Ok, Im stuck half way through this problem. heres what i got:(adsbygoogle = window.adsbygoogle || []).push({});

a hyopthetical substance A_2 reacts with B_2:

3 A_2 + 4 B_2 --> 2 A_3 B_4

delta H = ??? kcal/mole A_2

1 mole of A = 56.4g

1 mole of B = 29.6g

when 15.6g of A_2 and an excess of B_2 react in a calorimeter that contains 0.00186 mL of water, the water temp changes from 23/5 celsius to 86.7 celsius. What is the delta H of the reaction in kcal/mole?

I approached this by first solving for q , then divide it by mole. But im not sure if i solved for the mole correctly because i multiplied 56.4g by 6 since its "3 A_2". Also, after i get the answer, am i suppose to divide it by 3 because in the reaction, the coefficient for A_2 was 3, that doesn't match with what the answer wanted, which is kcal/ mole A_2. (coefficient is 1) Any help?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Calorie Problem

**Physics Forums | Science Articles, Homework Help, Discussion**