Question

How much heat is needed for the decomposition of 168.4 g of sodium nitride into nitrogen and sodium? Your answer should have 4 significant figures in it make sure you include a positive or negative symbol as a part of your answer.

2Na3N ---> N2 + 6Na. \DeltaΔH = +42.7 kJ



Use 14.01 g/mol = N

Use 22.99 g/mol= Na

Answer 1

+43.32 kJ

Step-by-step explanation:

Step 1: Write the thermochemical equation for the decomposition of sodium nitride

2 Na₃N ⇒ N₂ + 6 Na ΔH = +42.7 kJ

Step 2: Calculate the moles corresponding to 168.4 g of Na₃N

The molar mass of Na₃N is 82.98 g/mol.

168.4 g × 1 mol/82.98 g = 2.029 mol

Step 3: Calculate the heat needed for the decomposition of 2.029 moles of Na₃N

According to the thermochemical equation, 42.7 kJ are required for the decomposition of 2 moles of Na₃N. The heat needed for the decomposition of 2.029 moles of Na₃N is:

2.029 mol × 42.7 kJ/2 mol = 43.32 kJ