Chemical calculations
Calculate the Mr of Magnesium oxide (MgO)
Mg = 24, O = 16
40
What is electrolysis?
using electric current to break down and ionic substance.
What is an exothermic energy transfer?
Energy transferred to the surroundings
What is a pure substance
something made of only one type of substance
What is a Hydrocarbon?
Something made of Hydrogen and Carbon atoms ONLY
Calculate the Mr of sulfuric acid (H2SO4)
H = 1 , S = 32 , O = 16
98
What is the name of the positive electrode?
Anode
What is the endothermic energy transfer?
energy taken in from the surroundings
What is a formulation
A mixture designed for a specific purpose
Name the first 4 alkanes
(monkeys eat peeled bananas)
Methane, Ethane, Propane, Butane
How do you calculate concentration of a solution?
mass of solute divided by volume of solvent
How can ionic substances be electrolysed?
when molten or dissolved in water (aqueous)
What is the overall energy change
The difference in energy between the reactants and products
What is chomatography (what is it used for)
A method used for separating coloured substances
What is the general formula of the alkanes?
CnH2n+2
How do you convert volume units of cm3 into dm3
divide by 1000
In the electrolysis of aluminium oxide, what substance is the aluminium oxide mixed with (and why)
Cryolite (it lowers the melting point - less energy is used)
What is the activation energy?
The minimum energy required for a reaction to occur. (from the reactants to the top of the curve)
What is the test (and result) for oxygen
a glowing splint will re-light
What process is used to separate crude oil into its fractions?
Fractional distillation
Give one way in which you can increase the concentration of a solution
either: add more solute
or add less solvent
In the electrolysis of aluminium oxide, why do the graphite electrodes need to be frequently replaced?
the carbon electrode reacts with the oxygen produced, so gets burned away
Why is there an activation energy for every reaction?
Because old bonds have to be broken so new bonds can be made (and therefore new molecules)
What is the test (and result) for hydrogen
a lit splint gives a squeaky pop
What is the purpose of cracking?
To break long, less useful molecules into shorter, more useful ones.