A chemist measures the energy change AH during the following reaction: 2H2O(l) ?

Question

A chemist measures the energy change AH during the following reaction: 2H2O(l) ?2H2(g)+02(g) &H-572.; kJ Use the information to answer the following questions. 7-10 This reaction is... O exothermic O Yes, absorbed. O Yes, released. O No. Suppose 82.5 g of H20 react Will any heat be released or absorbed If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed. 1310 ? Be sure your answer has the correct number of significant digits.

Explanation / Answer

1)
since ?H is positive, the reaction is endothermic
Answer: endothermic

2)
Reaction is endothermic
SO, heat is being absorbed
Answer:
yes, absorbed

3)

Molar mass of H2O = 2*MM(H) + 1*MM(O)
= 2*1.008 + 1*16.0
= 18.016 g/mol


mass of H2O = 82.5 g

we have below equation to be used:
number of mol of H2O,
n = mass of H2O/molar mass of H2O
=(82.5 g)/(18.02 g/mol)
= 4.579 mol
Since delta H is positive, heat is absorbed
when 2 mol of H2O reacts, heat absorbed = 572.0 KJ
So,
for 4.579 mol of H2O, heat absorbed = 4.579*572.0/2 KJ
= 1.31*10^3 KJ
Answer: 1.31*10^3 KJ

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