11759099
Descripción
Fichas por Aryan Mohajerani, actualizado hace más de 1 año
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Creado por Aryan Mohajerani
hace casi 7 años
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| Pregunta | Respuesta |
| 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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