Chemistry 11

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Chemistry 11 Introduction to Molarity Lesson 1
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Prescription drugs in the correct concentration
make you better. In higher concentration they can
kill you.
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Chemists need to make solutions that have precise
concentrations
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Pesticides must be in proper concentrations. Food
additives must be in correct concentrations. A
driver is legally impaired at 0.08 mg/mL blood
alcohol content. Chemists control the
concentration of chemicals using the concepts we
will develop in this unit.
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The concentration of a solution tells you how
much solute that is dissolved in a given amount
of solvent (water). The molarity is the
concentration of a solution. Molarity Moles
Litre 1. 2.255 moles of NaCl is dissolved in
4.0 L of water, calculate the molarity. Molarit
y
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The concentration of a solution tells you how
much solute that is dissolved in a given amount
of solute (water). The molarity is the
concentration of a solution. Molarity Moles
Litre 1. 2.255 moles of NaCl is dissolved in
4.0 L of water, calculate the molarity. Molarit
y 2.255 moles 4.0 L
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The concentration of a solution tells you how
much solute that is dissolved in a given amount
of solute (water). The molarity is the
concentration of a solution. Molarity Moles
Litre 1. 2.255 moles of NaCl is dissolved in
4.0 L of water, calculate the molarity. Molarity
2.255 moles 4.0 L 0.56
moles/litre 0.56 M (Molar) where M
means moles per 1 litre
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2. 5.00 g KOH is dissolved in 250. mL of water,
calculate the molarity. Molarity
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2. 5.00 g KOH is dissolved in 250. mL of water,
calculate the molarity. Molarity 5.00 g

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2. 5.00 g KOH is dissolved in 250. mL of water,
calculate the molarity. Molarity 5.00 g
x 1 mole 56.11 g
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2. 5.00 g KOH is dissolved in 250. mL of water,
calculate the molarity. Molarity 5.00 g
x 1 mole 56.11 g 0.250 L
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2. 5.00 g KOH is dissolved in 250. mL of water,
calculate the molarity. Molarity 5.00 g x 1
mole 56.11 g ---------------------------
0.250 L 0.356 M
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3. How many moles are there in 205. mL of a
0.172 M solution?
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3. How many moles are there in 205. mL of a 0.172
M solution? 0.205 L
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3. How many moles are there in 205. mL of a 0.172
M solution? 0.205 L x 0.172 moles 1 L
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3. How many moles are there in 205. mL of a 0.172
M solution? 0.205 L x 0.172 moles 0.0353
moles 1 L
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4. How many grams NaCl are there in 250.0 mL of
0.500 M solution?
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4. How many grams NaCl are there in 250.0 mL of
0.500 M solution? 0.250 L
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4. How many grams NaCl are there in 250.0 mL of
0.500 M solution? 0.250 L x 0.500
moles 1 L
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4. How many grams NaCl are there in 250.0 mL of
0.500 M solution? 0.250 L x 0.500 moles x
58.5 g 1 L 1 mole
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4. How many grams NaCl are there in 250.0 mL of
0.500 M solution? 0.250 L x 0.500 moles x
58.5 g 7.31 g 1 L 1 mole
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5. How many grams of NaCl must be used to
prepare a 100.0 mL of 0.250 M solution.
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5. How many grams of NaCl must be used to prepare
a 100.0 mL of 0.250 M solution. 0.1000 L
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5. How many grams of NaCl must be used to prepare
a 100.0 mL of 0.250 M solution. 0.1000 L x
0.250 moles 1 L
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5. How many grams of NaCl must be used to prepare
a 100.0 mL of 0.250 M solution. 0.1000 L x
0.250 moles x 58.5 g 1 L 1
mole
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5. How many grams of NaCl must be used to prepare
a 100.0 mL of 0.250 M solution. 0.1000 L x
0.250 moles x 58.5 g 1.46 g 1
L 1 mole
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g?
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g? 25.0 g
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g? 25.0 g x 1
mole 129.9 g
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g? 25.0 g x 1
mole x 1 L 129.9 g 0.200
mol
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g? 25.0 g x 1
mole x 1 L x 1000 mL 129.9 g
0.200 mol 1 L
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6. How many millilitres of a 0.200 M solution of
CoCl2 will contain 25.0 g? 25.0 g x 1
mole x 1 L x 1000 mL 962 mL
129.9 g 0.200 mol 1 L
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7. Describe how you would prepare 100.0 mL of a
0.200 M solution of CoCl2. 0.1000 L x
0.200 moles x 129.9 g 2.60 g 1
L 1 mole Weigh 2.60 g of
CoCl2 Dissolve in water Transfer to a 100 mL
volumetric flask and fill to the line