Question

what is the limiting reagent when 3.1 0f 2so react with 2.7 mol of 2o according to the equation 4so+2o-6so

Answer 1

What is the limiting reagent when 3.1 mol of $\mathrm{SO}_2$ react with 2.7 mol of $\mathrm{O}_2$ according to the equation:

$$2 \mathrm{SO}_2 + \mathrm{O}_2 \rightarrow 2 \mathrm{SO}_3$$

Answer: According to the reaction equation, 2 moles of $\mathrm{SO}_2$ fully react with 1 mole of $\mathrm{O}_2$, theoretical molar ratio is 2:1. And the real molar ratio is: $\frac{n(\mathrm{SO}_2)}{n(\mathrm{O}_2)} = \frac{3.1}{2.7} = 1.15:1$.

As you can see, $\mathrm{SO}_2$ is in deficit in comparison to the theoretical ratio. It means, that $\mathrm{SO}_2$ is the limiting reagent.