Molar Mass Problem

  • #1
104
0

Homework Statement



2 A + 3 B + 1000 kJ ==> 4 C

where A,B,C are molecules. A mass of 35.5 g of A is used with the right quantity of B, and the mixture of reactants is heated with an energy of 750 kJ. Find the molar mass of A.

2. The attempt at a solution

Heat released per mole in terms of "A" : 1000 kJ / 2 = 500 kJ/mole "A"

Finding number of moles used:

(750 kJ) / (500 kJ/mole) = 1.5 mol "A"

Molar mass = (35.5 grams) / (1.5 mol) = 23.7 g/mol
 

Answers and Replies

  • #2
Borek
Mentor
28,825
3,343
Your approach looks OK, but the question is poorly worded - it doesn't say anything about whether there was enough heat to react all of A.
 

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