Question

2.955g of Cu metal was dissolved in nitric acid and the solution evaporated to dryness.
The residue was heated strongly to obtain black CuO. The oxide weighed 3.700g.
Another 1.865g sample of the metal was dissolved in concentrated sulphuric acid. The
solution was treated with dilute NaOH solution and then heated. The resulting black CuO
weighed 2.335g. Do the data support the law of constant properties?

Answer 1

Answer:

given =   2.955g of Cu

              oxide weighed 3.700g.

              1.865g concentrated sulphuric acid.

              dilute NaOH

              CuO  = weighed 2.335g

to find = Do the data support the law of constant properties?

solution =

in the 1st experiment in fixed ratio,  3,700g of copper oxide formed and 2.995g of cu is present.

% of copper = mass of cuinoxide / mass of oxide X 100

                    =  2.995 / 3.700 X 100

                    =   80.95%

In the 1st experiment 2.335g of copper oxide formed and 1.865g of Cu is present

% of Cu = mass of CU in oxide / mass of oxide X 100

             =  1.865 / 2.335 X 100

             = 79.875%

the % of copper obtained in both the cases , we can conclude that from above 2 solution

so, the law of constant proportions is supported by the data.