MCAT Question A Day - 10/17/14 - Answer!
A natural sample of carbon contains 99% of 12C. How many moles of 12C are likely to be found in a 48.5 gram sample of carbon obtained from nature?
A. 1
B. 4
C. 12
D. 49.5
B is correct. Don't do any complicated calculations. This is the type of problem that everyone will get right, but many will spend too much time trying to be exact. First assume that 100% of the sample is 12C. Now use the formula: moles = grams/molecular weight. This is very close to 4. The 1% that is not 12C is insignificant.
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B is correct. Don't do any complicated calculations. This is the type of problem that everyone will get right, but many will spend too much time trying to be exact. First assume that 100% of the sample is 12C. Now use the formula: moles = grams/molecular weight. This is very close to 4. The 1% that is not 12C is insignificant.
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