Need Help with Conversions

Sep 2013
2
0
Hello all, this is my first time ever taking a chemistry class. My teacher has us using the Mastering Chemistry software and I'm pretty sure he's not making it easy on us. I was wondering if it would be possible to get some help with some of the problems that he assigned to us on the homework. I've attempted to figure out these problems, but have not come up with any luck. Since he only gives us so many attempts of answering a question right I would like to get them all right. Here's the ones I'm having problems with:

A patient receives 2500mL of an IV solution containing 2g of glucose per 100 mL.

1. How much energy, in kilojoules, does the patient obtain from glucose, a carbohydrate?
Express your answer to two significant figures and include the appropriate units.


2500 mL (2g/100mL) = 50g

50g (4kcal/1g) = 200kcal

200 kcal (4.184J/1kcal) = 836.8J

836.8J (0.001kJ/1J) = 0.8368kJ rounded to 2 significant figures would be 0.84kJ correct?



2. How much energy, in kilocalories, does the patient obtain from glucose?
Express your answer to two significant figures and include the appropriate units.


2500 mL (2g/100mL) = 50g

50g (4kcal/1g) = 200kcal rounded to 2 significant figures would be 2.0 x 102 correct?


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Using the following data, determine the kilocalories for each food burned in a calorimeter.

1. One cup of popcorn that changes the temperature of 1.20×103g water from 28.5∘C to 52.7∘C

1.20 x 103g (4.184J / 1g x 1 degree C)(52.7 degrees - 28.5 degrees) = 121503.36J

121503.36J (1 kcal/ 4.184J) = 29040 kcal rounded to 3 significant figures would be 29.0 x 103 kcal correct?


2. A sample of olive oil that increases the temperature of 417g water from 25.6∘C to 41.7∘C

417g (4.184J / 1g x 1 degree C)(41.7 degrees - 25.6 degrees) = 28090.1208J

28090.1208J (1 kcal / 4.184J) = 6713.7 kcal rounded to 3 significant figures would be 6.71 x 103 kcal correct?



Thanks for any help!
 
Sep 2013
2
0
And honestly I don't even know where to begin on these problems. Could anybody give me a hint or some help? Thanks!

When a 1.30-g sample of ethanol (alcohol) is burned in a calorimeter, the heat released increases the temperature of 870 g of water in the calorimeter from 18.5 ∘C to 28.9 ∘C.


1. What is the energy value, in kJ/g, of ethanol?

2. What is the energy value, in kcal/g, of ethanol?

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The combustion of 1.0 g of gasoline releases 11 kcal of heat (density of gasoline = 0.74 g/mL).

1. How many megajoules are released when 1.9gal of gasoline burns?
Express your answer using two significant figures.

2. When a color television is on for 2.0 h, 320kJ are used. How long can a color television run on the energy from 1.9gal of gasoline?
Express your answer using two significant figures.

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Oct 2013
1
0
2 Botas Ug

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