Question

Question #ce200

Answer 1

The reaction will release 159.0 kJ.

Explanation:

Given:

Balanced equation

Mass of `"SO"_2`

`ΔH_f`

Find:

Heat released

Strategy:

1. Use the molar mass to convert mass of `"S"` to moles of `"S"`.
2. Use the molar ratio from the equation to convert moles of `"S"` to moles of `"SO"_3`.
3. Use `ΔH_"f"` to calculate the heat released.

Solution:

1. Moles of `"S"`

`"Moles of S" = 6.44 color(red)(cancel(color(black)("g S"))) × "1 mol S"/(32.06 color(red)(cancel(color(black)("g S")))) = "0.2009 mol S"`

2. Moles of `"SO"_3`

`"2S" + "3O"_2 → "2SO"_3; ΔH_f = "-791.4 kJ"`

`"Moles of SO"_3 = 0.2009 color(red)(cancel(color(black)("mol S"))) × (color(red)(cancel(color(black)(2))) "mol SO"_3)/(color(red)(cancel(color(black)(2))) color(red)(cancel(color(black)("mol S")))) = "0.2009 mol SO"_3`

3. Heat released

`ΔH = 0.2009 color(red)(cancel(color(black)("mol SO"_3))) × "-791.4 kJ"/(2 color(red)(cancel(color(black)("mol SO"_3)))) = "-159.0 kJ"`

The reaction releases 159.0 kJ of heat.