Question

Each part has its own answer & part 2/2 is a continuation of the first part 1/2 :)

Answer 1

Explanations:

1) According to the first question, we are to find the molar mass of Na₂SO₄.

Find the molar mass of each element present on the compound

• Molar mass of Sodium (Na) = 23g/mol

,

• Molar mass of sulfur (S) = 32g/mol

,

• Molar mass of Oxygen (O) = 16g/mol

Get the molar mass of Na₂SO₄.

`\begin{gathered} \text{Molar mass of }Na_(2)SO_(4)=2(23)+32+4(16) \\ \text{Molar mass of }Na_2SO_4=46+32+64 \\ \text{Molar mass of }Na_(2)SO_(4)=142g\text{/mol} \end{gathered}`

Therefore the molar mass of Na₂SO₄ is 142g/mol

2) The formula for calculating the number of moles of the compound Na₂SO₄ is expressed as:

`n=\text{Molar conc.}*\text{volume}`

Given the following parameters:

• Molar concentration = 0.202M = 0.202mol/L

,

• Volume = 784mL= 0.784L

Substitute the given parameters into the formula:

`\begin{gathered} n=0.202\frac{mol}{\cancel{L}}*0.784\cancel{L} \\ n=0.1584\text{moles} \end{gathered}`

Hence the number of Na₂SO₄ needed is 0.1584moles.