Question

1. What is the oxidation number for each of the elements in Cu(NO3)2?

2. What is the oxidation number for each element in MgCr2O7?

3. The oxidation number of

a. any substance is the charge of the substance

b. an uncombined element is zero

c. hydrogen is +2 when combined with nonmetals

d. none of the above is correct

4. The oxidation numbers of ______ are equal to their ionic charges.

5. The term oxidation can be used to describe reactions in which

a. oxygen is removed from the reactants

b. oxygen is gained by the reactants

c. a substance loses one or more electrons

d. a substance gains one or more electrons

Answer 1

1. What is the oxidation number for each of the elements in Cu(NO₃)₂?

The general oxidation state of O is -2

When Cu(NO₃)₂ dissolved in water it produces Cu²⁺ & NO₃^-

So the oxidation state of Cu is +2

We know that the sum of the oxidation state of elements in a compound or ion is equal to the charge present on the ion.

Let x be the oxidation state of N , then x + (3(-2))=-1

x = +5

2. What is the oxidation number for each element in MgCr₂O₇?

The general oxidation state of second group element is +2 and that of O is -2

Let x be the oxidation state of Cr then

(+2)+2x+(7(-2)) = 0

x = +6

3. The oxidation number of

b. an uncombined element is zero

4. The oxidation numbers of metal/non-metal ions are equal to their ionic charges.

5. The term oxidation can be used to describe reactions in which

b. oxygen is gained by the reactants

c. a substance loses one or more electrons