Oxidation Number

What is the oxidation number of Na⁺

• +1

• -1

• +2

• 0

What is the oxidation state of Cr in CrO₄^2- ?

• +6

• +2

• -2

• +8

What is the charge, or oxidation number, for elements in Group 17?

• + 1

• -7

• -1

What is the charge, or oxidation number, for elements in Group 2?

• -2

• +2

• -3

What is the charge, or oxidation number, for elements in Group 13?

• + 3

• -5

• +13

Tags

NGSS.HS-PS1-1

What is the charge, or oxidation number, for elements in Group 14?

• 14

• +4/-4

• -16

Consider both statements and then decide whether the statements are correct and whether Statement 2 is an explanation of Statement 1.

• Both statements are correct and the second statement is a correct explanation of the first.

• Both statements is correct, but the second statement is not a correct explanation of the first.

• Only 1 statement is correct.

• Only statement 2 is correct

• Neither statement is correct.

Answer explanation

Statement 1 & 2 are correct.

H₂S where hydrogen = +1 therefore sulfur is -2.

(+1) x 2 - 2 = 0.

H₂S has no charge and therefore the oxidation must combine to equal zero.

Consider both statements and then decide whether the statements are correct and whether Statement 2 is an explanation of Statement 1. 

Statement 1 - Sodium, Na, has an oxidation number of 0.

Statement 2 - Sodium, Na, is an element.

• Both statements are correct and the second statement is a correct explanation of the first.

• Both statements is correct, but the second statement is not a correct explanation of the first.

• Only 1 statement is correct.

• Only statement 2 is correct

• Neither statement is correct.

Consider both statements and then decide whether the statements are correct and whether Statement 2 is an explanation of Statement 1.

• Both statements are correct and the second statement is a correct explanation of the first.

• Both statements is correct, but the second statement is not a correct explanation of the first.

• Only 1 statement is correct.

• Only statement 2 is correct

• Neither statement is correct.

Consider both statements and then decide whether the statements are correct and whether Statement 2 is an explanation of Statement 1. 

Statement 1 - Oxygen always has an oxidation number of -2 except in peroxides where it is -1.

Statement 2 - Sodium oxide, Na₂O, has sodium with an oxidation number of +1 and oxygen it is -1.

• Both statements are correct and the second statement is a correct explanation of the first.

• Both statements is correct, but the second statement is not a correct explanation of the first.

• Only 1 statement is correct.

• Only statement 2 is correct

• Neither statement is correct.

Answer explanation

Na2O is sodium oxide - not a peroxide. So sodium here has an oxidation number of +1 and oxygen is -2 and te sum of the oxidation numbers combine to equal the charge on the compound. There is no charge and so they must combine to equal 0. (2 x +1) -2 = 0.

Tags

NGSS.HS-PS1-1