C5 Flashcards
What does the reactivity series do?
Order metals on how reactive they are
Reactivity series ?
Potassium Sodium Lithium Calcium Magnesium Carbon Zinc Iron Hydrogen Copper
How are metals reactivity determined?
How easily they lose electrons forming positive ions. The higher on the reactivity series , the more easily they form positive ions
What does the place of the metal in the reactivity series say about how is reacts with water or acid?
When a metal reacts with water or acid , they lose electrons and form positive ions. So the higher the metal on the reactivity seriees the more easily it reacts with water or acid
How was the reactivity series made?
Comparing the relative reactivity of different metals with either acid or water and put them in order from most reactive to least reactive .
What happens if a metal and acid react?
Acid + metal —-> salt + hydrogen
How to measure the speed of a reaction between acid and a metal?
Indicated by the rate at which bubble of hydrogen are given off.
What does the ph go from ?
0-14
What does the ph measure?
How alkaline or acidic a substance is
How will certain metals react with acid ?
More reactive the metal , the faster the reaction. Potassium , sodium , lithium and calcium react explosively. Less reactive metals like magnesium , zin and iron react less violently. Copper wont react with cold dilute acids in general.
How to investigate the reactivity of metals?
Measure the temperature change of the reaction with an acid or water over a set period of time. If you use the same mass and surface area of metal each time , the more reactive the metal , the greater the temperature
What happens when a metal and water react together ?
Metal + water —-> metal hydroxide + hydrogen
What metals react with water?
Potassium , sodium , lithium , calcium
Which metals wont react with water?
Zinc, iron , copper
What type of substance is low in ph?
Acidic
What type of substance is high in ph ?
Alkaline
What type of substance is in the middle of the ph scale?
Neutral substance, water
What is an indicator?
A dye that changes colour depending on whether its above or below a certain PH
What is a wide range indicator?
Contains a mixture of dyes that menas they gradually change colour over a broad range of ph. Useful for estimating the ph of a solution
What is an acid?
A substance that forms an aqueous solutions with ph of less than 7. Acids form H+ ions in water.
What is a base?
A substance with a ph greater than 7
What is an alkali ?
A base that dissolves in water to form a solution with a PH greater than 7. It forms Hydroxide ions in water
What is neutralisation?
The reaction between acids and bases
What is the equation for neutralisation?
Acid + base —-> salt + water
What is the product hydrogen ions react with hydroxide ions?
H+ + OH- —–> H2O(water)
What is a strong acid?
An acid that ionises completely in an aqueous solution. All acid particles dissociate to release H+ ions.
Examples of strong acids ?
Sulfuric, hydrochloric and nitric
What is a weak acid ?
Am acid that does not fully ionise in an aqueous solution . Only a small proportion of acid particles dissociate to release H+ ions
Examples of weak acids?
Ethanoic , citric and carbonic acids
What type of reaction it the ionisation of a weak acid?
Reversible reaction , which sets up an equilibrium between the undissociated and dissociated acid . Since only a few of the acid particles release hydrogen ions, the equilibrium is more to the left of the reaction
What type of acid is more reactive and why?
Strong acids. The concentration of hydrogen ions is higher so the rate of reaction will be faster.
What does a reaction of acids involve?
Involves hydrogen ions reacting with other substances
How does the strength of an acid effect its ph?
Stronger the acid the lower the ph
What happens to an acid if the ph decreases by 1 unit
Hydrogen ion concentration increases by 10
What must you take into account when you measure the ph of a strong and weak acid?
The concentration of them both
What does the acid strength tell you?
The proportion of the acid molecules that ionise in water
What is the concentration of an acid?
Measures how much acid there is in a certain volume of water.
What is a concentrated acid solution ?
Large amount of acid in the certain volume
What is a dilute acid?
When there is more water than acid .
What are metal oxides and metal hydroxides?
Bases
What is formed if an acid reacts with a metal oxide or hydroxide ?
Acid + metal oxide/hydroxide —> salt + water
How to form a metal oxide?
metals react with oxygen
Properties of metal oxides and hydroxides?
- some dissolve in water
- soluble compounds
- alkali
How are acids neutralised?
By alkalis , (soluble metal hydroxides)and bases (insoluble metal hydroxides and oxides) to produce salts an water. Also by metal carbonates that produce carbon dioxide also
What are metal carbonates ?
Base
What happens if a metal carbonate reacts with an acid?
Acid + metal carbonate —-> salt + water + carbon dioxide
The particular salt produced in any reaction between an acid and a bas or alkali depends on ?
- acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates , sulphuric acid produces sulfates)
- positive ions in the base , alkali or carbonate
How can soluble salts be made?
From acids by reacting them with solid insoluble substances , such as metals , metal oxides , hydroxides or carbonates. Solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt.
What can you do to a salt solution to produce solid salt ?
Crystallisation
Why do you have to extract metals?
Unreactive metals such as gold are found as pure gold but most are found as compounds that require a chemical reaction to extract the metal
What is oxidation?
When metals react with oxygen to form an oxide.
What is a reaction that separates a metal from its oxide?
Reduction reaction.
What happens for the formation of a metal ore?
Oxidation reaction . Gain of oxygen means creates a metal oxide
What is the reaction when you extract a metal?
Reduction reaction . Loss of oxygen so the metal oxide is reduced to just the metal
How can metals be chemically extracted from their ores ?
By reduction using carbon.
What happens during reduction using carbon?
Ore is reduced as oxygen is removed from it , and carbon gains oxygen so it is oxidised
Examples of a reduction reaction with carbon?
Iron(III) oxide + carbon —> iron + carbon dioxide
What determines whether a metal oxide can be reduced using carbon?
Its place in the reactivity series
How do metal high than carbon In the reactivity series get extracted ?
Electrolysis
How do metals below carbon get extracted ?
Extracted using reduction with carbon. This is because carbon can only take away the oxygen from metals which are less reactive than carbon itself
What non metals are in the reactivity series ?
Hydrogen and carbon
What does oxidation mean in terms of electrons?
Loss of electrons
What does reduction mean in terms of electrons ?
Gain of electrons
What does OILRIG show?
Oxidation Is Loss Reduction Is Gain
(In terms of electrons)
Why is there the term REDOX reactions?
Because oxidation and reduction happen at the same time.
Examples of a REDOX reaction?
Iron atoms oxidised to Fe2+ when react with dilute acid :
Fe + 2H+—> Fe2+ + H2
Iron atom loses electrons . They are oxidised by hydrogen ions:
Fe- 2e- —-> fe2+
Hydrogen ions gain electrons . They’re reduced by the iron atoms:
2H+ + 2e- —-H2
What type of reaction are all metals + acids?
Redox reactions
What is a displacement reaction?
A more reactive metal will displace a less reactive metal from its compound
Examples of ionic equation from displacement reactions?
Iron + copper sulfate —> iron sulfate + copper
In terms of ions:
Fe —> Fe2+ + 2e- = oxidisation . Iron loses 2 electrons to become a 2+ ion
Cu2+ + 2e- —->. Cu. = reduction . Copper gains 2 electrons to become a copper atom
What is shown in an ionic equation?
The particles that react and the products
