Oxidation States and Chromium Compounds

Oxidation States and Chromium Compounds

Assessment

Interactive Video

Chemistry

9th - 10th Grade

Hard

Created by

Amelia Wright

FREE Resource

The video tutorial explains how to find oxidation numbers for each element in magnesium dichromate (MgCr2O7). It begins by noting that the compound is neutral, meaning the oxidation numbers must sum to zero. Magnesium, being in group two, has an oxidation number of +2. Chromium, a transition metal, has variable oxidation states, so it is represented as 'x'. Oxygen is consistently -2. An equation is set up to solve for 'x', resulting in an oxidation number of +6 for chromium. The video concludes by mentioning an alternative method using the dichromate ion's charge.

Read more

9 questions

Show all answers

1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the overall charge of the compound MgCr2O7?

Positive

Variable

Neutral

Negative

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the oxidation number of magnesium in MgCr2O7?

+1

0

+3

+2

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Why is the oxidation number of chromium initially unknown?

It has multiple oxidation states

It is a non-metal

It is always zero

It is a noble gas

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the oxidation number of oxygen in most compounds?

+1

0

-2

-1

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

How many chromium atoms are present in MgCr2O7?

4

1

2

3

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the oxidation number of each chromium atom in MgCr2O7?

+6

+3

+4

+5

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the total contribution of oxygen atoms to the oxidation state in MgCr2O7?

-8

-10

-12

-14

8.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the charge of the dichromate ion (Cr2O7)?

1+

2-

1-

2+

9.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What alternative method can be used to find the oxidation number of chromium?

Using the charge of the dichromate ion

Assuming chromium is a noble gas

Using the periodic table

Guessing based on color