Chem test 2

Line spectrum

Series of discrete wavelengths emitted by atoms

Strong electrolyte

Completely dissociates into ions in water

Strong acid

Acid that completely ionizes in water

Precipitation reaction

Reaction that forms a precipitate

Molecular equation

Equation showing compounds as complete formulas

Complete ionic equation

Equation showing all strong electrolytes as separate ions

Net ionic equation

Equation showing only species involved in the reaction

Acid-base reaction

base Reaction between an acid and a base producing water and a salt

Reducing agent

Substance that is oxidized and causes another substance to be reduced

Oxidation number

Assigned charge used to track electron transfer

Monatomic ion oxidation number

Equal to the ion charge

Oxygen oxidation number

Usually -2

Molarity (M)

Moles of solute per liter of solution

Molarity formula

M = mol/L

Stock solution

Concentrated solution used to prepare less concentrated solutions

Dilution formula

M1V1 = M2V2

Titration

Procedure used to determine unknown concentration

Titrant

Solution of known concentration

Equivalence point

Point at which stoichiometric amounts of reactants have reacted

Solution stoichiometry

Stoichiometry involving solution concentrations and volumes

Thermochemistry

Study of heat changes accompanying chemical reactions

Thermodynamics

Study of energy and its transformations

Internal energy equation

ΔE = q + w

Examples of state functions

Enthalpy, internal energy, pressure, temperature

Examples of path functions

Heat and work

Enthalpy (H)

Heat content of a system at constant pressure

Enthalpy equation

ΔH = ΔE + PΔV

Exothermic process

Releases heat; ΔH is negative

Temperature change formula

ΔT = Tf - Ti

Bomb calorimeter constant

volume calorimeter used for combustion reactions

Constant pressure calorimeter

Calorimeter open to atmosphere where pressure remains constant

Hess's Law

Overall enthalpy change equals sum of enthalpy changes of individual steps

Reversing a reaction in Hess's Law

Changes sign of ΔH

Multiplying a reaction in Hess's Law

Multiply ΔH by same factor

Standard state

Most stable form of substance at 1 atm and 25°C

Planck constant (h)

6.626 × 10⁻³⁴ J·s

Photon energy wavelength equation

E = hc/λ

Electromagnetic spectrum

Complete range of electromagnetic radiation

Highest

energy electromagnetic radiation - Gamma rays

Lowest

energy electromagnetic radiation - Radio waves

Solute

Substance being dissolved in a solution

Solvent

Substance that dissolves the solute

Solution

Homogeneous mixture of solute and solvent

Electrolyte

Substance that produces ions in solution and conducts electricity

Nonelectrolyte

Substance that does not produce ions in solution and does not conduct electricity

Weak electrolyte

Partially dissociates into ions in water

Weak acid

Acid that partially ionizes in water

Strong base

Base that completely dissociates in water

Weak base

Base that partially dissociates in water

Like dissolves like

Polar substances dissolve polar substances; nonpolar substances dissolve nonpolar substances

Precipitate

Insoluble solid formed during a reaction

Spectator ion

Ion that does not participate in the reaction

Neutralization reaction

Acid-base reaction that produces water and a salt

Oxidation

Loss of electrons

Reduction

Gain of electrons

OIL RIG

Oxidation Is Loss, Reduction Is Gain

Oxidizing agent

Substance that is reduced and causes another substance to be oxidized

Free element oxidation number

Always 0

Hydrogen oxidation number

Usually +1

Dilution

Process of reducing concentration by adding solvent

Analyte

Solution of unknown concentration

Indicator

Substance that changes color near the endpoint of a titration

First Law of Thermodynamics

Energy cannot be created or destroyed

System

Portion of the universe being studied

Surroundings

Everything outside the system

Internal energy (E)

Total energy of a system

q

Heat

w

Work

Positive q

Heat absorbed by system

Negative q

Heat released by system

Positive w

Work done on system

Negative w

Work done by system

Pressure

volume work formula - w = -PΔV

State function

Property that depends only on current state, not path taken

Path function

Property that depends on the process used

Endothermic process

Absorbs heat; ΔH is positive

Energy profile diagram

Graph showing energy changes during a reaction

Calorimetry

Measurement of heat flow

Calorimeter

Device used to measure heat transfer

Heat capacity (C)

Amount of heat required to raise temperature by 1°C

Specific heat capacity (Cs)

Heat required to raise 1 g of substance by 1°C

Molar heat capacity (Cm)

Heat required to raise 1 mole of substance by 1°C

Specific heat equation

q = mcΔT

Molar heat capacity equation

q = Cm × mol × ΔT

Standard enthalpy of formation (ΔHf°)

Enthalpy change when 1 mole of compound forms from elements in standard states

Standard enthalpy reaction equation

ΔH°rxn = ΣΔHf°(products) − ΣΔHf°(reactants)

Bond enthalpy

Energy required to break one mole of bonds

Breaking bonds

Requires energy; positive value

Forming bonds

Releases energy; negative value

Electromagnetic radiation

Energy transmitted through space as waves

Wavelength (λ)

Distance between corresponding points on adjacent waves

Frequency (ν)

Number of wave cycles passing a point per second

Speed of light equation

c = λν

Photon

Packet of electromagnetic energy

Photon energy equation

E = hν

Quantized energy

Energy exists only in specific amounts

Ground state

Lowest energy state of an atom

Excited state

Higher energy state of an atom

Absorption

Electron gains energy and moves to higher level

Emission

Electron releases energy and moves to lower level