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Posts: 5
Joined: Fri Jan 11, 2019 12:04 am


Post by » Fri May 17, 2019 10:33 pm

Q-bank chemistry Atoms and reactions
1st question:
A sample of gas is collected from a vent on the ocean floor and analyzed. Three types of molecules are isolated. The results of the analysis are summarized in the following table.
How many moles of Molecule C does the sample contain?
molecule c in the table has 2.4x10 to the 28th power molecules

the way I did it:

molecules/avagadro's number = 1.5x10 to the 5th power.
the correct answer is 4x10 to the 4th power.
the explanation tells me to do it the same way I did do it, so
I checked my math on my calculator and still got 1.5x10 to the 5th power.

What am I doing wrong?
Posts: 230
Joined: Sat Mar 30, 2019 8:39 pm

Re: chemistry

Post by NS_Tutor_Mathias » Sun May 19, 2019 1:40 am

Only one possible explanation: Arithmetic error both by hand and on your calculator.

(2.4*10^28) / (6*10^23) is most easily calculated as (24*10^27) / (6*10^23). 24/6 is just 4. 10^27/10^23 is just 10^4. Therefore, 4*10^4 is your answer.

Hope this helps! Reviewing order of operations and how to do quick arithmetic with exponents might be a strategy for figuring out exactly where the error in your thinking was.
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