questions Flashcards
Explain why fluorine has a greater electronegativity than chlorine.
Fluorine is smaller, has less shielding and a smaller distance between the outer shell and the nucleus.
Bond pair is more strongly attracted to nucleus
Why does fluorine have a greater hydration enthalpy than chlorine?
Fluorine is small and has a greater charge density so can better attract water
What is the requirement for a reaction to be feasible?
Gibbs free energy change being equal or less than zero
Why does nitrogen have a greater entropy than graphite?
Nitrogen is a gas so has more disorder than graphite which is a solid.
Why is entropy zero when temperature is 0K?
Particles are stationary so there is no disorder.
Explain why entropy increases with temperature?
As R increases, particles start to move and disorder increases.
Why in oxygen is the first electron affinity an exothermic process?
There is an attractive force between the nucleus of an O atoms and an external electron.
Explain the interactions between water molecules and fluoride ions when F- becomes hydrated.
Water is polar so fluoride ions attract water.
Suggest how 🔺H, 🔺S and T can be used to predict if a temperature change is feasible. I
🔺G = 🔺H -T🔺S
If 🔺G is less than zero, then the reaction is feasible.
Explain why the evaporation of water is spontaneous even though this change is endothermic.
In your answer, refer to the change in the arrangement of water molecules and the entropy change.
The molecules become more disordered
Therefore entropy charge is positive
T🔺S > 🔺H
🔺G < 0
Explain why the enthalpy of lyrics dissociation for calcium fluoride is greater than for calcium chloride.
Electrostatic attraction between ions stronger as fluoride ion is smaller than chloride.
Explain why the theoretical enthalpy of lattice dissociation for an ionic substance is different from the experimental value calculated using a born haber cycle.
Experimental value allows covalent interaction whilst theoretical value only assumes ionic interaction.
