3.2 Alkanes Flashcards
What is the trend in boiling points as you increase the carbon chain in alkanes?
Increase in boiling point as the more atoms there are the greater intermolecular van der Waal’s forces, meaning more energy is needed to separate the molecules
What is the difference in boiling points between long chain alkanes and branched alkanes?
Straight chains have a larger surface area meaning there are more intermolecular forces of attraction than the branched alkanes, which are less compact, and therefore form less intermolecular forces. Means that straight chains have a higher boiling point than branched
Describe the conditions of thermal cracking?
450-900°C
High pressure
No catalyst
Describe the conditions of catalytic cracking?
450°C
Moderate pressure
Zeolite catalyst
Describe the products of thermal cracking?
High proportion of straight-chain alkanes and alkenes, useful as raw materials for the chemical industry
Describe the products of catalytic cracking?
High proportion of branched alkanes and alkenes, cyclic and aromatic hydrocarbons, useful for motor fuels.
What are the products of the combustion of alkanes?
Carbon dioxide (complete) Carbon monoxide (incomplete) Carbon (soot) (even more incomplete)
What environmental issues are there with releasing carbon dioxide?
Carbon dioxide is a greenhouse gas, which contribute to the greenhouse effect by gathering in the atmosphere and preventing radiation that hits the earth from leaving. Also can lead to acidic rain/water
What health issues are there with breathing in carbon monoxide?
Carbon monoxide binds irreversibly to the haemoglobin in our blood, forming carboxyhaemoglobin, meaning these red blood cells become useless at carrying oxygen, so oxygen cannot be delivered to respiring tissues. Can affect the development of foetuses
What 3 metals are used in the catalytic converter of a car?
Platinum, rhodium and palladium
Why are metals in a catalytic converter coated on a ceramic support?
Metals are expensive, so it reduces the cost as only a thin coating is needed
What health issues are there with breathing in carbon?
Can cause respiratory issues, eg worsening asthma as it can irritate airways
What environmental issues are there with releasing soot particles?
Soot can build up in the atmosphere, blocking sunlight from reaching the atmosphere, leading to a cooling effect known as global dimming
How is sulfur dioxide formed?
From burning fuel with sulfur impurities in oxygen
What health issues are involved with breathing in sulfur dioxide?
Causes irritation and inflammation to the eye, skin, nose, etc.
