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How much heat is released in the explosion 28 liters (cn) mixture of hydrogen and oxygen molar ratio of 3:1, with the formation of H2O (g)?A. 75.5 kJ B. 178 kJ C. 201 kJ D. 302 kJ E. answers A-D do not correspond

Posted in Chemistry, asked by Diana, 6 years ago. 2089 hits.
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Let us assume 3x amounts of Hydrogen and x amounts of Oxygen is present in the mixture.

So 4x = 28 L

=> x = 7 L

So we have 7 L of oxygen and 21 L of Hydrogen


Balanced reaction equation : 2H+ O2 ---------> 2H2O

So for a perfectly balanced reaction, the molar ratio of H2 to O2 needs to be 2:1.

And for gases, their molar ratio is same as their volumetric ratio.

Therefore, the ratio available is 3:1. Thus Hydrogen is present in excess and Oxygen is the limiting reagent.

Assuming STP conditions :

Moles of Oxygen present = 7/22.4 = 0.3125 moles

Standard Heat of formation of 1 mole H2O(g) = -241.82 kJ/mol


According to balanced reaction, 1 mole of Oxygen produces 2 moles of H2O (g)

So, 0.3125 moles of oxygen will produce, 2*0.3125 = 0.625 moles of H2O(g)


Heat of formation = 0.625*241.82 = 151.1375 kJ


The correct answer is 151.1375 kJ which does not correspond to any option.

Piyush Chauhan
Piyush Chauhan - 5 years ago
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