Question

Given the equation Si(s) + 2Cl2(g) → SiCl2(g) ?SiCl2(l) + 687 kJ, how much heat is produced when 106 g of Cl2 react?

Answer 1

Answer : The heat produced will be, 511.8 KJ

Explanation : Given,

Molar mass of
`Cl_2` = 71 g/mole

First we have to calculate the moles of
`Cl_2`

`\text{Moles of }Cl_2=\frac{\text{Mass of }Cl_2}{\text{Molar mass of }Cl_2}=(106g)/(71g/mole)=1.49mole`

Now we have to calculate the heat produced.

The balanced chemical reaction is,

`Si+2Cl_2\rightarrow SiCl_2`

From the balanced reaction, we conclude that

As, 2 mole of
`Cl_2` react to produces heat = 687 KJ

So, 1.49 mole of
`Cl_2` react to produces heat =
`(687KJ)/(2mole)* 1.49mole=511.8KJ`

Therefore, the heat produced will be, 511.8 KJ

Answer 2

no of moles of Cl2 = mass of Cl2 / molar mass of Cl2
= 106g / (35.4*2)g/mol
= 106g / 70.9 g/mol = 1.495 moles
the heat produced = no of moles of Cl2 * ΔHrxn/2mol Cl2
when we have ΔHrxn from the equation = + 687 KJ so,
by substitution:
= 1.495 mol * 687 KJ/2 mol Cl2
= 513.5 KJ