Exam 3

Question 1

Solution

Answer 1

homogeneous mixture (uniform) of two or more substances

Question 2

Solute

Answer 2

component of a solution that is present in lesser quality than the solvent

Question 3

solvent

Answer 3

solution component presented in the largest quality

Question 4

aqueous solution

Answer 4

when the solvent is water

Question 5

electrolytes

Answer 5

formed from solutes that are soluble ionic compounds that disassociate in solution to produce ions that behave as charge carriers; they conduct energy

Question 6

true solution

Answer 6

homogeneous mixture with uniform properties throughout

Question 7

pure substance

Answer 7

has only one component (ie water)

Question 8

true substance

Answer 8

has more than one substance; and is homogeneous throughout solution (particles are not large enough to scatter light)

Question 9

colloidal susbention

Answer 9

has solute particles distributed throughout a solvent; but it is not completely homogeneous **larger particles, not identical, particles participate.

Question 10

whats the difference between a solution particle and precipitant?

Answer 10

1nm = solution particles

particles larger than 200nm are precipitates

Question 11

suspension

Answer 11

heterogenous mixture that contains particles much later than colloid suspension (overtime particles settle at bottom and form second phase)

Question 12

solubility

Answer 12

how much solute can dissolve in a given volume of solvent

Question 13

what affects the solubility?

Answer 13

• polarity of solute & solvent-like goes with like (more similar the more they dissolve & greater distance, the less soluble the solute)
• temperature- increased temp increased solubility (usually)
• pressure (little affect on solids & liquids)

Question 14

saturated solute

Answer 14

when a solution contains all the solute that can be dissolved at a particular temperature **increased temp, you can dissolve more- decreased temp it will dissolve less

Question 15

supersaturated solute

Answer 15

as solute is cooling, the excess solute may remain in a solution only for a portion of time before the excess will fall to the bottom… It is unstable

Question 16

What is a dynamic equilibrium?

Answer 16

When an excess solute is added to solvent, it begins to dissolve & contains until it establishes a “dynamic equilibrium btwn dissolved and undissolved.

Question 17

What is Henry’s Law?

equation?

Answer 17

the number of moles of a gas dissolve in a liquid at a given temp to proportionally to the pressure of gas…
-solubility is directly proportional to pressure of gas in atmosphere… temp must stay the same
Equation:
M=kp (at fixed temp)

**solubility increases at lower temp, decreases at higher temp.

Question 18

concentration:

Answer 18

the amount of solute dissolved in a given amount of solution. Has a profound effect on properties of solution.

• Physical- melting point & boiling point
• Chemical- solution reactivity

Question 19

How do you calculate the mass to volume percent of a concentration?

Answer 19

concentration= m (amount of solute in g)/ v (amount of solution in mL) X 100 —which will give the percent of concentration

Question 20

How do you calculate the mass to mass percent of a concentration?

Answer 20

percent of mass/mass = (g solute)/(g of solution) X 100

Question 21

How do you calculate the parts per thoustand (ppt) and parts per million of a concentration %?

Answer 21

PPT= g solute/g solution X 10 to the third

PPM= g solute/ g solution X 10 to the sixth

Question 22

Molarity

Answer 22

M = moles of solute/L solution

Question 23

What is the equation for a dilution?

Answer 23

M1V1=M2V2

Question 24

what are the 4 colligative properties?

Answer 24

1: Vapor Pressure Lowering
2: Freezing point Depression
3: Boiling point elevation
4: osmotic pressure

Question 25

calculating molality?

Answer 25

molality= mol solute/kg solvent

Question 26

diffusion

Answer 26

net movement of solute or solvent molecules from an area of high concentration to an area of low concentration

Question 27

concentration gradient

Answer 27

the area where the concentration decreases over distance

Question 28

selective permeable membrane

Answer 28

a membrane that only allows small molecules to pass through freely, larger molecules & highly charged ions are restricted to cross

Question 29

semipermeable membranes

Answer 29

a membrane that allows a solvent but not the solute to diffuse from one side to the otehr

Question 30

osmosis

Answer 30

is the diffusion of a solvent (water) through a semipermeable membrane in response to a water concentration gradient.

Question 31

osmotic pressure

Answer 31

the pressure that must be exerted to stop the flow of water across a semipermeable membrane by osmosis

Question 32

osmolarity

Answer 32

the molaritry of particles in solution

Question 33

hypotonic solution

Answer 33

a solution that has a lower osmolarity

Question 34

hypertonic solution

Answer 34

a solution with a greater osmolarity

Question 35

what is the calculation for an equivalent?

