Acids And Bases Flashcards
What is hydrochloride acid
Hcl
Sulphuric avid
H2 so4
Nitric avid
HNO3
Ethanoic acid
Ch3cooh
What do acids do when dissolved in water ?
Dissociate to release hydrogen ions
Proton donors
What is dissociation
Process of giving up a proton
Strong acids
Release all their atoms ( hydrogen ) into a solution as H+ ions
Completely dissociate
Have a low pH
Example of strong acids
Hcl
H2 so 4
Weak acids
Only release a proportion of its available hygogrn atom is to solution
Reversible
Lower concentration of h + ions in solution
Partially dissociate
What is an alkali
A base that dissolved in water release ing hydroxide ions
What are alkalis
Proton acceptors
Neutralise acids
Strength depends on its solubility
Bases
Metal carbonates
Metal oxides
Metal hydroxides
Ammonia
Strong bases
Almost all of the base dissociates in water to produce oh
Forward reaction favoured
Eg NaOH
Weak bases
Ionise only slightly in water
Backwards reaction favoured - small amount dissociates
Few OH- released
Neutralisation
H+ ions react with a vase to forma salt and neutral water
The h+ionsfrom the acid are replaced by metal or ammonium ions from the base
Acid + base =
Salt and water
Acid + metal oxide/ hydroxide
Salt and water
Acid and carbonate =
Salt and water and co2
Ammonia
Doesn’t produce hydroxide ions, but aqueous ammonia is an alkali
This is because the reaction between ammonia and water produce hydroxide ions
Ammonia accepts a hydrogen ions from h20 molecule - forming an ammonium ion and hydroxide ion
Nh3+ h20 = nh4+ + oh-
Sulphuric avid
Strong avid
When mixed with water each h2so4 molecule dissociates releasing 1 of its 2 hydrogen atoms as a h+ ion
What is a titration
Measure he volume of one solution that reacts exactly with another solution
What can triteations be used for
Finding conc of solution
Identification of unknown chemicals
Finding the purity of a substance
standard solution ?
Known concentration
Volumetric flask
- Weigh solid
- Dissolve solid using distilled water
- Transfer to volumetric flask
- Rinse last traces
- filled to graduation line
- Invert
The titration
Add 2nd solutions to burette
Record initial burette Reading
Drop one solution into the toher - use white tile
End Point
Repeats - so 2 concordant results are obtained ( within 0.1)
MEAN TITRE
Indicators - methyl orange
Yellow - orange < acid to alkali
Phenophthalein
Pink to colourless ( acid to alkali)
Systematic error
Constant error due to equipment
Eg balance
Random error
May not always occur eg air bubble in burette
Margin of error of equipment
Limits of precision of equipment used to take measurements
Eg pippette
Percentage error of equipment
Max margin of error / measured value
- 100
Titration calculation
Concentration = amount/ volume
C1v1= c2v2
What is oxidation number
Inform u about he number of electrons used when an atom binds with another element
Positive oxidation number
Electrons lost
Negative oxidation number
Electrons gained
Name of FeCl3
Iron (111) chloride
Rules for oxidation numbers
All I combined elements have an oxidation number of 0 and sum of oxidation number in a compound is 0
Sum of all oxidation numbers in an ion equals the charge on that ion
Group 1,2,3= 1+, 2+, 3+
Fluorine - oxidation number -1
Hydrogen +1 , metal hydride = -1
Oxygen - -2
Compound with fluorine, peroxide and superoxide - e.g. h202 =-1
Fluorine oxidation number
-1
Roman numerals
Used in the names of compounds of elements that form ions with different charges
Shoes oxidation state of elementary without a sign
Iron (2)= Fe2+
What is a redox reactions
Electron transmitted
What is oxidation
Loss of electrons , increase in oxidation number = more positive
Metals commonly lose electrons to form positive ions
Reduction
Gain in electron
Decrease in oxidation number
Non medals - gain electrons to form negative ions
Oxidising agent
Receive / take in electrons
Are themselves reduced
E.g. oxygen
Reducing agent
Donate electrons to
Other species
Are themselves oxidised
What is disproportion
Species reduced and oxidised