## E.7 Chemical Principle 7th edition

Ziyan Wang 3J
Posts: 51
Joined: Wed Sep 18, 2019 12:22 am

### E.7 Chemical Principle 7th edition

A molecule of human DNA was found to contain 2.1 * 10^9 atoms of carbon. Calculate the chemical amount (in moles ) of carbon atoms in the molecule of DNA.

Samuel Tzeng 1B
Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

### Re: E.7 Chemical Principle 7th edition

3.5*10^-15 moles of Carbon

Chem_Mod
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### Re: E.7 Chemical Principle 7th edition

Recall Avogradro's number is 6.022 x 10^23. In this problem, you're given 2.1 x 10^9 atoms of carbon, so divide by Avogadro's to find the number of moles.

If you're still having trouble understanding the above step, then I would recommend attending Step-Up sessions.

Jenna Ortiguerra 4G
Posts: 50
Joined: Sat Aug 17, 2019 12:18 am

### Re: E.7 Chemical Principle 7th edition

The question is asking you to calculate the amount of carbon ATOMS in the molecule of DNA. To convert atoms into moles, you use Avogadro's number (6.022*10^23).

(2.1*10^9 atoms) * ((1molC)/(6.022*10^23 C)) = 3.5*10^-15 moles C

The amount of moles in carbon is 3.5 * 10^-15 moles C

Montana James 4G
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Joined: Wed Sep 18, 2019 12:21 am

### Re: E.7 Chemical Principle 7th edition

The above responses are perfect, but for conversion questions in general it may also be helpful to think of Avogadro's number as 6.022 x 10^23 "things" (be it atoms, molecules, etc.) in one mole. From there it makes it easier to see what you need to divide or multiply.