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# Solution for Pragya tested the solubility of three different substances at different temperatures and collected the data as given below - CBSE Class 9 - Science

#### Question

Pragya tested the solubility of three different substances at different temperatures and collected the data as given below( results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).

 Substance dissolved Temperature in K 283 293 313 333 353 Potassium nitrate 21 32 62 106 167 Sodium chloride 36 36 36 37 37 Potassium chloride 35 35 40 46 54 Ammonium chloride 24 37 41 55 66

(a)  What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?

(b)  Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.

(c)  Find the solubility of each salt at 293 K. What salt has the highest solubility at this temperature?

(d)  What is the effect of change of temperature on the solubility of a salt?

#### Solution

(a) At 313 K, 62 grams of Potassium nitrate dissolved in 100 grams of water. So to produce a saturated solution of potassium nitrate in 50 grams of water, we need
62 x 50 = 31 grams of potassium nitrate
100

(b) Some soluble potassium chloride will separate out in the form of crystals at room temperature because the solubility of potassium chloride will decrease with decrease in temperature.

(c)

(i)   Solubility of Potassium nitrate at 293 K is 32 grams.

(ii)  Solubility of Sodium chloride at 293 K is 36 grams.

(iii) Solubility of Potassium chloride at 293 K is 35 grams.

(iv) Solubility of Ammonium chloride at 293 K is 37 grams.

The solubility of Ammonium chloride is highest at this temperature.

(d) The solubility of salt increases with increase in temperature.

Is there an error in this question or solution?

#### APPEARS IN

NCERT Science Textbook for Class 9 (with solutions)
Chapter 2: Is Matter around us Pure
Q: 3 | Page no. 28

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Solution for question: Pragya tested the solubility of three different substances at different temperatures and collected the data as given below concept: Concept of Solution. For the course CBSE
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