1012593
| Questão | Responda |
| What is the study of carbon compounds called? | organic chemistry |
| What kind of bonding takes place in organic chemistry? | covalent bonding |
| Describe three of the physical properties of the alkanes. | They're oily, they don't dissolve or mix with water and are gas at <4 atoms, liquid at 4-17 atoms and solid at >17 atoms. |
| How do the alkanes burn? | They burn easily, and produce carbon dioxide and water in lots of air or carbon/carbon monoxide and water in little air. |
| How reactive are the alkanes and why? | They don't reactive with common acids or alkalis as they C-C and the C-H bonds are too hard to break. |
| Why are the alkenes more reactive than the alkanes? | Alkanes are saturated with a single C-C bond, whilst the alkenes are unsaturated with a double C=C bond that is more reactive. |
| What are the alcohols? | Organic compounds containing the reactive group -OH. |
| What state are methanol and ethanol at room temperature and what does this show? | They're liquids, whilst similar alkanes are gases. This shows that the presence of an -OH group makes liquids stick together/more energy is needed to break the bonds (just as in water). |
| Do the alcohols mix with water and why? | Ethanol and methanol do, as they have the -OH, but the heavier alcohols don't as despite having the -OH they're too oily. |
| What is the -OH part of an alcohol called? | The functioning group. |
| Do the alcohols burn? | Yes, they're very flammable. |
| What would happen if you combined ethanol with sodium? | You'd get sodium ethoxide and hydrogen gas produced. |
| Which of the hydrogen atoms are involved in the reaction between an alcohol and sodium and why? | Only the hydrogen atoms that are attached to the oxygen atom become hydrogen gas, as the hydrogen atom attached directly to the carbon atom is inert or nonreactive. |
| In what three ways can ethanol be produced? | fermentation, biotechnology, chemical synthesis |
| What does it mean, that ethanol is fermented? | Essentially it's produced in the same way as beer - with yeast and crops. |
| In a fermenter, the most amount of ethanol that can be produced before the yeast are killed is quite low. What happens if a higher concentration is required? | The ethanol goes through a process of distillation, where it's heated above it's own boiling point but below 100oC, the boiling point of water. This means the ethanol can be condensed and collected. |
| If there's an energy balance value in a table, what does this mean? | How many more times energy is released (when the product is burnt) than (fossil fuel) energy used in production. A higher number means a process is more green. |
| What is now being used in place of yeast, as it can convert all sugars rather than just glucose to ethanol? | genetically modified E.coli bacteria |
| What is the main feedstock for making synthetic ethanol and what two sources are there of it? | ethene from natural gas and crude oil |
| What is used to purify ethanol and how does this work? | Special compounds with zeolites or tiny holes all over their surface absorb water as they're big enough to fit through the water molecules but not big enough to fit through the ethanol molecules. |
| What is the main acid in vinegar called? | ethanoic acid |
| What are the organic compounds that contain the reactive group -COOH called? | the carboxylic acids |
| What makes a strong or a weak acid? | A strong acid ionises fully to produce hydrogen ions when dissolved in water, whilst a weak acid is only slightly ionised. |
| What does a (carboxylic) acid plus a metal form? | A salt and hydrogen. |
| What does a (carboxylic) acid plus a soluble hydroxide form? | A salt and water. |
| What does a (carboxylic) acid plus a metal carbonate form? | A salt and water and carbon dioxide. |
| What is an ester? | An organic compound made from a carboxylic acid and an alcohol. (They often have strong smells/tastes and are used as flavorings among over things.) |
| What five stages are there to making an ester, without descriptions, in order? | heating under reflux, distillation, purification, drying, distillation |
| What does a reflux condenser do? | It cools vapors to return them to a liquid as the reactants are boiled. |
| In the second stage of making an ester, what happens to the reaction mixture after refluxing? | It has separated into two layers. |
| What is a tap funnel? | A funnel with a tap to allow the controlled release of a fluid. |
| In the drying stage of the ester making process, granules of calcium chloride are added - what are these used as? | a drying agent |
| What is the alcohol in fats and oils called and how many groups of what does this compound have? | glycerol has three -OH groups |
| What are the carboxylic acids in fats and acids called? | fatty acids |
| Describe the physical and structural properties of animal fats. (4 points) | They're generally solids at room temperature, and are 'saturated'. All the bonds are single bonds, so the molecules are also straight. |
| Describe the physical and structural properties of vegetable oils. (4 points) | They're generally liquids at room temperature, and are 'unsaturated'. One of the bonds is a double bond, so the molecules are curved. |
| What happens when an ester reacts with water, in the presence of a catalyst? What makes a good catalyst? | It splits up into an acid and an alcohol. Strong alkalies are good catalysts. |
| What does it mean for a fat to be cis-fatty or trans-fatty? | Cis means the same and the molecule reverses direction at the double bond to be all on the same side. Trans means opposite and the molecule cross to the other side (almost in a straight line) at the double bond. |
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