Molarity: The concentration of a solution

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Molarity The concentration of a solution
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A solution is a mixture

• The solute is the substance dissolved (Usually
  the substance that there is less of)
• The solvent is the substance that does the
  dissolving

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Solute Solvent Solution

• 1. What is the solvent in air?
• A) Nitrogen B) oxygen C) carbon dioxide
• 2. What is the solvent in coca cola?
• Sugar B) water C) carbon dioxide
• 3. What is an aqueous solution?
• Dissolved in methane
• Dissolved in water
• Dissolved in petrol

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Molarity (M)

• The molar concentration shows the number of
• moles of solute in one liter (dm3) of solution
• Molarity (M) moles of solute
• 1 dm3 solution

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Volumetric Flask
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Note
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Molarity Calculations

• If 4.0 g NaOHare used to make 500. mL of NaOH
  solution, what is the molarity (M) of the
  solution?

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If 4.0 g NaOH are used to make 500. mL of NaOH
solution, what is the molarity (M) of the
solution?

• Step 1 Find the moles (Divide by the molar mass)
• 4.0 g NaOH x 1 mole NaOH 0.10 mole NaOH
• 40.0 g NaOH
• Step 2 convert to dm3 (Divide mL by 1000)
• 500. mL x 1 L _ 0.500 L
• 1000 mL
• Step 3 Divide moles of solute by volume of
  solution
• 0.10 mole NaOH 0.20 M
• 0.500 L

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Molarity Calculation

• A KOH solution with a volume of 400 mL contains
  2.0 mole KOH. What is the molarity of the
  solution?
• A) 8.0 M
• B) 5.0 M
• C) 2.0 M

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A KOH solution with a volume of 400.0 mL
contains 2.0 moles of KOH. What is the molarity
of the solution?

• B) 5.0 M
• M 2.0 mole KOH 5.0 M
• 0.4 L

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Calculation

• A glucose solution with a volume of 2.0 L
  contains 72.0 g glucose (C6H12O6). If glucose
  has a molar mass of 180.0 g/mole, what is the
  Molarity of the glucose solution?
• A) 0.20 M
• B) 5.0 M
• C) 36 M

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A glucose solution with a volume of 2.0 L
contains 72.0 g glucose (C6H12O6). What is the
Molarity of the glucose solution?

• A) 72 g x 1 mole x 1 0.20 M
• 180. g 2.0 L

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Molarity Conversion Factors

• A solution is a 3.0 M NaOH.. Write the molarity
  in the form of conversion factors.
• 3.0 moles NaOH or 1 L NaOH soln
• 1 L NaOH soln 3.0 moles NaOH

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Example

• Stomach acid is a 0.10 M HCl solution. How
  many moles of HCl are in 1500 mL of stomach acid
  solution?
• A) 15 moles HCl
• B) 1.5 moles HCl
• C) 0.15 moles HCl

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Stomach acid is a 0.10 M HCl solution. How many
moles of HCl are in 1500 mL of stomach acid
solution?

• C) 1500 mL x 1 L 1.5 L
• 1000 mL
• 1.5 L x 0.10 mole HCl 0.15 mole HCl
• 1 L
• (Molarity factor)

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Calculation

• How many grams of KCl are present in 2.5 L of
  0.50 M KCl?
• A) 1.3 g
• B) 5.0 g
• C) 93 g

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How many grams of KCl are present in 2.5 L of
0.50 M KCl?

• Answer C)
• 2.5 L x 0.50 mole x 74.6 g KCl 93 g KCl
• 1 L 1 mole KCl

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Calculate

• How many milliliters of stomach acid, which is
  0.10 M HCl, contain 0.15 mole HCl?
• A) 150 mL
• B) 1500 mL
• C) 5000 mL

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How many milliliters of stomach acid, which is
0.10 M HCl, contain 0.15 mole HCl?

• B) 0.15 mole HCl x 1 L soln x 1000
  mL
• 0.10 mole HCl 1 L
• 1500 mL HCl

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Calculation

• How many grams of NaOH are required to prepare
  400. mL of 3.0 M NaOH solution?
• A) 12 g
• B) 48 g
• C) 300 g

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How many grams of NaOH are required to prepare
400. mL of 3.0 M NaOH solution?

• B) 400. mL x 1 L 0.400 L
• 1000 mL
• 0.400 L x 3.0 mole NaOH x 40.0 g NaOH
  1 L 1 mole NaOH
• 48 g NaOH

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Solution preparation

• Weigh out a solid solute, pour into a volumetric
  flask and dissolve in the given quantity of
  solvent.

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5.00 g of NiCl26 H2O are dissolved in enough
water to make 250 mL of solution. The molar mass
of Nickel(II) Chloride hexahydrate is 237.7
g/mol. Find the Molarity.

1. 0.0841
2. 0.0000841
3. 189
4. 0.189

Answer A