Solute

Agenda
• Warm Up
• Introduction to Solutions
• Demo: Acetone and Foam
• Assign Solutions Poster Assignment
(Due Monday April 20th)
**HW: Work on Poster
Warm Up
• In your notebook, write 2-3 sentences
describing what you think a solution
is.
Solutions
• There are many types of solutions
Solutions
A solution is a homogeneous mixture. The
components are not chemically combined, but
just intermingled uniformly.
Example: Coffee is the same from the first sip, to
the last.
Solutions
A solution is made up of a solute and
solvent.
•Solute: a dissolved substance
•Solvent: the most abundant
component of a solution, i.e what
does the dissolving
•In a salt water solution, what is the
solute and what is the solvent?
Solutions
• Solvation is the scientific term for the
process of dissolving a solute in a
solvent.
• If a solute dissolves in a solvent, it is
said to be soluble. Conversely, if a
solute does not dissolve in a solvent it
is said to be insoluble.
Solutions
Water is called the “universal
solvent” because it has the ability to
dissolve so many substances. Why?
Solutions
• Remember, water is a polar molecule.
• Polar and ionic solutes will dissolve in
water because of the interactions of
opposite charges.
Dissolving Polar Molecules
• Polar water molecules surround the polar
solute molecules, pulling them away from
each other.
• All the molecules themselves, remain
intact!
Dissolving Ionic Compounds
• The cations and anions
that make up the ionic
compound break apart
and each is surrounded
by polar water
molecules.
• “Dissociation”: ionic
compounds separate
into cations and
anions.
Solutions
When something is dissolved in water
the resulting solution is said to be an
aqueous solution.
Agenda
• Warm Up
• Factors affecting dissolving rate,
saturated/supersaturated solutions
• Very brief video
• Solutions practice ws
**HW: Solutions practice ws, continue
working on poster due 4/20
Warm Up
• In your notebook,
write 2-3 sentences
fully describing how
an ionic compound
(such as salt)
dissolves in water.
Solubility
• Solubility describes how well a solute
dissolves in a solvent (usually water).
• Soluble solutes dissolve readily
• ex. Salt in water
• Insoluble solutes do not dissolve
readily
Solubility of Liquids
• Miscible: two liquids which uniformly mix
together (ex: milk and water)
• Immiscible: two liquids which will not
mix, forms two layers (ex: oil and water)
As a general rule: “Like dissolves like”
Non-polar + non-polar = miscible
Polar + Polar = miscible
Non-polar + Polar = immiscible
Solubility of Liquids
Solubility Factors
• Recall that solubility is how well one substance
dissolves in another
• Several factors can speed up the dissolving of
solid solutes in a solvent
• Surface area; Powdered substances dissolve
faster than cubed substances
• Temperature; solids dissolve faster at higher
temperatures than at lower temperatures
(**Gases are an exception to this rule**)
• Agitation: Stirring causes solids to dissolve
faster
Describing Solutions
Solutions are described as:
•Saturated: No more solute can dissolve
•Unsaturated: More solute can dissolve
•Supersaturated: More solute is dissolved
than theoretically possible
•These descriptions ultimately depend on
the type/amount of solute and
amount/temperature of water
Describing Solutions
• To further describe a solution we must
also specify the relative amount of
solute and solvent.
• Concentration indicates the amount of
solute dissolved in a given quantity of
solvent.
• Dilute: a small amount of solute
• Concentrated: a large amount of solute
Describing Solutions
Describing Solutions
•Supersaturated solutions
are fun for Chemists;
Here’s why!
Agenda
• Review HW
• Saturated vs. Unsaturated POGIL
• If you need your NB checked, bring it
to me up front.
• If you qualify for SG enrichment, let
me know
**HW: Complete POGIL due tomorrow,
continue working on poster due
Monday
Agenda
• POGIL Key will be posted online
• Warm Up
• Concentration, Molarity and Mass
Percent
• Molarity Practice ws
**HW: Complete Practice ws, Finish
poster due Monday
Warm Up
1. A solution that has the maximum amount of solute
dissolved in it is known as what type of solution:
2. A solution that has the less than the maximum
amount of solute dissolved in it is known as what
type of solution:
3. A solution that has the more than the maximum
amount of solute dissolved in it is known as what
type of solution:
4. How could someone increase the rate at which the
solute that dissolves?
5. If you have a polar solvent like water, what kind
of compound would most likely dissolve in it?
Molarity
• Recall that concentration of a
solution indicates how much solute
is dissolved in a given amount of
solvent.
• Concentration is expressed
mathematically as Molarity
• Molarity expresses concentration as
number of moles of solute per liter
of solution (units are mol/L = M)
Molarity
The formula for Molarity is:
Let’s practice! What is the molarity of
a solution that contains 1.4 moles of
solute in 2L of solution?
0.7 M
Molarity
• Molarity questions are often not as
straightforward as that.
• Sometimes you will need to convert
mass of solute (g) to moles of solute.
Molarity Practice
What is the molarity of a solution containing
0.900 g NaCl in 100 mL of solution?
