# Page 7

Analysis:

A. 3.07g/63.546 amu =<span style="text-decoration: underline;">0.0483 mol</span> &lt;-1.

 0.0483 mol \*6.022\*10<sup>23</sup>=<span style="text-decoration: underline;">2.91\*10<sup>22</sup> atoms</span> Cu. &lt;-2.

B. 0.72g/20=0.036g 0.036g/(1.00794+15.9994)=<span style="text-decoration: underline;">0.0021 mol</span> &lt;-1.

 0.0021 mol \*6.022\*10<sup>23</sup>=<span style="text-decoration: underline;">1.26\*10<sup>21</sup></span> molecules &lt;-2.

C. 6.49/\[2(12.0107)+3(1.00794)\]=<span style="text-decoration: underline;">0.104 mol </span>PVC &lt;-1.

 0.104\*6.022\*10<sup>23</sup>=<span style="text-decoration: underline;">6.26\*10<sup>22</sup></span> molecules &lt;-2.

 6.26\*10<sup>22</sup>\*2=<span style="text-decoration: underline;">1.25\*</span><span style="text-decoration: underline;">10<sup>23</sup></span><span style="text-decoration: underline;"> carbon atoms</span> &lt;-3.

 6.26\*10<sup>22</sup>\*3=<span style="text-decoration: underline;">1.88\*10<sup>23</sup></span><span style="text-decoration: underline;"> hydrogen atoms</span> &lt;-4.

D. 3.61g/(8\*12.0107+8\*1.00794)=<span style="text-decoration: underline;">0.0347 mol</span> &lt;-1.

 0.0347\*6.022\*10<sup>23</sup>=2.090 molecules

 2.090\*(8+8)=<span style="text-decoration: underline;">3.34 atoms</span>

Conclusion:

Avogadro's number links the amount of atoms or molecules in a substance to the mole. the molar mass is used to convert between mass of a substance and the mole. {mole}={number of atoms or molecules}/{Avogadro's number} {mole}={mass(g)}/{molar mass(amu)} {atoms}={molecules}\*{atoms per molecules} {molecule}={moles}\*{Avogadro's number}. Molecules are made of atoms.