1. First, to calculate the molar mass, we're going to use the periodic table where you can see the molar mass of each element of sucrose. The molar mass of carbon is 12 g/mol, hydrogen is 1 g/mol and oxygen is 16 g/mol. We have to do an algebraic sum, which means that we're going to multiply the number of atoms of each element by its molar mass, like this:
[tex]\begin{gathered} \text{molar mass of C}_{12}H_{22}O_{11}=12\cdot12\frac{\text{g}}{mol}+22\cdot1\frac{\text{g}}{mol}+11\cdot16\frac{g}{mol}, \\ \text{molar mass of C}_{12}H_{22}O_{11}=(144+22+176)\frac{g}{mol}, \\ \text{molar mass of C}_{12}H_{22}O_{11}=342\text{ }\frac{g}{mol}. \end{gathered}[/tex]The molar mass of sucrose (C12H22O11) would be 342 g/mol.
2. To calculate the mass percent of a certain element, we have to take its molar mass and divide it by the total molar mass of the compound and multiply this result by one hundred, like this:
[tex]\begin{gathered} \%\text{ mass of C=}\frac{molar\text{ mass of C}}{\text{total molar mass}}\cdot100, \\ \%mass\text{ of C=}\frac{144\text{ }\frac{g}{mol}}{342\text{ }\frac{g}{mol}}\cdot100, \\ \%mas\text{s of C=42.11}\%. \end{gathered}[/tex]The answer is that the mass percent of carbon is 42.11 %.
3. We do the same process for hydrogen as we did before for carbon:
[tex]\begin{gathered} \%mass\text{ of H=}\frac{22\frac{g}{mol}}{342\frac{g}{mol}}\cdot100, \\ \%mass\text{ of H=6.43}\%. \end{gathered}[/tex]
The mass percent of hydrogen is 6.43%.
4. We applied for oxygen, the two last processes:
[tex]\begin{gathered} \%mass\text{ of O=}\frac{176\text{ }\frac{g}{mol}}{342\text{ }\frac{g}{mol}}\cdot100, \\ \%mass\text{ of O=51.46}\%. \end{gathered}[/tex]The mass percent of oxygen is 51.46 %.
6. To calculate the mass percent of sugar in the bubble gum, we have to divide the amount of sugar in the bubble gum (18.9 g) by its total mass (mass of the gum and wrapper - mass of the wrapper = (20 - 0.1) g = 19.9 g). And then, we multiply this result by 100:
[tex]\begin{gathered} \%mass\text{ of sugar in bubble gum =}\frac{\text{mass of sugar}}{\text{mass of bubble gum}}\cdot100, \\ \%mass\text{ of sugar in bubble gum }=\frac{18.9\text{ g}}{19.9\text{ g}}\cdot100, \\ \%mass\text{ of sugar in bubble gum }=94.97\%. \end{gathered}[/tex]The mass percent of sugar in bubble gum would be 94.97 %.
