Exam 2 Flash Cards

Contains: Chapter 11 - Solutions and colloids and Chapter 12

Solution

Solution

A homogeneous mixtures of two or more substances

Solute

One component of a solution is present at a significantly greater concentration

Solvent

The other components of the solution present are relatively lesser concentration

When a covalent solid is dissolved in water…

… its molecules become uniformly distributed among the molecules of water

When an ionic solid is dissolved in water…

… it dissolves and dissociates with its ions uniformly distribution throughout the mixture.

The five defining traits of a solution

1. They are homogeneous

2. The physical state of a solution is typically the same as the solvent

3. The components of a solution are dispersed on a molecular scale

4. The dissolved solute will not settle out or separate from the solvent

5. The concentration can vary infinitely

Spontaneous Process

A process that occurs under specified conditions without the requirements of energy from some external source

Ideal Solution

The solution is formed with no accompanying energy change

Electrolyte

Substance that produce ions when dissolved in water

Nonelectrolyte

A substance that does not produce ions when dissolved in water

Strong electrolytes

A substance that dissociates completely when dissolved in water

Weak electrolytes

A substance that ionizes only partially when dissolved in water

Ion-Dipole Attraction

The electrostatic attraction between and ion and a molecule with a dipole

Dissociation

Physical prosses accompanying the dissolution of an ionic compound in which the compounds constituent ions are solvated and dispersed through out a solution

Covalent Electrolytes

Compounds that conation no ions but produces ions when in water.

Solubility

The maximum concentration that may be achieved under given conditions

Saturated

When a solutes concentration is equal than its solubility

Unsaturated

When a solutes concentration is less than its solubility

Supersaturated

When a solutes concentration is more than its solubility

The primary rule of solubility

Like dissolves Like

Solubility of gases generally --- with increasing temperature.

Decreases

Solubility of solids generally --- with increasing temperature.

Increases

Henrys Law

The quantity of an ideal gas that dissolves in a definite volume of liquid is directly proportional to the pressure of the gas

• Cg= k x Pg

Miscible

Liquids that may be mixed in an proportion to yield solutions

Immiscible

Two liquids that do not mix to an appreciable extent

Molality

A measure of the number of moles of solute is a solution to 1 kg of solvent measure

• m= mol of solute / kg of solvent

Mole fraction

Molar amount of a compound / total moles

Vapor Pressure

Pa = Xa x Pa*

• Pa: Partial pressure

• Xa: Mole fraction

• Pa*: vapour Pressure

Boiling point Elevation

A dissolved nonvolatile solute in a solution causes the boiling point to be higher than the pure solvent presence.

• Delta Tb = Kb x m x i

Freezing point Depression

A dissolved nonvolatile solute in a solution causes the freezing point to be lower than the pure solvent presence.

• Delta Tf = Kf x m x i

Colligative Properties of Electrolytes

How many particles are dissolved in solution one the ions sperate from each other

Van’t Hoff Factor

i = moles of particles in solution / Moles of formula units dissolved

• How many ions does this compound break into when dissolved?

Rate

The measure of how some property varies with time

Average Rate

Using the concentrations at the beginning and end of a period of time over which the reaction is changing

Instantaneous Rate

At any specific time, the ratio at which a reaction is proceeding

Initial Rate

The instantaneous rate of a reaction at “time zero”, when the reaction is proceeding is known.

As time progresses, the concentration of the reactants ---.

Decrease

As time progresses, the concentration of the products ---.

Increase

In the equation aA→bB

What is the equation for the rate of A?

Rate= -(1/a)(delta A/delta t)

In the equation aA→bB

What is the equation for the rate of B?

Rate= (1/b)(delta B/delta t)

What are the factors that affect reaction rates?

1. The chemical nature of the reacting substances

2. Physical states of the reactants

3. The temperature of the reactants

4. Concentrations of the reactants

5. Presence of a catalysts

Rate Law

The relationships between rate of a chemical reaction and the concentration of its reactants

In reaction A→B, with the general rate law of rate = k[A]^1

If A is doubled the rate will ---.

Double

In reaction A→B, with the general rate law of rate = k[A]^2

If A is doubled the rate will ---.

Quadruple

In reaction A→B, with the general rate law of rate = k[A]^0

If A is doubled the rate will ---.

Stay the same

Integrated rate law

The amount of reactant/ product present after a period of time

The integrated rate law for a First-Order Reaction

ln[A]t = ln[A]0 - kt

The integrated rate law for a Second-Order Reaction

1/[A]t = kt 1/[A]0

The integrated rate law for a Zero-Order Reaction

[A]t = -kt + [A]0

Graphing a First-Order integrated Rate law what is its Axis and Slope?

Axis: ln[A]t vs time

Slope: -k

Graphing a Second-Order integrated Rate law what is its Axis and Slope?

Axis: 1/[A]t vs time

Slope: k

Graphing a Zero-Order integrated Rate law what is its Axis and Slope?

Axis: [A]t vs time

Slope: -k

Collision theory Postulates

1. The rate of a reaction is proportional to the rate of reactants collisions

2. The reactants must be in the correct orientation

3. The reactions must occur with enough energy to react

Activation energy (Ea)

The minimum energy necessary to form a product during a collision

Reaction Mechanism

provides details regarding the precise, step-by-step process by which a reaction occurs

Intermediates

Species that are produced in one step and consumed in a supplemental step

Molecularity

the number of reactant entities

Rate limiting step

The slowest step in reaction mechanism

What are the three conditions that a reaction mechanism must meet?

1. The steps in the mechanism must sum to the overall reaction

2. The rate law predicted by the mechanism must be the same as the actual

3. The elementary step must be reasonable

Catalyst

A substance that can increase the reaction rate without being consumed in the reaction