Chemistry 11
Introduction to Molarity
Lesson 1
Prescription drugs in the correct concentration make you
better.
In higher concentration they can kill you.
Chemists need to make solutions that have precise
concentrations
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.
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
1.
=
Moles
Liter
2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the
molarity.
Molarity
=
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
1.
=
Moles
Liter
2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the
molarity.
Molarity
=
2.255 moles
4.0 L
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
1.
=
Moles
Liter
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/liter
=
0.56 M (Molar)
where M means moles per 1 liter
2.
5.00 g KOH is dissolved in 250. mL of water, calculate the
molarity.
Molarity
=
2.
5.00 g KOH is dissolved in 250. mL of water, calculate the
molarity.
Molarity
=
5.00 g
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
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
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
3.
How many moles are there in 205. mL of a 0.172 M solution?
3.
How many moles are there in 205. mL of a 0.172 M solution?
0.205 L
3.
How many moles are there in 205. mL of a 0.172 M solution?
0.205 L x
0.172 moles
1L
3.
How many moles are there in 205. mL of a 0.172 M solution?
0.205 L x
0.172 moles
1L
=
0.0353 moles
4.
How many grams NaCl are there in 250.0 mL of 0.500 M
solution?
4.
How many grams NaCl are there in 250.0 mL of 0.500 M
solution?
0.250 L
4.
How many grams NaCl are there in 250.0 mL of 0.500 M
solution?
0.250 L x
0.500 moles
1L
4.
How many grams NaCl are there in 250.0 mL of 0.500 M
solution?
0.250 L x
0.500 moles
1L
x 58.5 g
1 mole
4.
How many grams NaCl are there in 250.0 mL of 0.500 M
solution?
0.250 L x
0.500 moles
1L
x 58.5 g
1 mole
=
7.31 g
5.
How many grams of NaCl must be used to prepare a 100.0 mL
of 0.250 M solution.
5.
How many grams of NaCl must be used to prepare a 100.0 mL
of 0.250 M solution.
0.1000 L
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
1L
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
1L
x 58.5 g
1 mole
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
1L
x 58.5 g
1 mole
=
1.46 g
6.
How many millilitres of a 0.200 M solution of CoCl2 will
contain 25.0 g?
6.
How many milliliters of a 0.200 M solution of CoCl2 will
contain 25.0 g?
25.0 g
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
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
x 1L
0.200 mol
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
x 1L x
0.200 mol
1000 mL
1L
6.
How many milliliters of a 0.200 M solution of CoCl2 will
contain 25.0 g?
25.0 g x
1 mole
129.9 g
x
1L x
0.200 mol
1000 mL =
1L
962 mL
7.
Describe how you would prepare 100.0 mL of a 0.200 M
solution of CoCl2.
0.1000 L x 0.200 moles
1L
x
129.9 g
1 mole
Weigh 2.60 g of CoCl2
Dissolve in water
Transfer to a 100 mL
volumetric flask and fill to the line
=
2.60 g