Chemical Changes Flashcards
describe how metals react with oxygen and state the compound they form
many metals react with oxygen through oxidation to make metal oxides
define oxidation
the gain of oxygen, or loss of electrons, by a substance during a chemical reaction
define reduction
the loss of oxygen, gain of electrons, or gain of hydrogen by a substance during a chemical reaction
list the reactivity series from most reactive to least reactive
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Aluminium
- Carbon
- Zinc
- Iron
- Tin
- Lead
- Hydrogen
- Copper
- Silver
- Gold
- Potassium
how are metals above carbon in the reactivity series extracted?
- electrolisis because carbon is less reactive so they can’t be displaced with carbon
- found in ores (metals containing compound in rock= metal oxides)
how are metals below carbon and above hydrogen in the reactivity series extracted?
- reduction with carbon because carbon is more reactive
- metal oxide is reduced to form a metal and carbon is oxidised to form carbon dioxide
- displacement of the metal, removes oxygen from the oxide, leaving the metal
how are metals below hydrogen in the reactivity series extracted?
- they aren’t because they are found native as pure metals
recall and describe the reactions of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids
- all react with dilute acid except copper whereas magnesium, zinc and iron react less violently
- acid + metal = salt + hydrogen
- reaction gives off bubbles
- potassium, sodium, lithium, calcium and magnesium react with water (p, s and l react more violently) whereas zinc, iron and copper don’t
- metal + water = metal hydroxide + hydrogen
what is the link between reactivity and tendency to form positive ions
- the most reactive metals have the greatest tendency to lose electrons to form positively charged ions
- (greater tendency of getting oxidised/ losing electrons)
how can metals be extracted from their compounds by reduction with carbon?
the carbon displaces the metal from the compound, and removes the oxygen from the oxide, this leaves the metal
what reaction happens betweenmetals and acids in terms of gain or loss of electrons
redox,
what 3 things can acids be neutralised by?
alkalis, bases and metal carbonates
what are the products of the reactions in neutralisation of acids with alkalis, bases and metal carbonates
- alkalis- salt and water
- bases- salt and water
- metal carbonates- salt, water and carbon dioxide
predict the salt produced in neutralisation of acids with alkalis, bases and metal carbonates
- alkalis- Acid + alkali → salt (alkali 1 acid- ate/ ide)+ water
- e.g. Nitric acid + sodium hydroxide → sodium nitrate + water
- bases (metal oxides)- Acid + metal oxide → salt (metal acid- ate/ ide) + water
- e.g. Sulfuric acid + copper oxide → copper sulfate + water
- metal carbonates- Acid + metal carbonate → salt (metal acid-ate/ ide)+ water + carbon dioxide
- e.g. Hydrochloric acid + copper carbonate → copper chloride + water + carbon dioxide
what charges do ions of each group have?
- group 1- +1
- group 2- +2
- (group 3- +3)
- (group 4- +4 or -4)
- (group 5- -3)
- group 6- -2
- group 7- -1
how can soluble salts be made from acids and how to obtain pure, dry samples of salt
- a soluble salt can be prepared by reacting an acid with a suitable insoluble reactant
- pure, dry samples are obtained by crystallisation where the solution is heated to evaporate off the water leaving behind the pure, dry crystals of the salt
define acid and alkali in terms of what ions they produce in solution
- acids produce hydrogen ions, H+ in aqueous solution
- alkalis produce hydroxide ions, OH- in aqueous solution
define base
any substance that reacts with an acid to neutralise it to produce a salt and water only
how is universal indicator used to measure the approximate pH of a solution?
If universal indicator is added to a solution it changes to a colour that shows the pH of the solution according to the pH scale
what happens in a reaction between acids and some metals electron wise and what type of reaction is it?
- redox reaction
- the metal will lose electrons, becoming oxidised into a positive ion
- hydrogen is reduced as they gain electrons
how do you write displacement reactions as ionic redox reactions?
- get rid of any substances that appear on both sides of the equation that don’t take part in the reaction (doesn’t change)
- write an equation for each element (one will be reduced, one will be oxidised)
- you can do this by writing the symbols for the element on both sides like how they are in the equation except the two different elements are in different equations
- add the right amount of electrons to each side to balance the equations
- identify which is reduced and which is oxidised
how do you calculate the quantities in titrations involving concentrations in mol/ dm3 and g/ dm3
- calculate the amount of solution in moles by converting the voume to dm3 (if its in cm3) (divide by 1000) and then multiply it by the concentration (moles= conc x vol)
- find the amount (moles) of the unknown substance by using the ratio in the balanced equation
- calculate the volume of the unknown substance using vol= moles/ conc
what equation links moles, concentration and volume?
concentration in mol/ dm3 or g/ dm3= amount of solute in mol or g/ volume in dm3
how do you convert between mol/ dm3 and g/ dm3?
- to convert from mol/dm3 to g/dm3, multiply by the relative formula mass of the solute
- to convert from g/dm3 to mol/dm3, divide by the relative formula mass of the solute
