retrieval practice

Question 1

What is the shape and bond angle around the xenon in a molecule of XeF₄?

Answer 1

square planar 90 degrees

Question 2

What is meant by the term quenching

Answer 2

Taking a sample of a reaction mixture and stopping it from reacting further so that concentrations can be measured.

Question 3

What is the definition of second electron affinity?

Answer 3

Enthalpy change when 1 mole of gaseous ions with a single negative charge form 1 mole of gaseous ions 2- charge.

Question 4

What must be checked with regards to a burette before beginning a titration?

Answer 4

1. The funnel is removed.
2. The jet is full and there are no air bubbles.

Question 5

What is the ionic equation for AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)?

Answer 5

Ag⁺(aq) + Cl⁻(aq) → AgCl(s)

Question 6

Why does electronegativity increase across a period (left to right)?

Answer 6

Shielding remains constant so an increase in nuclear charge and decrease in atomic radii across period leads to stronger attraction between bonding pair and nucleus.

Question 7

Why do first electron affinity values have a negative value?

Answer 7

There is an attraction between the negative electron added and positive nucleus

Question 8

How can concentrations of other reagents be kept constant whilst trying to investigate the order with respect to one reagent during a continuous rates method?

Answer 8

Have a very large excess of all reagents apart from the one being investigated.

Question 9

What are the two criteria that is required for a molecule to have an overall dipole?

Answer 9

1. At least one polar bond
2. Molecule must be assymetrical

Question 10

Why do second electron affinity values have a positive values?

Answer 10

There is a repulsion between negative electron added and negative ion that requires energy to overcome.