C5 - Chemical changes Flashcards
Recall the reactivity series:
-potassium
-sodium
-lithium
-calcium
-magnesium
-aluminium
-CARBON
-zinc
-iron
-tin
-lead
-HYDROGEN
-copper
-silver
-gold
(Please Stop Laughing Cuz My Animals Can Zip Into The Large House Cuz Snakes Glow)
What determines a metal’s reactivity?
its tendency to form a positive ion
What defines a metal ore?
a metal ore contains enough metal to make it economically worthwhile to extract it
When do metals need to be extracted? How are they extracted?
-if the metal is reactive enough, it will be found in the Earth as an oxide compound
-elements less reactive than carbon can be extracted using carbon in a reduction reaction (removes oxygen)
It won’t need to be extracted if it is unreactive, like gold
What is oxidation and reduction in terms of electrons?
oxidation is loss of electrons
reduction is gain of electrons
(OIL, RIG)
metal + water →
metal hydroxide + hydrogen
metal + acid →
salt + hydrogen
acid + metal hydroxide →
salt + water
acid + metal oxide →
salt + water
acid + metal carbonate →
salt + water + carbon dioxide
What is the difference between an alkali and a base?
-alkalis dissolve in water to form a solution of pH > 7
-bases are insoluble in water
Give some examples of insoluble bases:
-metal oxides
-metal carbonates
-metal hydroxides (mostly)
Lithium, sodium, and potassium hydroxides are soluble, but all others are not
RP1 - How can you prepare a dry sample of a soluble salt using an acid and an insoluble solid?
-pour acid in beaker and heat gently over a BB (^RoR)
-add insoluble solid until no more reacts
-filter off excess solid with funnel + filter paper
-evaporate solution until crystals begin to form using a boiling water bath
-leave solution to finish crystallising for a few days, and gently pat crystals dry with filter paper
Why are acids acidic and alkalis alkaline? How can you measure their pH?
-acids produce H+ ions in water, and alkalis produce OH- ions
-measure with UI or pH probe
How does the colour of UI change when in solutions of different pH?
same as light spectrum - ROYGBIV
How can a general neutralisation reaction be represented?
What is the difference between a strong and weak acid? Give some examples of each:
-strong acids are completely ionised in aqueous solution (hydrochloric, nitric, sulfuric)
-weak acids are partially ionised in aqueous solution (ethanoic, citric, carbonic, phosphoric)
Why can an acid be described as both strong and dilute?
-strong because completely ionised in aqueous solution
-dilute because small amount of acid per unit volume
How does the hydrogen ion concentration change with pH?
as pH decreases by one unit, H+ ion concentration increases by a factor of 10 (logarithmic)
Copper, copper carbonate, and copper oxide are all mixed with hydrochloric acid - which of the compounds react to form a salt?
-only copper carbonate and copper oxide
-copper itself is below hydrogen in the reactivity series, and can’t displace it
