Question

part a
how many o2 molecules are needed to react with 3.32 g of s?
express your answer numerically in units of molecules.
view available hint(s)
molecules

Explanation:

Step1: Calculate moles of S

The molar mass of S is 32.07 g/mol. The number of moles of S, $n_{S}=\frac{m}{M}$, where $m = 3.32$ g and $M=32.07$ g/mol. So $n_{S}=\frac{3.32}{32.07}\text{ mol}\approx0.1035$ mol.

Step2: Determine mole - ratio from chemical equation

The reaction between S and O₂ is $S + O_{2}=SO_{2}$, and the mole - ratio of S to O₂ is 1:1. So the number of moles of O₂, $n_{O_{2}}=n_{S}= 0.1035$ mol.

Step3: Calculate number of O₂ molecules

We use Avogadro's number $N_{A}=6.022\times 10^{23}$ molecules/mol. The number of O₂ molecules, $N = n_{O_{2}}\times N_{A}$. So $N=0.1035\times6.022\times 10^{23}$ molecules $\approx6.23\times 10^{22}$ molecules.

Answer:

$6.23\times 10^{22}$ molecules