Question #ce200

1 Answer
Ernest Z.
Feb 25, 2016

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.

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