The ions Cr3+ and O2- combine to form the ionic compound chromium oxide. In what proportions do these ions combine to produce a neutral compound?

Question

A.
3:2
B.
3:3
C.
1:1
D.
2:3
E.
1:3

Answer 1

To determine the proportions of Cr³⁺ and O²⁻ ions that combine to form a neutral compound, we need to consider the charges of the ions:

• Each Cr³⁺ ion has a charge of +3.
• Each O²⁻ ion has a charge of -2.

To achieve a neutral compound, the total positive charge must equal the total negative charge.

Let x be the number of Cr³⁺ ions and y be the number of O²⁻ ions. The equation for neutrality can be written as:

\[ 3x = 2y \]

To find the simplest whole number ratio, we can solve for one of the variables. Let's rearrange it:

\[ \frac{x}{y} = \frac{2}{3} \]

This means that for every 2 O²⁻ ions, there will be 3 Cr³⁺ ions. Therefore, the ions combine in the ratio of:

• Cr³⁺ : O²⁻ = 3 : 2

So the answer is A. 3:2.