Question #5715d

1 Answer
Jul 27, 2015

Answer:

(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"#