Chemistry Flashcards
Recall the Colour of Litmus in an acidic solution
Litmus is red in an acidic solution
Recall the Colour of Litmus in a basic solution
Litmus is blue in a basic solution
Recall the Colour of Universal Indicator [Increasing pH]
Red — Purple
Recall the pH Colour Range of Phenolphthalein
Colourless - Pink; Colour Change [8.3 - 10]
Recall the pH Colour Range of Methyl Orange
Red - Yellow; colour change [3.1 - 4.4]
Recall the pH Colour Range of Bromothymol Blue
Yellow - (Green) - Blue; colour change [6.0 - 7.6]
Describe the detoxification process of the cycad
The seeds of the cycad are toxic and carcinogenic, thus:
Anaerobic Fermentation and Leaching:
Fermentation involves soaking and burning the plant to fully ripen.
Leaching involves placing the cycad seeds in dilly bags and dissolve the water-soluble toxins under running water. Still water is not used as the toxins are not fully soluble and in a closed system, an equilibrium would be formed
Identify a natural buffer system
Seawater has a buffer system involving carbonic acid and hydrogen carbonate.
Describe the Indigenous treatment of acids and bases
Clay and ochre were dried and crushed before adding water to form a paste, applied to the skin or ingested.
Clay is a detoxifying agent that neutralises excess acid in the stomach, relieving stomach pains
Aluminium
Recall the compound(s) used for neutralisation reactions in industry
Sodium Carbonate is used to neutralise acid spills and acidic wastage to minimise environmental damage; weak bases are used as exothermic.
Recall the limitations of pH indicators
Limitations:
- The substance must be in solution or gaseous; can only measure moisture
- Destroys sample
- Slightly acidic
- Qualitative not quantitative
- Solution must be colourless/ transparent or translucent or will distort results
- Affected by temperature
Recall the properties of a primary standard
A primary standard has:
- High purity
- Stable in air and in solution; does not react with moisture
- Soluble
- High molar mass
In preparation for titration, recall rinsing
Volumetric Flask - Distilled water (water is added eventually to the graduation mark)
Burette - Distilled water + Titrant
Pipette - Solution
Conical Flask - Distilled water
Recall the equivalence point in a titration
The point in a titration where the acid and base react in their stoichiometric ratios
Recall the end point in a titration
The point in a titration where a permanent colour change begins to be observed
Recall aldehyde
An aldehyde [-al] has a carbonyl group bonded to a terminal carbon and a hydrogen atom; CHO
Recall ketone
A ketone [-one] has a carbonyl group bonded to carbons
Recall carboxylic acid
A carboxylic acid [-oic] has a carboxyl group bonded to a terminal carbon; COOH
Recall esters
Esters are formed in acid [concentrationed sulfuric acid] catalysed condensation reactions called esterification (reactants: alkanol + alkanoic acid; product: ester + water)
Alkyl alkanoate
Carbonyl group bonded to the alkanoate
Reversible reaction; reflux surrounded by a condenser.
Hydrogen or hydroxide ions as catalyst
Recall amine
An amine [-amine] has a nitrogen atom bonded to carbon and hydrogen atoms
Recall amide
An amide [-amide] has a carbonyl group bonded to a nitrogen atom, which is bonded to hydrogen or alkyl groups
Order the homologous groups in increasing boiling points
- Hydrocarbons
- Halogenated hydrocarbons
- Amines
- Esters, ketones, aldehydes
- Alcohols
- Carboxylic acids
- Amides
State Markovnikov’s Rule
The proton (H) is attached to the carbon atom with greater number of adjacent hydrogen atoms.
Which addition reaction(s) of alkenes requires a catalyst
Hydrogenation of alkene [metal catalyst Pt or Pd/C]
Hydration of alkene [weak acid catalyst (strong acids, e.g. HCl will react)]; forms an alcohol
Recall the substitution reaction of alkanes
Under UV as a source of energy; not catalyst:
Alkane + Halogen –> Halogenated Alkane
Preference to displace tertiary and secondary hydrogens
Recall the bromine water test
The bromine water test is a test to differentiate between saturated and unsaturated hydrocarbons
Under conditions without UV light, an alkane cannot undergo a substitution reaction with bromine water but an addition reaction can occur
Decolourises from orange to colourless
Explain why alcohols become more non-polar as the size increases
Alcohols consist of a non-polar and a polar region, with the hydroxide causing the polar region. As the alcohol increases in size, the non-polar region dominates the polar hydroxide
Thus as the size of the alcohol increases, it becomes less soluble in water
Given a halogenated hydrocarbon, how can an alcohol be formed?
