Reactivity of Metals Flashcards
What is the equation for a reaction between a metal and water?
Metal + water → Metal hydroxide + hydrogen
What is the order of reactivity? Describe their reactions with water and acid
Potassium - reacts quickly with cold water - vigorous reaction with acid
Sodium - reacts quickly with cold water - vigorous reaction with acid
Calcium - reacts quickly with cold water - vigorous reaction with acid
Magnesium - very slow reaction with water - reaction becoming less vigorous
Aluminium - none - reaction becoming less vigorous
Zinc - reacts with steam - reaction becoming less vigorous
Carbon (not a metal)
Iron - reacts with steam - reaction becoming less vigorous
Tin
Lead
Hydrogen
Copper - no reaction with water - no reaction with acid
Silver - no reaction with water - no reaction with acid
Gold - no reaction with water - no reaction with acid
Platinum - no reaction with water - no reaction with acid
Why does aluminium not react with water?
It has a layer of aluminium oxide which stops the water from reacting with the metal below
Why does calcium not react as quickly with sulfuric acid?
A layer of insoluble calcium sulfate forms which slows down the reaction
Why does magnesium react very slowly with water?
A sparingly soluble layer of magnesium hydroxide forms which slows the reaction
How does displacement work?
A more reactive metal displaces another metal from a metal compound, this means that the more reactive metal is now part of the compound and the less reactive metal is on it’s own as an element
What is an ore?
A rock that contains enough metal to make the extraction of the metal economical
What is a low-grade ore?
A rock that contains too little metal to make the extraction worthwhile
What form are unreactive metals found in in the earth’s crust?
Their native state (uncombined with other metals) however they may naturally occur as alloys (mixtures of metals)
What is the trend in how easily a metal corrodes in terms of reactivity?
The less reactive a metal is the slower it corrodes, until it gets to gold and below which don’t corrode
How are metals that are more reactive than carbon extracted?
Using electrolysis of the molten compound
How are metals less reactive than carbon extracted?
Using reduction of its oxide using carbon
What is the example reaction of oxidation using carbon?
Metal compound + carbon → Metal + carbon compound
Why do metals such as silver and gold not need to extracted?
They are naturally found as the element
How can copper be extracted other than using reduction with carbon?
Using displacement with scrap iron, iron is more reactive than copper so it can displace it from a compound
What is phytoextraction?
Biological method of extraction that uses plants, it extracts metal compounds from the ground
How does phytoextraction work?
- Metal compounds is absorbed by roots of a plant
- Plant concentrates metal compounds in its shoots and roots
- The plant is then burned
- The ash contains metal compounds
What is bioleaching?
Biological method of metal extraction using bacteria
How does bioleaching of copper sulfide work?
- Sulfide ions (S2-) are oxidised by the bacteria
- Copper sulfide ores break down
- Cu2+ ions are released
- A leachate is produced containing a high concentration of copper ions
- Copper can be obtained from the leachate using scrap iron
What are the key facts about low-grade ores?
- They’re more common that high-grade ores
- They’re less profitable
- Take more energy to extract
- Produce more waste
What are the advantages of recycling metals?
- Metal ores will last longer
- Less energy is needed than extraction
- Fewer quarries are needed
- Less noise and dust is produced
What are the disadvantages of recycling metals?
- Used metal items must be collected and transported to the recycling centre
- Different metals must be removed from used items and sorted
- Recycling won’t always save a lot of energy as it depends on the metal involved
What are the basic stages of a life-cycle assessment?
- Raw materials are obtained
- These materials are manufactured into the product
- The product is used
- The product is disposed of
