4 - Acids and redox Flashcards
strong acid
releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution
HCl -> H+ + Cl-
weak acid
only releases a small proportion of its available hydrogen atoms into solution as H+ ions
- it partially dissociates in aqueous solution
CH3COOH <-> CH3Coo- + H+
base
- classify 3
a compound that neutralises an acid to form a salt
metal oxides
metal carbonates
alkalis
give 3 examples of metal oxides
MgO
CaO
CuO
3 examples of metal carbonates
Na2CO3
CaCO3
CuCO3
what is an alkali
- give 3 examples
it is a base that dissolves in water releasing OH- into solution
NaOH
KOH
NH3
what is neutralisation
H+ ions react with a base to form a cat and neutral water
acid + metal oxide
salt and water
acid + metal hydroxide
salt and water
acid + alkali
salt and water
ionic equation of acid + alkali
2H+ + O- -> H2O
metal carbonates + acid
salt water and CO2
How to prepare a standard solution
1) weigh the solid
2) dissolve the solid in a beaker using less distilled water than will be needed to fill the volumetric flask to the mark
3) transfer to volumetric flask and rinse thee beaker with distilled water into the volumetric flask
4)dropwise fill the volumetric flask up to the bottom of the meniscus
5) invert the volumetric flask several times
acid-base titration procedure
1) add a measured volume of one solution to a conical flask using a pipette
2) add the other solution to a burette and record the initial burette reading to the nearest 0.05
3) add a few drops of the indicator to the conical flask
4) carry out a trial titration
5) complete the titration each time to the end point - where the indicator changes colour and record the volume needed
6) repeat until concordant results
what is oxidation number
the number of e- lost or gained in a chemical reaction
ON for uncombined element
0
ON combined group 1 element
+1
ON combined group 2
+2
combined aluminium ON
always +3
ON combined flourine
-1
Combined oxygen ON
-2
exceptions
-> peroxide it is -1
-> combined with fluorine +2
combined hydrogen ON
+1
exception
- when combined with group 1 or 2 metals it is -1
combined chlorine ON
- -1
exceptions
- when combined with fluorine and oxygen
Cl2O = +1
ClF2 = +2
ON for polyatomic ion
sum of all the ON is equal to he charge of ion
ON for compound
the sum of all ON is 0
oxidation
gain of oxygen/loss of hydrogen
- or loss of e-
reduction
gain of hydrogen/loss if oxygen
- gain of e-
