Question

Not a timed or graded assignment. Prompt “a donut contains 37.8 grams of sucrose (C12H22O11), how many moles of sugar are in the donut?” Quick answer = Amazing review

Answer 1

Step 1 - Understanding mole and molar mass

The molar mass is, by definition, the mass of one mole of something. One mole is a very big number representing 6*10^23 entities.

When we say, for example, that the molar mass of water is 18 g/mol, we mean that one mole of water molecules, i.e., 6*10^23 water molecules, weight 18g.

In order to solve this question, we must first calculate the molar mass of sucrose (C12H22O11). The molar masses for C, H and O are, respectively, 12 g/mol, 1 g/mol and 16 g/mol. Therefore:

$M_{\text{sucrose}}=12\times12+11\times1+11\times16=342g/mol$

Step 2 - Converting mass of sucrose to moles of sucrose

Now that we have calculated the molar mass of sucrose, we can convert mass to moles:

$\begin{gathered} 1\text{ mole of sucrose ----- 342g} \\ x\text{ moles of sucrose ---- 37.8g} \\ \\ x=\frac{37.8}{342}=0.11\text{ moles of sucrose} \end{gathered}$

37.8 grams corresponds thus to 0.11 moles of sucrose.