Ib Chemistry Definitions (Hl)

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ligand

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Neutral molecule or anion which contains a non-bonding pair of electrons. They can form coordinate covalent bonds with a metal ion to form complex ions.

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standard enthalpy change of formation

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The enthalpy change on the formation of one mole of a compound from its elements in their standard states at 298 K and 1 atm pressure

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standard enthalpy of atomization

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The standard enthalpy change when one mole of gaseous atoms is formed from the element in its standard state under standard conditions

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electron affinity

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The enthalpy change when an electron is added to an isolated atom in the gaseous state (usually exothermic)

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lattice enthalpy

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The endothermic process of turning a crystalline solid into its gaseous ions or the exothermic process of turning gaseous ions into a crystalline solid

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buffer solution

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A solution that maintains a relatively constant pH when small amounts of strong acid or strong base are added to it

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Standard enthalpy change of combustion

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the enthalpy change on the complete combustion of one mole of the compound in its standard state in excess oxygen under standard conditions

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Rate Constant (k)

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the constant in the rate equation:

Rate = k[A]^m [B]^n

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Order of reaction

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with respect to a reactant: the powered to which its concentration is raised in the rate equation
overall: sum of the orders with respect to the individual reactants