C3 - Exam Mistakes Flashcards
What is added to ethanol to produce ethanoic acid and what type of reaction is that?
Oxygen added
Oxidation reaction
Give 2 differences between reactions of potassium with water and lithium with water
Potassium dissolves faster
Potassium moves around surface more rapidly
In flame tests, why is it hard to identify potassium at the same time as sodium?
Lilac colour is obscured by yellow colour
How could you confirm that a solution contains magnesium ions and not aluminum ions? 2 marks
Add excess of sodium hydroxide
Aluminum would re-dissolve but magnesium wouldn’t
How does the energy level diagram show that a reaction is exothermic?
ENERGY OF REACTANTS is higher than ENERGY OF PRODUCTS
Give the 2 main steps used to treat water from reservoirs and give a reason for each
Chlorinated
Kills harmful MICROBES
FILTERED
To remove solids
What is it in water filters that removes hardness from water?
Ion exchange resin
Suggests why home water filters contain silver particles
Prevents growth of MICROBES
Why is distillation not an economic method of treating water?
High cost OF ENERGY
What did Mendeleev use to decide the alkali metals will be in the same group?
They had similar properties
How is the modern periodic table organised in terms of protons?
Organised in order of the proton number
Why shouldn’t hydrochloric acid be used to dissolve scale in kettles?
It is corrosive
Why is a low pressure NOT used in the Haber process?
There would be a lower yield of ammonia
Explain how ammonia is separated from unreacted hydrogen and nitrogen after the Haber process. 2 marks
Gases are cooled
So ammonia is liquefied
Why would the UK encourage the use of hydrogen fuel cells? 2 reasons
Saves crude oil
Don’t release polluting gases
What do you have to remember to add in energy level diagrams?
An upward arrow representing the activation energy
Why did Mendeleev leave gaps for undiscovered elements?
So that elements with similar properties could be placed together
Explain why lithium, sodium and potassium are all in group 1. 2 marks
They all have one electron in their outer shell
So they have similar properties
Which gas is produced when sodium reacts with ethanol?
Hydrogen
Explain why solution of ethanoic acid has a higher pH than hydrochloric acid solution. 2 marks
Ethanoic acid is a weaker acid
Because ethanoic acid doesn’t completely ionise
What does volatile mean?
Evaporates easily
What is meant by a closed system?
Nothing can enter or leave the reaction
Where does hydrogen for the Haber process come from?
NATURAL GAS
Explain how a catalyst speeds up a reaction. 2 marks
Provides an alternative pathway for the reaction
Lowering the activation energy of the reaction
Where is the arrow for activation energy on an energy level diagram?
From the reactants to the peak
Explain why increasing the amount of alkali in the conical flask has no effect on the overall temperature increase. 2 marks
More energy produced
But more water to heat up
