Question

1. In the laboratory a student combines 22.9 mL of a 0.110M magnesium bromide solution with 16.9 mL of a 0.487M zinc bromide solution.

What is the final concentration of bromide anion ?

  M

2. In the laboratory a student combines 22.9 mL of a 0.110M magnesium bromide solution with 16.9 mL of a 0.487M zinc bromide solution.

What is the final concentration of bromide anion ?

  M

3.

In the laboratory a student combines 36.0 mL of a 0.374M calcium chloride solution with 22.0 mL of a 0.431 M calcium bromide solution.

What is the final concentration of calcium cation ?

M

Answer 1

1)

Concentration of mixture = (n1*C1*V1+ n2*C2*V2) / (V1+V2)

where C1 --> Concentration of 1 component

V1-->volume of 1 component

C2 --> Concentration of other component

V2-->volume of other component

n1 --> number of particle from 1 molecule of 1st component

= 2 as 1 molecule of MgBr2 has 2 atom of Br

n2 --> number of particle from 1 molecule of 2nd component

= 2 as 1 molecule of ZnBr2 has 2 atom of Br

use:

C = (n1*C1*V1+ n2*C2*V2) / (V1+V2)

C = (2*0.11*22.9+2*0.487*16.9)/(22.9+16.9)

C = 0.5402 M

Answer: 0.540 M