In a generic chemical reaction involving reactants A and B and products C and D,

Question

In a generic chemical reaction involving reactants A and B and products C and D, aA+bBcC+dD, the standard enthalpy Hrxn of the reaction is given by Hrxn=cHf(C)+dHf(D) aHf(A)bHf(B) Notice that the stoichiometric coefficients, a, b, c, d, are an important part of this equation. This formula is often generalized as follows, where the first sum on the right-hand side of the equation is a sum over the products and the second sum is over the reactants: Hrxn=productsnHfreactantsmHf where m and n represent the appropriate stoichiometric coefficients for each substance. Part A What is Hrxn for the following chemical reaction? CO2(g)+2KOH(s)H2O(g)+K2CO3(s) You can use the following table of standard heats of formation (Hf) to calculate the enthalpy of the given reaction. Element/ Compound Standard Heat of Formation (kJ/mol) Element/ Compound Standard Heat of Formation (kJ/mol) H(g) 218 N(g) 473 H2(g) 0 O2(g) 0 KOH(s) 424.7 O(g) 249 CO2(g) 393.5 K2CO3(s) 1150kJ C(g) 71 H2O(g) 241.8kJ C(s) 0 HNO3(aq) 206.6 Express the standard enthalpy of reaction to three significant figures and include the appropriate units.

Explanation / Answer

CO2(g)+2KOH(s) ----> H2O(g)+K2CO3(s)

DH0rxn = (1*DH0f,H2O + 1*DH0f,K2CO3)-(1*DH0f,CO2+2*DH0f,KOH)

       = (-241.8+1*-1150)-(1*-393.5+2*-424.7)

       = -149 Kj

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