Question

Calculate the number of C,H, and O atoms in 1.50g of glucose (C6H12O6).

Answer 1

First, we have to calculate the number of moles of 1.50 grams of glucose, using its molar mass which is 180 g/mol (you can calculate it using the periodic table and doing the algebraic sum):

`1.5gC_6H_(12)O_6\cdot\frac{1\text{ mol }C_6H_(12)O_6}{180\text{ g }C_6H_(12)O_6}=0.0083\text{ moles }C_6H_(12)O_6`

And now, let's use Avogadro's number, which is 6.022 x 10^(23) /mol. This number is telling us that there are 6.022 x 10^(23) atoms or molecules in 1 mol. The number of atoms of glucose is:

`0.0083\text{ moles }C_6H_(12)O_6\cdot\frac{6.022\cdot10^(23)molecules\text{ }C_6H_(12)O_6}{1\text{ mol }C_6H_(12)O_6}=5.0\cdot10^(21)\text{molecules }C_6H_(12)O_6.`

To find the number of atoms in C, you can see that there are 6 atoms of this in glucose, so we're going to calculate:

`5.0\cdot10^(21)\text{molecules }C_6H_(12)O_6\cdot\frac{6\text{ atoms C}}{1\text{ molecule }C_6H_(12)O_6}=3.0\cdot10^(22)\text{atoms C.}`

For hydrogen, we have 12 atoms of this in glucose:

`5.0\cdot10^(21)\text{molecules }C_6H_(12)O_6\cdot\frac{12\text{ atoms H}}{1\text{ molecule }C_6H_(12)O_6}=6.0\cdot10^(22)ato\text{ms H.}`

And finally, we have 6 atoms of oxygen in glucose:

`5.0\cdot10^(21)\text{molecules }C_6H_(12)O_6\cdot\frac{6\text{ atoms O}}{1\text{ molecule }C_6H_(12)O_6}=3.0\cdot10^(22)\text{atoms O.}`

The answer is that we have 3.0 x 10^(22) atoms of oxygen (O), 3.0 x 10^(22) atoms of carbon (C), and 6 x 10^(22) atoms of hydrogen (H).