Unit 2 - Nature's Chemistry Flashcards
1 mol
Formula mass in grams
Molar volume
The volume occupied by 1mol of gas at a given temperature and pressure.
Excess reactions
Moles, ratio, conclusion
Equilibrium
Equal rates of forward and backwards reactions. Constant concentrations.
% yield
Measures efficiency.
Atom economy
GFM x moles = mass
Plug in mass
Bond enthalpy
The energy required to break 1 mol of bonds between two atoms.
Bond enthalpy formula
ΔH = ΔEHbonds broken + ΔEH bonds made
Enthalpy definition
The measure of energy stored in a chemical.
Catalysed PE diagrams
Lower activation energy
Molar volume is _____ for all gasses at the same pressure and temperature.
The same
Le Chateliers Principle
An equilibrium will move to undo any change imposed upon it by temporarily favouring either the forward or backward reaction until a new equilibrium position is reached.
Steps to balancing ion-electron redox equations
- Balance main element
- Add water
- Add hydrogens
- Add electrons
An oxidising agent is..
a substance that accepts electrons
A reducing agent is…
a substance that donates electrons
Reducing agents have ___ electronegativity values.
low
Oxidising agents have ___ electronegativity values
high
Carboxylic acids are polar molecules and can therefore…
Hydrogen bond
Hydrogen peroxide is effective as..
Bleach
Unsaturated compounds ____ bromine water
rapidly decolourise
Saturated compounds ____ bromine water
Do nothing in
Factors on solubility, BP and MP
- hydrogen bonding
- PDs
- molecular size for LDFs
- polarities of solute and solvent
Smaller non-polar hydrocarbons like ethane are ______ volatile and have ______ BPs
More, lower
Smaller non-polar hydrocarbons like ethane are more volatile and have lower BPs because…
They have more electrons for LDFs
non-polar hydrocarbons ____ dissolve in water
Do not
Alcohol general formula
Cn H2n+1 OH
Primary alcohols
OH is joined to the end of the carbon chain
Secondary alcohols
Joined to a carbon in the middle of a carbon chain
Tertiary alcohols
Joins to a carbon which is attached to three other carbons
Alcohols conform hydrogen bonds because..
The -OH group makes them polar
More hydrogen bonds make a liquid more viscous because..
PD-PD interactions mean stronger intermolecular forces
Carboxylic acids react with
Bases
Metal oxide + carboxylic acid
salt + water
metal hydroxide + carboxylic acid
salt + water
metal carbonate + carboxylic acid
Salt + water + CO2
Acids contain
More H+ ions
Bases contain
More OH¯ ions
Carboxylic acids are acidic because they can break up…
to leave hydrogen ions in an aqueous solution
COOH becomes COO and H+
When salts are formed the H+ part of the acid
Is replaced by an alkali metal
lithium oxide + ethanoic acid
Lithium ethanoate + water
Potassium hydroxide + methanoic acid
Potassium methanoate + water
Calcium carbonate + propanoic acid
Calcium propanoate + water + CO2
In a condensation reaction
two molecules are joined together with the elimination of a smaller molecule
An ester link is formed by
A hydroxyl group and a carboxyl group
Esters are formed by
A condensation reaction between an alcohol and a carboxylic acid
Hydrolysis
A molecule is broken down into smaller molecules by reacting with water
Edible fats and oils are Esters formed by
The condensation of glycerol + three carboxylic acid molecules
Glycerol’s molecular formula
Propane-1,2,3-triol
The greater the degree of saturation in a fat, the ____ the MP, because..
Higher, double bonds prevent molecules packing closely together and weaken the van der waals forces
Biological uses of fats
- a concentrated source of energy
- transporting fat soluble vitamins in the body
Ethanol + ethanoic acid
ethyl ethanoate (ester) + water
Methanol + ethanoic acid
Methyl ethanoate (ester) + water
Ethanol (alcohol) + butanoic acid (carboxylic acid)
Ethyl butanoate (ester) + water
Ester uses
- Flavours
- solvents for np compounds
Ester BP
Low
Ester hydrolysis
When an ester reacts with water and breaks down to form an alcohol and a carboxylic acid
Forming an Ester is a _____ reaction
Condensation
Breaking up an Ester is a ______ reaction
Hydrolysis
Edible fats and oils are also known as
tri-esters
Facts are formed by reaction between
Propan-1,2,3-l (glycerol) and 3 carboxylic acid molecules
Carboxylic acids that react to form fats are called
Fatty acids
Fats are formed from _____ fatty acids
Saturated
Oils are formed from _____ fatty acids
Unsaturated
Saturated fats are (state)
Solid
Oils have a lower melting point than fats because
Double bonds prevent them packing tightly, weakening intermolecular bonds
One way to test degree of unsaturation in oils
React with bromine water, the more solution that can be reacted, the more double bonds
Esters are soluble / insoluble in water
Insoluble
Fats are formed from
Saturated fatty acids and glycerol
Oils are formed from
Unsaturated fatty acids and glycerol
Edible fats and edible oils are what kind of homologous series
Esters
The hydrolysis of edible fats and edible oils produces
Glycerol and carboxylic acids (fatty acids)
The hydrolysis of edible fats and edible oils with an alkali eg. NaOH produces
Salts from the fatty acids
Salts produced from the fatty acids are also known as
Soaps
