Question

Морская вода содержит 5% солей( по массе).Сколько кг пресной воды нужно добавить к 100 кг морской воды,чтобы содержание соли стало составлять 2%( Массой солей в пресной воде пренебречь)?

Answer 1

200+2x/100=5. 2x-300/100=0. 2x=300. x=150 кг пресной воды))))

Answer 2

Calculation of Freshwater Needed to Reduce Salt Content in Seawater

To calculate the amount of freshwater needed to reduce the salt content in seawater, we need to determine the initial salt content in the seawater and the desired final salt content.

Given: - Seawater contains 5% salts by mass. - We want to reduce the salt content to 2% by mass.

Let's assume we have 100 kg of seawater.

To find the amount of salt in 100 kg of seawater, we can multiply the mass of seawater by the salt content: - Initial salt content in 100 kg of seawater = 5% of 100 kg = 5 kg of salt.

To find the amount of freshwater needed to achieve a final salt content of 2%, we can set up the following equation:

Amount of salt in freshwater + Amount of salt in seawater = Total amount of salt in the mixture

Let's assume we need to add x kg of freshwater.

The amount of salt in the freshwater is negligible, so we can ignore it.

Therefore, the equation becomes:

0 kg (salt in freshwater) + 5 kg (salt in seawater) = (5 kg + x kg) (total salt in the mixture)

Simplifying the equation:

5 kg = 5 kg + x kg

x kg = 0 kg

This means that no freshwater needs to be added to the seawater to achieve a final salt content of 2%. The seawater already contains enough freshwater to dilute the salt content to the desired level.

Please note that this calculation assumes that the salt content is evenly distributed throughout the seawater and that the addition of freshwater does not change the volume of the mixture.