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97 terms

Year 12 Chemistry

Vocab for Year 12 Chemistry
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acid rain
rain that has a pH lower than 5
activation energy
the minimum energy required by reactants in order to react
addition polymerisation
the process in which monomers with at least one double bond react together to form a polymer by addition reactions
addition reaction
a reaction in which one molecule bonds covalently with another molecule without losing any other atoms
alkane
a simple, saturated binary compound of carbon and hydrogen atoms with single bonds between the carbon atoms. The general formula for all members of this homologous series is CnH2n + 2.
alkenes
the family of hydrocarbons that contain one carbon-carbon double bond
alkynes
a family of hydrocarbons with one carbon-carbon triple bond
amino acid
a molecule that contains an amine and a carboxyl group
amphiprotic substance
a substance that can donate or accept protons
anode
the electrode at which oxidation occurs. In a galvanic cell, it is the negative electrode, since it is the source of negative electrons for the circuit. If the reductant is a metal, it is used as the electrode material.
Avogadro constant
the number of elementary particles (atoms) in exactly 12 g of carbon-12. This number is equal to 6.02 × 1023.
back titration
an analytical technique in which the unknown concentration of a substance is found by adding an excess of another reactant then titrating back with another substance
bomb calorimeter
used to measure the heat of combustion of a substance
buffer solution
a solution that resists the change in pH of the addition of a small amount of acid or base
calibration
correlating readings with a standard or series of standards
calorimeter
apparatus used to measure heat changes during a chemical reaction or change of state
carbohydrate
general name for a class of carbon compounds that includes sugars, starch and cellulose. Carbohydrates contain the elements carbon, hydrogen and oxygen.
carboxyl group
the COOH functional group, which has weakly acidic properties
carboxylic acid
an organic molecule containing the —COOH functional group
catalyst
a substance that alters the rate of a reaction without a change in its own concentration
cathode
the electrode at which reduction occurs. In a galvanic cell, it is the positive electrode, since the negative electrons are drawn towards it, then consumed by the oxidant, which is present in the electrolyte.
cell potential
the difference between the electrode potentials of the half-cells of a galvanic cell; also called voltage
condensation polymerisation
step-growth polymerisation in which two monomers combine and a smaller molecule is eliminated
condensation reactions
reactions in which molecules react and link together by covalent bonding with the elimination of a small molecule such as water or hydrogen chloride from the bond that is formed
conjugate acid (of a base)
the product the base forms when it has accepted a proton from an acid
conjugate base (of an acid)
the product the acid forms when it has donated a proton to a base
covalent bonding
sharing of electrons between nuclei that bonds them together in a molecule
denaturation
change in the structure of a large molecule, e.g. a protein
deoxyribonucleic acid (DNA)
a complex molecule that contains genetic information for the development and function of all living organisms
dissociation
the process by which ions separate when an ionic compound dissolves in a solvent
double covalent bond
a strong bond formed by two pairs of electrons that are shared by the two nuclei
electrode
a solid used to conduct electricity in a galvanic half-cell
electrolysis
the decomposition of a chemical substance (in solution or the molten state) by the application of electrical energy
electrolyte
a liquid that can conduct electricity
electrolytic cell
an electric cell in which a non-spontaneous redox reaction is made to occur by the application of an external potential difference across the electrodes
electroplating
adding a thin metal coating by electrolysis
emission spectrum
a set of separate coloured lines emitted by excited electrons returning to the ground state from an excited state. Each element has a unique emission spectrum.
