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Ch.8 Gases
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
All textbooksTimberlake 13th EditionCh.8 GasesProblem 78a
Chapter 8, Problem 78a

A mixture of nitrogen (N2) and helium has a volume of 250 mL at 30 °C and a total pressure of 745 mmHg.
a. If the partial pressure of helium is 32 mmHg, what is the partial pressure of the nitrogen?

Verified step by step guidance
1
Step 1: Recall Dalton's Law of Partial Pressures, which states that the total pressure of a gas mixture is the sum of the partial pressures of the individual gases. Mathematically, this is expressed as: Ptotal = PHe + PN₂, where Ptotal is the total pressure, PHe is the partial pressure of helium, and PN₂ is the partial pressure of nitrogen.
Step 2: Identify the given values from the problem. The total pressure of the gas mixture is 745 mmHg, and the partial pressure of helium is 32 mmHg.
Step 3: Rearrange Dalton's Law equation to solve for the partial pressure of nitrogen: PN₂ = Ptotal - PHe.
Step 4: Substitute the known values into the equation: PN₂ = 745 - 32 mmHg.
Step 5: Perform the subtraction to determine the partial pressure of nitrogen. The result will give you the value of PN₂ in mmHg.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Dalton's Law of Partial Pressures

Dalton's Law states that in a mixture of gases, the total pressure exerted is equal to the sum of the partial pressures of each individual gas. This principle allows us to calculate the pressure of one gas in a mixture if we know the total pressure and the partial pressures of the other gases present.
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Partial Pressure

Partial pressure refers to the pressure that a single gas in a mixture would exert if it occupied the entire volume alone at the same temperature. It is a crucial concept for understanding gas behavior in mixtures and is calculated using the formula: P_partial = P_total - P_other_gases.
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Gas Laws

Gas laws describe the relationships between pressure, volume, temperature, and the number of moles of a gas. In this context, understanding how these variables interact helps in solving problems related to gas mixtures, particularly when applying the ideal gas law or Dalton's Law.
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Related Practice
Textbook Question

In 1783, Jacques Charles launched his first balloon filled with hydrogen gas, which he chose because it was lighter than air. If the balloon had a volume of 31 000 L, how many kilograms of hydrogen were needed to fill the balloon at STP?

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Textbook Question

A weather balloon is partially filled with helium to allow for expansion at high altitudes. At STP, a weather balloon is filled with enough helium to give a volume of 25.0 L. At an altitude of 30.0 km and –35 ⁰C, it has expanded to 2460 L. The increase in volume causes it to burst and a small parachute returns the instruments to Earth.

b. What is the final pressure, in millimeters of mercury, of the helium inside the balloon when it bursts?

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Textbook Question

What is the total pressure, in millimeters of mercury, of a gas mixture containing argon gas at 0.25 atm, helium gas at 350 mmHg, and nitrogen gas at 360 Torr?

Textbook Question

At a restaurant, a customer chokes on a piece of food. You put your arms around the person's waist and use your fists to push up on the person's abdomen, an action called the Heimlich maneuver.

b. Why does it cause the person to expel the food item from the airway?