Calculating the number of moles in nitrogen?

Question

Calculate the number of moles of nitrogen collected.
n= PV/RT
P= Patm -Ph2o - (23.5/13.6)
V=28.5 ml .0285L
R= .082
T = 22c 295.15K

I keep getting a negative number for P is this right.


formula given for P
(760 mmHg/ 1) x (1 atm/ 760 mmHg) - (Ph2o in torr/ 1) x (1 atm/ 760 mmHg) - ( height of bubble 23.5 cm h2o/ 1) x (760mmHg/ 13.6 cm h2o) x (1atm/ 760mmHg) =
Report It

Answer 1

P = 1 atm - (PH2O where PH2O is the vapor pressure of water) - effect of the pressure of 23.5 cm water.

At least,I think that's what the formula is trying to tell you.

23.5 cm water have the same effect as 23.5/13.6 cm Hg because the density of mercury is 13.6

I wonder if you multiplied by 13.6 when you should have divided.

With problems like this, it helps to ask yourself what each term in the equation means, and then tackle the bits one at a time.

Hope this helps. Good luck!