Exam Flashcards
Strongest type of attraction when Silicon dioxide melts
(Polar) Covalent (Network) bonds
State why it is important for chemists to predict whether reactions in an industrial process are exothermic or endothermic (3)
If reactions are exothermic heat will need to be removed
If reactions are endothermic heat will need to be supplied
Chemists can create conditions to maximise yield
The reaction that produces NaHC03 involves this equilibrium: HC03- + Na+ —>=
Adding brine increases sodium ion concentration hence equilibrium shifts to right
Rate of forward reaction is increased (by addition of brine)
Describe in detail how a burette should be prepared and set up for a titration (3)
(1) Rinse the burette with the required solution/ solution to be put in.
( 1 mark for each of the following, max of 2) -
Fill the burette to above the scale with the required solution
Remove the filter funnel used to fill the burette
the tap should be opened and some solution should be drained to ensure there are no air bubbles
solution run into scale reading should be made from the bottom of the meniscus
Describe in detail how a burette should be prepared and set up for a titration (3)
(1) Rinse the burette with the required solution/ solution to be put in.
( 1 mark for each of the following) - Fill the burette to above the scale with the required solution
Why does Chlorine have a higher melting point than Argon(3)
The strongest intermolecular force in both molecules is LDFs.
Since Chlorine is diatomic it has more electrons than Argon.
This means the Van Der Wals between Chlorine are stronger since there are more electrons.
Why do some titrations have to be carried out under acidic conditions?
To provide H+ ions for the reaction
Chlorine and Aluminium are reacted to form Aluminium Chloride.
Despite this reaction being highly exothermic why would the Aluminium be heated? (1)
To provide activation energy to form activated complex
Describe a condensation reaction
The joining of two molecules with the loss of a small molecule (usually water)
Describe how free radicals are formed (1)
Bond breaking by UV light
Why is less air required to burn alcohols than alkanes
they contain hydroxyl functional groups which already have oxygen in them
What can be oxidized to a carboxylic acid?
Aldehydes and primary alcohols
Ketones, secondary and tertiary alcohols cannot
What is the difference between a bond enthalpy and a mean bond enthalpy?
Mean bond enthalpy must refer to average energy and to a number of compounds and bond enthalpy must relate to one compound/diatomic molecule
Name the reaction used to make soaps from fats and oils
Alkaline Hydrolysis
How are emulsifiers made?
By reacting edible oils with glycerol
