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2 votes
A solution is made by dissolving

37.5 g of sodium sulfide (Na2S) in

217 g of water.

What is the molality of the solution?

2 Answers

4 votes

Answer:

2.21

Step-by-step explanation:

6 votes

Answer:

2.21m

Step-by-step explanation:

Molality, m, is defined as the ratio between moles of solute (The substance that is in less amount, sodium sulfide) and kilograms of solvent (Water, in this case).

Thus, we need to convert mass of sodium sulfide to moles using its molar mass and grams of water to kilograms:

Moles Na2S (Molar mass: 78.0452g/mol):

37.5g * (1mol / 78.0452g) = 0.48 moles Na2S

Kilograms water:

217g * (1kg / 1000g) = 0.217kg

Molality:

0.48 moles Na2S / 0.217kg =

2.21m

User Andris Zalitis
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