure was 755 Torr. What volume would the same amount of dry Dinitrogen oxide have occupied if collected at 755 Torr and 21 C. The vapor pressure of water is 18.65 Torr at 21 C.

Hint 1: If the total pressure is 755 Torr, what is the pressure of N2O?

Hint 2: How do you determine the volume of a gas at a new pressure?

What is the volume of dry gas?

A) 126 mL B) 736 torr C) 129 mL D) 123 mL E) none of the above

- A 115 mg sample of eugenol, the compound responsible for the odor of cloves, was placed in an evacuated flask with a volume of 500.0 mL at 280.0 C. The pressure that eugenol exerted in the flask under those conditions was found to be 48.3 torr. In a combustion experiment, 18.8 mg of eugenol burned to give 50.0 mg of carbon dioxide and 12.4 mg of water. What is the molecular formula of eugenol?

Hint 1: Due to the combustion reaction, it must be all CxHyOz. Find the empirical formula, and therefore empirical mass as in fundamental sections.

Hint 2: You know grams of eugenol, so if you know the T, V, and P you can find moles. Can you use grams and moles to find molecular mass? (hint what are the units on molecular mass).

Density, Molar mass and Ideal Gas Law

(likely won’t get to this one, answers online if we don’t)

- The density of a gaseous compound was found to be 0.943 g/L at 298K and 53.1 kPa. What is the molar mass of the compound?

Hint1 :

you have g/L

You want g/mol

What units will cancel the L and give you mol?

Hint 2: Can you get that (hint 2.a, maybe by using the ideal gas law)