Chemistry problem involving gas laws

In summary, a 2.80g sample of an unknown chlorofluorocarbon decomposed to produce 552mL of chlorine gas at a pressure of 756 mmHg and a temperature of 298K. Using the PV=nRT equation, it was found that the molar mass of the unknown compound was 124.69 g/mol. However, when trying to solve for the mass percent of chlorine using an algebraic equation, the answer obtained was incorrect. To determine the correct mass of chlorine, the molar mass and number of moles of chlorine were used. It was determined that there were 0.02245 mol of chlorine in the sample, which is equivalent to 0.789 g of chlorine
  • #1
MellowOne
44
0
A 2.80g sample of an unknown chlorofluorocarbon is decomposed and produces 552mL of chlorine gas at a pressure of 756 mmHg and a temperature of 298K.
What is the percent chlorine (by mass) in the unknown chlorofluorocarbon? PV= nRT
D= m/vOk, so for this problem I tried using the PV=nRT (756*.552=n*62.364*298) equation to solve for n and I got 0.02245 mol. And from that, I figured the molar mass was 124.69 g/mol (having used the mass of 2.80 to derive this answer). And then I tried to set up an algebraic equation with variables to solve for the mass percent. I used the equation (1-x)(31.008) + 35.45x = 124.69. The (1-x) represents the Carbon and Fluorine components of the compound, and the 31.008 is their combined molar mass. The 35.45 is the molar mass of Clorine, and by solving this equation i got 21.09, but this was incorrect. So what should i do?
 
Last edited:
Physics news on Phys.org
  • #2
How many grams of chlorine are in 0.02245 mol of Cl2?

Compare that to 2.80 g.
 
  • #3
but we don't know how many grams we have of chlorine...?
 
  • #4
You know how many moles and how many grams/mole for chlorine. Use that.
 
  • #5
okay thank you i got it!
 

1. What are the basic gas laws in chemistry?

The basic gas laws in chemistry are Boyle's law, Charles's law, Gay-Lussac's law, and the combined gas law. Boyle's law states that at a constant temperature, the volume of a gas is inversely proportional to its pressure. Charles's law states that at a constant pressure, the volume of a gas is directly proportional to its temperature. Gay-Lussac's law states that at a constant volume, the pressure of a gas is directly proportional to its temperature. The combined gas law combines all three laws and states that the pressure, volume, and temperature of a gas are all related to each other.

2. How do I calculate gas pressure?

To calculate gas pressure, you can use the equation P = nRT/V, where P is pressure, n is the number of moles of gas, R is the gas constant, T is the temperature in Kelvin, and V is the volume of the gas. Make sure to use consistent units for all variables in the equation.

3. What is the ideal gas law?

The ideal gas law is a combination of all the basic gas laws and is represented by the equation PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is the temperature in Kelvin. This law assumes that gases behave ideally, meaning they have no intermolecular forces and occupy no volume.

4. How does temperature affect gas pressure?

According to Charles's law, temperature and volume are directly proportional, so an increase in temperature will result in an increase in volume. This increase in volume causes an increase in the number of collisions between gas particles and the walls of the container, resulting in an increase in pressure. Therefore, as temperature increases, gas pressure also increases.

5. What is the difference between an ideal gas and a real gas?

An ideal gas is a hypothetical gas that follows the ideal gas law under all conditions, while a real gas deviates from the ideal gas law at high pressures and low temperatures. This is because real gases have intermolecular forces and occupy a small volume, whereas ideal gases do not. Real gases also follow different gas laws, such as the Van der Waals equation, to account for these deviations.

Similar threads

Chemistry Ideal Gas Law and Partial Pressures
    • Biology and Chemistry Homework Help
Replies
16
Views
2K
Calculating Mass in a Gas Stoichiometry Problem
    • Biology and Chemistry Homework Help
Replies
3
Views
1K
Incompatibility between ideal gas equations of state
    • Introductory Physics Homework Help
Replies
2
Views
722
Ideal Gas Law and Pressure at 80°C
    • Introductory Physics Homework Help
Replies
2
Views
2K
Chemistry Finding the molecular formula of an unknown hydrocarbon
    • Biology and Chemistry Homework Help
Replies
4
Views
1K
Henry's Law: Solving for Water Needed to Dissolve 1.48L of Gas
    • Biology and Chemistry Homework Help
Replies
3
Views
2K
Solve a Gas Law Problem: Find T in °C
    • Biology and Chemistry Homework Help
Replies
7
Views
2K
How Does the Ideal Gas Law Apply to Chemical Reactions?
    • Biology and Chemistry Homework Help
Replies
2
Views
4K
Calculating Mass Percent of Aluminum in a Sample Using Ideal Gas Law
    • Biology and Chemistry Homework Help
Replies
5
Views
1K
Question about Ideal Gas Law
    • Biology and Chemistry Homework Help
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top