28. Let's determine the amount of sulfur substance

According to the chemical reaction equation:

$$
\mathrm{n}(\mathrm{S})=\mathrm{n}\left(\mathrm{SO}_{2}\right)=1 \text { mole }
$$

29. Let's calculate the mass of pure sulfur:

$$
m(S)=n \cdot M=1 \cdot 32=32 \text { g }
$$

Determination of the mass of the substance - 2 points

30. Thus, in a sample of natural sulfur weighing 38 g, there are 32 g of pure substance.

Let's calculate the mass of the impurity:

$m($ impurity $)=38-32=6$ g

Determination of the mass of the impurity - 2 points
Answer: 6 g.

## TOTAL 10 points

## TASK № 2

Potassium phosphate was calcined with coke in the presence of river sand. The simple substance formed reacted with excess chlorine. The resulting product was added to an excess of potassium hydroxide solution. The formed solution was treated with lime water. Write the equations for the four described reactions.

## Solution: