When you add 0.857 g of sodium metal to an excess of hydrochloric acid, you find that 8910 J of heat are produced. What is the enthalpy of the reaction?

1 Answer
anor277
Sep 11, 2017

#DeltaH_"rxn"^@=-238.9*kJ*mol^-1#

Explanation:

We interrogate the reaction.....

#Na(s) + HCl(aq) rarr NaCl(aq) + 1/2H_2 + Delta#

#"Moles of sodium"=(0.857*g)/(22.99*g*mol^-1)=0.0373*mol#

And thus #DeltaH_"rxn"^@=(8910*J)/(0.0373*mol)=-238.9*kJ*mol^-1#, and we mean per mole of reaction as written.

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