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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: rj1027 on September 25, 2004, 02:51:43 PM

Title: Hess's law
Post by: rj1027 on September 25, 2004, 02:51:43 PM

Glucose and fructose are simple sugars with molecular formulas of C6H12O6. Sucrose has a molecular formulaof C12H22O11. If a sugar cube weighs 2.5g how high can aperson weighing 143lbs cimb on one cube of sugar if 25% is converted into work?
What i have doen is
H=Q/mg
where q is direct relation to the number of joules instead of heat.
I understand using Hess's law. But do i use combustion since i am breaking the sugar down?
I feel that i am almost complete with this question, i just need some help converting 2.5g of sucrose to calories. From this i can convert the calories to Joules.

Title: Re:Hess's law
Post by: Demotivator on September 25, 2004, 04:47:14 PM

Yes, use combustion for sucrose. From hess law, the energy per mole of sucrose can be determined, then per 2.5 g determined. According to the problem, the body can convert 25% of the total energy as the work needed for climbing. The rest is heat and is not used.