Question

Определите массу гидроксида калия прореагировавшего с 20 г речного песка(SiO2) содержащего 10% примесей

Answer 1

Вычислим кол-во примесей в граммах использую имеющийся процент

100% – 20г
10% – икс

икс=(20•10)/100=2г примесей

след. 20-2=18г чистого SiO2

Считаем моль SiO2 из того, что имеем

n(SiO2)=m/M=18/60≈0.47моль

Пишем реакцию

SiO2+2KOH=K2SiO3+H2O

по реакции KOH вдвое больше моль, чем SiO2
2•0.47=0.94моль

m(KOH)=n•M=0.94•56=52,64г

Answer 2

Calculation of the Mass of Potassium Hydroxide Reacted with River Sand

To determine the mass of potassium hydroxide (KOH) that reacted with 20 g of river sand (SiO2) containing 10% impurities, we need to consider the chemical reaction between KOH and SiO2.

The balanced chemical equation for the reaction between KOH and SiO2 is as follows:

KOH + SiO2 → K2SiO3 + H2O

From the equation, we can see that 1 mole of KOH reacts with 1 mole of SiO2 to produce 1 mole of K2SiO3 and 1 mole of water.

To calculate the mass of KOH, we need to determine the number of moles of SiO2 in the 20 g of river sand. Since the river sand contains 10% impurities, we can assume that 90% of the 20 g is SiO2.

Mass of SiO2 = 20 g × 0.9 = 18 g

Next, we need to convert the mass of SiO2 to moles using the molar mass of SiO2.

Molar mass of SiO2 = 28.08 g/mol (Si) + 2 × 16.00 g/mol (O) = 60.08 g/mol

Number of moles of SiO2 = Mass of SiO2 / Molar mass of SiO2 = 18 g / 60.08 g/mol ≈ 0.2997 mol

Since the reaction is 1:1 between KOH and SiO2