DIVE Chemistry Quarterly Exam 3

Arrhenius acid

A substance that forms hydrogen ions (H+) when dissolved in an aqueous solution.

Arrhenius base

A substance that forms hydroxide ions (OH-) when dissolved in an aqueous solution.

Bronsted-Lowry acid

Any substance that can donate protons (H+ ion) is an acid.

Bronsted-Lowry base

Any substance that can accept protons is a base.

deprotonation

The loss of a proton from a molecule.

protonation

The addition of a proton to a molecule.

conjugate acid

Is formed when a base receives a proton.

conjugate base

Is formed when an acid donates a proton.

conjugate pair

It is made up of a conjugate acid and a conjugate base, which only differ from each other by a hydrogen ion.

Lewis acid

A substance that can accept a pair of electrons.

Lewis base

A substance that can give up a pair of electrons.

hydronium ion

H3O+, created by the addition of a hydrogen ion (H+) to a water molecule (H2O).

hydroxide ion

OH-, a covalently bonded oxygen and hydrogen that is usually formed during the dissociation of a base.

solubility product constant

Equilibrium constants used for minimally soluble substances.

common ion effect

When two dissolved solutes have a common ion, the ionization of the weaker electrolyte is suppressed.

Le Châtelier's principle

When a stress (change in temperature, concentration, or pressure) is applied to a reversible reaction, the reaction will shift in the direction that relieves the stress.

Haber process

The use of catalysts, high temperature, and high pressure to produce ammonia from nitrogen and hydrogen gas.

irreversible reaction

The reactants react to form products, which cannot react to form the original reactants again.

reversible reaction

A reaction in which the products can react to form the original reactants.

chemical equilibrium

A dynamic equilibrium in a reversible reaction in which two opposing reactions are occurring at the same time, and at the same rate. The products from the first reaction are the reactants for the second reaction, and vice versa.

dynamic equilibrium

An equilibrium that is reached when opposing reactions occur at the same rate, which results in no net change.

equilibrium constant

A ratio of the concentration of the products over the concentration of the reactants.

collision theory

In order for a spontaneous reaction to occur, the collisions between reactants must be forceful enough and properly oriented.

activation energy

The smallest amount of kinetic energy required by the colliding molecules before a reaction will take place.

activated complex

An unstable intermediate structure formed by the reactants that can proceed to form the products, or break back apart into separate reactants.

reaction rate

How fast reactants turn into products.

catalyst

It helps a reaction to proceed, but the catalyst itself is not changed.

homogeneous catalyst

A catalyst that is in the same phase as the reactants.

heterogeneous catalyst

A catalyst that is in a different phase than the reactants.

enzyme

Naturally occurring catalysts that are important in many chemical reactions in living organisms.

inhibitor

Substances that can be used to slow down a reaction by bonding with catalysts, and reducing their effectiveness.

reaction mechanism

The series of steps that occur during a reaction.

rate law

Mathematical formulas used to describe the effects of concentration on reaction rates.

free energy

Also known as Gibbs free energy, it refers to the maximum amount of useable energy in a closed system, including the entropy and enthalpy of a substance.

free energy change

It is equal to the change in enthalpy, minus the temperature times the change in entropy. A negative change in free energy indicates a reaction than could proceed spontaneously.

second law of thermodynamics

In an energy conversion, some energy goes to an unusable form.

entropy

A measure of the disorder, or randomness, present in a system.

thermodynamics

The branch of physics that deals with the relationship between thermal and mechanical energy.

1st law of thermodynamics

Energy cannot be created or destroyed, it just changes form.

enthalpy

A measure of the amount of energy (chemical, thermal, etc.) contained in a substance. H is used for a unit because we usually use enthalpies to study heat absorbed or released during a reaction.

heat

The transfer of kinetic energy from one substance to another.

heat of reaction

The difference in the enthalpy of the products and the enthalpy of the reactants in a reaction.

enthalpy of formation

The measured values of heats of reaction at standard state (25 Co and 1 atm).

standard state

A defined set of conditions that specify temperature, pressure, and concentration. For gas laws this is usually 1 atm and 273 K, and for thermodynamics it is usually 298 K.

standard molar enthalpy of formation

The enthalpy change in a reaction that results in the formation of 1 mole of a compound, where the reactants and products are each in their standard states.

Hess's law

The total enthalpy change of a reaction is equal to the sum of the enthalpy changes of each step in the reaction.

enthalpy of bond formation

A measure of the enthalpy change required to break the bonds of a molecule.

colligative property

Properties of solutions that depend on the number of molecules in a given volume of solvent, not the properties of the molecules.

particle molality

It measures the molality of a solution based on the total number of moles of particles dissolved in the solution.

