C2 - Exam Mistakes Flashcards
What type of compound is a metal oxide?
A base
allows ionic
Which substance are used in electrolysis to form alumimium?
Cryolite and aluminium oxide (NOT BAUXITE)
When making polymers from monomers, what decides the density of the polymer?
Temperature of the conditions of the reactions
Give 2 reasons that instrumental methods are used to detect impurities in metals
Very accurate
Uses small samples
In relative atomic mass, what is the mass of the element compared with?
Carbon-12
How can a solid be obtained from its solution?
Water is evaporated off
Why does increasing surface area increase the rate of reaction? 2 marks
More of reactant exposed to other reactant so more FREQUENT collisions
What is the structure of a metal?
A giant lattice structure of many positive metal ions surrounded by a sea of delocalised electrons
Describe how the structure of an alloy is different to the structure of a pure metal and explain why. 3 marks
An alloy is a metal which has different sizes of atoms
Because it is made of 2 or more different metals and different s have differently sized atoms
This means that alloys gave distorted layers
Why is Nitinol used in dental braces?
It is a shape memory so it can return to its original shape
Why are coins not made of pure copper?
Too soft
Describe the structure and bonding of a named ionic compound. 4 marks
Giant lattice structure
Contains ions
Contains positive metal ions and negative non-metal ions
Bonded by electrostatic attractions
In paper chromatography, what is the start line drawn with and why?
Pencil and ruler
Pencil used because it will not smudge or run
Why do different compounds separate in gas chromatography?
DIFFERENT SUBSTANCES travel at different speeds
What do you have to say in questions about factors affecting rate of reaction?
More FREQUENT collisions
Why is it concluded that group 1 metals are not suitable for reacting with and acid? 2 marks
Group 1 metals are very reactive
So the reaction is too violent and therefore dangerous
Give 4 reasons that the actual yield is usually lower than the maximum theoretical yield
Reaction is reversible
Impure reactants
Some of the reactants may react in different ways than expected and produce unwanted products
Some reactants or products lost during reaction
Why are carbon nanotubes used as lubricants? 2 marks
Nanotubes can slide over each other
Because no COVALENT bonds between the molecules
Describe the structure and bonding in diamond. 4 marks
Giant lattice structure (macro molecular)
Strong bonds between carbon atoms
That are covalent
Each carbon atoms forms 4 bonds to other carbon atoms
Describe the structure and bonding in a thermosoftening polymer and explain why they melt when heated. 4 marks
Large chain molecules
With intermolecular forces between chains
That are weak
Meaning they are easily overcome when heated
Write the ionic equation for a neutralisation of hydroxide
H+ + OH- –> H^2O
Suggest why the mass of crystals formed was less than the student has calculated
Because of an incomplete reaction
DON’T SAY REVERSIBLE REACTION
300J are taken in when substance A forms substance B. What is energy change when B forms A. 2 marks
300J
Given out by the reaction
What do you have to do in empirical formula questions?
Calculate the ratio and then write the compound as the answer
Example: carbon to nitrogen = 3:1
So the answer is C^3N
