C8 Chemical changes

  • Created by: abiiwelsh
  • Created on: 29-09-18 10:45
What is an ore?
Rocks which contain metals that are economical to extract
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What does oxidised mean?
Oxygen added to compound
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What does reduced mean?
Oxygen removed from compound
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What is the reactivity series?
List of metals in order of reactivity
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What is one way to find order of reactivity series?
React the metals with water- most vigorous reaction is most reactive
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What is a good metal for water pipes?
Copper- unreactive with water
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When group 1 metals react with water what is given off?
Hydrogen gas and alkaline solution
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How can you test if hydrogen is given off from water + metal?
Lit splint over gas- pop shows hydrogen
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What is a limitation of putting metals in order of reactivity with water + metal?
Very slow reaction and it is difficult to distinguish reactivity lower down the series
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How can you order the less reactive metals in reactivity series?
Observe reaction with dilute acid
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What is an acronym for the reactivity series?
Please stop loudly calling my angry zebra in technology lesson cause she gallops
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What is the reactivity series order?
Potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, tin, lead, copper, silver, gold
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Which metals in reactivity series react vigorously with water? How do they react?
Potassium, sodium, lithium, calcium- fizz, hydrogen gas, alkaline solution of metal hydroxide
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Which metals in reactivity series react very slowly with water?
Magnesium, aluminium, zinc, iron
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Which metals in reactivity series react only with steam water?
Tin and lead
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Which metals in reactivity series have no reaction with water?
Copper, gold, silver
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Which metals in RS explode with dilute acid?
Potassium, sodium, lithium
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Which metals in RS react well with dilute acid? How is it like?
Fizz, hydrogen gas, salt
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Which metals in RS react slowly with warm acid?
Tin and lead
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Which metals in RS don’t react with dilute acid?
Copper, silver, gold
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Why can some reactive metals still be used outside?
They from layer of the metal oxide over them- doesn’t undergo reaction unless reduced
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How can you order metals in RS withought water and acid?
Put metals in competition with each other
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What is displacement reaction?
A more reactive metal displaces less reactive metal from its aqueous solution of one of its salts
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What is an ionic equation?
Shows only the atoms and ions that change in reaction
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What is the ionic equation for Mg + CuSO4 -> MgSO4 + Cu ?
Mg + Cu ^2+ -> Mg ^2+ +Cu——— SO4 is left out because it doesn’t change
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How would you know if zinc displace lead from lead nitrate?
Lead metal forming as crystals on zinc
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Why is hydrogen in the reactivity series where?
When some metals in RS react with dilute acid, hydrogen ions (H+) is displaced from the acid solution. It is between copper and lead
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Why is carbon in the reactive series? Where?
It is used for extracting metals from oxides, which is a displacement reaction- between aluminium and zinc
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What does OIL RIG mean?
Oxidation is loss, reduction is gain- in oxidation electrons are lost from atom but oxygen added and reduction electrons are gained but oxygen lost
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Why is oxidation the loss of electrons?
When oxygen and metals bond, the metal wants to lose electrons and oxygen wants to gain 2 electrons so the metal gives electrons to oxygen
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What is a half equation?
Equation to show what happens to the atoms and ions of each element
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What is the half equation for iron in this ionic equation. Fe + Cu ^2+ -> Fe ^2+ + Cu
Fe -> Fe^2+ + 2e-
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What is another name for displacement reactions?
Redox reaction (reduction and oxidation reaction)
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Does oxygen have to be involve in reduction or oxidation?
No- just the gain or loss of electrons
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What is a metal ore?
Rock that contains worthy amount of metal to extract
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How is copper in copper ore concentrated before extraction and purification?
Copper ore ground to powder, mixed with water, add chemical which makes copper repel water, air bubbles put through solution, copper compound (probably bonded to oxygen or sulfur) float to top, rock sinks, scrape copper compound off top of solution
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What factors assess if it is worth extracting metals from ore?
How easy, how much metal in ore, demand for metal
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What does the method of extraction of metal from ore depend on?
Where it is in the RS
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What is carbon used for?
Extracting less reactive metals from their oxides in industry by displacement of less reactive metals
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What must be added to the reaction of carbon + metal oxide for the reduction reaction to occur?
Heat which produces metal + carbon dioxide
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Why is carbon not used for the reduction of tungsten oxide?
