Unit 3 Flashcards
What pH range do acids have?
From below 7 (red)
What range does the pH scale have?
From below 0 to above 14
What pH range do alkali’s have?
More than 7 (blue)
What pH does water and other neutral substances have??
pH 7 (green)
What type of solution do non-metal oxides produce when dissolved in water?
Acid solutions
What type of solution do metal oxides and hydroxides produce when dissolved in water?
Alkaline solutions
What does ammonia dissolve in water to produce?
An alkali
Where can acids and alkalis be commonly used?
At home and in the laboratory
What solutions have the concentration of hydrogen ions equal to the concentration of hydroxide ions?
Water and other neutral solutions
What ions does an acidic solution contain?
More hydrogen ions than hydroxide ions
Which ions does an alkaline solution contain?
More hydroxide ions than hydrogen ions
How is the effect of dilution on the pH of an acid/alkali explained?
In terms of the decreasing concentration of hydrogen and hydroxide ions
Which solutions have an equilibrium between hydrogen and hydroxide ions?
Water and aqueous solutions
What happens when a reversible reaction is in equilibrium?
The concentrations of reactants and products remain constant although not necessarily equal
How is the concentration of a solution expressed?
Mol dm-3
Moles, concentration and volume can be found out from what??
M
V C
The triangle
What happens to strong acids in aqueous solutions? (In terms of dissolving and ionising)
They are completely dissolved and completely ionised
What happens to weak acids in aqueous solutions? (In terms of dissolving and ionising)
They are only partially dissolved and are only partially ionised
What are examples of strong acids? (3)
Hydrochloric acid, sulphuric acid, and nitric acid
What is an example of a weak acid?
Ethanoic acid
What do equimolar solutions of strong and weak acids/bases differ in?
pH, conductivity, rate of reaction
What’s an example of a strong BASE? (Type of solution)
Solutions of metal hydroxides
what’s a weak BASE?
Ammonia solution
What is neutralisation?
The reaction of acids with bases
What are examples of bases? (3)
Metal oxides, metal hydroxides, metal carbonates
Where does neutralisation move pH of an acid and an alkali?
Acid move up to 7, alkali moves down
What forms when a base dissolves in water?
Alkalis
What happens in a reaction of an acid and an alkali?
Hydrogen and hydroxide ions form water
What happens in the reaction of an acid with a metal oxide?
The hydrogen and oxide ions form water
What happens in a reaction of an acid with a metal carbonate?
The hydrogen and carbonate ions form water and carbon dioxide
What is given off when an acid reacts with some metals?
Hydrogen gas
What are every day examples of neutralisation?
The treatment of acid indigestion
And using Lime to reduce acidity in soil and lochs
What happens to hydrogen when it is formed in a reaction?
Hydrogen ions form hydrogen molecules
What is the test for hydrogen?
Burns with a pop
How is sulphur dioxide produced?
By the burning of fossil fuels
How is nitrogen dioxide produced?
By the sparking of air in car engines
How is acid rain made?
When sulphur dioxide and nitrogen dioxide dissolves in water in the atmosphere
What does acid rain have a damaging effect on?
Buildings made from carbonate rock
Structures made of iron/steel
Plant/animal life
How can the concentration of acids/alkalis be calculated?
From the results of volumetric titrations
What is a salt?
A compound in which the hydrogen ions of an acid have been replaced by metal ions (or ammonium ions)
How are salts formed?
In the reaction if acids with bases or metals
What salt does hydrochloric acid form?
Chloride salts
What does sulphuric acid form?
Sulphate salts
What does nitric acid form?
Nitrate salts
Which nitrogen salts are made by neutralisation reactions for use as fertilisers? (3 of them)
Ammonium nitrate, ammonium sulphate and potassium nitrate (these salts are soluble in water)
In preparation of a salt what is easier to use as a base?
An insoluble metal carbonate or metal oxide
What happens in precipitation?
Two solutions react together to form an insoluble product called precipitate
What can be formed from precipitation?
Insoluble salts
Which reactions can spectator ions be identified in?
