Oceans 1: Solution Calculations ( using enthalpies )

Question 1

What are 2 methods that can be used to calculate standard enthalpy of solution, deltaHsol

Answer 1

1. Experimental => q=mcAT

2. Theoretical => lattice enthalpy, ( L.E ) / ( deltaH LE )

Question 2

Definition of lattice enthalpy

Answer 2

Delta H LE = Enthalpy change when one mole of a solid is formed by the coming together of separate gaseous ions

Question 3

Does lockers and poppy tend to be exothermic or endothermic and why

Answer 3

EXOthermic = bonds being made

Ie. Separate gaseous ion COMING TOGETHER.

Question 4

Definition of solute

Answer 4

Solid dissolving eg. NaCl (s)

Question 5

Definition of solvent

Answer 5

Liquid solute dissolves in eg. H2O (l)

Question 6

Definition of solution

Answer 6

Solid dissolved in liquid eg. NaCl (aq)

Question 7

Definition of hydration enthalpy

Answer 7

Delta H hydr = enthalpy change when one mole of gassiest ions become hydrated ( i.e dissolve)

Question 8

Give equation for standard enthalpy of solution

Answer 8

Delta H sol = - (delta H LE ) + ( delta H hydr +ve ion ) + ( delta H hydr -ve ion )

Question 9

Be able to draw an enthalpy diagram for standard enthalpy of solution, delta H sol

Answer 9

Look at notes

• highest line = gaseous ions
• middle = solid solute ( s )
• bottom = dissolved solid ( aq )

Question 10

Be able to draw a Hess cycle for standard enthalpy of solution, delta H sol

Answer 10

Look at notes

- look at enthalpy diagram to help