Two 5dm^3 flasks are connected by a narrow tube of negligible volume. Initally the two flasks are both at 300K and contain a total of 2 moles of an ideal gas. One flask is heated to a uniform temperatiure of the 400K while the other is kept at 300K. Assuming their volume does not alter , calculate the no. of moles of gas in each flask of the gas and the final pressure.
I was stuck on this for ages until I finally decided to try it by assuming the pressures were equal. However why is the pressure equal in each flask of gas.