Question

Вычислите массу воды, которую надо выпарить из 1 кг 3%-ного раствора сульфата меди для получения 5 %-ного раствора.

Answer 1

3% раствор = 30 г меди. надо, чтобы 30 г составляли 5%, то есть всего раствора должно стать 30/0.05 = 600 г, значит надо выпарить 1000-600=400 г воды

Answer 2

Calculating the Mass of Water to Evaporate

To calculate the mass of water that needs to be evaporated from a 1 kg 3% solution of copper sulfate to obtain a 5% solution, we can use the following formula:

Initial mass of solute = Final mass of solute

Let's denote: - Initial mass of water as W1 - Initial mass of copper sulfate as C1 - Final mass of water as W2 - Final mass of copper sulfate as C2

The initial mass of water and copper sulfate can be calculated using the given percentage of the solution. Then, we can use the formula to find the mass of water that needs to be evaporated.

Calculation Steps

1. Calculate the initial mass of water and copper sulfate in the 1 kg 3% solution. 2. Use the formula to find the mass of water that needs to be evaporated to obtain a 5% solution.

Calculation

1. Initial mass of water (W1) in the 1 kg 3% solution: - W1 = 1 kg * 3% = 1 kg * 0.03 = 0.03 kg

2. Initial mass of copper sulfate (C1) in the 1 kg 3% solution: - C1 = 1 kg - W1 = 1 kg - 0.03 kg = 0.97 kg

3. Final mass of copper sulfate (C2) in the 1 kg 5% solution: - C2 = 1 kg

4. Using the formula Initial mass of solute = Final mass of solute, we can calculate the final mass of water (W2) in the 1 kg 5% solution: - W2 = C1 - C2 = 0.97 kg - 1 kg = -0.03 kg

Result

The negative value for the final mass of water (W2) indicates that no water needs to be evaporated from the 1 kg 3% solution to obtain a 5% solution of copper sulfate. Therefore, the mass of water to be evaporated is 0 kg.