1489550
Descrição
FlashCards por Chloe Winn, atualizado more than 1 year ago
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Criado por Chloe Winn
aproximadamente 10 anos atrás
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| Questão | Responda |
| Allotropes of Carbon | Allotropes are different structural forms of the same element. Diamond and graphite are giant molecular structures because carbon can form lots of covalent bonds with itself, and because all the covalent bonds, giant molecular structures are strong and have high melting points and do not dissolve in water. Also giant molecular structures usually do not conduct electricity because there are no free electrons. |
| Fullrenes | These are molecules of Carbon that are shaped as hollow tubes or spheres. They can be used to carry and deliver drug molecules around the body and to trap dangerous substances in the body and remove them. Fullerenes can be joined together to form nano tubes (tiny hollow carbon tubes). Nano tubes have a huge surface area so the could help make great industrial catalysts - individual catalyst molecules could be attached to the nano tubes. |
| Diamonds | Each carbon atom forms 4 covalent bonds in a 3D tetrahedral lattice with all the outer shell of electrons being shared meaning there are no free electrons so electricity cannot be conducted. These strong covalent bonds in all directions make it hard and take a lot of energy to break giving it a high melting point. The natural imperfections in diamonds form cleaving plates which allow them to be shaped. |
| Graphite | Each carbon atom forms 3 covalent bonds in flat hexagonal layers creating sheets of carbon atoms that can slide over each other. These layers are held together weakly attracted to each other so can be rubbed off onto paper also when force is applied weak forces between the layers slide over each other making it a good lubricant. Also it has a high melting point but the formation of graphite leaves an unshared outer shell electron these delocalised electrons are free to move which allows it to conduct electricity. |
| Endothermic & Exothermic Reactions | EXOTHERMIC - This reaction gives out energy to the surroundings. It gives out energy by forming new bonds, the energy released by forming new bonds is greater than the energy is used in breaking old bonds (burning fuels). ENDOTHERMIC - This reaction takes in energy from the surroundings. This is done by breaking existing bonds which requires energy. The energy required to break the bonds is greater than the energy released when new bonds are formed (thermal decomposition). |
| Rate of Reaction | The rate of reaction is how fast the reactants are changed into products. It measures how much product is formed in a fixed period of time. Slow Reactions: Chemical weathering and rusting. Moderate Reactions: Metal reacting to acid. Fast Reactions: Burning. |
| Rate of Reaction (continued) | The rate of reaction depends on the number of successful collisions between the reacting particles per second. The particles must have enough energy to react to be a successful collision. This is effected by 5 things: - Pressure - Temperature - Concentration - Catalyst - Particle Size The more reactant used the more product formed the yield you get from a reaction depends on the amount of reactants. More reactant = more particles = more product. The product formed is directly proportional to the amount of limiting reactants |
| Rate of Reaction Graphs |
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| Rate of Reaction Graphs (continued) |
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| Collison Theory | TEMPERATURE - As the temperature increases, the particles gain more kinetic energy and more around quicker, therefore the frequency of successful collisions increases. CONCENTRATION - As the concentration increases so does the number of particles but in the same volume. This means there will be more successful collisions. PRESSURE - As the pressure increases the particles are forced closer together. PARTICLE SIZE - Increasing the surface area means particles are more exposed than those in a solid block. In a block material only those on the surface can react with the reactants as the rest is trapped on the inside so cannot react. Therefore as the surface area increases the rate of reaction increases because more particles can collide. CATALYST - A catalyst speed up the rate of reaction without being chemically changed or used up in the reaction. You only need a little bit of a catalyst to catalyst large amounts of reactions. A catalyst works by lowering the activation energy of the reactants. (PER SECOND). |
| Batch or Continuous Production | BATCH - Drugs are complicated and has a low demand. This production is the most cost-effective way to produce small quantities (fixed amounts) when it is needed because it's flexible (several products, same equipment), start up costs are low. However, it's labor-intensive, costly, time consuming and be difficult to keep the same quality. CONTINUOUS - Large-scale industrial manufactures use this because production never stops, produces large amounts in 24 hours, runs automatically so little energy to maintain. However, start up costs are huge and the process inefficient if not in constant use. |
| Chromatography | Chromatography is how you extract a chemical from a plant. 1. Crushing to disrupt and break cell walls. 2. Boiling in a suitable solvent to dissolve the compounds. 3. Chromatography to separate and identify individual compounds. 4. Isolating, purifying and testing potentially useful compounds. Pure substances won't be separated by chromatography but move as one blob and they will have a definite melting point and boiling point. |
| Medicines | Medicines are expensive to make because: 1. Research and development to find a suitable compound. 2. Trailing on animals and humans to make sure it is safe and meets legal requirements. 3. Manufacturing is labour-intensive and cannot be automated. Other cost include energy and raw materials (which are rare) and then need to be extracted from plants. It is also expensive to develop a new drug because - thousands of compounds need to be tested to find effective ones. - long term trails - recommended does need to be shown to be effective. - similar compounds need to be to made to reduce side effects. |
| Percentage Yield | Percentage Yield compares how much you should get by what you actually got. Percentage Yield = Actual Yield/Predicted Yield x 100. Industrial process want a high yield so they can reduce waste and reduce cost (by ensuring that enough of the reactants are used). Yield is never 100% due to filtration, evaporation, transferring liquids, not all reactants reacting to make the product. |
| Atom Economy | Atom economy tells you how much of the mass of the reactants is wasted when manufacturing a chemical. Atom Economy = Mr of desired product/ total Mr of all products x 100 The higher the atom economy the better it is, it also reduces production of unwanted products that will need to be disposed of (increasing cost) and to make the process more sustainable by making better use of the reactants if atom economy is low materials will be be used more quickly, raw materials are also expensive, |
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