I'm guessing you're asked to find the amount of sodium carbonate to evolve a specific amount of gas that meet the given conditions. The idea in solving for it seems good.
The only problem I can see is that when applying the ideal gas law, the gas constant has a value of . Notice the pressure units are in kilo-Pascals not in torr. I don't know whether or not your class takes this into consideration but I'd say the conversion is necessary as I don't think 1 kPa = 1 torr.