Answer to Question #170402 in Chemistry for Ava Brooke

Question

How much nickel in grams is required to release 215 kJ of heat?

5 Ni + 2 P -> Ni₅P₂  

△ H

 = 436 kJ/mol

Answer 1

Solution:

The balanced thermochemical equation:

5Ni + 2P → Ni₅P₂, △H = 436 kJ/mol

 

The equivalences for this thermochemical equation are:

5 mol Ni ⇔ 2 mol P ⇔ 1 mol Ni₅P₂ ⇔ 436 kJ/mol

 

Using the thermochemical equation to determine the moles of nickel (Ni):

215 kJ × (5 mol Ni / 436 kJ) = 2.4656 mol

Mass of Ni = Moles of Ni × Molar mass of Ni

Molar mass of Ni is 58.6934 g mol^-1.

Hence,

Mass of Ni = 2.4656 mol × 58.6934 g mol^-1 = 144.714 g = 144.7 g

Mass of Ni = 144.7 g

Answer: 144.7 grams of nickel (Ni) is required to release 215 kJ of heat.