Question

Question #5715d

Answer 1

(a). `2xx10^22`

(b). `4xx10^22`

(c). `2xx10^22`

(d). `66"mg"`

Explanation:

(a).

`Cu^(2+)+2erarr Cu`

Mass Cu = 2.12g

So moles Cu = `2.12/63.6=0.033`

So no. atoms Cu = `0.033xx6.02xx10^(23)=2.0xx10^22`

(b).

From the above equation 1 mole `Cu^(2+)` ions require 2 moles of electrons to be discharged.

So no. moles electrons `=0.033xx2=0.066`

So no. electrons `= 0.066xx6.02xx10^(23)=4xx10^22`

(c).

`2H^(+)+2erarr H_2`

So you can see a mole of hydrogen gas also requires 2 moles of electrons to be discharged.

so no. molecules `H_2=2xx10^22`.

(d).

No. moles `H_2` = no. moles `Cu =0.033`

`M_rH_2=2.0`

So mass `H_2=0.033xx2=0.066"g"=66"mg"`