Fatty acids vs standard carboxylic acids
Fatty acids have long hydrocarbon chains
Alkaline hydrolysis of a fat produces
Glycerol + a soap
The salt of a carboxylic acid
Soap
The heads of soap molecules are
Hydrophilic, ionic and water soluble
The tails of soap molecules are
Hydrophobic and oil soluble
Steps to the functions of soaps
- The hydrophobic tail dissolves in the grease
- The grease now has a covering of negative charge
- It can form globules when agitated
- These globules are attracted to the water and can be washed away
Hard water contains
High levels of dissolved minerals such as calcium and magnesium ions
What is formed when soap is dissolved in hard water
Scum, an insoluble precipitate
Soaps are
Sodium salts of carboxylic acids with long hydrocarbon chains
Detergents are
Sodium or potassium salts of sulphonic acids with long hydrocarbon chains
Chemical formula structure of a soap molecule
R-COOH-K
or
R-COOH-Na
Chemical formula structure of a fatty acid molecule
R-COOH
Chemical formula structure of a fatty acid molecule to form a detergent
R-SO4
Any ion at the head, but not carboxylate (COO¯)
Emulsifier examples
Mono-glycerides and di-glycerides
Enzymes are
Proteins which act as biological catalysts
What building blocks are proteins formed from
Amino acids
Amino acids functional groups
Amino and carboxyl (NH2 and COOH)
Formation of proteins
H on a NH2 group and OH on a COOH joined in long chains
Peptide link formula
C=O(-NH)
Types of amino acids
Essential, non-essential
Digestive process to produce amino acids
Enzyme hydrolysis of protein
What is eliminated in the formation of amino acids
Water
Another name for amide link
Peptide link
Structure of an amide link
C=O
|
N-
|
H
Significance of nitrogen in amino acids and proteins
NH allows for hydrogen bonding
Describe denaturing proteins
Hydrogen bonds holding proteins together break causing the twisted structure to unfold and shape to change
Proteins can form hydrogen bonds because
They contain an
-NH
What kind of reaction is splitting up a protein
Hydrolysis
Oxidation is ____ of hydrogens
Loss
Aldehydes or alcanals are produced by the oxidation of
Primary alcohols
Ketones are produced by the oxidation of
Secondary alcohols
CH3 CH2 OH (ethanol) is oxidised to
CH3 CHO (ethanal)
CH3 CH2 CH2 OH is oxidised to (propan-1-ol)
CH3 CH2 CHO (propanal)
Oxidation of secondary alcohols produces
Ketones
CH3 CH(OH) CH3 (propan-2-ol) is oxidised to
CH3 C=O CH3 (propanone)
CH3 CH2 CH(OH) CH3 (butan-2-ol) is oxidised to
CH3 CH2 C=O CH3 (butanone)
Aldehyde suffix
-anal
(bond at the back of molecule, back -> anal)
Ketone suffix
-one
(ketones -> alkanones)
When primary alcohols are oxidised they produce
Aldehydes
When secondary alcohols are oxidized they produce
Ketones
Carbonyl group (C=O) is found on what type of molecule
Aldehydes and ketones
Systematic name of CH3 CH2 C=O CH(CH3) CH2 CH2 CH2 CH3
4-methyl octan-3-one
Ketones _____ oxidise
Don’t
Three most common oxidizing reagents
- Fehling’s solution
- Tollen’s reagent
- acidified potassium dichromate
Between pentan-2-one an ethanal, which would react with Tollen’s reagent
Ethanal, because it is an aldehyde and can therefore be oxidised
Oxidizing an alkanal involves
The addition of an oxygen
The oxidation of aldehydes produces
Carboxylic acids
Butanal oxidizes to
Butanoic acid
-C=0
|
H
Oxidises to
-C=O
|
OH
Oxidation involves either adding ____ or removing ____
Oxygens, hydrogens
The hydrogen oxygen ratio of a compound can be used to show
Whether oxidation or reduction has occurred
In the H:O ratio, more Oxygen means
Oxidation
In the H:O ratio, more H means
Reduction
Primary alcohols oxidise to ___ which oxidise to ___
Aldehydes, carboxylic acids
Which compounds are not readily oxidised
Ketones and tertiary acohols
Carboxylic acids can undergo reduction which involves
The removal of an oxygen from the OH group
Functional groups resulting in polar molecules
Hydroxyl, carbonyl, carboxyl, amino and amide
Hydroxyl, carbonyl, carboxyl, amino and amide molecular formula
-OH
-C=O
-C=O(OH)
NH2
CONH
Antioxidants are _____ to _______
Oxidised, prevent unwanted oxidation reactions happening
Changes oxidation can make to foods
- reacting with water to remove vit c
- making aldehydes into acids
- making fats go rancid
Terpenes are found in _____ and formed from ______
Essential oils, isoprene units
Isoprene formula
C5H8 (2 double bonds)
( 2-methyl-1,3-butadiene)
Free radicals are
Atoms or molecules which are highly reactive due to the presence of unpaired electrons
Steps of a free radical reaction, 1
- Initiation
Free radicals are formed by the splitting of a diatomic halogen molecule by UV light
Steps of a free radical reaction, 2
- Propagation
A free radical steals a hydrogen from an alkane
A free radical of that alkane is formed
That free radical then steals a halogen from a diatomic molecule, leaving another halohen free radical
The cycle continues
Steps of a free radical reaction, 3
- Termination
- Halogen free radicals can join together
- Alkane free radicals can join together
- An alkane free radical can join with a halogen free radical
Free radical scavengers are
Molecules that easily react with free radicals as Vitamin C, added to cosmetic products