Astrip of impure copper is given to you. how will you purify it by using chemical effects of electric current ?

This can be done through electrolysis. Electrolysis is the separation of a substance  into two or more substances that may differ from each other and from the original substance by passing an electric current through a solution that contains ions.

In the case of copper,  we use a  copper (II) sulphate  solution which we put in a large beaker. The impure copper will be used as the positive electrode (anode) and for the negative electrode (cathode)  will be a bar of pure copper.

When the electric current is switched on, the bar of pure copper which is the cathode  increases greatly in size as copper ions leave the anode of impure copper and attach to  the cathode.  The anode becomes smaller and smaller as it loses copper ions until all that is left of it is impurities in form of a sludge beneath it.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.