•  To have equilibrium in a certain structure, the parameters x, y, z, w must satisfy the following equations. Find the values of x, y, z, w (problem from D.R.Green, J.Lewis - "Science with Pocket Calculators").

Rounding:  x = 1.719·10−3, y = 8.680·10−4, z = 1.314·10−3, w = 5.182·10−4

•  Find x, y, z, w integers such that  x Cu + y H2SO4z CuSO4 + w H2O + SO2
Looking at the elements that appear on the two sides of the relationship, we have that it must be (for, in order, Cu, H, S, O):

Cu:   x      - z       = 0
 H:     2y       - 2w  = 0
 S:      y  -  z       = 1
 O:     4y  - 4z -  w  = 2

Cu + 2H2SO4 → CuSO4+ 2H2O + SO2