EXAM QUESTIONS Flashcards
Why is the percentage yield of ammonia less than expected?
Because the reaction is reversible
What ion makes something alkaline?
Hydroxide (OH-)
Why wouldn’t the electrolysis of a solid potassium salt work?
Because it needs to be molten or dissolved to make the ions move
What gas would be produced at the negative electrode for the electrolysis for potassium
Hydrogen because the ions are positive and potassium is more reactive
Why are alloys harder than pure metals?
Because they have different sized atoms,
This would distort the layers and they wouldn’t be able to slide
Describe the structure and bonding of a diamond
Giant lattice,
Strong bonds,
Covalent,
Each carbon atom has 4 bonds
Describe the structure and bonding in a thermos often if polymer and explain why they melt when heated
They are chains with weak intermolecular forces that are easily broken when heated
Why in terms of structure is carbon dioxide a gas even at low temperatures
Small molecules
Weak intermolecular forces,
Only a little energy is needed to overcome the bonds
What’s the purpose of gas chromatography
To separate
What information does the molecular ion peaks from the mass spectrometer give about the substances?
Their relative mass
What’s an isotope
They have the same amount of proton and electrons
Different number of neutrons
What ion makes something acidic?
Hydrogen H+
Why do different substances separate in a gas chromatography column?
The different substances travel at different speeds
Describe the structure and bonding of chlorine
Covalent bonds between atoms
Forms simple molecules
Weak attraction between molecules
Low boiling point
Describe the structure and bonding of sodium chloride
Ionic bonds which are strong
Giant lattice formed between oppositely charged ions
High energy needed to break bonds
High melting point
How does increasing the pressure affect the rate of reaction?
Rate increases,
Because particles are closer together
So frequency of collisions increases
What is meant by activation energy?
The minimum amount of energy to start a reaction
How else could you increase the rate of reaction other than using a catalyst?
Increase temperature
Increase surface area
Increase concentration
What happens to metals at the negative electrode?
All metals are positive ions they are attracted to the negative electrode
Gains electrodes and becomes reduced
What happens to the non metal in electrolysis
Loses electrons and is attracted to the positive electrode
Why are nanotubes used as lubricants
They can slide over eachother because of weak forces between layers
Why can graphite conduct electricity?
Because it has delocalised electrons which can move
Describe the structure of a metal
A lattice of positive ions with delocalised electrons
Why does copper conduct electricity?
It has delocalised electrons
(so electrons) can move through the structure/metal
