1. A chemist needs to determine the concentration of a solution of nitric acid,

Question

1. A chemist needs to determine the concentration of a solution of nitric acid, HNO3. She puts 745 mL of the acid in a flask along with a few drops of indicator. She then slowly adds 0.200 M Ba(OH)2 to the flask until the solution turns pink, indicating the equivalence point of the titration. She notes that 265 mL of Ba(OH)2 was needed to reach the equivalence point.

Solution map

In this titration, the concentration of base is known and can be used to calculate the unknown acid concentration:

concentration of base moles of base moles of acid concentration of acid

How many moles of Ba(OH)2 are present in 265 mL of 0.200 M Ba(OH)2?

Express your answer with the appropriate units.

Explanation / Answer

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

1 mole          2moles

Ba(OH)2                                    HNO3

M1 = 0.2M                              M2 =

V1   = 265ml                          V2 = 745ml

n1   = 1                                 n2 = 2

     M1V1/n1   =   M2V2/n2

        M2          = M1V1n2/v2n1

                     = 0.2*265*2/745*1   = 0.143M

conc of HNO3 = 0.143M

no of moles of Ba(OH)2 = molaity * volume in L

                                       = 0.2*0.265 = 0.053moles

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.