Question

question 7 of 15
how many grams of hno₃ are in 2.905×10²² molecules of hno₃?
show the conversions required to solve this problem and calculate the grams of hno₃.
2.905×10²² molecules hno₃×__×__ =? g hno₃
answer bank
6.022×10²³ molecules hno₃ 1 mol hno₃ 1 mol hno₃ 63.018 g hno₃
mass hno₃ = ____ g hno₃

Explanation:

Step1: Convert molecules to moles

Use Avogadro's number ($6.022\times 10^{23}$ molecules/mol). So, $2.905\times 10^{22}$ molecules of $\text{HNO}_3\times\frac{1\ mol\ \text{HNO}_3}{6.022\times 10^{23}\ molecules\ \text{HNO}_3}$.

Step2: Convert moles to grams

The molar - mass of $\text{HNO}_3$ is $63.018\ g/mol$. So, the result of step 1 $\times\frac{63.018\ g\ \text{HNO}_3}{1\ mol\ \text{HNO}_3}$.
\[

$$\begin{align*} \text{mass of }\text{HNO}_3&=2.905\times 10^{22}\text{ molecules}\times\frac{1\ mol}{6.022\times 10^{23}\text{ molecules}}\times\frac{63.018\ g}{1\ mol}\\ &=\frac{2.905\times 10^{22}\times63.018}{6.022\times 10^{23}}\ g\\ &=\frac{2.905\times63.018}{6.022\times 10}\ g\\ &=\frac{183.06729}{60.22}\ g\\ & = 3.04\ g \end{align*}$$

\]

Answer:

$3.04$