I obtained 0.0001876 for (1/259 - 1/247) which I left in the calculator. Your 0.00018 is not rounded correctly; however, that alone will not make that much difference. Then x 24900 and divide by 8.314 and I have 0.56179 (which I leave in the calculator) but I would round that to 0.562. The difference in our answers here probably is just due to the 18 vs 19 used for the initial subtraction. Now, why did you take the square root? There is no square root sign anywhere in the equation. At this point we have something like
ln(p2/368.3) = 0.562.
You have 0.562 in the calculator (or whatever is in there at this point), just punch the ex button. That gives something like 1.75 or so (you use your real numbers) so
ln(p2/368.3) = 0.562; punch ex to obtain (note the ln disappears)
(p2/368.3) = 1.75
p2 = 368.3 x 1.75 = ?
ln p2/368.3 mm Hg = -24900 J/mol / 8.314 J/k mol [1/259.7K - 1/247.4K]
I am having trouble doing the mathto solve for p2.
Chemistry - DrBob222, Sunday, February 5, 2012 at 12:44pm
The easy way is to calculate 1/259 = ? and 1/247 = ?, then subtract them and multiply that by -24900 and divide by 8.314.
That gives you an expression that looks like this.
ln p2/368.3 = a number
Then, making sure the number is punched into the calculator, hit the e^x button which then becomes p2/368.3 = the e^x value. Then solve for p2.
Chemistry - Hannah, Sunday, February 5, 2012 at 10:10pm
For some reason on my computer the answer that was posted was sort of cut of so I had a hard time reading it but when I did 1/259 - 1/247 I got -0.00018 then I multiplied by -24900 and divided by 8.314 and got 0.539.
Then I took the sqrt of this number and ended up with p2/368.3 = 0.734. Did I do this correctly so far?
2 answers
Ok thank you. I know what I was doing wrong. I was just hitting the e^x button and I was getting a different answer. I have to hit the 2nd button first and then e^x on my calculator.