Question

find the weight of Sodium nitrate required to prepare 60g pure crystal from its saturated solution at 70°C. Solubility of sodium nitrate is 140g at 70°C and 100g at 25°C.​

Answer 1

Q. Find the weight of Sodium nitrate required to prepare 60g pure crystal from its saturated solution at 70°C. Solubility of sodium nitrate is 140g at 70°C and 100g at 25°C.

$\huge{\underline{\tt{\green{Solution-}}}}$

• Solubility at 70°C = 140
• Solubility at 25°C = 100

Amount of crystals you will get when the solution will be cooled from 70°C to 25°C

$\longrightarrow \tt {140-100=40g}$

To obtain 40 g of crystals, sodium nitrate taken is 140 g.

To obtain 60 g crystals, sodium nitrate required

$\longrightarrow \tt \frac{ = 140}{40\times60}$

$\longrightarrow \tt\blue {=120\:g}$

• The weight of Sodium Nitrate is 120g.

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Answer 2

Solubility at 70°c=140g

Solubility at 70°c=100g

Amount of crystals obtained when the solution is cooled from 70°c to 25°c=140-100

=40g

To obtain 40g of crystals sodium nitrate is taken =140g

So,

To obtain 60g crystals , sodium nitrate required will be= 140/40*60

=210g