Question

What is true for the following reaction? Ca(s) + 2C(s) CaC2(s) + 62.8 kJ

a)It is an endothermic reaction and ∆H= +62.8 kJ.

b)It is an endothermic reaction and ∆H= -62.8 kJ

c)It is an exothermic reaction and ∆H= +62.8 kJ.

d)It is an exothermic reaction and ∆H= -62.8 kJ

Answer 1

hmm.. i assume the -> is in between 2C(s) and CaC2(s) ?
so the equation is...
Ca(s) + 2C(s) -> CaC2(s) + 62.8 kJ
if it is. then it would be
d) It is an exothermic reaction and ∆H= -62.8 kJ
because the heat is located in the products
and if u look at ur chemistry reference table I
you can see on the bottom it says * A MINUS SIGN INDICATES AN EXOTHERMIC REACTION *
so if its an exothermic reaction the heat will always have a minus sign :D
hope that helped!! XD