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A2 CHEMISTRY > EEE Definitions > Flashcards

Flashcards in EEE Definitions Deck (36):
1

Rate of reaction

The change in concentration of a reactant or product per unit time

2

Initial rate of reaction

The change in concentration of a reactant, or product per unit time at the start of the reaction when t=0

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Order with respect to a reactant

The power to which the concentration is raised in the rate equation

4

Overall order of a reaction

The sum of the individual orders

5

The rate constant, k

The constant that links the rate of reaction with the concentration of the reactants raised to the powers of their orders in the rate equation

6

Half life of a reactant

The time taken for the concentration of the reactant to halve

7

Reaction mechanism

A series of steps that together, make up the overall reaction

8

Rate-determining step

The slowest step in the reaction mechanism of a multi-step reaction

9

Dynamic equilibrium

The equilibrium that exists in a closed system when the rate of the forawrd reaction is equal to the rate of the reverse reaction

10

Homogeneous equilibrium

An equilibrium in which all the species making up the reactants and products are in the same physical state

11

Heterogeneous equilibrium

An equilibrium in which all the species making up the reactants and products are in the different physical state

12

Neutralisation

A reaction in which an acid and a base react together to form water and a salt

13

Acid-base pair

A pair of two species that transform into each other by gain or loss of a proton

14

Strong acid

An acid that completely dissociates in solution

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Weak acid

An acid that partially dissociates in solution

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Buffer solution

A mixture that minimizes pH changes on addition of small amounts of acid or base

17

Equivalence point

The point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution matching the stoichiometry of the reaction taking place

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End point

The point in a titration at which there are equal concentrations of the weak acid and conjugate base forms of the indicator

19

Standard enthalpy change of neutralisation

The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O under standard conditions

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Lattice enthalpy

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

21

Standard enthalpy change of formation

The enthalpy change that take place when one mole of a compound is formed from its constituent elements under standard conditions

22

Enthalpy change of atomisation

Enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state

23

Standard enthalpy charge of solution

Enthalpy change that takes place when one mole of a compound is completely dissolves in water under standard condtions

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Standard enthalpy change of hydration

The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions

25

Entropy

The quantitative measure of the degree of disorder in a system

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Standard entropy change of reaction

The entropy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

27

Free energy change

The balance between enthalpy, entropy and temperature for a process: ΔG = ΔH - TΔS

A process can take place spontaneously when ΔG < 0

 

28

Standard electrode potential of a half cell

The e.m.f of a half cell compared with a standard hydrogen half cell measured at 298 K with solution concentrations of 1 mol dm^3 and gas at 100k kPa

29

Transition element

A d-block element that forms an ion with an incomplete d sub shell

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Complex ion

A transition metal ion bonded to one or more ligands by coordinate bonds 

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Ligand

A molecule or ion that can donate a pair of electrons to a transition metal ion to form a coordinate bonds

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Coordination number

The total number of coordinate bonds formed between a central metal ion and its ligands

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Stereoisomers

Species with the same structural formula but with a different arrangement of the atoms in space

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Ligand sub.

A reaction in which one ligand in a complex ion is replaced by another ligand

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Stability constant 

The equilibrium constant for an equilibrium existing between a transition metal ion surrounded by water ligands and the complex formed when the same ion has undergone a ligand sub.

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