Year 12 Chemistry

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97 terms · Vocab for Year 12 Chemistry

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

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