Chemistry Unit 2 Flashcards
What do saturated compounds contain?
Saturated compounds only contain C-C single bonds.
What do unsaturated compounds contain?
Unsaturated compounds contain at least one C=C double bond.
What are the steps of an addition reaction?
- Hydrogenation - reaction between an alkene and H2 forming an alkane.
- Hydration - reaction between an alkene and water forming an alcohol.
- Alkenes reacting with halogens forming dihaloalkanes.
What is the difference between saturated and unsaturated compounds?
If a compound is unsaturated it will decolourise bromine water.
How to draw a full structural formula?
The shortened structural formula shows the order of the atoms but omits the carbon to hydrogen bonds.
What are isomers?
Isomers are compounds with the same molecular formula but different structural formulas.
What to look for when drawing isomers?
When drawing/identifying isomers, make sure you double check they have the same general formula and different structure.
What is the solubility of a compound?
The bigger the compound, the less soluble they are, the higher the boiling point and the volatility decreases.
What is the boiling point of a compound?
Boiling point increases as the compounds increase in size due to stronger LDFs (and even higher when Hydrogen bonding or Pd-Pd interactions are present).
What are polar and ionic compounds?
Polar and ionic compounds tend to be soluble in polar solvents.
How is volatility affected?
Volatility (measure of the ease of evaporation) is affected by intermolecular forces present.
What is the functional group in an alcohol?
Hydroxyl (-OH) functional group.
What to do when naming alcohols?
When naming alcohols, the name ends in -ol and you must state the position of the -OH group in the molecule.
How to name branched alcohols?
Naming branched alcohols is very similar to alkanes and alkenes - just remember to count from the -OH functional group and to include its position in the final name.
What is a diol?
Alcohol with 2 hydroxyl groups.
What is a triol?
Alcohol with 3 hydroxyl groups.
How do hydroxyl groups affect alcohols’ physical properties?
Alcohols with more hydroxyl groups will have higher melting and boiling points (due to greater degree of hydrogen bonding).
What is the functional group in a carboxylic acid?
Carboxyl (-COOH) functional group.
How to draw a branched carboxylic acid?
Branched carboxylic acids are named in similar ways to other homologous series. Always count from the carboxyl functional group.
What happens when carboxylic acid reacts with bases?
When reacted with bases, carboxylic acid takes part in a neutralisation reaction, producing a salt and water.
Examples of neutralisation reactions?
- A metal oxide + a carboxylic acid → a salt + water.
- Metal hydroxide + a carboxylic acid → a salt + water.
- Metal carbonate + a carboxylic acid → a salt + water + carbon dioxide.
How to name salts?
The name of a salt depends on the acid and alkali in the neutralisation reaction.
What is the first part of naming salts?
Salts have 2 parts to their name; the first part of the name is the metal from the alkali.
What is the second part of naming salts?
The second part comes from the acid.
What are esters?
Esters are produced from a reaction between an alcohol and a carboxylic acid.
Where does the name of esters come from?
The name of an ester comes from its ‘parent’ alcohol and carboxylic acid.
What is an ester link?
An ester link is formed during the reaction between an alcohol and a carboxylic acid.
What are the uses of esters?
Esters are used as flavourings, fragrances (often have pleasant, fruity smell) and solvents for other non-polar compounds.
What is condensation?
Condensation forms esters.
What is hydrolysis?
Hydrolysis breaks esters.
What happens during condensation?
Esters are formed by a condensation reaction between an alcohol and a carboxylic acid with the elimination of water.
What happens during hydrolysis?
Hydrolysis is breaking a large molecule to smaller ones by the addition of water.
How are edible fats and oils formed?
Edible fats and oils are esters formed from the condensations of glycerol (propan-1,2,3-triol).
What are oils’ melting points?
Oils have a lower melting point than fats.
What is oils’ saturation?
Oils have more unsaturated (more double bonds).
How to test if something is saturated?
Unsaturated compounds will decolourise bromine water quicker.
Why do we need fats and oils?
Fats and oils are a really concentrated source of energy for us.
How are soaps formed step 1?
Soaps are produced by the alkaline hydrolysis of edible fats and oils (sometimes known as saponification).
How are soaps formed step 2?
This hydrolysis produces 3 fatty acid molecules and glycerol.
How are soaps formed step 3?
The fatty acid molecules are then neutralised by an alkali, forming ionic (water soluble) salts, which we call soaps.
