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A solution is made by dissolving 373.5 g of Pb(NO3)2 (molar mass: 331.2 g/mol) in 2.00 × 103 g of water. What is the molality of the solution?

2 Answers

3 votes

Answer:

0.564

Step-by-step explanation:

User Tobonaut
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4 votes
Answer:
molality = 0.564 m

Step-by-step explanation:
Molality = number of moles of solute / kg of solvent

1- getting moles of solute:
number of moles = mass / molar mass
we have:
mass = 373.5 g
molar mass = 331.2 g/mol
Therefore:
number of moles = 373.5 / 331.2 = 1.128 moles

2- getting kg of solvent:
mass in kg = mass in grams * 10⁻³
mass in kg = 2 * 10³ * 10⁻³
mass in kg = 2 kg

3- getting molality:
Molality = number of moles of solute / kg of solvent
Molality = 1.128 / 2
Molalty = 0.564 m

Hope this helps :)
User NicolasKittsteiner
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