C5.1 - C5.8 Chemical Changes✔️ Flashcards
What is the reativity series?
Is a list of metals in order of their reactivity with most reactive at the top-least at the bottom
Features of metal ores?
Most metal ores chemicaly bonded to other elements in compounds - many have been oxidised - to form their oxides eg Iron(III) Oxide
What does it mean if a metal is oxidised?
Oxidised - have oxygen added usualy from oxygen in the air to form oxides
How do you extract metals from their oxides?
Metal oxide must be reduced - have oxygen removed
How do you test for hydrogen gas with a beaker and lighted splint?
There will be a ‘pop’ sound when hydrogen gas comes into contact with lighted splint
Potassium to calcium reaction with water?
-Fizz
-gives of hydrogen gas leaving an alkaline solution of metal hydroxide
Mangensium to iron reaction with water?
-very slow reaction
Tin and leads reaction with water?
-slight reaction with steam
Copper,silver,gold reaction with water?
-no reaction
Potassium,sodium,lithium reaction with dilute acid?
Explode
Magnesium,aluminium,zinc,iron reaction with dilute acid?
-fizz giving off hydrogen gas
-forming a salt
Tin and lead reaction with dilute acid?
-React slowly with warm acid
Copper,silver,gold reaction with dilute acid?
No reaction
How are metal ordered on the rectivity series?
-in order of reactivity by their reactions with water and dilute acid
What will displace a less reactive metal from an aqueous solution of its salts?
A more reactive metal will displace a less reactive metal from an aqueous solution of one of its salts.
What does an ionic equation show?
Shows only the atoms an ions that change in a reaction
Why does zinc displace lead?
Zinc is more reactive the lead - higher on reactivity series - therefore zinc displaces lead from its solution.
Zinc (s) + lead nitrate (aq) - zinc nitrate (aq) + lead (s)
What is oxidation?
Oxidation - loss of electrons
What is reduction?
Reduction - gain of electrons
Why is carbon used to extract ores?
Carbon(non-metal) also displaces less reactive metals from their oxides - used to extract metals from ores
Metal oxide + carbon —–> metal + carbon dioxide
What is a purpose of the reactivity series?
Helps you decide best way to extract a metal from its ore - oxides of metals below carbon in series can be reduced by carbon to give metal element
What determines weather metal is worth extracting?
-how easy it is to extract from ore
-how much metal ore cotains
-changing demands for a particular metal
Why are Gold and silver found in the earth as metals?
They are so unreactive that they exist in their native state
How are metals more reactive then carbon extracted?
Metals more reactive then carbon are not extacted via reduction but by electrolysis of the molten metal compound
What is a salt?
A Salt is a compound formend when the hydrogen in an acid is wholly,or partially replaced by metal ions
Equation and example of formation of salt?
Metal + acid - a salt + hydrogen
Iron + hydrochloric acid - iron(II)chloride + hydrogen
How can pure dry salts be extracted from their solution?
The water is evaporated from the solution by heating it until the point of crystalisation is reached - solution now saturated and crystals will appear
How to test for crystals in a solution?
Dip a glass rod into the hot salt solution - removing it and seeing if crystals form on it as it cools
How are salts made?
Salt can be made by reacting a suitable metal with an acid - metal must be above hydrogen in reactiviy series but not to reactive
Why type of reaction is a metal and an acid?
Example of a redox reaction - metal atoms loose electrons and are oxidised and hydrogen ions from the acid gain electrons and are reduced
what are bases?
Bases are compounds that can neutralise acds - alkalis are bases that are insoluble in water eg the hydroxides of group 1 metals - lots of bases are metal oxides
What is formend when you react an acid and a base?
A salt and water are produced
Acid + base - a salt + water
What is the equation for neurtalisation?
Acid + base - a salt + water
What are salts made up of?
Made up of positive metal ions and a negatie ion from a an acid - positive ions come from a metal,base or carbonate
What is the overall charge of salts?
Like all ionc compounds they have no overall charge - as sum of charges on their ions equal zero
How do you make copper sulfate crystals?
1)Add insoluble coper oxide to sulfuric acid - stir - warm on a tripod and gauze
2)solution turns blue - shows copper sulfate is being formend - excess black copper oxide can be seen
3)when reaction complet - filter - removed excess copper oxide
4)evaporate water - so crystals of copper sulate can form - stop heating when first crystals appear - leave rest of water to evaporate slowly - gives larger crystals - filter any small excess with fiter paper
Equation for making copper sulfate crystals?
Sulfruic acid + copper(II) oxide - copper(II) sulfate + water
Reactions to make salts?
A soluble salt can be prepared by reacting an acid with a suitable insoluble reatant including:
-a metal
-a metal oxide
-a carbonate
Why is it hard to tell when an acid and an alkali have completley reacted?
-no gas given off which would stop when acid had been neutralised
-no excess insoluble base visible
How do you tell when an acid and alkali have completley reacted?
You need to use an acid/base indicator
What happens when an acid and alkali reacts?
A neutralision reaction occurs
Acid + alkali - a salt + water
What happens when an acid and base react?
Neutralisation reaction occurs?
Acid + base - a salt + water
What happens when an acid and carbonate react?
Give a salt , water and carbon dioxide
Acid + a carbonate - a salt + water + carbon dioxide
What do you do to collect a pure,dry sample of crystal?
-carry out titration with the indicator added - see how much acid reacts completley with the alkali
-run that volume of aid into the solution of alkali again without indicator this time
-crystalise and dry crystals of salt from reaction mixture.
What are alkalis?
Soluble hydroxides are called Alkalis,example sodium hydroxide solution
What are bases?
Base Include alkalis and are substances that can neutralise acids - metal oxides and metal hydroxides are bases
What is an acid?
An acid is a substance that produces hydrogen ions, H +(aq), when dissolved in water an example is sulfuric acid
It pure water acidic or alkaline?
Pure water is neutral pH 7
What happens when you add acid into water ?
All acids release H+ ions into solution when added to water - these excess H+ ions make solution acidic
What type of ions do all alkalis form when added to water?
All alkalis form aqueous hydroxide ions OH- when added to water these excess OH- ion makes a solution alkaline
Name and example of an indicator?
Litmus example of an indicator - turns red in acid - blue in alkaline
What is the pH scale?
Scale shows how acidic or alkaline a solution is - 0 most acidic - 14 most alkaline - can use universal indicator to find pH of a solution - pH7 is neutral
What is a pH meter?
Glass probe attached to dip in solution being tested - some electronic pH sensors give digital display of pH directly - or attached to computer to monitor pH changes overtime
What happens to acids in water eplain in terms of mollecules?
In water all acids ionise (split up) , their mollecules split up to from H+ ions and negative ions - all acidic solutions have H+ ions
What is a strong acid?
Lower pH value - ionise completley in solution - reaction is not reversiable
What is a weak acid?
Higher pH value - most of the molecules stay as they are - do not release H+ ions into solution - reaction is reversible
What happens to mollecules in a weak acid?
Small portion split up to form H+ ions and negative ions - the ions recombine to form orginal molecules again - position of equalibrium is reached
How much does concentration of H+ ions increase by?
Concentration of H+ ions increase by a factor of 10 the pH value decreases by one unit.
Or
Concentration of H+ decreases by a factor of 10 the pH value increases by one unit
What are H+ ions?
Hydrogen ions
Why can copper chloride not be produced by reacting copper with hydrochloric acid?
Copper is less reactive on the reactivity series and can not displace hydrogen
How are metals more reactive then carbon extracted from their ores?
Electrolysis of the molten metal compound
