Question

2.8g of silicon react with 3.2g of oxygen to give a compound, which is shown below. The relative atomic mass of silicon is 28 and of oxygen is 16. What is the value of y in the formula below?

Answer 1

Answer: The value of 'y' in the formula given is 2

Step-by-step explanation:

We are given:

The given chemical formula of the compound is
`SiO_y`

Mass of Si = 2.8 g

Mass of O = 3.2 g

To formulate the empirical formula, we need to follow some steps:

• Step 1: Converting the given masses into moles.

Moles of Silicon =
`\frac{\text{Given mass of Silicon}}{\text{Molar mass of Silicon}}=(2.8g)/(28g/mole)=0.1moles`

Moles of Oxygen =
`\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=(3.2g)/(16g/mole)=0.2moles`

• Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.1 moles.

For Silicon =
`(0.1)/(0.1)=1`

For Oxygen =
`(0.2)/(0.1)=2`

• Step 3: Taking the mole ratio as their subscripts.

The ratio of Si : O = 1 : 2

The chemical formula of the compound becomes
`SiO_2`

Hence, the value of 'y' in the formula given is 2