Chapter 4 - Acids and redox Flashcards
What is an acid?
It is a H+ (proton) donor
What will be produced when a strong acid reacts with water?
H3O (proton + water)
What are bases?
Proton acceptors
Formula of sulfuric acid
H2SO4
Formula of hydrochloric acid
HCl
Formula of nitric acid
HNO3
Formula of ethanoic acid
CH3COOH
What will the salt of hydrochloric acid look like?
xCl
What will the salt of sulfuric acid look like?
X2SO4
What will the salt of nitric acid look like?
x(NO3)2
Formula of sodium hydroxide
NaOH
Formula of potassium hydroxide
KOH
Formula of ammonia
NH3
What is a strong acid?
One which fully dissociates in water
What is a weak acid?
One which partially dissociates in water - this reaction is reversible
What is produced when ammonia reacts with an acid?
Ammonium salt
What are titrations used for?
To find out how much acid is needed to neutralise a known quantity of alkali
Where must we read the results of a titration from?
The meniscus
Top tips for titrations
Balance the equation
Work out moles of known substance
Work out moles of unknown substance
Work out concentration or volume of unknown
What colour change indicates a titration is over?
Pink to colourless when acid is added to alkali
What is a standard solution?
One with a known concentration
Equation for number of moles in a solution
Number of moles = concentration x volume
How to prepare a standard solution
Weigh out an exact amount of solid using a balance
Add water to the beaker to dissolve the solid
Transfer to a volumetric flask and top up with water until it meets the graduation line
Thoroughly mix the solution
What are polyprotic acids?
Acids that donate more than one electron
What is important to remember about di and tri protic acids?
They will take double or triple the numbers of moles of base to be neutralised
What is the oxidation number?
How many electrons need to be donated or accepted to form a compound or ion
What will all pure elements have an oxidation number of?
0
What will ions consisting of one ion have the oxidation number of?
The charge of the ion
For moleular ions, what will the sum of the oxidation numbers equal?
The overall charge of the ion
Oxidation number of oxygen
-2
Oxidation number of hydrogen
+1
Oxidation number of fluorine
-1
How can roman numerals help us with the oxidation number?
The numeral next to an element shows its oxidation number - Fe (II) has an oxidation number of +2
What do -ate compounds contain?
Oxygen and another element
What does the number after the non-oxygen element in an -ate compound show us?
Its oxidation number
What is a loss of electrons called?
Oxidation
What is a gain of electrons called?
Reduction
What will happen to the oxidation number as electrons are lost?
It will increase
How to remember oxidation and reduction
OIL RIG
What happens to metals when they react with acids?
They are oxidised
What is produced when a base neutralises an acid?
A salt
What is an alkali?
A base that dissolves in water and releases hydroxide ions
What is formed when an acid reacts with a metal hydroxide or oxide?
A salt and water
What is produced when an acid and an alkali react?
A salt and water
What is produced when an acid reacts with a metal carbonate?
A salt, water and carbon dioxide
What will the oxidation number for all elements be?
0
Where does the sign go when writing an oxidation number?
Before the number
What is a salt?
The metal ion is replaced by a hydrogen ion
What is the difference between a base and an alkali?
A base accepts H+ ions from an acid and an alkali releases OH- ions into solution
