Flashcards in Test 2 Deck (33):

1

## Change in heat of a solution

### change in heat(1) + change in heat(2) + change in heat(3)

2

## Exothermic reaction

### Change in heat of solution < 0

3

## Endothermic reaction

### Change in heat of solution > 0

4

## Molarity

###
(M)

Molarity = moles of solute / liters of solution

5

## Percent mass of solute

### % mass of solute = (mass solute/mass of soln) * 100%

6

## Molality

###
(m)

The number of moles of solute per Kg of solvent.

m = #moles of solute / Kg of solvent

7

## Mole Fraction

###
If a solution contains components A and B, then:

Xa + Xb = 1

Xa = moles A / total moles

Xb = moles B / total moles

8

## Solid solubility in relation to temperature

### generally increases with increase in temperature

9

## Gas solubility in relation to temperature

### generally decreases with increase in temperature

10

## External pressure in relation to solubility of liquids and solids

### has no influence on the solubility of liquids and solids

11

## LeChatellier's principle

### When a system in equilibrium is disturbed by a change of temperature, pressure, or concentration variable, the system shifts in equilibrium composition in a way that tends to counteract this change of variable, i.e., the system will shift left if the right side increases and vice-versa.

12

## Henry's law

###
The solubility of a gas in a liquid is proportional to the P of the gas over the liquid.

c = kP, where:

c = molar concentration of the dissolved gas (mol/L, i.e., molarity)

k = constant value depending only on temperature (mol/L *atm)

P = pressure, in atm, of the gas over the solution

13

## Rauolt's Law

###
P1 = X1 * Pnot1

change in P = X2 * Pnot1

14

## Vapor pressure of a solution, P(total) =

###
Pt = Xa * PnotA + XbPnotB

A = solvent

B = solute

15

## Boiling point elevation

###
change in temp boiling = i * Kb * Cm

i = van't Hoff factor

Kb = molal boiling point constant

Cm = concentration (molality)

16

## Freezing point depression

###
change in temp freezing = i* Kf * Cm

i = van't Hoff factor

Kb = molal freezing point constant

Cm = concentration (molality)

17

## Osmotic pressure

###
pi = iMRT

pi = osmotic pressure

i = van't Hoff factor

M = molarity of the solution

R = gas constant, 0.0821 L * atm/ K * mol

T = absolute temperature

18

## Gas constant

### 0.0821 L * atm/K * mol

19

## How to convert Celsius to Kelvin

### C + 273.15

20

## How to convert mmHg to atm

###
1 atm = 760 mmHg

Ex: 100 mmHg * (1 atm / 760 mmHg)

21

## van't Hoff factor

###
count number of particles from chemical formula

Ex: What is van't Hoff factor of Fe2(SO4)3?

i = 5

2 Fe and 3 SO4

22

## Boiling point of water

### 100 degrees C

23

## Freezing point of water

### 0 degrees C

24

## Rate of a Reaction

###
Change in the concentration of a reactant or a product with time.

A -> B

rate = (change in concentration of B)/(change in time)

rate = -(change in concentration of A)/(change in time)

units of mol/L * s

25

## Rate Law

###
rate = k[A]^x[B]^y

Reaction is xth order with respect to A, yth order with respect to B, and (x + y)th order overall

26

## Steps for determining rate order, rate constant and, rate of reaction given information.

###
1.) Using the experimental data, place rate law over rate law, i.e., rate y/rate x, where

rate x = k[A]^x[B]^x

rate y = k[A]^y[B]^y

2.) Simplify the expression until the order of the reaction with respect to the reactant is determined.

3.) Perform steps 1 and 2 for each reactant in the experiment.

4.) Now that order with respect to each reactant is known, Use any experiment to determine k, i.e.,

rate = k[A]^x[B]^y, where

rate = rate of any experiment

x and y are known from steps 1 - 3

5.) Using the k that was found in step 4, determine any requested information using provided data from the question.

27

## 0th order reaction

###
Rate Law:

rate = k

k Units:

M/s or mol/L * s

Concentration-Time Equation

[A]t = -kt + [A]o

Half-life Equation:

[A]o/2k

[A]t vs time = straight line with slope of -k

28

## 1st order reaction

###
Rate Law:

rate = k[A]

k Units:

1/s or s^-1

Concentration-Time Equation:

[A]t = [A]o * e^-kt

Half-life Equation:

0.693/k

ln[A]t vs time = straight line with slope of -k

29

## 2nd order reaction

###
Rate Law:

rate = k[A]^2

k Units:

1/M * s or M^-1 * s^-1 or mol/L * s or mol * L^-1 * s^-1

Concentration-Time Equation:

(1/[A]t) = kt + (1/[A]o)

Half-life Equation:

1/k[A]o

1/[A]t vs time = straight line with slope of k

30

## Arrhenius Equation

###
k = Ae^-(Ea/RT)

k = rate constant

A = frequency factor

Ea = activation energy

R = 8.314 J/K * mol

T = absolute temperature in Kelvin

ln(k1/k2) = (Ea/R)((T1 - T2)/(T1 * T2))

k1 and k2 = rate constants (at least one given)

Ea = activation energy of the reaction (kJ/mol)

R = 8.314 J/K * mol

T1 and T2 = temperature in Kelvin (at least one given)

ln(k) vs 1/T = straight line with slope of (-Ea/R)

31

## Catalyst

### A substance that increases the rate of a chemical reaction without being consumed.

32

## Units for k when rate = k[A][B]

### M^-1 * s^-1

33