Answer 35

``` eq/l = (eq/mol ion) (mol ion/L) then goes to.... M= (mol ion/L) then to... eq/L = (eq/ mol ion)M ```

Question 36

what are the three basic laws about thermodynamics?

Answer 36

1: Energy cannot be created nor destroyed (only converted from one form to another) 2: the universe spontaneously tends towards increasing disorder or randomness 3: The disorder of a pure, perfect crystal @ absolute zero (O Kelvin) is zero

Question 37

heat flow

Answer 37

transfer of the thermal energy to the surroundings

Question 38

system

Answer 38

only contains the process that is under study

Question 39

surroundings

Answer 39

encomposed as the rest of the universe (energy can either be lost from the system to the surroundings or energy can be gained by the system from the surroundings.)

Question 40

The first law of thermodynamics?

Answer 40

energy of the universe is constant (cannot be created nor destroyed)

Question 41

exothermic

Answer 41

energy leaves the system during chemical reactions (gives off heat)

Question 42

endothermic

Answer 42

energy enters system during chemical reactions (takes in heat, to break bonds)

Question 43

enthalpy

Answer 43

term used to represent heat (delta H) - delta H + = if energy is absorbed in a reaction (endothermic) - delta H - =energy is released in reaction, exothermic

Question 44

entrophy

Answer 44

measure of the randomness of a chemical system (delta S) - delta S + = exothermic & spontaneous - delta S - = endothermic & nonspontaneous

Question 45

which one has greater entrophy? He (s) or Na (s) H2O(l) or H2(g)

Answer 45

Na H2O liquid

Question 46

what is the 2nd law of thermodynamics?

Answer 46

everything in the universe is spontaneous & tends toward increasing disorder or randomness (entropy)

Question 47

free energy equation?

Answer 47

delta G; represents the combined contribution of the enthalpy and entropy values for a chemical formula: delta G = (delta H) - (T) X (delta s) - delta G + = always spontaneous - delta G - = never spontanous

Question 48

calorimetry

Answer 48

the measurement of heat energy changes in a reaction

Question 49

calorimeter

Answer 49

device that measure heat changes in calories

Question 50

specific heat equation?

Answer 50

SH of a substance is defined as the number of Calories of heat needed to raise the temp of 1g of substance 1 deg of C. We need to know SH; mass of solute, temperature change Q= (m) X (delta T-change in temp) x (SH)

Question 51

what is the SH of water?

Answer 51

I Cal/g degree of C

Question 52

activation energy

Answer 52

the minimum amount of energy required to initiate a chemical reaction

Question 53

activated complex

Answer 53

an extremely unstable, short lived intermediate complex

Question 54

what factors affect reaction rates?

Answer 54

1: structure of reacting species (opposite charges react faster, same charges have no reaction & if it is already dissociated than it has a low activation energy) 2: molecular shape & orientation 3: concentration of reactant (increased concentration, increased rate) 4: temperature of reactants (temp increase = rate increase) 5: physical state of reactants (how far apart the particles are/how often them collide ( liquids>gas>solid) 6: presents of a catalyst (increases reaction rate)

Question 55

higher kinetic energy rate order:

Answer 55

liquids>gas>solid

Question 56

equilibrium reactions

Answer 56

chemical reactions that do not go to completion; represented by reactants only: rate= k(r) --depending on if it is first order or second order the (r) will be to that power **once it reaches an equilibrium then it will be balanced.

Question 57

reversible reaction equation?

Answer 57

a process that can occur both ways keq = products/reactions **comes from a balanced equation; the product or reactant can be to a specific power depending on how many ions of that particular

Question 58

dynamic equilibrium

Answer 58

when the rate of the forward process in a reversible rate is exactly balanced by the rate of the reverse process. ie: N2 + 3H2 = 2NH3 rate r= kr [N2] [H2] to the third power rate f= kf [NH3) to the second power (product over reactant)

Question 59

what happens when you have a larger k constant? smaller k constant?

Answer 59

larger - more products | smaller- more things stay in reactant form

Question 60

what is LeChaletier's principle?

Answer 60

if a stress is placed on a system that is at equilibrium, the system will despond by altering the equilibrium composed in such a way to minimize stress. ie: product introduced - shift to the right reactant introduced - shift to the left