Chemistry Unit 7 Flashcards
What are the types of solutions?
Liquid-Liquid
Solid-Liquid
Liquid-Gas
Gas-Gas
Solid-Solid
Example of liquid-liquid solution
ethanol and water – ALC
Example of Liquid-Solid solution
water and salt – salt water
Ex. Liquid - gas solution
co2 and water – fizzy water
ex. of gas gas solution
n2 and o2 – air
ex. of solid solid solution
alloys – bronze steel etc
What does immiscible mean
parts of solution cant mix ( wont form a homogenous mixture together)
ex: oil and water
What does miscible solution mean
The parts of a solution can be mixed in any proportion
Ex. Water and ethanol
What does solubility mean
It is the ability of a solute to dissolve in a solvent to form a solution
What are intramolecular forces
strong forces within molecules
Ex: covalent bonds
What are intermolecular forces
forces between molecules
** due to dipoles
Why is water a good solvent
because its a very polar substance
How does water interact with other polar molcules?
by making h bonds or dipole dipole
What are the most polar substances?
Ionic compounds
ex: NaCl –> Na+ and Cl-
What happens to ionic compounds when they disolve
They DISSOCIATE into hydrated ions (aq)
what represents the Dissociation of ionic compounds
Dissociation equation
Ex: NaCl(s) –> Na+(aq) + Cl-(aq)
Do non polar molecules dissolve in polar solvents
NO – Like disolves like
Will molecules that have non polar and polar sections dissolve in water?
Yes, however the size of the non polar section decreases its ability to dissolve in water
Name of molecule thats both polar and non polar
Amphipathic
What three diff types of attractions must occur for something to dissolve
- Attraction of solvent to solvent
- Attraction of solvent to solute
- Attraction of solute to solute
To dissolve 1 substance in another three things must occur:
forces holding solute particles together must break
forces holding solvent particles break
attractions between solvent and solute must form
What factors affect rate of dissolving
1) solubility
2) temperature
3) surface area
4) stirring
how does solubility affect dissolving rate
things that are more soluble will disolve faster than those less soluble
how does temperature affect dissolving rate
solid solutes will disolve faster in warmer water
** fast water molcules keep solid suspended
gas solute are less soluble in warm water
** fast moving gas molecules separate from solvent
how does surface area affect dissolving rate
when you increase surface are you increase solubility (exposes more solute to solvent)
how does stirring affect dissolving rate
dissolves faster because particles are moving faster
what is molarity (M)
moles solute/1L solution
Units of solubility
1) g solute/ml solution
2) g solute/ g solutoin
3) PPM: parts per million - typical in gases
What is a precipitate
a solid that is formed in a chemical reaction
What are spectator ions?
bystanders!
ions that dont participate in chemical reactions but are still there
Example of a precipitation reaction
(aq) + (aq) –> (aq) + (s)
why does precipitation reactions occur
when solute ions are more attracted to eachother than to the solvent molcules they stick together forming clusters (the precipitate)
what is a total ionic equation
this shows all the things involved in a reaction
what is a net ionic equation?
an equation that only shows the things that are involved in the solute reaction
Steps to precipiate problems:
1) identify precipitate
2) find mass of precipitate
3) find concentration of excess ions
4) find concentration of spectator ions
what does identifying precipitate entail
1) make balanced chemical equation
2) using solubility table find precipitate
how to find mass of precipitate:
1) write net ionic equation
2) calculate moles of each ion
3) determine the limiting ion by calculating mass of precipitate
how to determine the concentration of excess ion
1) find moles of ion in excess
2) calculate total volume of solution
3) calculate concentration of excess ions
(moles/volume= Molarity)
how to determine the concentration of the spectator ions
1) calculate moles of each spectator ion in solution
2) calciulate concentration of the spectator ions (moles/volume=Molarity)
All solutions have the qualities that they do because of 3 properties:
1) molecular structure
2) pressure
3) temperature
what is molality (m)?
mol solute/kg solvent (mol/kg)
What is mass precent
mass solute/mass solution * 100%
Why does pop go flat faster on the counter than in fridge
it will have greater solubility in cooler temp therefore on counter the co2 will want to escape faster
what order should you add acid and water
always add acid to water
What is a saturated solution?
A solution that has dissolved as much solute as it can therefore if you add more it will not be dissolved
what is a super-saturated solution
a solution that has more dissolved solute than there would typically be.
What diff is there between an ionic substance dissolving in water and a polar one?
Ionic substances dissociate into individual ions whereas polar substances form either dipole dipole or h bonds
what is a way to increase solubility in most substances
by increasing the pressure and the temp
What does dilution involve
Adding more solvent into a solution
What doesnt change during dilution?
The number of MOLES!
What is the dilution calculation?
M1V1=M2V2
What is conductivity
somethings ability to conduct electricity
What are solutions that conduct electricity called?
electrolytes
Why do some solutions carry electric charge
because they have charged particles
What are two solutions that have high conductivity?
Ionic compounds and strong acids and bases
What are solutions that dont conduct electricity called?
Nonelectrolytes – No ions are present
What is a solution that wont conduct electricity
polar covalent compounds
Ex: ethanol and water
What are colligative properties
These are things that only rely on the concentration of the solute rather than what the solute actually is
name two colligative properties
1) Boiling point elevation
- adding solute to water increases boiling point
2) Freezing point depression
- adding solute to water decreases freezing point
Which of the following would melt ice the best?
C6H12O6
NaCl
CaCl2
CaCl1 because it has most particles when dissolved
What is titration
Titration is a process used to determine the concentration of an unknown solution
How does titration work?
One reacts a measured amount with a known concentration until their concentrations are equal!
When is titration commonly used?
During neutralization reactions to know the concentration of an acid or base
How to do acid based titration
1) In Erlenmeyer flask put the accuratly measured unknown concentration
2) The solution you know put in a burette
3) Add indicator to unknown solution
4) Add known solution until reaction is complete
5) Using known solution calculate unknown concentration
