Depth Flashcards
A student adds a small amount of strontium to water. When the reaction had finished the student measures the PH of the final solution
Describe 2 observations which would be different if the student had used calcium in place of strontium
- Less bubbling
- Dissolves more slowly
- Solution has a lower ph
- Precipitate forms / less soluble
What are the trends down group 2?
Increases in reactivity down the groups
Trends of group 2 metal hydroxides down the group
- Solubility increase
- pH increases
- Alkalinity increases
What is the definition of
the Standard Enthalpy change of formation?
When one mole of a compound is formed from its elements under standard conditions with all reactants and products in their standard states
Definition of the standard Enthalpy change of combustion
Enthalpy change that takes place when
One mole of a substance completely reacts with oxygen under standard conditions with all reactants and products in their standard states
Define
Standard Enthalpy change of neutralisation
Energy change that accompanies the reaction of an acid and base to form one mole of H2O under standard conditions with all reactants and products in their standard states
Suggest why the student takes 4 readings of the mass of the crucible and residue?
To make sure all water is removed
(Don’t just say to hear to constant mass - the qs is asking why)
Suggest 2 modifications to the method that would probably reduce the percentage uncertainty in the mass of the residue
- Use a larger mass
- Use a balance that weighs to 3/or more decimal places
1-iodopentane was found to react faster than 1-bromopentane
Why?
- C-I bond has a lower bond Enthalpy than C-Br bond
- Carbon-halogen bond breaks
What does the second highest peak on the mass spec give?
The molecular mass
How does a catalyst increase the rate of reaction?
- Lowers activation energy (by providing an alternative route)
- A greater proportion of molecules have more energy greater than activation energy
Waste polymer … can be disposed of usefully by recycling.
State 2 other methods of disposing of polymers that ven be beneficial to the environment
- Use as organic feedstock
- Combustion for the production of energy
Conditions for conversion of alkene to alcohol
Steam
H3PO4 catalyst
Electrophilic addition
Alcohol to alkene?
Dehydration
Concentrated acid catalyst - eg H2SO4
Alcohol to halogenoalkane
Nucleophilic substitution
Reflux
NaX
H2SO4 catalyst
