Chemistry problem involving gas laws

  • Thread starter MellowOne
  • Start date
  • #1
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/v


Ok, 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:

Answers and Replies

  • #2
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,133
160
How many grams of chlorine are in 0.02245 mol of Cl2?

Compare that to 2.80 g.
 
  • #3
44
0
but we don't know how many grams we have of chlorine...?
 
  • #4
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,133
160
You know how many moles and how many grams/mole for chlorine. Use that.
 
  • #5
44
0
okay thank you i got it!
 

Related Threads on Chemistry problem involving gas laws

  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
1
Views
9K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
1
Views
2K
Replies
1
Views
3K
  • Last Post
Replies
1
Views
5K
  • Last Post
Replies
1
Views
6K
Top