How Does Gas Escape Affect Volume and Mass in Thermodynamics?

[fluidistic]

Homework Statement

A container contains 1g of O_2 at a pressure of 1 atm and temperature T_i=47°C. At a certain time, due to an escape of gas, the pressure is 5/8 atm and the temperature decreases to 27°C.
1)What is the volume of the container?
2)How much mass of O_2 has escaped?

Homework Equations

PV=NRT.

The Attempt at a Solution

1g of O_2 is worth 1/32 mol of O_2. Thus V=\frac{N_iRT_i}{P_i}. I took care of converting degrees celsius to kelvin, took 1atm =10⁵ pascal. This gave me V=8.31m^3.
While N_f = \frac{P_fV}{RT_f} \approx 208.25 mol which makes absolutely no sense. I should get less than 1/32, yet I get a number greater than 200. I don't know what I did wrong, I tried another approach leading to another inconsistency: N_f=1.5 N_i.

 

[I like Serena]

Let's see...

$$V_i={N_i R T_i \over P_i}={\frac 1 {32} \cdot 8.31 \cdot 320 \over 10^5}=8.31 \cdot 10^{-4} m^3$$
How did you get $V_i=8.31 m^3$?

 

[fluidistic]

Let's see...

$$V_i={N_i R T_i \over P_i}={\frac 1 {32} \cdot 8.31 \cdot 320 \over 10^5}=8.31 \cdot 10^{-4} m^3$$
How did you get $V_i=8.31 m^3$?

Hi! Thanks Misuse of calculator apparently. I must be extremely careful to put all parenthesis I think. I now get your result.
Number of moles in the end: 0.005 or about 1/200. Thus about 0.16 g of O_2.

 

[I like Serena]

Yeah, I thought as much.
And this is a problem with numbers that are "nice", so you can easily do it without calculator! ;)