chemistry Flashcards
diameter of nucleus vs atom
1/20000
electron to proton size
1/1837
radius of nucleus/radius of atom
nucleus/27000
cathodes
reduces cations
cations are postitve
cathodes are negatiove
anodes
oxides anodes
anodes are postitve
anions are negatives
Fractional Distillation
Crude Oil is a mixture of lots and lots of hydrocarbons. We use fractional distillation to separate them from one another.
The heavier a compound (ie: the more carbons it has), the higher its boiling point. That means that as you go up the fractional distillation column, and as the temperature decreases, the heavier compounds leave the column first (towards the bottom of the column where the temperature is highest), and the really light compounds leave the column towards the top where the temperature is lower.
The majority of hydrocarbons in crude oil are alkanes (which we’ll go over in the next topic), with just a few alkenes (in the topic after that).
Properties Of Fractions
Boiling Point - We’ve already mentioned that the heavier compounds have higher boiling points.
Volatility -
The volatility of a compound is its propensity to evaporate at a given temperature. The heavier compounds are less volatile.
Flammability -
The smaller compounds are more flammable. This is because it’s easier for Oxygen molecules to react with smaller compounds than bigger ones.
Viscosity -
The heavier compounds are more viscous. This makes intuitive sense - we can imagine bigger, heavier compounds being thicker in their liquid form than smaller ones.
Burning Hydrocarbons
When you burn a hydrocarbon properly (complete combustion), you should get Carbon Dioxide and Water (and energy).
When you burn a hydrocarbon not-properly (incomplete combustion), you get a mixture of carbon, carbon dioxide, water and carbon monoxide. Carbon Monoxide (CO) is very bad for you and will kill you if you inhale too much of it [1]
Because combustion produces energy, hydrocarbons are often used as fuels. Of course, this produces lots of CO2 which is bad for the environment.
alkene test
bromine test
alkenes undergo
electrophillic reactions
alkenes attract
electrophiles
alkens are technolically
Alcohols have the -OH functional group, and the suffix -ol.
The first three (the ones shown above) have similar properties.
They’re flammable, and so they’re used as fuels that burn to produce CO2 and H2O.
They dissolve in water to form neutral solutions.
They react with Sodium to form Alkoxides (functional group -ONa).
They can be used as solvents to dissolve other things
alcohols
Carboxylic acids react with carbonates to produce a salt, CO2 and water.
Eg: Sodium Carbonate + Ethanoic Acid –> Sodium Ethanoate + CO2 + H2O
Eg: Calcium Carbonate + Propanoic Acid –> Calcium Propanoate + CO2 + H2O
Carboxylic acids dissolve in water to produce weak acids. [1]
Carboxylic acids are used to make soaps and detergents.
reactionsn
Acid + Metal -> Salt + Hydrogen
Acid + Metal Hydroxide -> Salt + Water
Acid + Metal Oxide -> Salt + Water
Acid + Metal Carbonate -> Salt + Water + Carbon Dioxide
reactivity
Potassium Sodium Calcium Magnesium Aluminium CARBON Zinc Iron Tin Lead HYDROGEN Copper Silver Gold Platinum
how to remember reactivity
Please stop calling me a cute zebra, I like her call (me) smart goat.
carbon and metals
Metals higher than Carbon are extracted by electrolysis of molten compounds (similarly, more on electrolysis in that tutorial). This is far more expensive. It is also crucial to remember that in electrolysis, the less reactive cation will be reduced at the cathode. So, in an aqueous solution of Zn(NO3)2, where there are both Zn2+ and H+ ions, the more reactive Zinc ions will prefer to stay in their ionic state, whilst the less reactive H+ ions will gain electrons and be released as H2 gas.
what are acids
h+
bases
oh-
h + acceptors
d. chlorine
– damp blue litmus paper turns red and then is bleached (paper turns
white)
hydrogen –
explodes with a ‘squeaky pop’ when a burning splint is held at the open end of a test tube
c. carbon dioxide
– limewater turns cloudy when shaken with the gas
b. oxygen –
relights a glowing splint
a. Al
3+, Ca2+ and Mg2+
each form a white precipitate.
b. Cu2+
forms a blue precipitate.
c. Fe2+
forms a green precipitate.
d. Fe3+
forms a brown precipitate.
flame tests
Li (crimson red), Na (yellow-orange), K (lilac), Ca (red-orange), Cu (green)
anhydrous copper(II) sulfate
(colour change from white to blue)
a. carbonates –
using a dilute acid
b. halides –
using an aqueous solution of silver nitrate in the presence of dilute
nitric acid (chlorides form a white precipitate; bromides form a cream precipitate;
iodides form a yellow precipitate)
c. sulfates –
using an aqueous solution of barium chloride in the presence of dilute
hydrochloric acid
