56. Solving a chemistry problem

193. Various volumes of a standard solution containing 1 mg of copper in 1 ml, after treatment with a solution of lumogallion, were diluted with water to 100 ml and the intensity of their luminescence was measured. The following results were obtained:

Volume of standard solution, ml 2 4 6 8 10
Luminescence intensity, c.u. 22 37 51 65 79
A weighed portion of 1 g of metal containing traces of copper was dissolved in acid and the solution was diluted with water to 10 ml. From 1 ml of this solution, 25 ml of a solution were obtained, the luminescence intensity of which was 43 conventional units. Determine the copper content in the metal (in %).