AP chem stoichometry

Question

If 0.644 grams of an acid was required to neutralize 10.0 mL of 0.800 M NaOH, calculate the molar mass of the acid given it reacts with sodium hydroxide in a 1:2 ratio. (1 ACID : 2 BASE).

Answer 1

To find the molar mass, we to know the number of grams and then number of moles, since molar mass = g/mols.

We know the grams are 0.644 g. So, we need to now find the moles.

We are told that 1 mol acid reacts with 2 mols NaOH. So, first we'll find the mols NaOH used.

mols NaOH = 10.0 ml x 1 L / 1000 mls x 0.800 mols/L = 0.008 mols NaOH

Now we can find mols of acid (1 acid : 2 base)...

mols acid = 0.008 mols NaOH x 1 mol acid / 2 mols NaOH = 0.004 mols acid

molar mass acid = 0.644 g / 0.004 mols = 80.5 g / mol