Types of Chemical Reaction Pt1 Flashcards
(20 cards)
What is an exothermic reaction?
Gives out heat
What is an endothermic reaction?
Takes in heat.
Give 3 examples of exothermic reactions
Combustion
Neutralisation
Displacement
Give three examples of endothermic reactions
Cracking
Photosynthesis
Thermal Decomposition
Give four indications that a chemical reaction has taken place.
Temperature change
Colour change
Precipitate
Gas production
Define the term neutralisation reaction
When an acid and alkali react together the hydrogen and hydroxide ions form water.
H+ + OH- –> H2O
Define the term combustion
Reaction of a fuel with oxygen to produce at least one oxide and releases energy.
Fuel + oxygen —> carbon dioxide + water + heat
Define the term displacement reaction
When a more reactive element will remove a less reactive element from its compound
Zinc + copper sulfate –> zinc sulfate + copper
Chlorine + potassium bromide –> potassium chloride + bromine
Define the term thermal decomposition
Breaking down using heat
Copper carbonate –> copper oxide + carbon dioxide
Green –> black
Define the term cracking
Breaking long chained hydrocarbon compounds into shorter chain
Bond breaking is endothermic or exothermic
Endothermic
Bond making is endothermic or exothermic
Exothermic
Consider the reaction between hydrogen and chlorine
H2 + Cl2 –> 2HCl
Explain in terms of bond breaking and bond making why this is an exothermic process.
Energy is required to break bonds in H2 and Cl2
Energy is released when new bonds are made in HCl
More energy is given out than taken in so the reaction is exothermic
Give an equation for the thermal decomposition of limestone to form quick lime
Calcium carbonate –> calcium oxide + carbon dioxide
Give a use for limestone
Blast furnace, the extraction of iron ore.
The calcium carbonate thermally decomposes and the calcium oxide combines with acidic impurities forming slag (calcium silicate)
CaCO3 —-> CaO + CO2
CaO + SiO2 –> CaSiO3
Give two uses for quick lime CaO
To mix with water making limewater
CaO + H2O –> Ca(OH)2
To make plaster
Give three advantages of limestone quarrying
Provides jobs
Boosts economy
Provides a raw material for blast furnace and neutralising soil
Give three disadvantages of limestone quarrying
Eye sore
Ruins animal’s habitats
Noise or dust pollution
In a chemical reaction if more heat is given out than taken in in will be
Exothermic
In a chemical reaction if less heat is given out than taken in it will be.
Endothermic
