C.5 Flashcards
What is the equation for a metal and oxygen reaction?
metal + oxygen –> metal oxide
e.g. - magnesium + oxygen –> magnesium oxide
What type of reaction is a metal + oxygen reaction?
An oxidation reaction as the metal has gained oxidation and become oxidised.
What is the equation for a metal and water reaction?
metal + water –> metal hydroxide + hydrogen
e.g. potassium + water –> potassium hydroxide + hydrogen
What metals react with water?
Potassium, sodium and lithium react vigorously and rapidly in water, calcium reacts fairly rapidly in water.
What metals do not react in water?
Magnesium, zinc, iron and copper. A reactivity series can be constructed based off of these reactions but a reaction with dilute acid is needed to order these 4 metals.
How do metals react with dilute acid?
- Potassium, sodium and lithium react dangerously fast
- Calcium reacts extremely vigourously
- Magnesium - rapidly
- Zinc - quite rapidly
- Iron - quite slowly
- Copper - no reaction
What two elements are added to the reactivity series and where are they?
Carbon and hydrogen. Carbon is considered more reactive than zinc but less than magnesium. Hydrogen is more reactive than copper only.
What happens to metals when they react in acid?
They lose electrons and form a positive ion. A metal’s reactivity is dependant on it’s ability to do this, therefore, group 1 and 2 elements are the most reactive as they have the fewest electrons to lose.
How are metals extracted from the earth?
Unreactive elements such as gold are found naturally in the Earth.
Metals such as iron and copper react with oxygen to form metal oxides, meaning displacement reactions are used to seperate them.
What element is usually used to displace metal oxides?
Carbon - as it is cheaper than most metals and more reactive than metals such as iron.
Give an example of using a displacement reaction to extract metals.
Carbon + iron oxide –> carbon dioxide + iron
- The carbon has been oxidised and the iron has been reduced
What is the difference between oxidation and reduction reactions?
Gaining oxygen = oxidation
Losing oxygen = reduction
What does oxidation and reduction mean in terms of electrons?
Oxidation means the LOSS of electrons (OIL)
Reduction means the GAIN of electrons (RIG)
What happens to acids in an aqueous solution?
They release positive hydrogen ions.
- e.g. HCl –> H+ + Cl-
H2SO4 –> 2H+ + SO4 2-
HNO3 –> H+ + NO3 -
What is a base?
A chemical (usually a metal oxide or hydroxide) which neutralises an acid, producing a salt and water.
What is an alkali?
An alkali is a base which is soluble in water. This means that all alkalis are bases, but not all bases are necessarily alkaline.