FWAQ (frequently wrong answered questions)
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What is a Hydrocarbon
A compound made up of only hydrogen and carbon only
What two words are important in the definition of a hydrocarbon
Compound Only
Give the name of the acid that forms when nitrogen dioxide dissolves in water
Nitric acid
Name a pollutant gas that forms from acid rain
Nitric acid Sulphur dioxide
What gas has the highest percentage in dry unpolluted air
Aragon- 0.96
Describe how the student should collect a sample of pure oxygen at the positive electrode
Fill a test tube with copper sulfate solution place the tube over the positive electrode collect gas/oxygen by displacement solution
Describe a chemical test other than using an indicator, to show that the reaction mixture contains ethanoic acid
Add carbonate Effervesces Add metal Bubbles/effervesces
Explain why the enthalpy change for the reaction between and ester and water =0kj/mol
Same amount of energy is needed to break the bonds in the reactants as is give off bonds broken= bonds made
Describe what is meant by a dynamic equilibrium
Rate forward reaction equals the rate of the backward reaction concentrations of reactants and products remain constant
Explain why adding a catalyst does not change the position of the equilibrium
Increases the rate of forward and backward reaction equally
Definition of a compound
different elements which are chemically bonded together
Explain how galvanization continues to protect iron when the layer of zinc is damaged
Zinc is a more reactive metal Zinc corrodes instead of iron
Give a reason why the white ring of ammonium chloride takes several minutes to form
gas particles collide with air particles Gas particles move in random direction Gas particles collide with wall of tube
Explain why argon is highly unreactive
has a complete outer electron shell Argon does not gain or loose electrons
Suggest one reason why the calculated percentage of oxygen in the mixture may not be accurate
Leak in the apparatus Temperature was not the same for all readings Apparatus not left to cool
Explain why sodium oxide does not conduct electricity
Sodium oxide has ions in a giant ionic structure no delocalised electrons ions /electrons can not flow
What is the colour of silver precipitate
White
Describe the particle arrangement and movement of particles in a gas
Radom arrangement more freely and quickly in all different directions far apart
suggest how a melting point of a pure substance changes when an impurity is added
Melts over a range of temperatures
Explain why cracking is important process int the oil industry.
Crude oil produces long chain of hydrocarbons Longer chains are less useful shorter chains are in higher demand as they are more useful cracking breaks down longer chains into smaller shorter ones shorter alkanes are flammable more useful in the fuels alkenes are used to make polymers
Describe the forces of attraction in a covalent bond
Strong electrostatic attraction between a nuclei of bonded atoms and a shared pair of electrons
what is the word equation for fermentation reaction
Glucose —-> ethanol +carbon dioxide
what is meant by the term functional group
group of atoms in a compound that determines it’s chemical properties/ reactions
what do the arrows represent in an equilibrium reaction
Reversible reaction Reaction goes both ways