Molarity & Molality

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What is Molarity?

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Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution.

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What is Molality?

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Molality (m) is a measure of concentration defined as the number of moles of solute per kilogram of solvent.

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How do you calculate Molarity?

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Molarity (M) = moles of solute / liters of solution.

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How do you calculate Molality?

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Molality (m) = moles of solute / kilograms of solvent.

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What is the formula to find moles from Molarity?

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Moles = Molarity (M) x Volume (L).

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What is the formula to find moles from Molality?

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Moles = Molality (m) x Mass of solvent (kg).

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What are the units of Molarity?

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The units of Molarity are moles per liter (mol/L) or simply M.

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What are the units of Molality?

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The units of Molality are moles per kilogram (mol/kg) of solvent.

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Calculate the mass of 0.75 moles of (NH₄)₃PO₄.

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111.75 g.

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What is the molality of a solution made by dissolving 2 moles of NaOH in 400 grams of water?

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5 mol/kg solvent.