Question

A solution contains 1.12×10^-2 M copper(II) nitrate and 9.22×10^-3 M nickel(II) acetate.
Solid potassium hydroxide is added slowly to this mixture.

What is the concentration of copper(II) ion when nickel ion begins to precipitate?
[Cu²⁺] =

Answer 1

Mass= concentration*volume*molecular weight

concentration=mass/(volume*M.W)

find we have to calculate percentage of above mentioned compounds

molarity of copper nitrate=(% of copper nitrate * density)/M.W

% of copper nitrate=(1.12*10^-2*187.56)/3.05

=68%

68% of copper nitrate convert to grams by using google converters=127.54grams

molarity of nickel acetate=(% of nickel acetate * density)/M.W

% of nickel acetate=(9.22*10^-3*176.78)/1.798

=90%

90% of nickel acetate convert to grams by using google converters=165.62grams

let us take potassium hydroxide as 10grams

total compound mass in grams=127.54+165.62+10

=303.16grams

now we calculate volume for each compound

volume=mass/density

therefore

volume of copper nitrate=127.54/3.05

=41.81V

volume of nickel acetate=165.62/1.798

=92.11V

volume of copper nitrate=10/2.12

=4.71V

there fore total volume of given compoundin V=41.81+92.11+4.71

=138.63V

now we calculate total molecular weight of given compounds=187.56+176.78+56.1056

=420.4456g/mol

so finally concentration of total mixture of compounds are=Total mass/(Total volume*Total molecular weight)

=303.16/559.0756

=0.542N

THEREFORE CONCENTRAION OF COPPER ION IS 0.542N