Water, concentration, equilibrium, constants, pH

Question 1

Describe the bonding in a water molecule

Answer 1

2 Hydrogen atoms from a single polar covalent bonds with an oxygen atom. Oxygen is more electronegative than hydrogen, the area around oxygen has a partial negative charge.

Question 2

Shape of simple molecules in terms of hybridisation and lone pairs

Answer 2

Each bond is directed towards one corner of a tetrahedron(109.5°)

Lone pairs repel each other more than bonding pairs, reducing the bond angle to 104.5°

Question 3

Electronegativity

Answer 3

The tendency of an atom to attract electrons

Question 4

Properties of water which are attributable to hydrogen bonding

Answer 4

-Higher boiling point

-Higher cohesion

-High heat of vaporisation

-Ice floats(open structure )

-Higher surface tension

-Higher specific heat

-Water is a good solvent for polar molecules

-Water is a good solvent for ionic compounds

-The ‘oil drop effect’

Question 5

Equilibrium constant of a given chemical reaction

Answer 5

The ratio between the amount of reactant and the amount of product which is used to determine chemical behaviour. At equilibrium, the rate of the forward reaction = rate of the backward reaction.

Question 6

Terms ‘moles’ and ‘molarity’

Answer 6

Molarity - the amount of a substance in a certain volume of solution.

Moles - the unit of measurement for amount of substance, a quantity proportional to the number of elementary entities of a substance.

Question 7

Deduce the pH of a solution, given concentrations of H+ or HO-

Answer 7

PH = - log 10[element]