What are the uses of soaps?
Soaps are used to remove non-polar substances like grease and oil.
What do soaps contain?
Soaps have a polar, hydrophilic, ionic head and a non-polar, hydrophobic tail.
What are micelles?
The oil/grease is then formed into small balls called micelles.
What is hard water?
Hard water is water containing high levels of dissolved metal ions.
What are soapless detergents?
Soapless detergents have non-polar hydrophobic tails and ionic hydrophilic heads.
What is the role of proteins?
Proteins are major structural materials of animal tissues.
How are proteins formed?
Proteins are made from amino acids (building blocks of proteins).
What groups are in an amino acid?
All amino acids contain an amino group, -NH2 and a carboxyl group, -COOH.
How are proteins formed?
Proteins are formed when one amino group and the carboxyl group of another amino acid join together with the elimination of water.
What is the peptide link?
-CONH-
What is an essential amino acid?
Essential amino acids are ones required by the body for protein synthesis but must be acquired through the diet.
What are emulsifiers?
Emulsifiers have similar structures to fats and oils but have one or two fatty acid groups.
What do emulsifiers form?
This means that there is a non-polar hydrophobic part which can dissolve in oil and a polar, hydrophilic (OH) group which can dissolve in water.
Where are emulsifiers used?
They are used in foods (eg mayonnaise, milk, bread, sauces etc) to prevent oil and water separating.
What happens during digestion?
Proteins are broken down during digestion via enzyme hydrolysis.
What can proteins form?
Proteins can form spirals, sheets and other complex shapes.
What does denatured mean?
When they are heated, these bonds are broken which allows the protein to change shape (denatured).
What does oxidation mean?
Increase in the oxygen to hydrogen ratio.
What does reduction mean?
Decrease in the oxygen to hydrogen ratio.
What is the oxidation of alcohols?
Primary alcohols → aldehydes → carboxylic acids.
Secondary alcohols → ketones.
What happens when oxidising hot copper (II) oxide?
Black to brown solid.
What happens when oxidising acidified dichromate (VI) solution?
Orange to green.
What happens when oxidising Fehling’s solution?
Blue - brick red.
What happens when oxidising Tollen’s reagent?
Forms a silver mirror.
What can oxidising agents be used for?
Oxidising agents can be used to identify aldehydes (not ketones).
Can tertiary alcohols be oxidised?
Tertiary alcohols cannot be oxidised due to the position of the hydroxyl group.
What are the functional groups found in aldehydes and ketones?
Aldehydes contain a carbonyl group (C=O) at the end of the carbon chain, while ketones contain a carbonyl group within the carbon chain.
What is the oxidation reaction of aldehydes and ketones?
Aldehydes → Carboxylic acids.
Ketones → no oxidation.
What is the reduction reaction of aldehydes and ketones?
Aldehydes → primary alcohol.
Ketones → secondary alcohol.
What are the uses of aldehydes?
Aldehydes often have distinct flavours and aromas so can be used in food products or essential oils.
What happens to food when it reacts with oxygen?
Food reacts with oxygen from the air, giving them a rancid flavour.
What is an antioxidant?
Antioxidants are molecules that prevent unwanted oxidation reactions to occur.
What is an example of an antioxidant?
Vitamin C is an example of an antioxidant.
What is an essential oil?
Essential oils are concentrated extracts of volatile, non-water soluble aroma compounds, which come from plants.
Where are essential oils used?
Often used in perfumes, cosmetic products, cleaning products and as flavourings.
What is a terpene?
Terpenes are unsaturated hydrocarbons made from isoprene units bonding together.
What happens when terpenes are oxidised?
When oxidised, terpenes release the distinctive aroma found in spices.
How to count isoprenes in a terpene?
Count the number of carbon atoms and divide by 5.
What is the UV effect on the body?
Ultraviolet (UV) light is high-energy which can break bonds within molecules.
What is a free radical?
A free radical is an atom (or molecule) that is highly reactive as it has an unpaired electron.
What are the steps of a chain reaction?
- Initiation
- Propagation
- Termination
What is initiation?
All the free radicals will be on the products side.
What is propagation?
There will be a free radical on both the product and reactant side.
What is termination?
Both free radicals will be on the reactant side.
What are free radical scavengers?
Free radical scavengers are molecules that react with free radicals to form stable molecules.
Where are free radical scavengers used?
They are added to skin care products, cosmetics, plastics and foods to prevent any chain reactions.