Neutralisation and precipitation (the equation can be written omitting these ions)
How is a cell that makes electricity produced?
By connecting different metals together with an electrolyte
What does sulphuric acid form?
Sulphate salts
What does nitric acid form?
Nitrate salts
Which nitrogen salts are made by neutralisation reactions for use as fertilisers? (3 of them)
Ammonium nitrate, ammonium sulphate and potassium nitrate (these salts are soluble in water)
In preparation of a salt what is easier to use as a base?
An insoluble metal carbonate or metal oxide
What happens in precipitation?
Two solutions react together to form an insoluble product called precipitate
What can be formed from precipitation?
Insoluble salts
Which reactions can spectator ions be identified in?
Neutralisation and precipitation (the equation can be written omitting these ions)
How is a cell that makes electricity produced?
By connecting different metals together with an electrolyte
What is corrosion?
A chemical reaction which involves the surface of a metal changing from an element to a compound
Do different metals corrode at different rates or the same rate?
Different rates
What does the term rusting apply to?
The corrosion of iron
What from the air is required for rusting? (2)
Water and oxygen
What initially happens when iron rusts?
The iron loses 2 electrons to form iron(II) ions
How does iron (II) ions change to iron (III) ions
Oxidation
How are hydride ions formed by electrons lost by the iron during rusting?
By the electrons being accepted by the water and oxygen
What leads to the electro chemical series?
The variation in voltage between different pairs of metals
When do displacement reactions take place?
When a metal is added to a solution containing ions of a metal lower in the electro chemical series
What can be established from the reaction of metals with acids?
The position of hydrogen in the electrochemical series
How can electricity be produced in a cell?
By connecting two different metals in w solution of their metal ions
When at least one of the half-cells doesn’t involve metal atoms, can electricity be produced?
Ye bro
Where do electrons flow?
In the external circuit from the species higher in the electrochemical series to the one lower in the electrochemical series
What’s the purpose of the iron bridge (salt bridge)
To allow the movement of ions to complete the circuit
What’s oxidation?
Loss of electrons by a reactant in any reaction
What’s reduction?
Gain or electrons by a reactant in any reaction
What’s an example of oxidation?
A metal element reacting to form a compound
What’s an example of reduction?
A compound reacting to form a metal
What happens in a redox reaction?
Reduction and oxidation go on together
What can be written for for oxidation and reduction reactions?
Ion-electron equations
What can ion-electron equations be combined to produce?
Redox equations
What happens during electrolysis? (Oilrig)
Oxidation occurs at the positive electrode and reduction occurs at the negative electrode
What reacts with oxygen, water and dilute acid?
Metals
What gives an indication of the reactivity of metals?
Differences in the reaction rates
What are ores?
Naturally occurring compounds of metals
Which metals can be found Uncombined in the earths crust?
The less reactive metals eg gold, silver, copper
Which metals have to be extracted from their ores?
More reactive metals eg lithium, iron
How are most metals extracted from their ores? (Except the most reactive)
With heat, some heat alone, others heated with other substances eg C, CO2
How is iron extracted from its ore?
Produced in a blast furnace
Which are the two key reactions which take place in a blast furnace?
Production of carbon monoxide and reduction of iron oxide
How are the more reactive metals obtained from their ores?
Electrolysis
What does acid rain do?
Increases the rate of corrosion
What increases the corrosion on car bodyworks?
Salt spread on the roads
What does electrons flowing to the iron prevent?
Rusting
When does iron not rust?
When attached to the negative terminal of a battery
When are anti-corrosion methods used?
In everyday situations
What can galvanising and the use of scrap magnesium can result in what?
Electrons flowing to the iron giving sacrificial protection
What happened when iron is attached to metals higher in the electrochemical series?
Electrons flow TO the iron
What happened when iron is attached to metals lower in the electrochemical series?
Electrons flow FROM the iron
Which ways can provide physical protection to iron by giving a surface barrier to air and water?
Painting Greasing Electroplating Galvanising Tin-plating Coating with plastic
What does scratching the tinplate increase? (Iron)
The rate of rusting of iron!
