Question

A flask of known volume was filled with air to a pressure of 3.6atm. This flask was then attached to an evacuated flask of known volume and the air was allowed to expand into the flask. The final pressure of the air (in both flasks) was 2.7atm and the volume of the second flask was 4.9L. Calculate the volume of the first flask.

I understand this is Boyle's Law, but I keep getting 3.6375L. However the real answer is ~14.7L. Dividing the real answer by the answer I got is exactly 4. I do not understand the concept of evacuated flask, as my intro Chemistry teacher never taught me that, nor my current Chemistry teacher.

Answer 1

p₁ v₁ = p₂ v₂

3.6 * v = 2.7 * (v + 4.9)

.9 v = 2.7 * 4.9 ... v = 14.7


the evacuated flask means that no additional air was introduced into the system ... just a volume increase with a corresponding pressure decrease

Answer 2

How did the left side of the equation went from 3.6*V to .9V?

Answer 3

distributing on the right
... 3.6 v = 2.7 v + (2.7 * 4.9)

subtracting 2.7 v
... .9 v = 2.7 * 4.9

Answer 4

p₁ v₁ = p₂ v₂

3.6 * v = 2.7 * (v + 4.9)
<b>You are right to here. The next step you failed to multiply every thing inside the parentheses by 2.7.
3.6v = 2.7v + (2.7*4.9)
3.6v = 2.7v + 13.2
3.6v-2.7v = 13.2
0.9v = 13.2
v = 14.66 which rounds to 14.7</b>