Respuesta :
Solution:
Molality:-It is a measure of the concentration of a solute in a solution in terms of amount of substance in a specified amount of mass of the solvent
Therefore,
Molality = moles solute / kg solvent
Therefore kg solvent = moles solute / molality
moles solute = mass / molar mass
= 25.31 g / 101.1 g/mole
= 0.2503 mole
kg solvent = 0.2503 mole / 0.1982 m
= 1.263 kg
= 1263 g
This is the required answer.
Answer: The mass of water that is needed to dissolve the given amount of potassium nitrate is 1263.1g
Explanation:
To calculate the mass of solvent for given molality of solution, we use the equation:
[tex]\text{Molality of solution}=\frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}[/tex]
where,
Molality of the solution = 0.1982 m
[tex]m_{solute}[/tex] = Given mass of solute [tex](KNO_3)[/tex] = 25.31 g
[tex]M_{solute}[/tex] = Molar mass of solute [tex](KNO_3)[/tex] = 101.1 g/mol
[tex]W_{solvent}[/tex]= Mass of solvent (water) = ?
Putting values in above equation, we get:
[tex]0.1982=\frac{25.31\times 1000}{101.1\times \text{Mass of water}}\\\\\text{Mass of water}=\frac{25.31\times 1000}{101.1\times 0.1982}=1263.1g[/tex]
Hence, the mass of water that is needed to dissolve the given amount of potassium nitrate is 1263.1g
