Stoichiometry Quiz???

Question

What is the molarity of a solution of nitric acid if 0.216 of barium hdroxide is required to neutralize 20.00mL of nitric acid?

Answer 1

0.216 what?????

If Ba(OH)2 = 0.216 g

First write a balanced equation

Ba(OH)2 + 2HNO3 --------> Ba(NO3)2 + 2H2O

You can see that 2 moles of HNO3 are required to neutralise 1 moles of Ba(OH)2

If Ba(OH)2 = 0.216 g

First convert grams to moles

moles = mass / molecular weight

molecular weight Ba(OH)2 = 137.3 + (16.00 x 2) + (2 x 1.008) = 171.316 g/mol

Therefore moles Ba(OH)2 = 0.216 g / 171.316 g/mol

= 0.001261 moles of Ba(OH)2

So it took 0.001261 moles of Ba(OH)2 to neutralise 20.00 mL of HNO3

2 moles of HNO3 are required for every 1 mole of Ba(OH)2. Therefore number of moles of HNO3 that must be in the 20.00 mL of HNO3 = (2 x 0.001261) moles

= 0.002522 moles of HNO3 must be in 20.00 mL

Molarity = moles / Litres

= 0.002522 mole / 0.0200 L

= 0.126 M HNO3

Answer 2

If you mean .216 moles of Ba(OH)2, then there are .432 moles of Nitric Acid in the 20 ml. .432/.020 = 21.6M