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4.5 Molarity

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1. Molarity

  1. Equation p. 480
  2. M is read as “molar”

Molarity is defined as moles of solute per 1 liter of solution.

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Ex VIDEO

What is the molarity of a solution that contains 75.0 g of KNO3 dissolved in 0.350 L of solution?

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Ex VIDEO

How many milliliters of a 2.25 M HCl solution will provide 4.12 g of HCl?

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Ex VIDEO

How many grams of NaHCO3 are in 325 mL of a 4.50 M NaHCO3 solution?

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2. Dilutions

  1. Dilutions keep amount of solute the same but increase the amount of solvent.
  2. Equation: C1V1 = C2V2

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Ex VIDEO

Given 20.0 mL of 8.00 M NaCl solution, explain how to prepare a 0.50 M solution.

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Ex VIDEO

What volume of 6.00 M HCl solution was needed to make 25.0 mL of 0.125 M HCl solution?

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3. Gravimetric Analysis

  1. Use the mass of a precipitate in stoichiometric relationships.

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Ex VIDEO

A 5.00 L sample of tap water is distilled to 0.854 L. Then a 50.0 mL sample is removed and excess Na2CO3 is added to precipitate calcium carbonate. The precipitate is filtered, dried, and weighed as 23 mg. Calculate the water hardness in mg CaCO3/L.

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Ex VIDEO

A 25 g powder with sodium sulfate is dissolved in water. It is then treated with barium chloride to precipitate barium sulfate. The mass of the precipitate is determined to be 5.342 g. Find the grams of sodium sulfate in the original sample.