Organic reactions (C.11) Flashcards
Define a functional group:
a group of atoms/ bonds that determine the chemical properties of a substance.
Define a homologous series:
a series of molecules that are in the same functional group.
Explain how the differences between when you burn an alkene to when you burn an alkane influence how they are used:
When burning an alkene, it burns through incomplete combustion, this produces a smoky red flame and takes more energy to burn completely, therefore releases less energy.
When you burn an alkane, it combusts completely, meaning it releases more energy through a cleaner flame.
since alkanes are easier to combust and produce higher amounts of energy, it is used as a fuel unlike alkenes.
Compare and explain the reactivity between alkenes and alkanes, include an example:
Alkenes are more reactive than alkanes due to being unsaturated, their double bonds can be broken to react with other atoms.
eg. when we test for an alkene we use iodine water, when added to an alkene, the iodine from the water breaks the double bond to react, this solution loses its original orange hue as a result of alkenes being present.
Describe what happens when an alkene reacts with hydrogen gas:
The double bond breaks and reacts to the alkene. the alkene becomes hydrogenated, and becomes a saturated hydrocarbon. this fixes its structure making them more solid
eg, olive oil (unsaturated fat) becomes hydrogenated to make margarine (solid)
What is the functional group of alcohols?
OH
What is the general formula of alcohols?
CᴺH²ᴺ⁺¹OH
What are the uses of alcohols?
-drinks
-disinfectant
-fuels
What is the most used alcohol and how can we use/make it?
Ethanol is used as a solvent, disinfectant, drink and fuel. it is made either by fermentation or hydration.
Describe how ethanol is made through fermentation and its required conditions:
Ethanol can be made by fermentation, this is when a glucose aerobically produces ethanol and carbon dioxide. it mustn’t have oxygen added must be left at room temperature with yeast over a period of time.
Describe how ethanol is made through hydration and its required conditions:
Ethene can be hydrated using steam and a catalyst to make pure ethanol. it needs to be at a high temperature and have steam and a catalyst.
Compare the two methods of making ethanol:
Fermentation is cheaper as it doesn’t require the energy for high temperatures and pressures unlike hydration that needs high temperatures / pressures.
hydration produces pure ethanol, unlike fermentation (which needs further distillation) and due t the presence of a catalyst, it produces a more productive yield.
hydration uses products from crude oil whereas fermentation uses plants as a raw material, this makes fermentation more renewable and sustainable.
fermentation is a batch process that is time consuming therefore less economic whereas hydration is a continuous process.
fermentation requires lots of land to produce crops for it, meaning the land cannot be used for food production.
How do you test for hydrogen gas?
Holding a lit splint will produce a squeaky pop
How do you test for carbon dioxide?
bubble it with limewater, it should become cloudy is it is present.
Acid + metal ⇨ …
salt + hydrogen
