Acids and bases Flashcards
What can acids be neutralised by?
Metal hydroxides (alkalis)
Metal oxides
Metal carbonates
What is always produced during neutralisation?
A salt and water and a metal carbonate produces CO2(g) as well
What is a salt formed from?
Positive ion of the base and the negative ion of the acid
E.g.
SODIUM hydroxide + hydroCHLORIC acid —> sodium chloride + water
What can a titration be used for?
Calculate experimentally the concentration of an acid or alkali. At the end point the number of moles of the H+ ions must equal the number of moles of the OH- ions.
Number of acid moles = number of alkali moles
q
What do some acids / alkalis have more than one of?
Therefore…
H+/OH- ions
PVC acid = PVC alkali
P =number of H+ or OH- ions
Titrations are repeated until what…
Two results are concordant -they are within 0.2cm3 of eachother- an average of these Is then calculated to get the average titre
Chemical formula for hydrochloric acid?
HCl
Chemical formula for sulfuric acid?
H2SO4
Chemical formula for nitric acid?
HNO3
How can we check if a solution is an acid or alkali?
use universal indicator -universal indicator changes the colour of the solution depending wether or no it is an act or an alkali -
What pH range does acids have?
1-6
red/orange
pH of neutral
7
pale green
pH range of alkalis
8-14
green/blue
Definition of pH
pH is a number which indicates how acidic or alkaline a substance is
Strongest acid and alkaline pH
Acid:1
Alkaline:14
How are some common acids made
Some common acids are made by dissolving non metal oxides in water
What acids when dissolved in water in the atmosphere cause acid rain
Carbon oxide
Sulfur
Nitrogen
How are alkalis formed
by dissolving soluble metal oxides
What is the ionic formula of hydrochloric acid
H+(aq)+Cl-(aq)
What is the ionic formula of sulphuric acid
2H+(aq) + S42-(aq)
What is the ionic formula of nitric acid
H+(aq)+NO3-(aq)
What will happen if water is added to an acid
the pH will increase
What will happen if water is added to an alkaline
the pH will decrease
What is special about acidic solutions
all acidic solutions are ionic and thus they can conduct electricity when they dissolve in water
What do all acids contain
H+ ions
Give an example of what happens when the acid HCl (aq) dissolves in water
HCl(aq) —> H+(aq) + Cl-(aq)
What is a reduction reaction
the gain of electrons (electrons will be on left side of arrow)
What is an oxidation reaction
loss of electrons (electrons on the right side of the arrow)
What is pH dependent on
pH is dependent on the concentration of hydrogen ions in the solution
What does water do
water naturally slightly dissociates (dissociates means breaking up) into an equal amount of hydrogen (H+) and hydroxide ions (OH-)
Equation for the disassociation of water
H2O—> H+ + OH-
Why does water dilute an acid
it increases the OH- to H+ ratio
Why does water dilute an alkaline
It increases the H+ to OH- ratio
Tell me what do acids have more of
acids are solutions containing a greater concentration of Hydrogen ions than hydroxide ions
Tell me what do alkaline have more of
alkaline are solutions containing a greater concentration of hydroxide ions than hydrogen ions
Tell me what does water have
water is a neutral solution containing an equal concentration of hydrogen and hydroxide ions
Properties of acids
all acids can be corrosive if they are concentrated enough meaning when they react with something they will break that substance up
the higher the concentration the more corrosive the acid is
What are the affects of acid rain on buildings
corrodes stone on buildings such as limestone and marble
tarnishes glass, rubber and steel
destroys brickwork and statues
What are the affects of acid rain on fish
it suffocates the fish
acid kills fish eggs due to the protecting skin being destroyed by acid
the young fail to live
What are the affects of acid rain on iron structures
iron structures are corroded and the rate of reaction of rusting increases weakening the structures
What are the affects of acid rain on trees
soil becomes infertile and sparse
lack of timber
three quarters of forests die as they are harmed by acid in the ozone
leafs fall off and weaken trees
trees get stunted
interrupts photosynthesis
What are the main sources of acid rain?
power plants
combusting coal and oil omits the gas
cars, trucks and buses
decaying vegetation
volcanic eruptions as they release sulphur
What is neutralisation
this is when one adds a base to an acid
this means that the amount of hydrogen ions decreases until the number of hydrogen ions is the same as in water
What are the three bases
metal hydroxides (alkalis)
metal oxides (alkalis)
carbonates
Show a neutralisation reaction formula
H+(aq) + OH-(aq) —->H2O(l)
What is produced in a neutralisation reaction
When an acid is neutralised by an alkaline salt and water are formed and when neutralised by a carbonate salt and water and CO2 are formed
How do we work out what salts are produced in a neutralisation reaction?
use first work of the alkali and then use the following for labelling acids
Hydrochloric acid - chloride
sulphuric acid - sulphate
nitric acid - nitrate
phosphoric acid - phosphate
What are spectator ions
ions that are on both sides of the equation
what can an alkaline be used for
It is possible to use an alkaline to help work out the exact concentration of an acid this procedure is called. titration an is a more accurate experiment than the one you have just carried out
what does a reaction between a metal oxide and an acid produce
salt and water
what does a reaction between a metal hydroxide and an acid produce
salt and water
what does a reaction between a metal carbonate and an acid produce
salt, water and carbon dioxide
what are the spectator ions in this equation -
N+Cl+Na+OH–>Na+Cl+H2O
Na+Cl
what is a standard solution (titration)
a solution of accurately known concentration.
what is an indicator used for (titration)
to show when the end point of the reaction has been reached.
when are titre volumed deemed concordant
when the measurements are between 2cm^3.
