28°C. Explanation: The correct equation to use with these kinds of questions is the Combined Gas Law. P 1 ⋅ V 1 T 1 = P 2 ⋅ V 2 T 2 This equation, though, is a little unnecessary at times because of the possibility of extra constants. In this case you have a pressure constant which enables us to shorten your longer equation down to Charles' Law because pressure remains the same and doesn't affect the calculation. V 1 T 1 = V 2 T 2 The next step is to isolate the variable that you want, which is, in this case, T 2 . T 2 = V 1 T 1 V 2 Now it is time to replace your known variables with numbers T 2 = 350 m L ⋅ 45 ° C 400 m L And calculate... T 2 = 28.125 ° C Significant digits... T 2 = 28 ° C
