Calculate the standard free energy change for the combustion of methane at 25oC. Assume that all reactants and products are gases. Provide an answer correct to 3 significant figures. For example, if you calculate that the correct answer is 500.0 kJ, simply type "500" in the box without the quotation marks (") as part of your answer. If the answer is -500.0 kJ, simply type "-500" in the box without the quotation marks (") as part of your answer. If the answer is a positive value do not include the "+" as a part of your answer. Do not answer this question using scientific notation.