3. how many grams of n₂ gas have a volume of 11.2 liters at stp?

Explanation:

Step1: Recall molar volume at STP

At STP (Standard - Temperature and Pressure), 1 mole of any gas has a volume of 22.4 L.

Step2: Calculate the number of moles of N₂

Let $n$ be the number of moles of N₂. We know that $V = n\times V_m$, where $V$ is the volume of the gas, $n$ is the number of moles, and $V_m$ is the molar volume. Given $V = 11.2$ L and $V_m=22.4$ L/mol. Then $n=\frac{V}{V_m}=\frac{11.2\ L}{22.4\ L/mol}=0.5$ mol.

Step3: Calculate the mass of N₂

The molar mass of N₂ ($M$) is $M = 2\times14\ g/mol=28\ g/mol$. The mass ($m$) of a substance is given by $m = n\times M$. Substituting $n = 0.5$ mol and $M = 28$ g/mol, we get $m=0.5\ mol\times28\ g/mol = 14$ g.

Answer:

14 g