chemistry specification part 5 Flashcards
what is bitumen used for
used to surface roads and roofs
what is a homologous series
a family of molecules which have the same general formula and share similar chemical properties
how do physical properties in a homologous series vary
the bigger the molecule is the higher the boiling point because more energy is required to break the intermolecular forces in larger molecules. Differ by Ch2 in formulas
why are shorter hydrocarbons easier to ignite and why are longer hydrocarbons harder to ignite
have lower boiling points so tend to be gas at room temperature. These gas molecules mix with oxygen in the air to produce a gas mixture which bursts into flames if it comes in contact with a spark.
longer hydrocarbons are usually liquid at room temperature and they have higher boiling points
what is the viscosity of hydrocarbons
viscosity measures how easily a substance flows.
The stronger the force between the hydrocarbons, the harder it is for the liquid to flow. This is typically seen in longer hydrocarbons that have high viscous like black treacle. Shorter hydrocarbons are runnier and have low viscous
what happens in combustion reactions and what are the products
(incomplete and complete)
why are hydrocarbons good fuels?
hydrocarbons are good fuels because the combustion reaction that happens when you burn them in oxygen gives out lots of energy-exothermic
the only products are carbon dioxide and water-this is called complete combustion
when there is a limited supply of oxygen you get carbon and carbon monoxide in the form of soot-incomplete combustion
Explain how carbon monoxide behaves as a toxic gas
-combine with red blood cells and stop your blood from carrying oxygen around the body.Lack of oxygen supply in the blood to the brain can lead to fainting,coma or death
-soot makes buildings dirty and reduces air quality which causes respiratory problems
Explain some problems associated with acid rain caused when sulfur dioxide dissolves in rainwater
causes lakes to become acidic and many plants and animals die as a result. Kills trees, damages limestone buildings and can also make metal corrode
how are nitrogen oxides created and how are they harmful
created from a reaction between nitrogen and oxygen in the air, caused by an energy release by combustion.
harmful pollutants that contribute to acid rain and at ground level can cause photochemical smog. (type of air pollution that cause breathing issues)
Evaluate the advantages and disadvantages of using hydrogen,
rather than petrol, as a fuel in cars
-hydrogen gas is very clean. combines with oxygen to make energy and the only waste product is water. Comes from a renewable source
-you need special expensive engines. Very expensive to manufacture and uses energy from another source which comes from burning fossil fuels.Hard to store and not widely available
