Organic Chemistry Flashcards
What is a hydrocarbon?
Molecule that only contains the elements carbon and hydrogen
What is the simplest type of hydrocarbon?
Alkanes
Why is carbon a useful element for making large compounds?
Carbon can form four strong bonds with other atoms, including carbon and hydrogen
Give an example of a hydrocarbon and a non-hydrocarbon
Hydrocarbon - Butane (C4H10)
Non-Hydrocarbon - butanol (C4H9OH): Contains Oxygen
What is organic chemistry?
The study of compounds that contain carbon
What is the general formula for alkanes?
CnH2n+2
List the first four alkanes and their molecular formulas
- Methane: CH4
- Ethane: C2H6
- Propane: C3H8
- Butane: C4H10
Why are Alkanes Saturated?
Every carbon atom has four single covalent bonds
What is the definition of a homologous series?
A homologous series is a group of organic compounds that have similar chemical properties, due to them having the same functional group
What is the general formula for alkanes?
CnH2n+2
What happens to an alkane if one of its single bonds is replaced by a double bond?
It becomes an alkene
Why is methane classified as an alkane?
Has a single carbon atom bonded to 4 hydrogens
Explain why butanol is not classified as a hydrocarbon?
Contains an oxygen atom in addition to carbon and hydrogen
Describe the difference between saturated and unsaturated hydrocarbons
- Saturated Hydrocarbons - Have single bonds only
- Unsaturated Hydrocarbons - have at least 1 double bond
How does the molecular formula of an alkane change as the series progresses?
Each alkane increases by one carbon atom and two hydrogen atoms
What is crude oil?
is a mixture of many different compounds
Most of the compounds are hydrocarbons
How is crude oil formed?
It forms from the remains of dead plants and animals, particularly plankton, buried in mud and exposed to high pressure and temperature over millions of years
Why is crude oil considered non-renewable?
It takes millions of years to form
What are examples of Crude Oil?
- Natural gas
- Coal
What is fractional distillation?
A process to separate crude oil into its components based on their different boiling points
How does a fractionating column work?
- It is hot at the bottom and cooler at the top.
- As gases rise, they condense into liquids when they reach a temperature lower than their boiling point
What are hydrocarbons with long chains used for?
- Bitumen for roads
- heavy fuel oil for heating
- lubricating oil
What fuels are obtained from shorter chain hydrocarbons?
- Diesel
- Petrol
- Kerosene
What is LPG, and what does it contain?
- Liquefied petroleum gas;
- It contains propane and butane, which are short-chain alkanes
Which hydrocarbons make the best fuels and why?
Short-chain hydrocarbons, because they are more flammable
What is cracking?
A process that breaks long-chain hydrocarbons into shorter ones
What are Petrochemicals?
Is a substance made from crude oil via chemical reactions
What is a Feedstock?
Is a raw material used to provide reactants for an industrial reaction
Why do hydrocarbons with longer chains condense first in fractional distillation?
They have higher boiling points and cannot stay gaseous at lower temperatures
What is the main component of crude oil?
Hydrocarbons, especially alkanes
What products are obtained at the top of the fractionating column?
Short-chain hydrocarbons like LPG and petrol, which have low boiling points
What is the significance of feedstock in the petrochemical industry?
It provides raw materials to make various products like polymers and detergents.
What are alkanes?
Homologous series of hydrocarbons that contain only carbon and hydrogen atoms with no double bonds
What happens to the boiling point of alkanes as the carbon chain length increases?
The boiling point of alkanes increases with the length of the carbon chain.
What is the state of short-chain alkanes at room temperature?
Have low boiling points and exist as gases at room temperature
What happens to longer alkanes at room temperature?
Longer alkanes, with more than four carbon atoms, are liquids at room temperature, and if the chains are very long, they can be solids.
What does “volatile” mean in relation to alkanes?
Volatile means that a substance evaporates easily. Short-chain alkanes are more volatile due to their low boiling points.
What is the viscosity of longer alkanes?
Longer alkanes are more viscous, meaning they are thicker and stickier, like honey.
Which type of alkanes is more flammable?
Shorter alkanes are more flammable, meaning they are easier to ignite or burn.
What is combustion in relation to alkanes?
Combustion is the process where hydrocarbons like alkanes react with oxygen to produce carbon dioxide and water, releasing energy.
What are the products of complete combustion of alkanes?
The products of complete combustion of alkanes are carbon dioxide (CO2) and water (H2O).
What type of reaction is combustion?
Combustion is an exothermic reaction because it releases energy.
What happens to the hydrogen and carbon atoms during combustion?
The hydrogen and carbon atoms in the hydrocarbon are oxidized, combining with oxygen to form CO2 and H2O.
How do you balance the equation for complete combustion?
Adjust the number of CO2 and H2O molecules based on the number of carbon and hydrogen atoms in the hydrocarbon, then balance the oxygen atoms on both sides.
What is the relationship between the carbon chain length and the flammability of alkanes?
Shorter alkanes are more flammable due to their lower boiling points and higher volatility
What is the importance of oxygen in combustion?
If there’s insufficient oxygen, incomplete combustion may occur, producing carbon monoxide instead of carbon dioxide
What is cracking in chemistry?
Cracking is the process of breaking down long-chain hydrocarbons into shorter, more useful hydrocarbons.
What is thermal decomposition?
Thermal decomposition is the process of breaking down molecules by heating them
What are the two types of cracking you need to know?
The two types of cracking are catalytic cracking and steam cracking.
What is the first step in cracking hydrocarbons?
The first step is to heat the long-chain hydrocarbons and vaporize them (turn them into a gas).
How does catalytic cracking work?
In catalytic cracking, the vaporized hydrocarbons are passed over a hot powdered catalyst (e.g., aluminium oxide), causing the molecules to split into smaller hydrocarbons.
How does steam cracking work?
In steam cracking, the vaporized hydrocarbons are mixed with steam and heated to a high temperature, causing the molecules to split into smaller hydrocarbons.
What is the general equation for cracking a long-chain alkane?
A long-chain alkane (e.g., decane) splits into a smaller alkane and an alkene (e.g., heptane and propene).
What is the key difference between alkanes and alkenes?
Alkanes have only single bonds between carbon atoms (saturated), while alkenes have at least one double bond between carbon atoms (unsaturated).
What is the test for alkenes?
Alkenes will decolorize bromine water from orange to colorless.
Why are alkenes more reactive than alkanes?
Alkenes are more reactive because of the double bonds, which can break to form new bonds with other molecules.
What can alkenes be used to produce?
Alkenes can be used to produce polymers and other chemicals.
What happens to the number of carbon and hydrogen atoms when cracking a hydrocarbon?
The number of carbon and hydrogen atoms must remain the same on both sides of the equation after cracking.
What is an example of a cracking reaction?
Decane (C10H22) can be cracked into ethene (C2H4) and another alkane (C8H18).
What does it mean for a hydrocarbon to be “unsaturated”?
Has at least one double bond between carbon atoms
Why are alkenes used in polymer production?
Alkenes can be used in polymer production because their double bonds can break to form new bonds with adjacent molecules
