Question

Knowing that the solubility of a salt at 80°C is 45g/100 g of H,O, calculate the mass of water required for dissolve 250 g of this salt at 80º C.​

Answer 1

The mass of water required will be approximately
`\bf = 555.6\: g`.

• To solve this question, just make a simple rule of three between the amount of salt dissolved at 80ºC and the mass of water:

`\qquad` 45g of salt
`\sf \longrightarrow` 100g of H₂O

`\qquad` 250g of salt
`\sf \longrightarrow` x g of H₂O

`\qquad`
`\red{\twoheadrightarrow\bf45* x = 250* 100}`

`\qquad`
`\twoheadrightarrow\sf45x=25000`

`\qquad`
`\twoheadrightarrow\sf x=\cancel{(25000)/(45)}`

`\qquad`
`\red{\twoheadrightarrow\bf x = 555.6\:g}`

• Therefore, knowing that the solubility of a salt at 80ºC is 45g/100g of water (H₂O), the mass of water needed to dissolve 250g of this salt at 80ºC will be
  `\red{\bf = 555.6\: g }`

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