Chemistry Unit 7 - Mixtures and Solutions

mixture

combination of 2 or more pure substances in which each pure substance retains its individual chemical properties

heterogeneous mixture

a mixture that does not blend smoothly throughout and in which individual substances remain distinct

homogenous mixture

a mixture that has constant composition throughout - it always is a single phase

suspension

mixture containing particles that are large enough that, if left undistributed, will settle out over time due to gravity

colloid

heterogenous mixtures of intermediate sized particles between atomic scale solution particles and large suspension particles

brownian motion

jerky, random movement of particles in liquid colloid, from the result of particle collisions

tyndall effect

scattering of light by dispersed colloid particles

solution

homogeneous mixtures that contain 2+ substances

solute

substance that dissolves in the medium (lesser amount)

solvent

the dissolving medium / the medium that does the dissolving (larger amount)

soluble

a substance that dissolves in a solvent

insoluble

when a substance does not dissolve in a solvent

miscible

2 liquids that are soluble in each other

immiscible

2 liquids that can be mixed but separate shortly after

concentration

measure of how much solute is dissolved in a specific amount of solvent or solution

dilute

small amount of solute per volume of solution

concentrated solution

large quantities of solute per unit volume of solution

percent by mass

mass of solute / mass of solution x 100

percent by volume

volume of solute / volume of solution x 100

molarity definition

number of moles of solute dissolved per liter of solution

M or mol/L

molarity unit

molarity

moles of solute / liter of solution

molality

moles of solute / kilograms of solvent

m

molality unit

solvation (dissolving)

the process of surrounding solute particles with solvent particles to form a solution. in water, it’s called hydration

dissaosciation

when an ionic compound breaks apart into its constituent ions

“like dissolves like”

general rule used to determine whether solvation will occur with a specific solvent. substances with similar IMFS will dissolve.

polar substances dissolve polar substances and ionic compounds with charges

nonpolar substances dissolve nonpolar substances.

heat of solution

overall energy change that occurs during the solution formation. can be exothermic or endothermic

exothermic

if there is leftover energy, it’s ___

agitation (factor that affects solvation)

shaking or stirring causing more collisions and increasing the rate of solvation

surface area (factor that affects solvation)

smaller pieces means more surface area which means more colisions

temperature (factor that affects solvation)

temperature increase means the particles will move faster and this means there are more collisions, thus increasing the rate of solvation

disassociation equation example

1. CaCal_2(s)

2. Ca⁺² + Cl^-_(aq)

3. Ca⁺² +2Cl^-_(aq)

endothermic

a chemical reaction where less energy is released than what is required to break the bonds

exothermic

a chemical reaction where more energy is released than what is required to break the bonds

decereases, kinetic

The solubility of a gas in a liquid will _____ temperature increases. This is because the _____ energy of the particles increases and more solute can reach the top of the solution and escape.  

water is polar with a slightly positive area (H) and a slightly negative area (O)

What is the statement that is true for the water molecule?

collide

Solvation occurs when the solute and solvent particles _____ with each other

increase, increase, increase

To increase the rate at which a solute dissolves there should be an ____ in stirring and sharing, an _____ in surface area, and an _____ in temperature.

similar

 Substances will dissolve with each other if the solute and solvent have ____ IMFs

solubility

property of a solute that describes its ability to dissolve in a solvent

unsaturated solution

solutions that contain less dissolved solute for a given temperature and pressure than a saturated solution

saturated solution

contains the maximum amount of dissolved solute for a given amount of solvent at a specific temperature and pressure

supersaturated solution

contains more solute than a saturated solution at the same temperature. hold more than what the solubility line allows

on the line

saturated on a graph

below the line

unsaturated on a graph

above the line

supersaturated on a graph
(won’t absorb - there will be solid particles in the liquid)

boiling point

Adding a solute to water at will cause the ________ to increase.

freezing point

Adding a solute to water will cause the ________ to decrease. 

direct

number of particles/ions and slope on a graph have a ___ relationship

vapor pressure

_____ is the pressure exerted in a closed container by liquid particles that escape the surface of the liquid and become a gas.

volataile solute, more, lowers, colligative property

When a _____ is dissolved in a solution, the surface area is occupied by a mix of solute and solvent particles, leaving  _____ surface area for the solvent particles to escape the surface.

