What mass of the substance T will be extracted from 150 g of the solution when we cool the solution from 50 ° C to 20 ° C?

In the table below, the solubility of the substances in water is expressed as the mass fraction of substance T in water at different temperatures.
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The answer should be: 9,41 g

2 Answers
May 19, 2018

The mass of solid T is 7,0 g.

Explanation:

At 50 °C,

#"Mass of T in solution" = 150 color(red)(cancel(color(black)("g solution"))) × "29,8 g T"/(100color(red)(cancel(color(black)( "g solution")))) = "44,70 g T"#.

At 20 °C,

#"Mass of T in solution" = 150 color(red)(cancel(color(black)("g solution"))) × "25,1 g T"/(100 color(red)(cancel(color(black)("g solution")))) = "37,65 g T"#

#"Difference = 44,70 - 37,65 = 7,0 g"#

The mass of solid T is 7,0 g.

May 20, 2018

I get answer as 5.44g

Explanation:

By definition of solubility we know

"Amount of a substance (called the solute) that dissolves in 100g of a liquid substance (called the solvent) to form a saturated solution under specified conditions of temperature and pressure."

Let at #50^@C# #xg#of T be dissolved in 150g saturated solution.

So amount of solvent in the solution #=(150-x)#g

Hence by deinition of solubility

#x/(150-x)xx 100==29.8#

#=>129.8x=150xx29.8#

#=>x=(150xx29.8)/129.8~~34.44g#

So amount of solvent in 150g solution at #50^@C# will be
#150-34.44=115.56g#

On cooling to #20^@C# this amount of solvent will accommodate

#25.1/100xx115.56g~~29.00g # solute T

Hence the amount of T extracted on cooling to #20^@C# will be #(34.44-29.00)=5.44g#