Raoult's Law

The vapor pressure of a solvent is proportional to the number of dissolved solute particles.

boiling point elevation

The addition of a solute, which raises the boiling point of the solvent.

molal boiling point elevation constant

A number used to determine the amount that a substance's boiling point is raised as its molality is raised.

freezing point depression

The freezing point of a pure solvent is lowered when a solute is added.

molal freezing point depression constant

A number used to determine the amount that a substance's freezing point is lowered as its molality is raised.

molal freezing point depression constant

A number used to determine the amount that a substance's freezing point is lowered as its molality is raised.

osmosis

Diffusion of particles through a semi-permeable membrane, from an area of high concentration, to an area of lower concentration.

osmotic pressure

The amount of pressure required to prevent osmosis from occurring.

colloid

A mixture in which one substance made up of very small particles is dispersed throughout another substance.

Tyndall effect

Light will not be dispersed when passing through a liquid or solution, but it will be dispersed by the particles suspended in a colloid or suspension.

Brownian movement

The random movement of particles in a liquid or gas.

flocculating agent

A compound that has ions that block the repulsive forces between colloidal particles that keep them suspended, causing them to collect and settle out.

coagulation

When particles from the dispersed phase of a colloid are made to separate and settle out.

adsorption

The adhesion of charged particles to particles in a colloid.

dilute

Refers to a solution that has a relatively low amount of solute, without quantitatively stating how much.

concentrated

Refers to a solution that has a relatively high amount of solute, without quantitatively stating how much

percent by mass

A method of specifying concentration, of grams of solute per 100 grams of solution.

molarity

The number of moles of solute for each liter of solution, used to measure concentration.

molality

The number of moles of solute for each kilogram of solvent, used to measure concentration.

equivalent

In an acid-base reaction, it is the amount of substance that gains or loses one mole of hydrogen ions. In a redox reaction it is the amount of substance that gains or loses one mole of electrons.

gram-equivalent mass

The mass of one equivalent, expressed in grams.

normality

The number of equivalents of solute for each liter of solution, used to measure concentration.

solution

A homogeneous mixture made up of two or more different substances, one of which is dissolved into the other.

solute

The portion of a solution that gets dissolved.

solvent

The portion of a solution that dissolved another substance.

miscible

The property of a liquid being able to dissolve into another liquid.

immiscible

Liquids that cannot be mixed with each other are immiscible.

dissociation

The process in which ions are separated from each other, allowing an ionic solid to be dissolved into a solute.

solvation

When a substance is being dissolved, it is the step where the solvent particles surround and interact with the solute particles.

hydration

A form of solvation when water is used at the solvent.

diffusion

When particles spread out to evenly fill a space.

insoluble

Not being soluble, not being able to be dissolved.

unsaturated

1) A solution that has the ability to dissolve more solute at its given condition. 2) An organic compound that has at least one double or triple-bond between carbons, and therefore less than the maximum number of hydrogens.

saturated

1) The property of a solution that has dissolved the maximum amount of solute under normal conditions. 2) An organic compound that has the maximum number of hydrogens, in single bonds.

dynamic equilibrium

An equilibrium that is reached when opposing reactions occur at the same rate, which results in no net change.

supersaturated

The property of a solution that contains more than the amount of solute possible under normal conditions.

Henry's law

The solubility of a gas in a liquid is proportional to the pressure on the gas on top of the liquid, when temperature is constant. The greater the pressure, the more gas that will be dissolved.

phase diagram

A diagram that shows what phase, or state, a substance will be in according to pressure and temperature.

triple point

The temperature and pressure that a substance can exist as a solid, liquid, and gas simultaneously.

electrolysis

A decomposition reaction that uses an electric current to decompose the reactants.

electrolyte

Substances that disassociate to form free ions, making the solution conductive, when dissolved.

anhydride

A compound that can be formed by removing the water from another compound. They can react with water in composition reactions.

basic anhydride

An anhydride formed by removing the water from a base.

acidic anhydride

An anhydride formed by removing the water from an acid.

water of hydration

Water molecules combined in a substance in a definite molar ratio to the rest of the substance. They can be removed from the substance by heating, without substantially changing the chemical makeup of the substance.

hydrate

Compounds that have extra water molecules attached to their crystal structure. These water molecules can be removed by heating.

hygroscopic

Substances that have a strong enough attraction to water that they will actually pull water into their structure from the air.

desiccators

Airtight containers used to seal off hygroscopic substances, which prevents them from being exposed to the air and drawing moisture out of it.

desiccant

A drying agent, made from a hygroscopic compound that will draw the water out of any air exposed to it.

deliquescence

The process by which a hygroscopic compound draws enough water out of the air so that it actually dissolves.

efflorescence

The process in which a hydrate can lose its water of hydration through exposure to air.