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TRIPLE1 Materials
TRIPLE AQA Chapter 15 Alloys, Rusting, Ceramics and Composites
| Question | Answer |
|---|---|
| Explain why an alloy is stronger than a pure metal. | A pure metal has identically sized atoms arranged in regular layers; layers slide over each other easily. Alloys are stronger because the different-sized atoms of the mixed metals make the atomic layers less regular, so layers cannot slide as easily. |
| Explain why pure metal is more malleable than alloys. | Because, when pushed, only one layer of atoms in a pure metal moves but in an alloy the movement is random. |
| What elements are alloyed together in stainless steel? | Iron, Carbon, Choromium and Nickel |
| Describe what happens to a metal after one layer of iron has rusted away. | The layer of rust will flake away and Oxygen can get into the next layer and the rusting process can continue. |
| What is the word equation of the reaction of Iron and Water to make Rust (Hydrated Iron Oxide)? | Iron + Water + Oxygen Hydrated Iron Oxide |
| What is the formula for hydrated iron oxide? | Fe3O2.H2O |
| Write the balanced equation of when iron reacts with water. | 4Fe + 3O2 + 2H2O -> 2Fe2O3 .H2O |
| Describe five ways to stop the corrosion of metals. | Galvanising , Cover with tin or paint or plastic or oil/grease |
| Explain why Aluminium, despite being very reactive, seems not to be corroded and can even hold some acidst | Aluminium reacts quickly with Oxygen, and forms a layer of Aluminium Oxide that is very unreactive, even against acids |
| Explain why stainless steel does not rust | Chromium is more reactive than Iron so the chromium reacts with oxygen first (before Iron) and forms a layer that prevents the oxygen from getting to the Iron |
| Explain why galvanised iron does not rust | The zinc covering the Iron is more reactive than Iron; Zinc will reacts reacts with Oxygen rather than the Iron |
| Explain why cans rust only when dented | the inside of the can is covered in Tin, a metal low in the reactivity series; Tin will not react with acids or oxygen; however when the tin is dented, the iron is exposed and the iron reacts with the acid or oxygen and is corroded |
| Compare the differences between the reaction of mild steel with water and the reaction of stainless steel with water. | Mild steel rusts in water however stainless steel does not react with water. |
| Compare the composition borosilicate and soda lime glass. | Both glass contain Sand (Silicon Dioxide); but Borosilicate contains boron trioxide, whilst Soda lime contains sodium carbonate, calcium carbonate (limestone). |
| Explain why Borosilicate glass is used instead of Soda Lime glass in cooking. | When heated, the particles in Soda Lime expand quickly and contract when cooled, therefore causing it to shatter. However, Borosilicate does not expand as quickly and rapidly as Soda Lime and is safer to use. |
| Name the six properties of ceramics. | Heat insulator, gets stronger when heated, water-resistant (insoluble), breakable (brittle), able to mould it, does not react chemically. |
| Describe how glass can break. | If it is cooled too quickly from a high temperature. If it is heated too quickly from a low temperature. |
| Why are ceramics strong? | There are MANY STRONG covalent BONDBETWEEN atoms(very strong bonds). |
| Why are ceramics brittle? | Some are charged particles (ions). So when they are close together they repel as they have the same charge. |
| What is an ion? | A charged particle |
| Compare the advantages of two types of glass | The content of borosilicate glass means that the structural movement caused by heating and cooling is reduced, while soda lime glass is cheaper to produce. |
| Evaluate the advantages and disadvantages of composites | while composites are much more robust and can be applied to more situations, the production and application can be expensive and they cannot be recycled, which makes them non-viable for long term use. |
| What metal rusts? | ONLY Iron rusts whilst other metals corrode |
| What are the disadvantages of composites? | They are difficult and expensive to produce, difficult to repair and cannot be recycled. |
| What's a composite? | A composite is two different materials combined, to make a material stronger |
| why are materials selected to make composites? | The materials for a composite material are chosen because they have different properties that can combine to make a more useful material. |
| What are the two components of composites? | Matrix and reinforcement |
| Explain why composites are used | Composites are used as they strengthen a material so it can be used for other purposes which need a stronger material. |
| Explain why carbon fiber (a composite) is used in aircraft's | Carbon fiber is very light weight however very strong meaning the planes lift-to-drag ratio would be improved. This makes the plane much more aerodynamically efficient, and also reduce its overall weight. |
| How does electroplating iron prevent it from rusting? | It coats the iron with a layer of different metal that won't be corroded. |
| Explain why gold is alloyed with copper in many wedding rings | Gold is alloyed with copper is rings to make it harder and stronger. Pure gold wears away more easily than its alloy with copper |
| Name some composite materials and what they are made of | Concrete (cement and gravel) Reinforced concrete (concrete and a steel mesh or bar) |
| Explain why composite materials are stronger than the individual materials | The rods inside the matrix are stopping cracks from getting bigger |
| Jenny made concrete bars: took 100g of cement and changed the mass of the gravel. She measured how strong each bar was by measuring how much mass each could withstand before bars broke. What variables should she control to make this a fair test | Volume of water added to the mix;length of beam;Width of beam;Thickness of beam;Time beam left to set;temperature where bar was left to set;temperature of the bar when the weights are added; place where the weights are added on bar |
| Why do crash helmets usually have an inner lining made from polystyrene foam? | Flexible; crushes on impact |
| Why do crash helmets usually have an inner lining made from polystyrene foam? | Hull of boats; tennis racquet |
| Suggest why laminated windscreens are used in cars rather than windscreens made just from glass. | The laminated glass does not shatter and "explode" like normal glass would |
| Suggest why laminated windscreens are used in cars rather than windscreens made just from glass. | Lightweight and flexible |
| Design an experiment to show the effect of increasing the mass salt on the rate of rusting | CONTROL: identical iron nail; volume of water; temperature room; left for same length of time; INDEPENDENT place increasing mass salt in each tube (0 to 4 g); DEPENDENT=weigh the tube at start; observe the increase in mass of the tube after a week |
| Why do you need at least 5 different mass of salt when investigating the effect of increasing the mass salt on the increase of mass of a nail after a week rusting? | 5 points on a graph gives you more confidence in the shape of the line of best fit |
| Why do you need to repeat each different mass at least 3 times when investigating the effect of increasing the mass salt on the increase of mass of a nail after a week rusting? | you RRRRepeat to make the RRRRRResults RRRRReliable |
| Describe how sacrificial protection works | It is using a metal more reactive than iron to coat the iron; when oxygen and water are present, the more reactive metal will react first and get corroded first, rather than iron: the more reactive metal has been sacrificed.... |
| Name alloys and state the elements mixed to make the alloys | Bronze (Copper+Tin) Brass (Copper+Zinc) Steel (Iron+Carbon) Stainless Steel (Iron+Chromium+Nickel) |
Created by:
ursulinechem2
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