College

Which is the limiting reactant in the following reaction given that you start with 42.0 g of [tex]$CO_2$[/tex] and 99.9 g of KOH?

Reaction: [tex]$CO_2 + 2KOH \rightarrow K_2CO_3 + H_2O$[/tex]

A. [tex]$K_2CO_3$[/tex]
B. [tex]$H_2O$[/tex]
C. KOH
D. [tex]$CO_2$[/tex]
E. Not enough information

Answer :

To determine the limiting reactant in the reaction between carbon dioxide ([tex]\(CO_2\)[/tex]) and potassium hydroxide (KOH), follow these steps:

1. Determine the Moles of Each Reactant:

- The molar mass of [tex]\(CO_2\)[/tex] is approximately 44.01 g/mol.
- The molar mass of KOH is approximately 56.11 g/mol.

For [tex]\(CO_2\)[/tex]:
[tex]\[
\text{Moles of } CO_2 = \frac{42.0 \, \text{g}}{44.01 \, \text{g/mol}} = 0.954 \, \text{mol}
\][/tex]

For KOH:
[tex]\[
\text{Moles of KOH} = \frac{99.9 \, \text{g}}{56.11 \, \text{g/mol}} = 1.780 \, \text{mol}
\][/tex]

2. Use the Balanced Chemical Equation:

The balanced chemical equation is:
[tex]\[
CO_2 + 2 \, \text{KOH} \rightarrow K_2CO_3 + H_2O
\][/tex]

This tells us that 1 mole of [tex]\(CO_2\)[/tex] reacts with 2 moles of KOH.

3. Calculate the Required Moles of KOH for the Available [tex]\(CO_2\)[/tex]:

If you have 0.954 moles of [tex]\(CO_2\)[/tex], the required moles of KOH would be:
[tex]\[
\text{Required moles of KOH} = 0.954 \times 2 = 1.909 \, \text{mol}
\][/tex]

4. Identify the Limiting Reactant:

You have 1.780 moles of KOH available but need 1.909 moles for the complete reaction with the [tex]\(CO_2\)[/tex] present. Since you have fewer moles of KOH than needed, KOH is the limiting reactant.

In summary, even though you might have started with a considerable amount of both reactants, KOH runs out first and thus is the limiting reactant in this chemical reaction.