The standard enthalpy of formation for sulfur dioxide gas is #"-296.8 kJ/mol"#. Calculate the amount of energy given off in #"kJ"# when #"30.0 g"# of #"SO"_2 "(g)"# is formed from its elements?

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Answer 1 · 2018-05-13T01:47:47

#139.125\ "kJ"#

Standard enthalpy of formation is the energy released/required to prepare #1# mol of compound from its elements.

#30.0\ "g SO"_2 = "30 g"/"64 g/mol" = "0.46875 mol"#

For #"0.46875 mol"# of #"SO"_2# energy released is

#0.46875 cancel"mol" × -296.8\ "kJ"/cancel"mol" = 139.125\ "kJ"#