4.2 Flashcards
Why is hydrated salts not good as a base for making a standard solution
What does efflorescent mean
This is because they lose a lot of their mass due to being water to the atmosphere as they are efflorescent.
This means their formula mass is VARIABLE
Why is sodium hydroxide NaOH not good for making standard solution
What does deliquescent mean
Sodium hydroxide absorbs moisture from the air (it’s DELIQUESCENT) so it also has variable formula mass, not goof
How to read burette
Get to eye level
- bottom of meniscus avoiding PARALLAX ERROR
- hold vertical
- add white sheet behind
- 0 and 5 second decimal place
Why adding water doesn’t affect titre
X
Read bottom meniscus, swirl, white tile etc
S
What is an acid , strong acid and weak acid
How represent strong and weak
Acid is that releases H+ ions as protons when dissolved in water
Strong acid is one that fully dissociates into H+ ions in aqueous solution
- represent by full arrow
Weak acid is one that partially dissociates into H+ ions in aqueous solution
- THIS REPRESENTED BY DOUBLE HALF ARROW
Examples of weak and strong acids
Weak
- organic are weak so ethanoic acid and other CARBOXYLIC ACIDS ARE WEAK
STRONG
- SHAND ACIDS ARE STRING + HCL
What is a base
What difference between bases and alkalis
Definition of alkali
What are examples of bases and alkalis out of three possible combos
A base is a substance that NEUTRALISES an acid to form a salt
2) alkalis are just bases that can dissolve in water, all alkalis are bases
3) Alkalis are bases dissolved into water that releases HYDROXIDE IONS
4)Metal carbonate, metal hydroxide , metal OXIDE = bases
Metal hydroxide = alkalis
What is a neutralisation reaction
Where a H+ ion from an acid and a OH- ion from a base react to produce water
A salt is also formed when the H+ reacts with the base
Three neutralisation reactions?
What is the state symbol of they are alkali ?
Metal hydroxide + acid = salt + water (this is alkali so always AQUEOUS )
Metal oxide + acid = salt + water (CAN BE SOLID )
Metal carbonate + acid = salt + water + carbon dioxide (CAN BE SOLID )
What did bronsted Lowry say about acids, strong and weak acids?
Acids are PROTON DONNORS
- strong acids FULLY ionise
- weak acid WEAKLY ionise
What is neutralisation reaction for carbonates
H+ + Co32-= Water and co2
What happens in PARTIAL NEUTRALISATION
Why is sodium hydrogen carbonate considered an acid salt? Made from partial neutralisation of carbonic acid and sodium hydroxide
1) Like only one of the Hydrogens are replaced !!!
2) One of the hydrogen from H2Co3 has been replaced with a metal, but still acts as an acid as has one hydrogen left to give
How can hydroxonium ions be made ?
Reactions of likeethanoic acid and water, acids are proton donnors so they will give a H+ to water marketing it H3O + which is dative
Oxidation number for elements and elements like diatomic bonded to themselves?
Compounds?
Ions?
1)0,
Anything like p8 h2 etc = 0
2) 0
3) charge in ion
Oxidation number for special case metal hydride H ?
Metal hydride H = -1
So NaH = -1