Question

john is working in the chemistry lab. he has 12 g of sucrose (c₁₂h₂₂o₁₁) to use in an experiment. john wants to find the number of molecules in 12 g of the compound. help him find an answer. select the correct answer for each step to solve the problem. what is step 1? find the molar mass of sucrose. find the number of moles of sucrose. find the mass of sucrose in kilograms. reset problem

Explanation:

Step1: Find molar mass of sucrose

The molar mass of carbon ($C$) is approximately $12\ g/mol$, hydrogen ($H$) is approximately $1\ g/mol$ and oxygen ($O$) is approximately $16\ g/mol$. For sucrose ($C_{12}H_{22}O_{11}$), the molar mass $M$ is calculated as follows:

$$M=(12\times12)+(22\times1)+(11\times16)=144 + 22+176 = 342\ g/mol$$

Step2: Calculate number of moles of sucrose

The number of moles $n$ of a substance is given by the formula $n=\frac{m}{M}$, where $m$ is the mass of the substance and $M$ is the molar - mass. Given $m = 12\ g$ and $M = 342\ g/mol$, we have $n=\frac{12}{342}\ mol\approx0.0351\ mol$.

Step3: Find number of molecules

We use Avogadro's number $N_A=6.022\times 10^{23}\ molecules/mol$. The number of molecules $N$ of sucrose is $N=n\times N_A$. Substituting $n = \frac{12}{342}\ mol$ and $N_A = 6.022\times 10^{23}\ molecules/mol$, we get $N=\frac{12}{342}\times6.022\times 10^{23}\approx2.11\times 10^{22}$ molecules.

Answer:

The steps to find the number of molecules of sucrose are:

1. Find the molar mass of sucrose.
2. Calculate the number of moles of sucrose using the formula $n=\frac{m}{M}$.
3. Find the number of molecules using the formula $N = n\times N_A$. The number of molecules of sucrose in $12\ g$ is approximately $2.11\times 10^{22}$ molecules.