Question

Aqueous solutions of Cu21 ion are blue. The higher the concentration, the darker the color. When a strip of zinc metal is immersed in a solution of Cu21, the blue color fades. What is happening?

Answer 1

Cu21?

Answer 2

cu^+2

Answer 3

The blue color should be coming from copper hydroxide. You know that copper is 2+ and "aqueous" means that copper 2+ is in water H2O. Cu(OH)2 is the blue color. You know copper is a solid so for there to be no ppt copper must have reacted to form some compound that is not solid. Adding zinc will take the hydroxide from the copper to form white Zn(OH)2.

Answer 4

thank you very much!!
i have another question, how can i determine the oxidizing agent and reducing agent in equation?

Answer 5

Which equation?

Answer 6

for example, tell which substance is reduced and which is oxidized in the following equation. Label the oxidizing agent and reducing agent in each equation.

CuO(s) + H2(g) → Cu(s) + H2O(g)

Answer 7

First thing about which is oxidized and which is reduced. These will be reactants always so you know Cu(s) and H2O(g) are not options. Next label the oxidation states. From left to right Cu=2+, O=2- + H2(g)=0 --> Cu(s)=0 + H=1+, O=2-. . Which substance gained e-?

Answer 8

oxygen ? i don't know am kinda confused.

Answer 9

Cu goes from 2+ to 0 so it must have gained e-. Hydrogen goes from 0 to 1+ so it must have lost e-

Answer 10

oh, okay. thank you there.

Answer 11

You should know how to label the oxidation states of all of the elements in that equation. There are simple rule you should know and follow.

Answer 12

yea, i am taking this class online, and i just start studying.

Answer 13

Cool

Answer 14

So if copper gained e- was copper oxidized or reduced?

Answer 15

reduced?

Answer 16

yes that make copper the oxidizing agent

Answer 17

ok, Why is galvanized iron less susceptible to corrosion than bare iron? any idea?

Answer 18

Zinc reacts with oxygen much more slowly than iron. Galvanized iron means a thin coating of zinc around the iron

Answer 19

appreciate it, thank you