C7 Flashcards
What are hydrocarbons?
Compounds formed from carbon and hydrogen atoms only.
What is the general formula for alkanes?
CₙH₂ₙ₊₂
What types of bonds do alkanes have?
C-C and C-H single bonds.
List the first four alkanes.
- Methane (CH₄)
- Ethane (C₂H₆)
- Propane (C₃H₈)
- Butane (C₄H₁₀)
What occurs during complete combustion of hydrocarbons?
Release of energy with carbon dioxide and water vapour as waste products.
What is the balanced equation for the complete combustion of methane?
CH₄ + 2O₂ → CO₂ + 2H₂O
What is oxidation in the context of combustion?
Gain of oxygen.
What are the waste products of complete combustion?
Carbon dioxide and water vapour.
Fill in the blank: The complete combustion of a hydrocarbon in oxygen releases lots of _______.
[energy]
What is crude oil formed from?
Remains of ancient marine organisms.
What are non-renewable resources?
Resources that take longer to form than to be consumed.
What are some important uses of hydrocarbons?
- Fuels
- Plastics
- Lubricants
- Detergents
True or False: The longer the carbon chain in hydrocarbons, the more runny they are.
False
What happens to the boiling points of hydrocarbons as the carbon chain length increases?
They increase.
What is a homologous series?
A series of compounds containing similar functional groups.
Fill in the blank: Hydrocarbons only contain two ingredients - carbon and _______.
[hydrogen]
Write a balanced symbol equation for the complete combustion of ethane, C₂H₆.
C₂H₆ + 7/2 O₂ → 2 CO₂ + 3 H₂O
What happens to the flammability of hydrocarbons as the carbon chain length increases?
It generally decreases.
What is crude oil primarily composed of?
Hydrocarbons
Hydrocarbons are compounds made up of hydrogen and carbon atoms.
What are plankton?
Tiny plants and animals in oceans and large bodies of water
Plankton serve as the primary source of organic matter in the ocean, contributing to the formation of crude oil.
What is a feedstock?
A raw material used for a chemical process
Feedstocks are essential for producing various chemicals and materials, including plastics.
What happens to the properties of hydrocarbons as the chain gets longer?
Properties change, becoming less viscous and having lower boiling points
Longer hydrocarbon chains generally lead to increased runniness and flammability.
True or False: Crude oil is an infinite resource.
False
Crude oil is finite, meaning it is limited in quantity and cannot be replenished on a human timescale.
What is the relationship between viscosity and boiling point in hydrocarbons?
Higher viscosity corresponds to higher boiling points
More viscous hydrocarbons tend to have higher boiling points compared to less viscous ones.
Fill in the blank: Crude oil can be processed to create a variety of products, including _______.
Plastics
Plastics are derived from the chemical processing of crude oil, showcasing its versatility.
What are homologous series?
Groups of hydrocarbons with similar properties
Homologous series consist of compounds that differ by a specific structural unit, such as a -CH2- group.
What is the significance of crude oil in everyday life?
It is essential for making many important products, like plastics
Without crude oil, many modern conveniences, such as plastic pens, would not exist.
What does it mean when we say crude oil is finite?
It means that crude oil is a limited resource
Finite resources cannot be replaced once consumed, highlighting the need for sustainable alternatives.
What is fractional distillation?
A process to separate compounds in crude oil by heating and cooling to isolate different fractions based on boiling points.
How does fractional distillation work?
The oil is heated to evaporate most of it, enters a fractionating column, and is then cooled as it rises, allowing different hydrocarbons to condense at various heights.
What happens to shorter hydrocarbons during fractional distillation?
They have low boiling points, rise near the top of the column, and remain as gases at low temperatures.
Where do longer hydrocarbons condense in a fractionating column?
They condense back into liquids and drain out of the column lower down where the temperature is higher.
What is the relationship between carbon atoms and boiling points in hydrocarbons?
Hydrocarbons in the same fraction have a similar number of carbon atoms, leading to similar boiling points.
True or False: Petrol drains further up a fractionating column than diesel.
True
Fill in the blank: The boiling point of petrol is ______ than that of diesel.
lower
What is cracking in organic chemistry?
A process that breaks down long-chain hydrocarbons into smaller molecules, including alkenes.
What are the two methods of cracking?
Catalytic cracking and steam cracking.
What is the result of adding bromine water to an alkene?
The bromine water turns from orange to colorless.
What is steam cracking?
A method where long-chain hydrocarbons are heated and mixed with steam to produce smaller molecules.
What is the significance of balancing chemical equations in cracking?
To ensure the number of carbon and hydrogen atoms is conserved during the reaction.
What is an example of a hydrocarbon that can be cracked?
Decane.
What is the formula for pentane?
C5H12
Fill in the blank: Cracking is a type of ______ decomposition reaction.
thermal
What is the approximate number of carbon atoms in LPG (Liquefied Petroleum Gas)?
3 to 4
What type of hydrocarbons does heavy fuel oil contain?
Long-chain hydrocarbons.
What is bitumen in the context of fractional distillation?
The residue left after all other fractions have been distilled off.
What is the process of breaking down long-chain hydrocarbons into smaller molecules called?
Cracking
Cracking can be performed through methods like steam cracking and catalytic cracking.
What are the two main methods of cracking hydrocarbons?
- Steam cracking
- Catalytic cracking
Each method has distinct processes; steam cracking involves mixing hydrocarbon vapour with steam and heating, while catalytic cracking uses catalysts to speed up the reaction.
In steam cracking, what is mixed with hydrocarbon vapour before heating?
Steam
This mixture is then heated to a very high temperature to split the hydrocarbons.
What role do catalysts play in catalytic cracking?
They speed up reactions without getting used up
Catalysts allow the cracking process to occur more efficiently.
What substance is typically used as a catalyst in catalytic cracking?
Powdered aluminium oxide
The vapour of long-chain hydrocarbons is passed over this catalyst.
Complete the equation: C10H22 → C8H18 + ….
C2H4
The missing product is determined by balancing the number of carbon and hydrogen atoms on each side.
True or False: The number of carbon atoms in the missing product equals the number of carbons in C10H22 minus the number of carbons in C8H18.
True
This is a key step in balancing the equation for cracking reactions.
How many hydrogen atoms would be in the missing product if C10H22 is cracked to form C8H18?
4
This is calculated by subtracting the number of hydrogens in C8H18 from those in C10H22.
What is the product of cracking pentane, C5H12?
Ethene and one other hydrocarbon
The balanced symbol equation for this reaction would need to be determined based on the products formed.
Fill in the blank: The process of cracking is important because it allows us to use all the long-chain hydrocarbons we otherwise _______.
wouldn’t need
Cracking helps to utilize hydrocarbons that are less useful in their original form.
What is the first step in the steam cracking process?
Heating long-chain hydrocarbons to turn them into a gas
This is essential before mixing with steam for further processing.