0.900 g NaCl x 1 mol NaCl = 0.0150 mol NaCl
58.44 g NaCl
Now we can plug into our molarity formula:
0.0150 mol NaCl = 0.150 M NaCl
0.100 L
100 mL = 0.100 L
Molarity Practice
What is the molarity of a solution with a
volume of 2.00 L containing 36.0 g of
C6H12O6 (glucose)?
36.0 g C6H12O6 x 1 mol C6H12O6 =
180.18 g C6H12O6
0.200 mol
C6H12O6
Now plug into the molarity formula
0.200 mol C6H12O6
2.00 L
=
0.100 M C6H12O6
Molarity Practice
How many moles of solute are in 3.80 L of
0.700 M NaClO (bleach)?
3.80 L x 0.700 mol NaClO
1L
0.700 M written as mol/L
=
2.66 mol NaClO
Molarity Practice
How many moles of solute are in 250 mL
of 2.20 M CaCl2?
0.250 L x 2.20 mol CaCl2 = 0.550 mol CaCl2
1L
250 mL = 0.250 L
Molarity Practice
What mass of sodium hydroxide (NaOH) is
needed to make 250mL of a 0.150M
solution?
0.250 L x 0.150 mol NaOH = 0.0375 mol NaOH
1L
0.0375 mol NaOH x 40.00 g NaOH = 1.50 g
NaOH
1 mol
Molarity Practice
How many liters of a 1.15 M solution are
needed to give 0.805 moles of solute?
0.805 mol x
1L
= 0.700 L
1.15 mol
How many mL are needed?
0.700 L = 700 mL
Molarity practice
• Molarity can also be expressed as Mass percent
• Mass percent =
mass of solute
X 100
mass of solution
Molarity practice
How many grams of a solution that is 32.7% by mass NaCl
would contain 45.0 g of NaCl?
Mass percent = mass of solute
mass of solution
32.7 % =
45.0 g
mass of solution
Mass of solution =
45.0 g
0.327
X 100
X 100
=
Divide both sides
by 100 and
Cross Multiply!
138g
Agenda
• Please turn in your poster.
• Warm Up
• Review Molarity HW
• Dilution lesson
• Dilution Practice ws
**HW: Complete dilution practice ws,
due next class
Constructed Response Gases on 4/28!!
Warm Up
• How many mL of a 1.63 M solution
would contain 12 g of NaOH?
• What is the molarity of a solution
that is made by adding 57.3 g of MgO
to 24.6L of solution?
Dilution
• Dilution is the process of adding more
solvent (always water) to a solution.
• By doing so, the concentration
(Molarity) of the solution becomes
lowered.
• It is important to note that the
amount of solute does not change.
Therefore, the moles of solute is the
same before and after the dilution.
Dilution
6 mol
in 100 mL
6 mol
in 200 mL
same
amount
of solute
Dilution
Dilution
• Because the moles of solute are the
same before and after the dilution, we
can relate this using the mathematical
formula:
initial
Molarity
initial
Volume
Molarity
of dilute
solution
Volume
of dilute
solution
Dilution Practice
• How many mL of 2.00 M MgSO4 must
be diluted to prepare 100 mL of 0.400
M MgSO4?
(2.00 M) x V1 = (0.400 M) x (100 mL)
(0.400 M) x (100 mL) = V1 = 20.0 mL
(2.00M)
Dilution Practice
200 mL of 10.0 M NaOH is diluted to
500 mL, what is the molarity of the
dilute solution?
(10.0 M) x (200 mL) = M2 x (500 mL)
(10.0 M) x (200 mL) = M2 = 4.00 M
(500 mL)
Agenda
• Molarity POGIL
**HW: Per 0,4,6: Complete POGIL for
Monday, CR review
due Monday
Constructed Response Gases on 4/28!!
Agenda
• Seat Change!
• Review for tomorrow’s Gases CR
• All KEYS are on my website
• PowerPoint Notes are on my website
• Extra Help Wednesday, C13 @ lunch
**HW: study for Gases CR tomorrow,
Study for Solutions Test Friday
Agenda
• Gases CR
• You need a pencil, eraser and
calculator
• After test, pick up Lab and Study
Guide
**HW: Complete Pre-Lab for Thursday’s
Kool-Aid Lab. Pre-Lab MUST be
complete for you to participate in
the lab. If it is not completed by
Thursday, you will receive a ZERO for
the lab!
Agenda
• Review problems to prepare for
Friday’s test
• Review Flyswatter!
**HW: Study for Friday’s test,
complete additional practice
problems, Pre-Lab due tomorrow!
If you don’t do it, you can’t
participate!
**Extra Help today @ lunch, C13
Agenda
• Molarity of Kool-Aid Lab
**HW: Study for test tomorrow, Study
Guide for Enrichment, Complete Lab
for Monday.
Agenda
• Solutions Test Today
• There is NO notebook check!
• Please turn in your study guide for
enrichment
• After your test, please pick up a
reading.
**HW: Complete reading and answer
questions, complete Kool-Aid lab