Using the provided data, calculate the standard entropy at 25 °C for magnesium fluoride. O2(g) + 2 MgF2(s) → 2 MgO(s) + 2 F2(g) ∆S°rxn = 140.76 J/K Solution: ΔS= S of products - reactants ΔS= (2(26.78)+2(203.34))-(205.0+2X)= 140.76J/K X= 57.24J/mol LINKS: General Chemistry Tutoring General Chemistry Study Guides LearnWithMayya

Consider the reaction for the decomposition of carbon tetrachloride gas: CCl4(g) → C(s, graphite) + 2 Cl2(g) ΔH rxn = +95.7 kJ; ΔS rxn = +142.2 J/K Calculate ΔG rxn at 25 °C and determine whether the reaction is spontaneous. Solution: ΔG=ΔH-TΔS First of all we notice that the unirs for ΔH and ΔS are different. We will convert ΔH from kJ into J by multiplying by 1000. ΔH= 95.7kJ(1000J/1kJ) = 95700J. We also need to convert temperature from Celcius to K. 25°C+273= 295K Now we