Brian M. answered • 02/24/21
Tutor for General Chem & Organic Chem
The thing about stoichiometry is that it allows you to tell on a molecular level the relationship and ratios between reactants and products.
For instance, this chemical equation here describes to you a stoichiomic relationship amongst the reactants and products.
The chemical equation here says "For every 1 mol of NaOH and 1 mol of HCl that react with each other 1 mol of NaCl and 1 mol of H2O will be created"
Essentially, it takes 1 mol of NaOH and 1 mol of HCl to create 1 mol NaCl and 1 mol H2O.
Remember "mol" is pertinent to saying # of atoms or molecules of something.
Note that mass isn't necessarily a measurement of how many atoms or molecules of something there is thus mass alone cannot be used to relate the molecules with one another.
Any mass values you are given must be converted into mols by utilizing the molecular weight (molar mass) of your reactants/products.
22.8 g HCl * (1 mol HCl/36.46 g HCl) = 0.62534 mol HCl
Now we have mols of HCl now we can refer to the chemical equation in order to determine the # mols of NaOH that'll react with our mols of HCl.
According to the chemical equation HCl to NaOH is a 1:1 mol ratio,
thus the # mols of NaOH needed = # mols of HCl
0.62534 mol HCl * (1 mol NaOH/1 mol HCl) = 0.62534 mol NaOH
Finally, use the molar mass of NaOH to convert your # mols NaOH into grams to find out the required mass (g) of NaOH needed.
0.62534 mol NaOH * (40.0 g NaOH/1 mol NaOH) = 25.01 g NaOH