empirical formula
formula that shows the simplest numerical ratio in which atoms are combined
endothermic
describes a chemical reaction in which energy is absorbed from the surroundings
end point
the experimentally determined equivalence point at which the indicator just changes colour or the pH curve becomes vertical
enzyme
proteins that catalyse chemical reactions
equivalence point
when two reactants have reacted in their correct mole proportions in a titration
ester
an organic compound formed from a condensation reaction between an alcohol and a carboxylic acid
exothermic
describes a chemical reaction in which energy is released to the surroundings
fatty acid
a long chain carboxylic acid
fossil fuel
fuel formed from once-living organisms
fractional distillation
a method of separating the components of a liquid mixture that depends on the ease of vaporisation of the components
fuel
a substance that burns in air or oxygen to release useful energy
fuel cell
an electrochemical cell that produces electrical energy directly from a fuel
functional group
a group of atoms attached to or part of a hydrocarbon chain that influence the physical and chemical properties of the molecule
galvanic cell
two half-cells connected by an external circuit that transfers electrons between an oxidant and a reductant that would react spontaneously if in direct contact
genomics
the study of an organism's entire genome rather than some of its individual genes
half-cell
one half of a galvanic cell containing an electrode immersed in an electrolyte that may be the oxidant or the reductant depending on the oxidising strength of the other cell it is connected to
half-equation
an equation that shows gain or loss of electrons
homologous series
a series of organic compounds that have the same structure but in which the formula of each molecule differs from the next by a CH2 group
hydrocarbon
compound containing only carbon and hydrogen
ionisation
a reaction in which uncharged atoms or molecules gain or lose electrons to form ions
isomers
species with the same chemical formulae but different structural formulae and therefore different properties
joule (J)
the SI unit of energy (heat)
limiting reactant
the reactant that is completely consumed when a reaction has run to completion
molar mass, M
the mass of one mole of a substance, measured in grams
mole
6 × 1023 particles of a substance
monomers
the molecules that link together to form a polymer
monosaccharide
the simplest form of carbohydrate, consisting of one sugar molecule
nuclear binding energy
the energy required to break a nucleus into individual neutrons and protons
nuclear fission
a nuclear reaction in which large nuclei are split into smaller nuclei
nuclear fusion
a nuclear reaction in which multiple nuclei are joined together to form a heavier nucleus
nucleotide
the monomer that makes up the DNA polymer. Nucleotides are composed of a sugar (deoxyribose) joined to a phosphate group and a heterocyclic base molecule
organic chemistry
the study of carbon-containing compounds and their properties
oxidant
an electron acceptor
oxidation
an increase in the oxidation number; a loss of electrons
oxidation number
used to find an oxidant and a reductant by a change in perceived valency
petroleum
viscous, oily liquid composed of crude oil and natural gas that was formed by geological processes acting on marine organisms over millions of years
polymers
giant molecules formed by repeated monomers that have been joined by covalent bonds
polyprotic acid
an acid that is able to donate more than one proton to a base
precipitate
a solid with low solubility that forms in a liquid then settles to the bottom of a container
primary cell
an electrolytic cell in which the cell reaction is not reversible
primary standard
a substance used in volumetric analysis that is of such high purity and stability that it can be used to prepare a solution of accurately known concentration
proteomics
the study of all of the proteins that an organism produces
qualitative analysis
investigations used to identify the presence or absence of elements, ions or molecules in a sample
quantitative analysis
investigations used to determine the amount of a given element or compound in a known weight or volume of material
reductant
an electron donor
reduction
a decrease in the oxidation number; a gain of electrons
reduction potential
the potential of a reduction half-cell relative to the standard hydrogen electrode; also called electrode potential
relative atomic mass, Ar
the mean mass of the naturally occurring mixture of the isotopes of an element on the relative atomic mass scale, on which the masses of particles are compared with the mass of the carbon-12 isotope
salt bridge
a component that provides a supply of mobile ions that balance the charges built up in the half-cells of a galvanic cell during reaction
saturated compound
compound in which all carbon-to-carbon bonds are single covalent bonds
secondary cell
an electrolytic cell in which the cell reaction is reversible
specific heat capacity
the amount of energy (measured in joules) required to raise the temperature of 1 g of a pure substance by 1°C
standard solution
a solution that has a precisely known concentration
stoichiometry
the amount and ratio of reactants and products in a chemical reaction
structural isomers
molecules that have the same molecular formula but a different structural formula
substitution reactions
reactions in which one or more atoms of a molecule are replaced by different atoms
titration
process to determine the concentration of a substance by using a pipette to deliver one substance and a burette to deliver another substance until they have reacted exactly in their mole ratios
titre
the volume delivered by a burette
unsaturated compound
compound in which not all carbon-carbon bonds are single bonds; the molecule could contain one or more double or triple bonds
zwitterion
dipolar ion containing equal positive and negative charges