Another confusting chemistry question from my pre test.. i think i can do most of it but I have a couple quest

Question

questions

here is the problem

Benzoic acid or HBz , only contains one hydrogen. If 28.75 mL of .660 M KOH neutralized a 2.316 g of HBz, what is the molar mass of the acid?

How do I get molar mass when on the test because I wont have google. I know I could look it up now but on the test can I get this answer with out google?

1) Write balanced equation of Hbz and KOH?

I think its

Hbz+ KOH ------> Kbz + H2O

2) how many moles did it take to neutralize the acid?

i have no ides to do this part but im guess one since there is no numbers before the first part? Could you do another example with more mores if the answer is one cause im still confused about the mole to mole ratio

3) How many moles of Hbz are there in 2.316 g of Hbz?

I think you do this by

2.316 grams of Hbz x (1 mol of Hbz/ ?? I only know the molar mass by google and its 122.12 grams of Hbz) = .01896 moles of Hbz

Answer 1

An acid and a base will react to produce a salt and water - you dont need to think about this you know it. However you are correct:

Hbz+ KOH ------> Kbz + H2O

- Since the KOH neytralized the acid, calculate mol KOH

mol KOH = 0.02875 * 0.660 = 0.018975 mol

1 mol KOH neutralizes/completely reacts with 1 mol HBz , according to the stoichiometric eqn. above.

therefore 0.018975 mol KOH will neutralize 0.018975 mol HBz

- you know the mass of HBz used and the mol HBz reated to reach neutralization, therefore :

molar mass = given mass / mol = 2.316/0.018975 = 122.1 g/mol