activation energy
the minimum amount of energy required in a collision for a reaction to occur
atmosphere
the layers of gas that surround Earth
catalyst
a substance that increases the rate of a reaction without itself being consumed in the reaction
closed system
a reaction vessel that is closed off, or has a lid, meaning that no reactant or product particles can escape
Concentration
the amount of solute dissolved in a solution
dynamic equilibrium
the state a reaction reaches when the rates of the forward and reverse reactions are equal
Enthaply
the energy stored within chemical substances, referred to as its chemical energy or heat content
equilibrium constant (Kc)
the ratio of reactants to products in a reaction when it is at equilibrium
equilibrium expression
the non-numerical representation of the equilibrium law, which states the chemicals to the power of their coefficients
equilibrium law
the concentration of products to the power of their coefficients, divided by the concentration of reactants to the power of their coefficients is equal to the equilibrium constant, (Kc)
fermutation
the chemical breakdown of glucose, with a yeast catalyst, to form ethanol and carbon dioxide
forward reaction
the reaction between reactants to form products
Hydrosphere
the bodies of water on Earth's surface, underground and in the atmosphere
La Chatelier's Principle
if an equilibrium system is subjected to a change, the system will adjust itself to partially oppose the effect of the change
Lithosphere
the outermost layer of Earth
open system
a reaction vessel that has no lid, meaning that reactants or products can be lost to the atmosphere
oxidation
a loss of electrons; also a reaction with oxygen
pH
a measure of hydrogen ion concentration in a solution and therefore a measure of the acidity or alkalinity of a solution
pressure
the force exerted, per unit are, by one substance upon another substance
reaction quotient (Qc)
the ratio of reactants to products in a reaction when it is not at equilibrium
reverse reaction
the backwards reaction in which the products react to re-form the reactants
sulfite
a group of organic compounds with an SO3 2- anion, which can also contain SO(g)
Temperature
a measure of the average heat energy of the particles within a system
volume
a measure of the space occupied by a substance
exothermic reaction
A reaction that releases energy in the form of heat (ΔH = -ve)
endothermic reaction
A reaction that absorbs energy in the form of heat (ΔH = +ve)
Amphiprotic
an organic compound or group containing carbon and hydrogen joined together in straight chains, branched chains, or non-aromatic rings
buffer solution
a solution that resists changes in pH when small quantities of acids or alkalis are added
conjugate acid
an acid formed when a base accepts an H+
conjugate base
an acid formed when a base accepts an H+ from an acid
electrical conductivity
the degree to which a material conducts an electric current
Electrolyte
a substance that conducts electricity when melted or dissolved in a solution
ionic constant product of water (Kw)
the equilibrium constant for the self-ionisation of water
monoprotic acid
an acid that can donate one hydrogen ion per molecule
pOH
a measure of hydroxide ion concentration in a solution and consequently a measure of basicity
polyprotic acid
an acid that can donate more than one hydrogen ion per molecule
proton donor
a substance that can donate H+ (hydrogen ions)
self-ionisation of water
the reaction in which a water molecule loses a hydrogen ion to become a hydroxide ion (OH-) and the hydrogen ion immediately reacts with another water molecule to form a hydronium (H3O+)
strength
the level of dissociation of an acid or a base
strong acid
an acid that completely ionises in water e.g. HCl, HBr, HNO3, H2SO4
strong base
a base that completely ionises in water e.g. NaOH, KOH, LiOH
weak acid
an acid that does not completely ionise in water
weak base
a base that does not completely ionise in water
cation
A positively charged ion
anion
A negatively charged ion
acid dissociation constant (Ka)
the equilibrium constant for the dissociation of an acid in aqueous solution
base dissociation constant (Kb)
the equilibrium constant for the dissociation of a base in aqueous solution
end point
the point in a titration when the indicator changes colour
equivalence point
the point in a titration when the reactants have reacted in the molar ratio of the balanced chemical equation
indicator
a chemical substance that changes colour at different pH values
pKa
a measure of acid strength; the negative logarithm (to base 10) of the acid dissociation constant
pKb
a measure of base strength; the negative logarithm (to base 10) of the base dissociation constant
titration
the addition of a solution of known concentration to a known volume of a solution of unknown concentration until reaction reaches neutralisation
titration curve
a graph of pH against volume of reactant added
aliquot
a fixed volume of liquid measured by a pipette
analyte
a solution of unknown concentration
buffer region
the section of a titration curve that is relatively flat because adding more acid or base does not drastically affect the pH
bulb
a piece of equipment responsible for drawing solutions into the pipette
burette
a graduated glass cylinder that dispenses highly accurate volumes of a standard solution
concordant titres
volumes of standard solution dispensed from a burette that differ by only 0.1 mL from the highest and the lowest
half-equivalence point
a point in a titration curve where the concentration of the titre is equal to half the original concentration of the analyte; also called the midpoint
meniscus
the curved upper surface of a liquid in a piece of measurement glassware
pitpette
a glass tube that dispenses highly accurate volumes of a solution of unknown concentration
precision
the consistency of a series of measurements
primary standard
a substance that is dissolved in a solvent to create a standard solution
solute
the minor component of a solution; the substance dissolved in the solvent
solution
a mixture of a solute dissolved in a solvent
solvent
the major component of a solution; what the solute is dissolved in
standard solution
a solution of accurately known concentration
stoichiometric ratio
the coefficient ratio in a chemical equation
stoichiometry
the calculation of reactants and products in chemical reactions by using a balanced equation
stopcock
the tap attached to a burette
titrand
a solution whose concentration is determined by titration