1.9 mol HCl and 3.2 mol NaOH react according to the equation
HCl + NaOH −→ NaCl + H2O .
Calculate the amount in moles of H2O
formed.
Answer in units of mol
This is a limiting reagent (LR) problem. You know that when amounts are given for BOTH reactants.
How much H2O could be formed from the HCl if you had all of the NaOH needed? That's 1.9 mols.
How much H2O could be formed from the NaOH if you had all of the HCl needed? That's 3.2 mols.
In LR problems the small number always wins so you will get 1.9 mols H2O and there will be NaOH left over. Why is that? After all of the HCl is used up there will be no more HCl to react with the NaOH no matter how much NaOH you started with.
To calculate the amount of H2O formed in the reaction, you need to examine the stoichiometry of the balanced chemical equation. In this case, the equation tells us that for each 1 mole of HCl reacting with 1 mole of NaOH, 1 mole of NaCl and 1 mole of H2O are produced.
Given that you have 1.9 mol of HCl, you can determine the amount of H2O formed by using the mole ratio from the balanced equation. Since the mole ratio is 1:1 between HCl and H2O, the amount of H2O formed will be the same as the amount of HCl used.
Therefore, the amount of H2O formed in this reaction is 1.9 mol.