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Flashcards in Chem 1b Deck (20):
1

Dynamic equlibrium

The concentrations of all substances are constant and the rate of the forward reaction equals the rate of the reverse reaction.

2

Le Chateliers Principle

If a change is made to a reaction at eqm. then the position of equilibrium will change so as to oppose that change if possible.

3

Enthalpy change

The amount of heat energy taken in or given out during any change in a system at constant pressure.

4

Standard enthalpy change

The enthalpy change for a reaction at 298 K and 100 kPa with all reactants and products in their standard states.

5

Specific heat capacity

The heat required to raise the temperature of 1 gram of a substance by 1 Kelvin. It is measured in J g–1 K–1.

6

Standard enthalpy of combustion

Enthalpy change which occurs when 1 mole of a substance is completely burnt in oxygen at 298K and 100kPa.

7

Standard enthalpy of formation

Enthalpy change which occurs when 1 mole of a substance is formed from its elements at 298K and 100kPa.

8

Bond dissociation enthalpy

Enthalpy change when 1 mole of a specific bond in a specific gaseous molecule is broken at 298 K and 100 kPa.

9

Mean bond enthalpy

The average amount of energy needed to break a covalent bond averaged over a range of gaseous compounds at 298 K and 100 kPa.

10

Enthalpy change of solution

Enthalpy change when 1 mole of an ionic substance dissolves in water to give a solution of infinite dilution.

11

Infinitely dilute solution

There is a sufficiently large excess of water that adding any more doesn't cause any further heat to be absorbed or evolved

12

Hydration enthalpy

Enthalpy change when 1 mole of gaseous ions dissolve in sufficient water to give an infinitely dilute solution. Hydration enthalpies are always negative.

13

Lattice enthalpy

Enthalpy change during the formation of one mole of an ionic compound from its oppositely charged gaseous ions under standard conditions.

14

Why does lattice enthalpy decrease as ions get bigger?

Charge remains consistent, but size:charge ratio decreases so there are weaker attractions between the cation and the anion.

15

Enthalpy change using formation data

Products - reactants

16

Enthalpy change using combustion data

Reactants - products

17

Brønsted-Lowry Acid

PROTON DONOR

18

Brønsted-Lowry Base

PROTON ACCEPTOR

19

Strong acid

Is virtually 100% ionised in solution

20

Weak acid

Doesn't ionise fully when it is dissolved in water.