CHEM Calculating the number of moles

Question

A flexible container at an initial volume of 5.12 L contains 7.51 mol of gas. More gas is then added to the container until it reaches a final volume of 17.9 L. Assuming the pressure and temperature of the gas remain constant, calculate the number of moles of gas added to the container.

Answer 1

With pressure (P) and temperature (T) constant ypu are left with n (moles) and volume (V) as the remaining variables. V1/n1 = v2/n2. This can be derived from PV = nRT.

5.12 L/7.51 mol = 17.9 L/x mol

solve for x to get moles