Question

5. If the solubility of common salt is 40 g at 45° C, what mass of the salt is
needed to make a saturated solution in 80 g of water at the same
temperature ?​

Answer 1

Answer:

Mass of the salt required = 32 g

Explanation:

Given:

• Solubility of common salt = 40 g

To Find:

• Mass of the salt required to make a saturated solution in 80 g of water

Solution:

We know that the solubility of a substance is the concentration of the substance in a saturated solution.

A saturated solution is a solution in which no more solute can be dissolved at at a given/constant temperature.

Now solubility is given by,

$\sf Solubility=\dfrac{Mass \:of\:the\:substance}{Mass\:of\:the\:solvent} \times 100$

Here substance = solute = common salt

Substitute the given data in the above equation,

$\sf 40=\dfrac{Mass\:of\:the\:salt}{80} \times 100$

$\sf Mass\:of\:the\:salt=\dfrac{40\times 80}{100}$

$\sf Mass\:of\:the\:salt=\dfrac{3200}{100}$

$\sf Mass\:of\:the\:salt=32\:g$

Hence the mass of the salt required to make the solution saturated is 32 g.

Answer 2

Given :-

If the solubility of common salt is 40 g at 45° C

To Find :-

Mass of salt

Solution :-

Let the mass be x

We know that

Solubility = Mass of solute × 100/Mass of solvent

45 = x × 100/80

45 × 80 = x × 100

3600 = 100x

3600/100 = x

36 = x

Hence

Mass of salt is 36 g

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