This ____ the vapor pressure. Since vapor pressure lowering is due to the number of solute particles in solution, it is a ________

vapor pressure, boiling point, lowers, kinetic energy, potential, solute

A liquid boils when its ______ equals ______ .Adding a nonvolatile solute _____ the solvent’s vapor pressure.

More _______ must be added to reach the solvent’s _______. The greater the number of ____ particles in the solution is, the greater the ​​​​​​​ boiling point elevation will be.

decreases

When a solute dissolves in a solvent, the vapor pressure of the solvent

colligative property

physical properties of a solution that are affected by the number of particles but not by the identity of the dissolved solute particles

colligative property examples

vapor pressure lowering, boiling point elevation, freezing point depression, and osmosis

electrolyte

compound that will conduct an electrical current with high conductivity.

ionic compounds

______ are electrolytes because they disassociate in water

nonelectrolyte

compound that does not conduct an electrical current

molecular/covalent compounds

many ________ are nonelectrolytes because they do not ionize.
they have 1 particle.

vapor pressure lowering

depends on the number of solute particles in a solution. is a colligative property of solutions

boiling point elevation

when a nonvolatile solute lowers the vapor pressure of a solvent, boiling point is affected.

more heat is needed to supply additional kinetic energy to raise the vapor pressure to atmospheric pressure.

freezing point depression

at a solvent’s freezing point, particles no longer have sufficient kinetic energy to overcome interparticle attractive forces

boiling point elevation formula

ΔTB = KB × m × (# of particles)

freezing point depression

ΔTF = KF × m × (# of particles)

osmosis

the passage of water and small molecules across a semipermeable membrane with a net flow from a less concentrated solution to a more concentrated solution.

temperature

the average kinetic energy of the particles in a sample of matter

energy

ability to do work or produce heat
exists as potential and kinetic

law of conservation of energy

states that any chemical reaction or physical process has energy that is neither created nor destroyed

chemical potential energy

energy that is stored in a substance b/c of its composition

heat (q)

energy that is in the process of flowing from a warmer object to a cooler object. always flows from a warm body to a cold body

calorie

the amount of energy required to raise the temperature of 1g of pure water by 1 degrees celsius

joule

SI unit of energy and heat. equivalent to 0.2390 calories

specific heat

amount of heat required to raise the temperature of 1g of that substance by 1 degrees Celsius. each substances has their own specific heat

q=mc(change in temperature)

heat formula

C, K

temperature units

J, cal, KJ, kcal

heat units

j/gc

specific heat unit

1

1 Cal = ____ kcal

4.18

1 cal = ___ J

4.18

1 kcal = ____ KJ

calorimeter

insulated device used for measuring the amount of heat absorbed or released during a chemical or physical process

thermochemistry

study of heat changes that accompany chemical reactions and phase changes

system

specific point of the universe that contains the reaction or the process you wish to study

surroundings

everything else other than the system in the universe

universe

system + surroundings

enthalpy

the heat content of a system at constant pressure. q = ∆H

enthalpy heat of reaction

change in enthalpy during a reaction, symbolized by ∆H_rxn

Hfinal - Hinitial

∆H_{rxn =}

Hproducts - Hreactants

(chemically) ∆H_{rxn =}

negative

exothermic sign

positive

endothermic sign

exothermic meaning

energy flows from the surroundings to the system

endothermic meaning

energy flows from the surroundings to the system

product

in exothermic reactions, energy is on the ___ side

reactant

in endothermic reactions, energy is on the ____ side

Consider a cup of "hot" hot cocoa.   The systems are the hot cocoa and the ___. The energy is transferred from the object that is ____ to the object that is  ____ until the temperature of both objects is equal.  

does

heat (does/does not) depend on the mass of the object

does not

temperature (does/does not) depend on the mass of the object

cooler, higher, your hand, copper

Granite has a specific heat of 0.79 J/gC and Copper has a specific heat of 0.38 J/gC.  The granite will feel ______ than the copper because it has a _____ specific heat than the copper. The heat will travel from ____ to the _____ more easily and thus feel cooler.