Calculate the amount of heat (in kJ) released when 18.5 g or calcium hydroxide is formed. The molar mass of calcium hydroxide is 74.09g

CaO (s) + H2O (I) - > Ca (OH) 2 (s) + 65.2 kJ

A. 16.3 kJ

B 260.8 kJ

C 130.4 kJ

D 4.18 kJ

16.23 kj

Explanation:

Given dа ta:

Mass of calcium hydroxide formed = 18.5 g

Molar mass of calcium hydroxide = 74.09 g/mol

Energy released = ?

Solution:

Chemical equation:

CaO + H₂O → Ca (OH) ₂ + 65.2 Kj

Number of moles of Ca (OH) ₂:

Number of moles = mass / molar mass

Number of moles = 18.5 g / 74.09 g/mol

Number of moles = 0.249 mol

when one mole of Ca (OH) ₂ formed 65.2 Kj energy is released.

When 0.249 moles formed energy released is,

0.249 * 65.2 kj = 16.23 kj