# What fraction of the air molecules

1. Dec 1, 2011

### lalahelp

1. The problem statement, all variables and given/known data
What fraction of the air molecules in a house must be pushed outside while the furnace raises the inside temperature from 17.0° C to 28.0° C? The pressure does not change since the house is not 100% airtight.

2. Relevant equations
v2/v1=17+273/28+273
=.963

2. Dec 1, 2011

### Staff: Mentor

You've calculated the fraction that's left inside rather than the fraction that was pushed outside.

3. Dec 1, 2011

is it .037?

4. Dec 1, 2011

### Staff: Mentor

Is that a guess or do you have a reason to back up that number?

5. Dec 2, 2011

### lalahelp

its supposed to says 3.7 percent... I subtracted the 96.3 from 100

6. Dec 2, 2011

### Staff: Mentor

Then that's okay. Looks good.

7. Dec 2, 2011

### lalahelp

I put the answer but for some reason its still saying its incorrect?

8. Dec 2, 2011

### Staff: Mentor

Is there a particular answer format that the question requires? Is it finicky about significant digits?

9. Dec 2, 2011

### lalahelp

No and No... Im not sure why its doing this.

10. Dec 2, 2011

### Staff: Mentor

I don't know what else to suggest. I can't think of any other reasonable interpretation of 'fraction of the air molecules' that would lead to a different result.

11. Dec 2, 2011

### lalahelp

yeh, Thank you for your help, Im going to email my proffessor about the question

12. Dec 2, 2011

### Staff: Mentor

Another Homework Helper* has suggested that it is perhaps possible that the question is looking for (n28C-n17C)/n28C ("what fraction of the gas was pushed out") instead of (n28C-n17C)/n17C ("what fraction of the gas will be pushed out"). It would make a small but noticeable difference in the result.

* Thanks D H!

13. Dec 2, 2011

### lalahelp

Yes!!! that was correct Thank you D H!!!