Question

К 200 г 3%-ного гидроксида калия прилили нитрат цинка.Вычеслите массу выпавшего осадка.

Answer 1

m(Zn(NO3)2)= 3*200г\100=6 гр

M(Zn(NO3)2)=189г\моль

n(Zn(NO3)2)=6\189=0,3 моль

n(Zn(OH)2)=0,3моль

M(Zn(OH)2)=99 г\моль

m(Zn(OH)2)=0,3 моль * 99г\моль=29,7 г

Answer 2

Calculating the Mass of Precipitate

To calculate the mass of the precipitate formed when 200 g of 3% potassium hydroxide is mixed with zinc nitrate, we can use the following steps:

1. Determine the reaction between potassium hydroxide and zinc nitrate. 2. Calculate the amount of precipitate formed based on the reaction.

Reaction Between Potassium Hydroxide and Zinc Nitrate

The reaction between potassium hydroxide (KOH) and zinc nitrate (Zn(NO3)2) can be represented as follows:

2KOH + Zn(NO3)2 → 2KNO3 + Zn(OH)2

Calculation

Given: - Mass of 3% potassium hydroxide = 200 g - Percentage of potassium hydroxide = 3%

First, we need to calculate the mass of potassium hydroxide in the 200 g solution. Then, we can use stoichiometry to find the mass of the precipitate formed.

Mass of Potassium Hydroxide in 200 g Solution

The mass of potassium hydroxide in the 200 g solution can be calculated using the percentage of potassium hydroxide.

Mass of potassium hydroxide = 3% of 200 g

Using the given percentage, we can calculate the mass of potassium hydroxide in the solution.

Mass of potassium hydroxide = 3/100 * 200 g

Mass of potassium hydroxide = 6 g

Stoichiometry Calculation

Now, we can use stoichiometry to find the mass of the precipitate formed. From the balanced chemical equation:

2 moles of KOH react with 1 mole of Zn(NO3)2 to produce 1 mole of Zn(OH)2.

The molar mass of Zn(OH)2 is 99.38 g/mol.

Moles of Zn(OH)2 = Moles of KOH / 2

Moles of Zn(OH)2 = 6 g / 56.11 g/mol

Moles of Zn(OH)2 ≈ 0.107 moles

Mass of Zn(OH)2 = Moles of Zn(OH)2 * Molar mass of Zn(OH)2

Mass of Zn(OH)2 ≈ 0.107 moles * 99.38 g/mol

Mass of Zn(OH)2 ≈ 10.64 g

Conclusion

The mass of the precipitate formed when 200 g of 3% potassium hydroxide is mixed with zinc nitrate is approximately 10.64 grams.