Chemistry 6-Chemical change Flashcards
What can irritants do?
Give an example
cause reddening / blistering of the skin
Bleach
What do Alkali’s form when placed in water?
OH- ions
What do Acids form when placed in water?
H+ ions
Acid + Base=
Salt+water
H+ + OH- =
H20
What do acids do to produce hydrogen ions in water?
Ionise
Give an example of a monoprotic acid
It gives off 1H+
HCl
Give an example of a diprotic acid
It gives off 2H+
H2SO4
Give an example of a triprotic acid
Phosphoric acid (H3PO4)
It gives off 3H+
What do strong acids do that weak acids dont do?
Strong acids fully ionise
weak acids dont fully ionise
Define ionising
Releasing of all H+
Name 3 weak acids that dont fully ionise when placed in water
ethanoic
citric
carbonic
Ionisation of weak acids are what type of reaction?
Reversible
Which side of the equilibrium do weak acids lie
left hand side
Acid strength shows what
What proportion of the acid molecules ionise in water
Concentration of an acid measures what
how many moles of acid molecules are in 1 litre of water
The more moles of acid molecules per dm3, the …
more concentrated the acid is
You can have a dilute but. …
or a concentrated but ….
strong acid
weak acid
Why does ethanoic acid have a much lower electrical conductivity than HCl?
HCl is a stronger acid with more H+ that are ionised
Ions carry charge
Acid + Metal =
Salt + Hydrogen
What sort of experiment can prove the acid+metal equation
Squeeky pop test with a burning splint
Why doesnt copper react with dilute acids?
less reactive than hydrogen
Nitric acid reacting with metals produce what instead of salt + Hydrogen?
Nitrogen oxides
Some metal hydroxides / oxides are what?
Hence what equation can be applied
Bases
Acid + metal oxide = salt + Water
Combination of a metal and its acid determines what
the name of the salt
Acid + Metal carbonates =
Salt + Water + CO2
Are common salts of Na / K / Ammonium soluble in water?
Yes
Are nitrates soluble in water?
Yes
Are common Chlorides soluble in water?
Yes
Except Silver Chloride + lead Chloride
Are common sulphates soluble in water?
Yes
Except lead,barium,calcium sulphate
Which carbonates / hydroxides are soluble in water?
sodium/potassium/ammonium
The rest are insoluble
How do you form insoluble salts
Using precipitation method
Adding two soluble salts together
Formation of an insoluble salt
How do you form soluble salts? (Insoluble reactant)
Acid + Metal or an insoluble base (metal oxide/hydroxide)
Give an example of the formation of a soluble salt equation
Copper oxide + hydrochloric acid =copper chloride
How do we make soluble salts using an acid and a soluble reactant?
Titration of alkali is needed to neutralise the acid
Then evaporate the water to form dry salt
An oxidising agent does what with electrons
Accepts electrons and gets REDUCED
a reducing agent does what with electrons
donates electrons and gets OXIDISED
With Iron(2) salt and chlorine gas, what colour does the solution turn from into?
What happens to the Iron?
Green to Yellow
Loses an electron to form Fe3+
With the iron(2)and chlorine, what is the reducing agent and why?
Iron is, as it donates an electron to the chlorine
With the iron(2) and chlorine, what is the oxidising agent and why?
Chlorine, as it accepts the electron from iron
Iron and a dilute acid, what gets oxidised and what gets reduced?
iron is the reducing agent and is being oxidised
the dilute acid will be the oxidising agent and is being reduced
Name the order of reactivity of metals
Magnesium
Zinc
Iron
Tin
WIth displacment reactions with metals, what is alwasy being oxidised?
Metal atom (the more reactive metal)
with displacement reactions with metals, what is always being reduced?
Metal ion (the less reactive metal)
the equation for rust is
iron + oxygen + water = hydrated Iron (3) oxide
Rust is redox reaction thus what is being oxidised and what is being reduced?
Whats the reducing agent/oxidising agent
Iron= oxidised and thus reducing agent
oxygen=reduced and thus oxidising agent
steels are alloys with what other things
iron
carbon
other metals
stainless steel contains what 3 things
iron/carbon/chromium
Tin plating to prevent rust can be found where
food cans
Galvanising involves what?
adding a zinc which is a more reactive metal than iron
this loses electrons to oxygen instead of iron
steel buckets/corrugated iron roofing
what can be also placed on ships/iron pipes as a sacrificial method?
Magnesium as its a more reactive metal
