Question

How much heat is required to decompose 25.5 grams of NaHCO3? 2NaHCO3(s) + 129 kJ 2Na2CO3(s) + H2O(g) + CO2(g)
129 kJ
39.2 kJ
19.6 kJ
1050 kJ

Answer 1

Answer ⇒ 19.6 kJ.

Explanation and Solution ⇒

We know, For the Sodium Hydrogen Carbonate, heat required to decompose 2 moles of it is 129 kJ.

∴ For 1 mole of the sodium hydrogen carbonate, heat required to decompose it is 129 /2 kJ = 64.5 kJ.

Now, Let us calculate the number of moles of the Sodium Hydrogen Carbonate in the 25.5 grams of it.

Molar Mass of the Sodium Hydrogen Carbonate = 84 g/mol.

∴ No. of moles of NaHCO₃ = Mass/Molar mass
 = 25.5/84
 = 0.304 mole.

Now, 
∵ For 1 mole , heat required for the decomposition is 64.5 kJ.
∴ For 0.304 mole, heat required for the decomposition is 64.5 × 0.304 kJ.
 = 19.608 kJ.
 ≈ 19.6 kJ.


Hence, the heat energy required for the decomposition of the sodium hydrogen carbonate of mass 25.5 grams is 19.6 kJ.


Hope it helps.