problem please help?

Question

form how long a current of for how long a current of 10A be passed through fused PbBr2 so as to obtain 10.35g

Answer 1

[I assume that you want 10.35g of lead?]

The key bits of information here are that current is a measure of electrons per second and that in PbBr2 the lead (Pb) has a 2+ charge, requiring two electrons.

Convert the required mass into a required number of mole, given the atomic mass of lead is 207.2 g / mol

10.35 g / 207.2 g / mol = 0.05 mol.

Convert the number of mole into number of atoms using Avagadro's number (6.023 x 10^23 atoms / mole)

.05 x 6.023 x 10 ^23 = 3.01x10^22 atoms.

You can then work out how many electrons are needed (remember, the lead is 2+)

2x 3.01 x 10^22 = 6.02 x 10^22 electrons needed

Finally, you then work out how long the current needs to be passed through. Remember - Amps = coulombs per second. 1 coulomb of charge = 6.241 x 10^18 electrons...

6.02 x 10^22 electrons / (10 coulombs per second x 6.241 x10^18 electrons per coulomb)
=
965 seconds.
= 16 minutes 5 seconds.