2006 Practice Final Question 1

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2006 Practice Final Question 1

Postby TeaK1C » Sat Mar 05, 2016 11:37 am

In question 1 stating:

During exercise, fats react with water to produce fatty acids. The fatty acids are then converted to water and carbon dioxide, a reaction that releases energy. The body uses this energy to perform activities. A typical fatty acid, lauric acid (CH3(CH2)10COOH), has the same amount of carbon atoms as sucrose, a sugar (C12H22O11). The delta H for lauric acid = -774.6kj mol and the delta H for sucrose = -2225.8 kj mol
What mass of sucrose is needed to produce the same energy as 15.0g of auric acid?

I am really confused on how to problems like these, can anyone explain how to go through it or how to get started?

Victoria Le 1E
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Joined: Fri Sep 25, 2015 3:00 am

Re: 2006 Practice Final Question 1

Postby Victoria Le 1E » Sun Mar 06, 2016 4:10 pm

This problem is essentially just setting a bunch of proportions to find a missing value. Start with converting the 15 g to number of moles. Once you have that, you can find out how much energy is released and then multiply that value by a proportion between the enthalpy of sucrose and auric acid, which should give you a number of moles. After that, convert to mass by multiplying this by the molar mass. That should be the answer!

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