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What is the molality of a solution containing 0.100 mol of NH3 dissolved in 500 g of methanol?
What is the molality of a solution containing 0.100 mol of NH3 dissolved in 500 g of methanol?
- 0.200 m (correct)
- 1.00 m
- 0.500 m
- 0.100 m
What is the mass (in g) of NH3 needed to prepare a 0.250 m solution in 1.00 kg of methanol?
What is the mass (in g) of NH3 needed to prepare a 0.250 m solution in 1.00 kg of methanol?
- 4.26 g
- 8.52 g
- 17.0 g (correct)
- 34.1 g
If 5.00 g of NH3 is dissolved in 250 g of methanol, what is the molality of the solution?
If 5.00 g of NH3 is dissolved in 250 g of methanol, what is the molality of the solution?
- 0.117 m (correct)
- 0.936 m
- 0.468 m
- 0.234 m
What is the mass of methanol (in g) needed to dissolve 10.0 g of NH3 to make a 0.500 m solution?
What is the mass of methanol (in g) needed to dissolve 10.0 g of NH3 to make a 0.500 m solution?
A student wants to prepare a 0.150 m NH3 solution using 200 g of methanol. What mass (in g) of NH3 should the student use?
A student wants to prepare a 0.150 m NH3 solution using 200 g of methanol. What mass (in g) of NH3 should the student use?
Flashcards
Molar Mass
Molar Mass
The mass of one mole of a substance, measured in g/mol.
Molality
Molality
Concentration measured in moles of solute per kilogram of solvent.
Solute
Solute
A substance that is dissolved in a solvent to form a solution.
Solvent
Solvent
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Calculating Mass of NH3
Calculating Mass of NH3
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Study Notes
Calculating Mass of NH3
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The problem asks for the mass of ammonia (NH3) needed to create a specific molality solution in methanol.
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Molality (m) is defined as the number of moles of solute per kilogram of solvent.
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The given information includes:
- Mass of solvent (methanol): 475 g
- Desired molality (m): 0.250 m
- Molar mass of NH3: 17.04 g/mol
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First, convert the mass of solvent from grams to kilograms:
- 475 g * (1 kg / 1000 g) = 0.475 kg
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Using the definition of molality, we can find the moles of NH3 needed:
- Molality = (moles of NH3) / (kilograms of methanol)
- 0.250 m = (moles of NH3) / 0.475 kg
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Solving for moles of NH3:
- Moles of NH3 = 0.250 m * 0.475 kg = 0.11875 moles
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Now, convert moles of NH3 to grams using its molar mass:
- Mass of NH3 = (moles of NH3) * (molar mass of NH3)
- Mass of NH3 = 0.11875 moles * 17.04 g/mol = 2.0275 g
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Therefore, approximately 2.03 g of NH3 must be dissolved in 475 g of methanol to create a 0.250-m solution.
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Description
This quiz focuses on calculating the mass of ammonia (NH3) needed to create a specific molality solution in methanol. You will use the definitions of molality and the molar mass of NH3 to solve for the mass required. Test your understanding of these concepts and improve your skills in solution preparation.
