Select the correct answer.

A chemist is working on a reaction represented by this chemical equation:
[tex]\[ FeCl_2 + 2 KOH \rightarrow Fe(OH)_2 + 2 KCl \][/tex]

If the chemist uses 4.15 moles of iron(II) chloride and 3.62 moles of potassium hydroxide, how many moles of iron(II) hydroxide will the reaction produce?

A. [tex]$1.81 \, \text{mol}$[/tex]
B. [tex]$3.62 \, \text{mol}$[/tex]
C. [tex]$4.15 \, \text{mol}$[/tex]
D. [tex]$7.24 \, \text{mol}$[/tex]



Answer :

Let's solve this problem step-by-step.

1. Identify the reaction and the stoichiometric coefficients:
The balanced chemical equation for the reaction given is:
[tex]\[ FeCl_2 + 2 KOH \rightarrow Fe(OH)_2 + 2 KCl \][/tex]
From this equation, we see that 1 mole of [tex]\( FeCl_2 \)[/tex] reacts with 2 moles of [tex]\( KOH \)[/tex] to produce 1 mole of [tex]\( Fe(OH)_2 \)[/tex].

2. Determine the moles of reagents:
- Moles of [tex]\( FeCl_2 \)[/tex]: 4.15
- Moles of [tex]\( KOH \)[/tex]: 3.62

3. Calculate the required moles of [tex]\( KOH \)[/tex] for 4.15 moles of [tex]\( FeCl_2 \)[/tex]:
According to the stoichiometric ratio, 1 mole of [tex]\( FeCl_2 \)[/tex] requires 2 moles of [tex]\( KOH \)[/tex]. Therefore, 4.15 moles of [tex]\( FeCl_2 \)[/tex] would require:
[tex]\[ 4.15 \text{ moles of } FeCl_2 \times 2 \text{ moles of } KOH / 1 \text{ mole of } FeCl_2 = 8.3 \text{ moles of } KOH \][/tex]

4. Compare the available moles of [tex]\( KOH \)[/tex] with the required moles:
- Required moles of [tex]\( KOH \)[/tex]: 8.3
- Available moles of [tex]\( KOH \)[/tex]: 3.62

Since the available moles of [tex]\( KOH \)[/tex] (3.62) are less than the required moles (8.3), [tex]\( KOH \)[/tex] is the limiting reagent.

5. Determine the amount of product ([tex]\( Fe(OH)_2 \)[/tex]) produced:
Since [tex]\( KOH \)[/tex] is the limiting reagent, we need to find out how many moles of [tex]\( Fe(OH)_2 \)[/tex] can be produced by the available [tex]\( KOH \)[/tex].

According to the stoichiometric ratio, 2 moles of [tex]\( KOH \)[/tex] produce 1 mole of [tex]\( Fe(OH)_2 \)[/tex]. Hence, 3.62 moles of [tex]\( KOH \)[/tex] will produce:
[tex]\[ \frac{3.62 \text{ moles of } KOH}{2} = 1.81 \text{ moles of } Fe(OH)_2 \][/tex]

Therefore, the reaction will produce 1.81 moles of iron(II) hydroxide.

The correct answer is:
A. [tex]$1.81 \text{ mol}$[/tex]