Question #117dd

1 Answer
May 13, 2016

2.9M

Explanation:

  • The current passed, # I=10 A#
  • The time of passing the current, #t=16 min 5 s=(16xx60+5) s = 965 s#
  • So the quantity of electricity passed is

#Q=Ixxt= "10 C·s"^"-1"xx"965 s"="9650 C"="9650 C"/("96500 C·F"^"-1")="0.10 Faraday"#

We know from Faraday's law that the passage of 1 Faraday of electricity accumulates 1 gm-equivalent ions (here #"Cu"^(2+)#)

So, in our case 0.10 gm-equivalent #"Cu"^(2+)# will be deposited.

Since #"Cu"^(2+)#is divalent, the amount of #"Cu"^(2+)# deposited will be

#"0.10 mol"/2="0.050 mol"#
{since #"molar mass" = 2xx "equivalent mass"# or #"1 gm-equivalent" =1/2 "mol"#)

Now, the initial concentration of the solution is 3 M.

Its 0.5 L will contain #0.5xx "3 mol"="1.5 mol Cu"^(2+)#

After deposition of 0.050 mol due to passage of electricity, there will be #"(1.5-0.05) mol"="1.45 mol Cu"^(2+)# in 0.5 L solution.

Hence the final concentration after electrolysis is

#"1.45mol"/"0.5 L"="2.9 M"#