How do calculate the the following problems?

Note:
"v" signifies an upside down caret ^
v2 signifies the subscript of 2
v6 signifies the subscript of 6

Calculate each of the following:
A. number of Li atoms in 4.5 mol of Li
B. number of CO v2 molecules in 0.0180 mol of CO v2
C. Moles of Cu in 7.8 * 10^21 atoms of Cu
D. Moles of C v2 H v6 in 3.75 * 10^23 molecules of C v2 H v6

1 Answer
Raknos
Oct 26, 2017

All of these can be solved by using unitary method.

A. 1 mol of Li =6.022⋅1023 atoms.
hence, 5.4 mol Li =5.4⋅6.022⋅1023 atoms
=3.252⋅1024 atoms.

B. 1 mol of CO2 =6.022⋅1023 molecules.
Hence, 0.0180 mol of CO2 =0.0180⋅6.022⋅1023 molecules.

C. 6.022⋅1023 atoms Cu = 1 mol Cu.
1 atom Cu = 16.022⋅1023 mol Cu.
hence, 7.8⋅1021 atoms of Cu = 7.8⋅1021⋅16.022⋅1023 mol Cu.

D. 6.022⋅1023 molecules of C2H6 = 1 mol C2H6.
1 molecule of C2H6 = 16.022⋅1023 mol C2H6.
Hence, 3.75⋅1023 molecules of C2H6 = 3.75⋅1023⋅16.022⋅1023 mol C2H6.

I haven't bothered to do the complete calculations, you can do them yourself.

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