Because carbon reacts with tungsten when produced so hydrogen used instead- the tungsten produced is pure
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Which metals aren’t extracted from their ores and oxide by carbon, what is used instead?
Aluminium, magnesium, calcium, lithium, sodium, potassium- electrolysis used because carbon is less reactive than these metals
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Why do copper, gold and silver not react with dilute acid?
They are less reactive than the hydrogen in the acid so they can’t displace hydrogen from compound (eg HCl)
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What is a salt?
Compound formed when the hydrogen (from acid) is partially or wholly replaced by metal- positive metal ion and negative ion from acid
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Metal + acid = ?
Salt + hydrogen
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Which metals are never added to acid?
Alkali metals- explosive and dangerous
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How do you produce iron chloride salt crystals from salt solution?
Heat salt solution over tripod and gauze and Bunsen burner, ontop of water bath, evaporated some water from salt solution, crystals appear around edge, stop heating, rest of water evaporate at room temp and dap filter paper
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What does it mean to be more reactive?
The is stronger tendency that that element will form a positive or negative ion from losing or gaining electrons easier
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What type of displacement reaction is metal + acid?
Redox reaction- metal always being oxidised and hydorgen always being reduced
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Is the half equation 2H^+ +2e- -> H2 reduction or oxidising?
Reduction because the H2 needs to gain 2 electrons to become an unstable atoms (not ion)
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What is a base?
Compounds that can neutralise acids
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What is an alkaline?
Bases that are soluble in water- hydroxides of alkali metals
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What is produced when salt + base is reacted?
Water and salt produced- neutralisation
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What does carbonate + acid produce?
Salt, water, carbon dioxide
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What is the charge of aluminium ions?
+3
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What is the charge of ammonium ions?
NH4 ^+
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What does the Roman numeral next to transition metals mean?
The size of the positive charge eg. Copper (II) = Cu^2+
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What is the charge of nitrate ions?
NO3 ^-
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What is the charge of sulfate ions?
SO4^2-
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How can you make copper sulfate crystals?
Insoluble copper oxide (base as it’s metal oxide) to sulfuric acid, warm, stir, solution goes blue- copper sulfate forming, filter solution- remove excess copper oxide, evaporate water, stop heating as crystals appear, leave to evaporate at room temp
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What compound is a base usually?
Metal oxide
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What happens with the OH- ions and H+ ions in an alkali + acid reaction?
They react to from water molecules H2O
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How can you form ammonium salts instead of metal salts?
React acid + alkali (the alkali is ammonia solution- NH4OH
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How can you tell when an acid + alkali reaction is complete?
Use acid/ base indicator- you need the correct amount of acid and alkali so they neutralise (form water and no excess H+ or OH- ions after) - use titration to find volume of acid that neutralises alkali
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When acids are added to water what happens to hydrogen?
H+ ions released into solution- these excess H+ ions make the solution acidic
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When alkali s are added to water what happens to the hydroxide?
Aqueous hydroxides ions(OH-) formed- these make the solution alkali
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What is the pH scale?
Shows acidity or alkalinity by scale of 1(acid) to 14(alkaline) -
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What is a pH meter?
Glass probe, dip in solution, electronic pH sensors give digital display of pH on data- loggers and computers- monitor pH changes
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What is a concentrated acid?
Acid which contains greater amount of that solute in the same volume of solution
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What are 3 strong acids?
Hydrochloric acid, nitric acid, sulfuric acid
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What are 3 weak acids?
Ethanoic acid, citric acid, carbonic acid
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What is the difference between strong and concentrated acid?
Strong acids ionise completely in a solution (this means all the hydrogen atoms ionise to become H+ ions) whereas concentrated is the amount of solute in the solution volume
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How do acids show there acidic properties?
When dissolved in water- they ionise and H+ ions released which makes the acid acidic
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What is a weak acid?
Most of molecules stay as they are- release less H+ so aren’t fully ionised and the reaction of weak acid + water is reversible- ions recombine to form molecules again
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What happens when you reduce the concentration of the H+ ions by factor of 10?
The pH value increase by 1- getting weaker and more neutral (7)
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If the concentration of H+ ions in acid is 0.1 mol/dm ^3, what is the pH?
1- strong
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Other cards in this set

Card 2

Front

What does oxidised mean?

Back

Oxygen added to compound

Card 3

Front

What does reduced mean?

Back

Preview of the front of card 3

Card 4

Front

What is the reactivity series?

Back

Preview of the front of card 4

Card 5

Front

What is one way to find order of reactivity series?

Back

Preview of the front of card 5
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