Question

10) Aluminum doesn’t readily corrode because:

a) its standard reduction potential is more positive than oxygen

b) its standard reduction potential is more negative than oxygen

c) it forms a dense coating of alumina, Al₂O₃, that slows oxidation.

d) It is already oxidized.

.

11) What best describes a glass?

a) A transparent, crystalline insulator.

b) A viscous liquid

c) An amorphous solid

d) The thermodynamic (lowest energy) state for a material

.

For the following reaction answer questions 13 & 14):

                       Fe(s) + Cu²⁺(aq)            Fe²⁺(aq) + Cu(s)

13) What is being oxidized (oxidant)?

a) Fe²⁺

b) Cu²⁺

c) Cu

d) Fe

.

14) What is being reduced (reductant)?

a) Fe²⁺

b) Cu²⁺

c) Cu

d) Fe

Please answer all of them without guessing!!! Thanks

Answer 1

Q. 10 ) Al is easily oxidized by oxygen. Lets show the reaction of oxidation of Al by O2.

4Al (s) +3 O2 (g) --- > 2Al2O3

When Al comes in contact with O2 it forms Al2O3. All surface of Al is not covered by Al2O3 quickly and this layer is very dense. Further diffusion of O2 is not possible due to this layer on surface of aluminum. This slows down oxidation of Al and so the correct answer for this question is :

c) It forms dense coating of alumina , Al2O3, that slows down oxidation.

Q. 11)

Glass is super cooled liquid. When solid is formed by extraordinary cooling then it is called as glass. Due to super cooling there is no long range order so the substance is amorphous. The state of gas is solid so the correct option for this question would be

c) an amorphous sold

Q. 13 )

Reaction shows that

Fe(s) is oxidized to Fe²⁺ and Cu²⁺is reduced to Cu(s).

So the correct answer for this question is a) Fe²⁺

Q. 14)

We can use same discussion here that Cu²⁺ is reduced to Cu(s).

So the correct option for this question is c) Cu