Answer: The final concentration is 0.16 M.
Explanation:
According to the dilution law:
[tex]M_1V_1=M_2V_2[/tex]
where,
[tex]M_1[/tex] = molarity of stock solution = 1.60 M
[tex]V_1[/tex] = volume of stock solution = 54.0 ml
[tex]M_2[/tex] = molarity of diluted solution = ?
[tex]V_2[/tex] = volume of diluted solution = 218 ml
Putting these values:
[tex]1.60\times 54.0=M_2\times 218[/tex]
[tex]M_2=0.40M[/tex]
Now 109 ml of this diluted solution is further diluted by adding 161 mL of water.
Again applying dilution law:
[tex]0.40\times 109=M_3\times (109+161)[/tex]
[tex]0.40\times 109=M_3\times 270[/tex]
[tex]M_3=0.16M[/tex]
Thus the final concentration is 0.16 M