chem chapters 6-8

Formula mass

The sum of the atomic masses of all the atoms represented in the chemical formula of the substance

A mole

6.02 × 10²3 objects

Avogadro’s number

The name given to the numerical value of a mole

Molar mass

The mass, in grams, of a substance that is numerically equal to the substance’s formula mass

How do you explain what a mole is?

The amount of a substance that contains as many elementary particles as there are atoms in exactly 12 grams of 12/6 C

The numerical subscripts in a chemical formula give…

…the number of atoms of the various elements present in 1 formula unit of the substance

A chemical equation

A written statement that uses chemical symbols and chemical formulas instead of words to describe the changes that occur in a chemical reaction

A reactant

A starting material in a chemical reaction that undergoes change in the chemical reaction

A Product

A substance produced as a result of the chemical reaction

Equation coefficient

A number that is placed to the left of the chemical formula of a substance in a chemical equation that changes the amount but not the identity of the substance

Balanced chemical equation

Chemical equation that has the same number of atoms of each element involved in a chemical reaction on each side of the equation

Theoretical yield

The maximum amount of a product that can be obtained from given amounts of reactants in a chemical reaction if no losses or inefficiencies of any kind occur

Actual yield

The amount of product actually obtained from a chemical reaction

Percent yield

The ratio of the actual (measured) yield of a product in a chemical reaction to the theoretical (calculated) yield multiplied by 100 (to give percent)

Compressibility

A measure of the change in volume of a sample of matter resulting from a pressure change

Thermal expansion

A measure of the change in volume of a sample of matter resulting from a temperature change

Kinetic molecular theory of matter

Set of five statements used to explain the physical behavior of the three states of matter (solid, liquid, gas)

Kinetic energy

Energy that matter processes because of particle motion

Potential energy

Stored energy that matter possesses as a result of its position, condition, and/or composition

Electrostatic interaction

An attraction or repulsion that occurs between charged particles

Solid

The physical state characterized by a dominance of potential energy (cohesive forces)

Liquid

The physical state characterized by potential energy (cohesive forces) and kinetic energy (disruptive forces) of about the same magnitude

Gas law

Generalization that describes in mathematical terms the relationships among the amount, pressure, temperature, and volume of a gas

Pressure

The force applied per unit area on an object. The total force on a surface divided by the area of that surface.

What is the mathematical equation for pressure?

Pressure = force/area

Barometer

Device used to measure atmospheric pressure

Boyle’s Law states that…

…the volume of a fixed amount of a gas is inversely proportional to the pressure applied to the gas if the temperature is kept constant

What is the mathematical equation for Boyle’s Law?

P1 x V1 = P2 x V2

Charles’s law states that…

…the volume of a fixed amount of gas is directly proportional to its kelvin temperature if the pressure is kept constant

What is the mathematical equation for Charles’s Law?

V1/T1 = V2/T2

The combined gas law states that…

…the product of the pressure and volume of a fixed amount of gas is directly proportional to its Kelvin temperature

What is the mathematical equation for the combined gas law?

P1V1/T1 = P2V2/T2

Ideal gas law states that…

…the relationships among the four variables temperature, pressure, volume, and molar amount for a gaseous substance at a given set of conditions

Dalton’s law of partial pressures states that…

…the total pressure exerted by a mixture of gases is the sum of the partial pressures of the individual gases present

Partial pressure

The pressure that a gas in a mixture of gases would exert if it were present alone under the same conditions

Change of state

A process in which a substance is transformed from one physical state to another physical state

Vapor

A gas that exists at a temperature and pressure at which it ordinarily would be thought of as a liquid or solid

Physical equilibrium

A state in which two opposing physical processes take place at the same rate

Vapor pressure

The pressure exerted by a vapor above a liquid when the liquid and vapor are in physical equilibrium with each other

Volatile substances

A substance that readily evaporates at room temperature because of a high vapor pressure

Intermolecular force

An attractive force that acts between a molecule and another molecule

Dipole - dipole interaction

An intermolecular force that occurs between polar molecules

Hydrogen bond

An extra strong dipole - dipole interaction between a hydrogen atom covalently bonded to a small, very electronegative atom (F, O, or N) and a lone pair of electrons on another small, very electronegative atom associated with another nearby molecule

London force

A weak temporary intermolecular force that occurs between an atom or molecule (polar or nonpolar) and another atom or molecule

Solution

Homogeneous mixture of two or more substances with each substance retaining its own chemical identity

Solubility

The maximum amount of solute that will dissolve in a given amount of solvent under a given set of conditions

Henry’s Law states that…

The amount of gas that will dissolve in a liquid at a given temperature is directly proportional to the partial pressure of the gas above the liquid

Saturated solution

A solution that contains the maximum amount of solute that can be dissolved under the conditions at which the solution exists

Supersaturated solution

An unstable solution that temporarily contains more dissolved solute than that present in a saturated solution

Unsaturated solution

A solution that contains less than the maximum amount of solute that can be dissolved under the conditions at which the solution exists

Concentrated solution

A solution that contains a large amount of solute relative to the amount that could dissolve

Dilute solution

A solution that contains a small amount of solute relative to the amount that could dissolve

Aqueous solution

A solution in which water is the solvent

Nonaqueous solution

A solution in which a substance other than water is the solvent

Concentration

The amount of solute present in a specified amount of solution

Percent by mass

The mass of solute in a solution divided by the total mass of the solution, multiplied by 100 (to put the value in terms of percentage)

Percent by mass mathematical equation

= mass of solute / mass of solution x 100

Percent by volume

The amount of solute in a solution divided by the total volume of solution, multiplied by 100

Percent by volume mathematical equation

= volume of solute / volume of solution x 100

Mass-volume percent

The mass of a solute in a solution (in grams) divided by the total volume of solution (in millimeters), divided by 100

Mass-volume percent mathematical equation

= mass of solute (g)/volume of solution (mL) x 100

Molarity

The moles of solute in a solution divided by the liters of a solution

= moles of solute/liters of solution

Dilution

The process in which more solvent is added to a solution in order to lower its concentration

Colloidal dispersion

A homogeneous mixture that contains dispersed particles that are intermediate in size between those of a true solution and those of an ordinary heterogeneous mixture

Tyndall effect

The light-scattering phenomenon that causes the path of a beam of visible light through a colloidal dispersion to be observable

Suspension

A heterogeneous mixture that contains dispersed particles that are heavy enough that they settle out under the influence of gravity

Collective property

A physical property of a solution that depends only on the number of solute particles present in a given quantity of solvent and not on their chemical identities

Osmosis

The passage of a solvent through a semipermeable membrane separating a dilute solution from a more concentrated solution

Semipermiable membrane

A membrane that allows certain types of molecules to pass through it but prohibits the passage of other types of molecules

Osmotic pressure

The pressure that must be applied to prevent the net flow of solvent through a semipermeable membrane from a solution of lower solute concentration to a solution of higher solute concentration

Osmolarity

The product of a solutions molarity and the number of particles produced by formula unit if the solute dissociates

Hypotonic solution

A solution with a lower osmotic pressure than that within cells

Hypertonic solution

A solution with a higher osmotic pressure than that within cells

Isotonic solution

A solution with an osmotic pressure that is equal to that within cells