Chemistry - Exam 3

A chemical change that forms new substances

A chemical reaction

Reactant

What reacts, on left

Product

What is made, on right

Combustion

when something combines with oxygen

Microscopic scale

molecule to molecule reactions

Macroscopic scale

mole to mole reactions

The calculation of the quantities of chemical elements or compounds involved in chemical reactions

Stoichiometry

Stoichiometry conversions

g-mol-mol-g

The amount of product formed in a chemical reaction

yield

the expected amount of a particular product based on reaction stoichiometry

theoretical yield

The amount of a particular product recovered in a chemical reaction

actual yield

The actual yield is usually ___ than theoretical yield

less

the ratio of the amount of product actually recovered compared to theoretically expected yield

percent yield

how to find percent yield

actual yield/theoretical yield (times 100)

limiting reagent

reactant that is completely used up in a reaction

excess reactant(s)

the amount greater than required for reaction

how to determine limiting reagent

calculate theoretical yield, the reactant with the least product is the limiting

How to determine how much excess reactant remains

calculate amount of excess reactant needed to completely react with limiting reagent, subtract amount needed from amount present

A homogenous mixture formed by dissolving a solute in a solvent

a solution

Aqueous solution

water is the primary component, solvent

Solute

component present in the lesser amount

Solvent

Component present in the larger amount

Dilute solution

small amount of solute compared to solvent

Concentrated solution

large amount of solute compared to solvent (still less than solvent though)

Quantitative measure of the amount of solute in a solution

Solution concentration

Concentration equation

amount of solute/amount of solution

Molarity equation

moles of solution/liters of solution

Molarity can be used as a conversation factor (True/False)

True

When adding solvent to dilute a solution, volume _____

increases

When adding solvent to dilute a solution, moles _____

remain constant

When adding solvent to dilute a solution, amount of solvent _____

increases

M(initial) V(initial) = M(final) * V(final)

Dilution equation

procedure for determining the concentration of a solution by reacting it with a second solution

titration

Different substances behave ____ when dissolved in water

differently

Good conductors of electricity, completely ionizes in aqueous solutions

Strong electrolytes

Do not conduct electricity in aqueous solutions, dissolves as molecules (ions are not formed)

Non-electrolytes

poor conductors of electricity, partially ionizes in aqueous solutions, mixture of undissociated molecules and ions

weak electrolytes

molecular compounds that ionize when they dissolve in water - form H+ cations and an anion

acids

each ion is attracted to surrounding water molecules and pulled away from the ionic solid

dissolution of an ionic compound

each molecule of the solute is attracted to surrounding water molecules and pulled away from the molecular solid or liquid

dissolution of a covalent compound

all solutes ____, forming a solution

dissolve

strong and weak electrolytes ____ when they dissolve

dissociate

dissociate

separate into cations and anions

CH3CO2H

weak acid

HCl

strong acid

HBr

strong acid

Ca(OH)2

strong base

H3PO4

weak acid

HNO3

strong acid

Ba(OH)2

strong base

HI

strong acid

HNO2

weak acid

HF

weak acid

KOH

strong base

NaOH

strong base

HClO4

strong acid

H2SO4

strong acid

HCN

weak acid

NH3

weak base

All soluble ionic compounds are ___

strong electrolytes

Not all ionic compounds dissolve in water (true/false)

true

General rule for solubility

as charge increases, solubility decreases

A compound is ___ in water if its not found on the solubility table

probably insoluble

There are ___ major types of reactions that take place in aqueous solutions

3

reactants form an insoluble product

precipitation reaction

Precipitation reaction: if no insoluble product forms, there is _____

no reaction

Shows the neutral chemical formula for each reactant and product

molecular equation

shows the actual state of each dissolved species

complete ionic equation

shows only species that change during the reaction, ions that don’t react are not shown

net ionic equation

spectator ions

ions that appear as both reactants and products

an acid solution is mixed with a base solution to form a salt (and sometimes water)

acid-base neutralization reaction

a salt in an acid-base reaction equation is what

any ionic compound

A substance that in aqueous solution produces H+ ions

acid

a substance that produces OH- ions in aqueous solution

base

Strong acid + strong base will always have what net ionic equation

2H + 2OH = 2 H2O

in a acid-base equation what are the spectator ions

the strong electrolytes

the transfer of electrons from an element in one solute to an element in another solute

Oxidation-reduction reaction (redox)

redox reactions involve:

transfer of electrons and changes in oxidation state

oxidation

loss of one or more electrons

reduction

gain of one or more electrons

a tool used when working with redox reactions

oxidation numbers

An oxidation number is ___ an ionic charge

not, but they can be the same

the sum of oxidation states is ___ for a neutral compound or ____ to the net charge for a polyatomic ion

zero, equal

If an oxidation number becomes more positive, the substance has been ___

oxidized

If an oxidation number becomes more negative, the substance has been ___

reduced

Absorbing energy is

endothermic

releasing energy is

exothermic

the study of heat evolved or absorbed in chemical reactions

thermochemistry

scalar physical quantity that is a property of objects and systems that is conserved by nature

energy

the capacity to make things happen

energy

capacity to do work or supply heat

energy

kinetic energy

energy of movement

thermal energy

the energy associated with the temperature of an object

the measure of a substances thermal energy

temperature

a quantity of energy transferred because of a temp difference

heat

work

another energy transfer process

potential energy

energy associated with the position, “stored” energy

form of potential, associated with positions of electrons and nuclei in atoms and molecules

chemical energy

system

reactants and products in a chemical process

surroundings

everything else