Question #bf193

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Answer 1 · 2015-03-27T18:42:20

You must burn 110.5 g of octane.

You know that 1 mol of octane liberates 5471 kJ of heat.

To liberate 5290 kJ of heat, the mass of octane must be

#5290 cancel("kJ") × (1 cancel("mol C₈H₁₈"))/(5471 cancel("kJ")) × "114.23 g"/(1 cancel("mol C₈H₁₈")) = "110.5 g C₈H₁₈"#

Answer 2 · 2015-03-27T18:42:31

#110.2g# is required.

#C_8H_18+12(1)/(2)O_2rarr8CO_2+9H_2O#

#DeltaH_c=-5471"kJ"#

#M_r=114#

So #5471"kJ"# is produced by #114g#

So #1"kJ"# is produced by #(114)/(5471)g#

So #5290"kJ"# is produced by #(114)/(5471)xx5290=110.2"kJ"#