Exam style questions and answers for Chemistry


GCSE Chemistry Flashcards on Exam style questions and answers for Chemistry, created by Aryan Mohajerani on 12/13/2017.
Aryan Mohajerani
Flashcards by Aryan Mohajerani, updated more than 1 year ago
Aryan Mohajerani
Created by Aryan Mohajerani over 6 years ago

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Question Answer
Why can carbon nanotubes be used as lubricating material? (2) The nanotubes can slide over each other as there are no covalent bonds between the nanotubes.
Why can graphite conduct electricity? (2) It has delocalised electrons so the electrons can carry charge through the graphite
6 MARK QUESTION: Explain why chlorine (Cl2) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature. Include a description of the bonding and structure of chlorine and sodium chloride in your answer. (6) Chlorine: 1 mark per point, but they should be linked with each other for a well structured response. covalent bonds between atoms forming (simple) molecules no / weak attraction / bonds between molecules low boiling point Sodium chloride: ionic bonds or electrostatic attraction strong bonds in all directions between oppositely charged ions forming giant lattice large amounts of energy needed to break bonds high melting point
Fill in the gap with either: 'high', 'low' or 'very low': Diamond has a _____ melting point (1) High melting point
Roughly how many atoms do nanoparticles contain? (1) A hundred.
Why are mixture of metals harder than pure metals? (2) There are different sized atoms, so the layers are distorted and therefore they can't slide over each other, which makes them harder.
Gold and stainless steel are also used for dental braces. Suggest two factors to consider when choosing which metal to use for dental braces. (2) • cost • toxicity • strength • appearance of brace •unreactive or resistant to corrosion / saliva rusting is accepted as an alternate to corrosion. IGNORE REFERENCES TO BEND AND MOULD.
What is the minimum amount of energy called that is needed to break bonds between particles. (1) Activation energy.
How do catalysts help speed up the rate of reaction? (2) They reduce the amount of activation energy needed by providing an alternate reaction pathway with a lower activation energy.
Sulfuric acid reacts with metals to produce salts. Why is potassium not a suitable metal to react with sulfuric acid? (2) It is too reactive and so it is too violent making it dangerous.
A student reacted zinc metal with sulfuric acid to produce a salt and another product. Complete the equation for this reaction. Zn + H2SO4 .............................. + ........................... (2) ZnSO4 and H2 in either order.
The student wanted to increase the rate of the reaction between the zinc and sulfuric acid. State one way, other than using a catalyst, that the student could increase the rate of the reaction. (1) • increase concentration (of sulfuric acid) • increase temperature or heat it •increase surface area of zinc
What is meant by an endothermic reaction and how is it shown in a thermometer when testing it? (2) A reaction which takes in energy from the surroundings, shown by a drop in temperature.
Magnesium oxide contains magnesium ions (Mg2+) and oxide ions (O2–). Describe, as fully as you can, what happens when magnesium atoms react with oxygen atoms to produce magnesium oxide. (4) •Magnesium loses •2 electrons and •oxygen gains 2 electrons which gives a •full outershell of electrons or, it forms ionic bonds with electrostatic attraction.
Silicon dioxide has a very high melting point. Other substances are added to silicon dioxide to make glass. Glass melts at a lower temperature than silicon dioxide. Suggest why. (1) It has weaker bonds IGNORE INTERMOLECULAR FORCES. Allow other substances react with the silicon dioxide.
Describe the structure of a metallic bond Giant structure of strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons. These forces of attraction hold the atoms together in a regular structure.
Why is there now less water vapour in the atmosphere? The atmosphere has cooled down, causing the water vapour to condense and form oceans.
Why is there less carbon dioxide in the atmosphere? The carbon dioxide has dissolved in/reacted with seawater and has formed carbonates The evolution of green plants meant more photosynthesis and removal of carbon dioxide.
If pressure increases in a closed system at dynamic equillibrium, what side is favoured in the reaction? (2) The equilibrium will try to reduce it so it moves in the direction where there are fewer molecules of gas.
Why can anhydrous copper sulfate be used as a drying reagent? (2) or 3 idk i made this up recalling from Mr.Hebbs It is a reversible reaction, so it can react with water again to form hydrated copper sulfate.
Write the structural formula for ethyl ethanoate
Write the structural formula for propanol (2)
How can you reduce the effect of random errors? (2) By taking repeat readings and finding the mean, this makes the results more precise.
How is a systematic error caused? (1) By using equipment that isn't zeroed properly.
Explain why diamond is hard. (2) Giant Lattice/each atom forms 4 bonds There are strong covalent bonds.
Explain why graphene is strong. (3) Giant Lattice Atoms are covalently bonded Bonds are strong so a lot of energy is needed to break them.
Pure iron would not be suitable for a replacement hip joint. Suggest why. (1) Not strong Too soft Rusts/corrodes/wear away Could change shape Layers could slide over each other.
Why is iron described as an element? (1) Because it is made up of only one type of atom.
Stainless steel is harder than pure iron. Explain why. (2) or (3) Structure is distorted as there are different sized atoms. So it's difficult for layers to slide over each other.
What is meant by a strong acid? When an acid is completely ionised in an aqueous solution.
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