transcript
- Slide 1
- MIXTURES, SOLUTIONS, AND SOLUBILITY Exploring non-pure
substances
- Slide 2
- Review: what is a mixture? Mixtures are physical combinations
of substances Mixtures can be separated into their original
components Mixtures can be evenly distributed (homogenous) or
unevenly distributed (heterogeneous).
- Slide 3
- Review: what is a mixture? Which of the two options below is a
homogenous mixture? Which is a heterogeneous one?
- Slide 4
- Review: what are solutions? Solutions are homogeneous mixtures
in which one part of the solution is dissolved into the other.
Solute: part that dissolves; present in smaller amount Solvent:
part that is dissolved into; present in larger amount Both the
solute and the solvent can be in any of the three states/phases of
matter; however, we usually only discuss liquid solvents.
- Slide 5
- Review: what are solutions? Think back to the ethanol and water
mixture. Which is the solute and which is the solvent?
- Slide 6
- Review: what are solutions? The ethanol was present in a
smaller amount, making it the solute. The water was present in a
greater amount, making it the solvent.
- Slide 7
- What is solubility? Solubility is a measure of how well a
particular solute dissolves in a particular solvent; it is the
ability to form a solution solution + ability solubility Therefore,
it is defined as a property of the solute. Solubility can be
effected by several factors, some of which we will explore in the
near future.
- Slide 8
- What is saturation? Saturation is a relative measure
(qualitative) of how much of a solute is dissolved compared to the
maximum amount allowed (based on solubility). A saturated solution
contains exactly that maximum amount dissolved in solution An
unsaturated solution contains less than the maximum amount A
supersaturated solution contains more than the maximum amount
- Slide 9
- What is saturation?
- Slide 10
- CONCENTRATION
- Slide 11
- What is concentration? Concentration is a quantitative measure
of how much (mass) solute is dissolved in an amount (volume) of
solvent The units are the same as those for density: g/mL or g/cm 3
General Formula = mass of solute dissolved / volume of solvent
Usually reported in g / 100 mL of solvent
- Slide 12
- Density v concentration What is density a measure of?
- Slide 13
- Density v concentration What is concentration a measure
of?
- Slide 14
- How to calculate concentration What is the concentration of a
solution if 15 g of sugar is dissolved in 50 cm 3 of water? What is
the concentration in g/100 cm 3 ?
- Slide 15
- How to calculate concentration What is the concentration of a
solution if 15 g of sugar is dissolved in 50 cm 3 of water? Ans
0.30 g/cm 3 What is the concentration in g/100 cm 3 ? Ans 30 g/100
cm 3
- Slide 16
- How to calculate concentration If the concentration of a
solution is 2.53 g/mL, how many grams of solute are dissolved in 75
mL of water?
- Slide 17
- How to calculate concentration If the concentration of a
solution is 2.53 g/mL, how many grams of solute are dissolved in 75
mL of water? Ans 190 g of solute
- Slide 18
- Concentration Practice #1 1) What is the concentration of a
solution composed of 8.21 g of potassium chromate dissolved in
enough water to make 500 mL of solution 2) If you had 11.27 g of
silver nitrate and wanted to make a solution with a concentration
of 0.15 g/mL, how much water would you need? 3) How many grams of
sugar must be added to 450 mL of water to make a solution with a
concentration of 0.12 g/mL?
- Slide 19
- Concentration practice #2 1) What is the concentration if 75.0
g of ethanol are dissolved in 0.5 L of water? What is this
concentration in g/100mL? 2) If you wanted to make 1000mL of a 6.0
g/mL solution of citric acid, how many grams must of citric acid
must you add? 3) Determine the concentration of a solution that
contains 0.034 lbs of salt and 300 mL of water. (Note that 1 lb =
453.4 g)
- Slide 20
- Bonus: another unit Another way of expressing concentration is
by percent. General formula = g of solute / 100 g of solvent
Example: A solution of 45 g of table salt in 100 mL of water
(density = 1.0 g/mL) is a 45% solution.
- Slide 21
- Concentration practice #3 1) What is the percent concentration
of a solution made using 43 g of sugar dissolved in 475 mL of water
(density = 1.0 g/mL)? 2) How many grams of potassium permanganate
would you need to add to 1 L of water to make a solution with a
concentration of 20%? 3) What is the percent concentration of a
solution made using 100 g of caffeine dissolved in 800 mL of
ethanol (density = 0.80 g/mL)?