Answer: 7.88 grams
Explanation:
Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.
[tex]Molarity=\frac{n}{W_s}[/tex]
where,
n = moles of solute
[tex]W_s[/tex] = weight of solvent in kg
moles of solute =[tex]\frac{\text {given mass}}{\text {molar mass}}=\frac{xg}{74.5g/mol}[/tex]
mass of solvent = 97 g = 0.097 kg (1kg=1000g)
Now put all the given values in the formula of molality, we get
[tex]1.09=\frac{x}{74.5g/mol\times 0.097kg}[/tex]
[tex]x=7.88g[/tex]
Therefore, the mass in grams of potassium chloride that must be added to 97 g of water to make a 1.09 m solution is 7.88
