Dalton's Law of Partial Pressures: Understanding the Concept
Dalton’s Law, also known as the Law of Partial Pressures, is a fundamental concept in chemistry that describes the relationship between the partial pressures of individual gases in a mixture and the total pressure of the mixture. In this article, we will delve into the details of Dalton’s Law, its significance, and provide a worksheet with answers to help you better understand the concept.
What is Dalton's Law?
Dalton’s Law states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of each individual gas in the mixture. Mathematically, this can be expressed as:
Ptotal = P1 + P2 + P3 +… + Pn
where Ptotal is the total pressure of the mixture, and P1, P2, P3,…, Pn are the partial pressures of each individual gas.
Understanding Partial Pressure
Partial pressure is the pressure exerted by a single gas in a mixture. It is a measure of the contribution of each gas to the total pressure of the mixture. The partial pressure of a gas can be calculated using the following formula:
Pgas = (n/V)RT
where Pgas is the partial pressure of the gas, n is the number of moles of the gas, V is the volume of the container, R is the gas constant, and T is the temperature in Kelvin.
Worksheet: Dalton's Law Partial Pressure Problems
Problem 1: A mixture of oxygen and nitrogen gases is contained in a 10 L tank at 25°C. The partial pressure of oxygen is 2 atm, and the partial pressure of nitrogen is 1 atm. Calculate the total pressure of the mixture.
Solution:
Ptotal = P1 + P2 Ptotal = 2 atm + 1 atm Ptotal = 3 atm
Problem 2: A gas mixture contains 2 moles of hydrogen gas, 3 moles of helium gas, and 4 moles of oxygen gas in a 5 L container at 30°C. Calculate the partial pressure of each gas and the total pressure of the mixture.
Solution:
PH2 = (2⁄5)RT = (2⁄5)(0.0821)(303) = 1.23 atm PHe = (3⁄5)RT = (3⁄5)(0.0821)(303) = 1.84 atm PO2 = (4⁄5)RT = (4⁄5)(0.0821)(303) = 2.45 atm
Ptotal = PH2 + PHe + PO2 Ptotal = 1.23 atm + 1.84 atm + 2.45 atm Ptotal = 5.52 atm
Problem 3: A mixture of carbon dioxide and water vapor is contained in a 2 L tank at 40°C. The total pressure of the mixture is 2.5 atm, and the partial pressure of carbon dioxide is 1.2 atm. Calculate the partial pressure of water vapor.
Solution:
PH2O = Ptotal - PCO2 PH2O = 2.5 atm - 1.2 atm PH2O = 1.3 atm
Notes
🔍 Note: Dalton's Law assumes that the gases in the mixture do not interact with each other, which is not always the case in real-world scenarios.
📝 Note: When calculating partial pressures, make sure to use the correct units for the gas constant (R) and temperature (T).
FAQ Section
What is the significance of Dalton's Law?
+Dalton's Law is significant because it allows us to calculate the total pressure of a gas mixture and the partial pressure of each individual gas, which is essential in various fields such as chemistry, physics, and engineering.
How does temperature affect partial pressure?
+Temperature affects partial pressure by increasing the kinetic energy of the gas molecules, which in turn increases the pressure exerted by each gas.
Can Dalton's Law be applied to all gas mixtures?
+No, Dalton's Law assumes that the gases in the mixture do not interact with each other, which is not always the case in real-world scenarios. Therefore, it is not applicable to all gas mixtures.
In summary, Dalton’s Law is a fundamental concept in chemistry that describes the relationship between the partial pressures of individual gases in a mixture and the total pressure of the mixture. Understanding partial pressure and how to calculate it is crucial in various fields, and the worksheet provided above should help you practice and reinforce your knowledge of Dalton’s Law.
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- Partial pressure Worksheet With answers
