Question

In a reaction, 34.0 g of chromium (III) oxide reacts with 12.1 g of aluminium to produce chromiumand aluminium oxide. If 23.3 g of chromium is produced, what mass of aluminium oxide is produced?

Short answer

The mass of aluminium oxide is 22.8 g.

Step-by-step solution

Law of mass conservation

This law states that the mass is neither created nor destroyed. This can be applied for this problem. The initial step is to use the reaction with specific mass. The reaction can be denoted as,

${\text{Cr}}_{\text{2}}{\text{O}}_{\text{3}}\text{+ 2Al}\to {\text{2Cr + Al}}_{\text{2}}{\text{O}}_{\text{3}}$

34g 12.1g 23.3g

Reaction with total mass of reactant and products

The total mass of reactants can be denoted as,

$$\begin{gathered} =34g+12.1g \\ =46.1g \end{gathered}$$

The total mass of products can be denoted as,

$=23.3g+xg$

x g denotes the aluminium oxide mass.

Mass of aluminium oxide

The mass of reactants and products are equal. On subtracting the product mass from reactant mass to calculate the aluminium oxide mass.

$\begin{array}{rcl}& & {\text{MassofAl}}_{\text{2}}{\text{O}}_{\text{3}}\text{=461.g - 23.2g}\\ & & \text{=22.8g}\\ & & \end{array}$

The mass of aluminium oxide is 22.8 g.