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Here is the problem (Concerning Avogadro's law):
When 0.15 moles of helium gas are added to a piston containing 0.82 moles of another gas, by what percent does the total volume increase?
A. 6.4%
B. 14.4%
C. 18.3%
D. 25.0%
My issue isn't with figuring out how to do this problem, it is with the explanation provided in the book. My method was just to compare the relative change in number of moles, and knowing that Volume was directly proportional, determine the percent increase. (In other words, 0.82/0.15 ~ .18) I of course approximated this value from the choices given and from the fact that 0.15 * 5 = .75, therefore 0.15 must be multiplied by a little over 5 and the actual value would be a little less than 20% (because the 5 would indicate an increase of 20%, a slightly larger factor would indicate slightly less than this 20%).
Anyway, the method in the book says this:
V1/n1 = V2/n2 *therefore* V2/V1 = n2/n1 ---> V2/V1 = 0.97/0.82,
So, n2/n1 = 0.97/0.82
[so far so good, but then:]
0.97/0.82 = (0.97 + 0.194)/(0.82 + 0.164) = 1.164/0.984 ~ 1.18
(The answer, again, is ~18% so they achieved the correct answer)
Where the hell did the +0.194/+0.164 come from?
I noticed this guy had the same issue, but didn't get any answers, so I decided to make a new thread with the whole problem. I'm sure it's a simple explanation but I couldn't figure it out and it was bothering me. Anyone know what's going on here?
Thanks in advance!
When 0.15 moles of helium gas are added to a piston containing 0.82 moles of another gas, by what percent does the total volume increase?
A. 6.4%
B. 14.4%
C. 18.3%
D. 25.0%
My issue isn't with figuring out how to do this problem, it is with the explanation provided in the book. My method was just to compare the relative change in number of moles, and knowing that Volume was directly proportional, determine the percent increase. (In other words, 0.82/0.15 ~ .18) I of course approximated this value from the choices given and from the fact that 0.15 * 5 = .75, therefore 0.15 must be multiplied by a little over 5 and the actual value would be a little less than 20% (because the 5 would indicate an increase of 20%, a slightly larger factor would indicate slightly less than this 20%).
Anyway, the method in the book says this:
V1/n1 = V2/n2 *therefore* V2/V1 = n2/n1 ---> V2/V1 = 0.97/0.82,
So, n2/n1 = 0.97/0.82
[so far so good, but then:]
0.97/0.82 = (0.97 + 0.194)/(0.82 + 0.164) = 1.164/0.984 ~ 1.18
(The answer, again, is ~18% so they achieved the correct answer)
Where the hell did the +0.194/+0.164 come from?
I noticed this guy had the same issue, but didn't get any answers, so I decided to make a new thread with the whole problem. I'm sure it's a simple explanation but I couldn't figure it out and it was bothering me. Anyone know what's going on here?
Thanks in advance!