1.38 mol HCl and 2.9 mol NaOH react accord-
ing to the equation
HCl + NaOH −→ NaCl + H2O .
If the limiting reactant is HCl, determine
the amount of excess reactant that remains.
Answer in units of mol.
mol HCl initially = 1.38
mol NaOH initially = 2.90
mol NaOH after reacting = 2.90 - 1.38 = ? mols.
To determine the amount of excess reactant that remains, we first need to find the limiting reactant. The limiting reactant is the reactant that is completely consumed first and determines the maximum amount of product that can be formed.
To find the limiting reactant, we compare the number of moles of each reactant to their stoichiometric coefficients in the balanced equation. The balanced equation shows that 1 mole of HCl reacts with 1 mole of NaOH.
Given:
- Moles of HCl = 1.38 mol
- Moles of NaOH = 2.9 mol
To find the limiting reactant:
1. Divide the number of moles of each reactant by its stoichiometric coefficient in the balanced equation.
Moles of HCl / coefficient of HCl = 1.38 mol / 1 = 1.38 mol
Moles of NaOH / coefficient of NaOH = 2.9 mol / 1 = 2.9 mol
2. The reactant with the smaller resulting value is the limiting reactant. In this case, we see that 1.38 mol < 2.9 mol.
Therefore, HCl is the limiting reactant.
The excess reactant is the reactant that is not completely consumed in the reaction. To find the amount of excess reactant that remains, we subtract the number of moles of the limiting reactant consumed from the initial moles of the excess reactant.
Moles of excess reactant remaining = Moles of excess reactant - Moles of limiting reactant consumed
In this case, the limiting reactant is HCl, so we need to find the moles of NaOH consumed:
Moles of NaOH consumed = Moles of limiting reactant (HCl) * (coefficient of NaOH / coefficient of HCl)
Moles of NaOH consumed = 1.38 mol * (1 / 1) = 1.38 mol
Now, we can find the amount of excess reactant that remains:
Moles of excess reactant remaining = 2.9 mol - 1.38 mol
Moles of excess reactant remaining = 1.52 mol
Therefore, there is 1.52 mol of excess reactant (NaOH) that remains.