Question

10. 17.5 g of NaOH were dissolved in 350 mL of water. The solution was titrated with HNO3 to a methyl orange endpoint (methyl orange is a pH indicating dye that is yellow in base but turns red when the solution turns acidic). What volume of 0.250 M HNO3 will be required to reach a methyl orange endpoint?

Answer 1

1747.2 ml of HNO3 is required to reach methyl orange endpoint.

Explanation:

Number of moles of NaOH solution having 17.5 gram NaOH in 350ml of water.

Atomic weight of NaOH = 40 g/mol

thus number of moles= 17.5/40

                                      =  0.437 moles

Now the molarity of the solution is calculated as

M=n/C

  = 0.437/O.35 LITRES

  = 1.248 M solution of the base

the molarity of acid is given as 0.25 M of HNO3

From the formula

M1V1=M2V2  we can calculate the volume of HNO3 required to make solution acidic.

1.248*350= 0.25*v2

v2=  1.248*350/0.25

     = 1747.2 ml

Thus 1747.2 ml of HNO3 is required.