- #1
Qube
Gold Member
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Homework Statement
Screenshot of some prof's website. This is just ridiculous.
http://i.minus.com/jnUa604Tz6bKX.png
Homework Equations
Molarity to molality.
Molality is moles / kg of solvent.
Molarity is moles / volume of solution.
The Attempt at a Solution
Pretty sure all the ones in the screenshot from the webpage of some university professor are wrong.
For 1)
a) Assume 1000 mL of solution. We therefore have 0.84 moles of sucrose (0.84 moles / 1 L = 0.84 M)
b) This means we have 1120 g of solution.
c) Solution mass = solute mass + solvent mass.
d) Solute mass = 0.84 moles * 342 g/moles = 287 grams.
e) 1120 - 287 = solvent mass = 833 g = 0.833 kg.
f) 0.84 / 0.833 isn't anywhere close to 3/4 molal solution.
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