Question

convert 4.92 l of hydrogen at stp to moles.
a 0.202 mol $h_2$
b 4.55 mol $h_2$
c 0.220 mol $h_2$
d 0.444 mol $h_2$

Explanation:

Step1: Recall STP molar volume

At STP (Standard Temperature and Pressure, 0°C and 1 atm), 1 mole of any ideal gas occupies 22.4 L. So the conversion factor is $\frac{1\ \text{mol}}{22.4\ \text{L}}$.

Step2: Calculate moles of $H_2$

Given volume $V = 4.92\ \text{L}$. Moles $n = V\times\frac{1\ \text{mol}}{22.4\ \text{L}}$. Substitute $V$: $n = 4.92\ \text{L}\times\frac{1\ \text{mol}}{22.4\ \text{L}}$. Calculate: $n=\frac{4.92}{22.4}\approx0.220\ \text{mol}$.

Answer:

c. 0.220 mol $H_2$