The halogenated hydrocarbon can undergo a substitution reaction in a solution of hydroxide ions or water as the hydroxide ions will displace the halogen
Recall the chemical process of fermentation
Fermentation is an anaerobic reaction [without oxygen]
Carbohydrate [Glucose] –> Alcohol [Ethanol] + Carbon Dioxide
Conditions:
- Yeast
- Acidic environment
Identify the acidity of amines. Elaborate why
Amines are bases. The nitrogen atom’s electron lone pair allows amines to accept protons [Bronsted-Lowry base] to form a positively charged conjugate acid
Recall the dehydration [elimination] of alkanol
The dehydration of alkanol requires a dehydrating agent [hot conc sulfuric acid] and forms alkene and water
Recall the oxidation of alcohol
Primary Alcohols oxidise to form alkanal, in turn, carboxylic acid
Secondary Alcohols oxidise to form ketones
Tertiary Alcohols do not oxidise
Recall oxidising agents
ACIDIFIED purple Potassium Permanganate ion [MnO4-] is reduced to the colourless Manganese ion [MN2+]
ACIDIFED orange Sodium Dichromate ion [Cr2O7 2-] is reduced to the green Chromium(III) ions, [Cr3+]
Recall common amphiprotic species
Amphiprotic species:
- Water
- Hydrogen carbonate ion
- H2PO4
- HPO4
Recall the purpose of reflux
Reflux:
- Uses heat to increase reaction rate
- Prevents the loss of volatile substances through condensation –> increases yield
- Releases pressure, preventing the round bottom flash from shattering
Recall the confirmation tests
Carboxylic acid:
- Litmus
- Sodium carbonate
Alkene:
- Bromine water
- Acidified potassium permanganate
Alcohol:
- CaCl2 [remove water] + sodium
Recall saponification
Saponification is the process of producing soaps. The process involves the hydrolysis of triglycerides (fats) using a strong base such as NaOH instead of water
Glycerol as a by-product
Describe the structures of soaps
Soap has a long hydrocarbon ‘tail’. As this component of the molecule is non-polar, it will repel polar substances like water, being hydrophobic.
The carboxylate (RCOO-) region of a soap molecule, the ‘head’, is anionic. This charged region is polar and readily dissolves in water, being hydrophilic.
Describe how soaps function
Soaps form an emulsion between oils and water:
The non-polar hydrocarbon tails are embedded into the oil particles, facing away from the water (solvent) as they are hydrophobic.
When soap molecules surround an oil particle, a micelle is formed. The polar, charged hydrophilic carboxylate heads, dissolved in the water, suspend the particle in water, creating an emulsion.
Explain why soaps cannot be used in acidic solutions
The protonation of the carboxylate head reduces its hydrophilicity and ability to act as an emulsifier
Explain how useful soaps are in hard water (high concentrations of calcium and magnesium ions)
Soaps have little to no use case in hard water as the soap molecules precipitate with the metal ions
Case Studies for Chemical Synthesis and Design
Haber Process:
Production of Ammonia from Nitrogen and Hydrogen gas
Exothermic – Temperature conflicts with Kinetic Factors
Iron Catalyst – Fe3O4
Location near natural gas / chlor-alkali factories
Possible thermal production; heat can be reused as energy
No by-products
Reactants are economically viable
Solvay Process:
Sodium Chloride + Calcium Carbonate –> Sodium Carbonate + Calcium Chloride
Calcium chloride slurry waste. Discharged into the ocean, minimal pH impact
Thermal pollution –> Calcium chloride is discharged at ~100 degrees
Location: Adelaide; Proximity to the ocean [disposal + salt] + limestone, coal
Recall how calorimetry can be improved
- Place a lid
- Move the flame closer
- Insulating materials on the side to shield
