Answer:
0.77mol/Kg.
Explanation:
The following data were obtained from the question:
Mass of NaCl = 4.5g
Mass of water = 100g.
Molality =...?
Next, we shall determine the number of mole in 4.5g of NaCl. This can be obtained as follow:
Mass of NaCl = 4g.
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of mole NaCl =..?
Mole = Mass /Molar Mass
Number of mole of NaCl = 4.5/58.5
Number of mole of NaCl = 0.077 mole.
Next, we shall convert 100g of water to kilograms. This is illustrated below:
1000g = 1kg
Therefore, 100g = 100/1000 = 0.1Kg.
Finally, we can determine the molality of the solution as follow:
Molality is simply defined as the mole of solute per unit kilogram of solvent (water). Mathematically, it is represented as:
Molarity = mole of solute / kg of solvent
Mole of solute, NaCl = 0.077 mole
Kg of solvent = 0.1kg
Molality = 0.077mol/0.1kg
Molality = 0.77mol/Kg
The molarity of the solution is 0.77mol/Kg.
Since
Mass of NaCl = 4.5g
Mass of water = 100g.
Here,
Mass of NaCl = 4g.
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Now
Mole = Mass /Molar Mass
= 4.5/58.5
= 0.077 mole.
Now
1000g = 1kg
So,
100g = 100/1000 = 0.1Kg.
Now
Molarity = mole of solute / kg of solvent
Mole of solute, NaCl = 0.077 mole
Kg of solvent = 0.1kg
So,
Molality = 0.077mol/0.1kg
= 0.77mol/Kg
Learn more about sodium here: https://brainly.com/question/14248836
