Flashcards
Exam style questions and answers for Chemistry
Flashcards do conjunto (32)
- 1Why 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.
- 2Why can graphite conduct electricity? (2)It has delocalised electrons so the electrons can carry charge through the graphite
- 36 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 - 4Fill in the gap with either: 'high', 'low' or 'very low': Diamond has a _____ melting point (1)High melting point
- 5Roughly how many atoms do nanoparticles contain? (1)A hundred.
- 6Why 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.
- 7Gold 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. - 8What is the minimum amount of energy called that is needed to break bonds between particles. (1)Activation energy.
- 9How 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.
- 10Sulfuric 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.
- 11A 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.
- 12The 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 - 13What 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.
- 14Magnesium 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.
- 15Silicon 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. - 16Describe the structure of a metallic bondGiant 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.
- 17Why is there now less water vapour in the atmosphere?The atmosphere has cooled down, causing the water vapour to condense and form oceans.
- 18Why 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. - 19If 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.
- 20Why can anhydrous copper sulfate be used as a drying reagent? (2) or 3 idk i made this up recalling from Mr.HebbsIt is a reversible reaction, so it can react with water again to form hydrated copper sulfate.
- 21Write the structural formula for ethyl ethanoate
- 22Write the structural formula for propanol (2)
- 23How can you reduce the effect of random errors? (2)By taking repeat readings and finding the mean, this makes the results more precise.
- 24How is a systematic error caused? (1)By using equipment that isn't zeroed properly.
- 25Explain why diamond is hard. (2)Giant Lattice/each atom forms 4 bonds
There are strong covalent bonds. - 26Explain why graphene is strong. (3)Giant Lattice
Atoms are covalently bonded
Bonds are strong so a lot of energy is needed to break them. - 27Pure 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. - 28Why is iron described as an element? (1)Because it is made up of only one type of atom.
- 29Stainless 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. - 30What is meant by a strong acid?When an acid is completely ionised in an aqueous solution.
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- Descrição
- GCSE Chemistry FlashCards sobre Exam style questions and answers for Chemistry, criado por Aryan Mohajerani em 13-12-2017.
- Criado por
- Aryan Mohajerani · dez 2017
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- 6 mai 2018
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