ACIDIC 9.3 Flashcards
Esterification general word formula
Alkanoic acid + alkanol Ester + water
Formation of HYDRONIUM equation
H+ + H2O —-> H3O+
General properties of ACIDS
- Corrosive
- Conduct electricity in solutions
- Neutralised by BASES
- Turns BLUE litmus RED
General properties of BASES
- Caustic
- Neutralised by ACIDS
- Mainly insoluble in water (aqueous bases are ALKALIS)
- Usually metal hydroxides or metal oxides
- Turns RED litmus BLUE
Common ACIDS
- Acetic acid (vinegar)
- Citric acid (lemon juice)
- Carbonic acid (fizzy drinks)
Common BASES
- Sodium hydroxide (drain cleaners)
- Ammonia (household cleaners)
- Sodium bicarbonate (baking powder)
Common NEUTRAL substances
- Pure water
- Milk
What is an INDICATOR?
A substance that changes colour in solution depending on whether the solution is ACIDIC/BASIC
What do you sprinkle over damp soil to test it’s pH?
Barium sulfate and then indicator
Identify Acetic Acid
- Ethanoic acid
- CH3COOH
- WEAK
Identify Citric Acid
- C6H8O7
Identify Hydrochloric Acid
- HCL
- Strong
Identify Sulfuric Acid
- H2SO4
- Strong
- Batteries
When is an acid classified as STRONG
When it ionises completely in solution
When is an acid classified as WEAK?
When it doesn’t ionise completely in solution (therefore equilibrium)
Outline how acids are used as PRESERVATIVES
- Ethanoic acid (vinegar) is used in “pickling”
- Kills bacteria (sulfurous acid)
- Citric acid (natural preservative)
Outline how acids are used as FLAVOURINGS
- Carbonic acids is added to soft drinks
- Ethanoic acid (vinegar) is added as flavouring
Examples of Natural ACIDS
- Hydrochloric acid (HCl)
- Citric acid (C6H8O7)
- Ethanoic acid (CH3COOH)
Examples of Natural BASES
- Ammonia (NH3)
- Calcium carbonate (CaCO3)
Results of the comparison of the pH of strong and weak acids practical
- Sulfuric acid has the lowest pH because it’s a DIPROTIC STRONG acid
- HCl is a MONOPROTIC STRONG acid
- Citric and ethanoic acid are weak
Outline the previous ideas of acids
- Lavoisier stated that acids contained OXYGEN
- Davy stated that acids contained HYDROGEN
- Arrhenius stated that acids produced H+ ions when in water
Outline the bronsted-Lowry theory of acids and bases
- Acids are proton DONORS
- Bases are proton ACCEPTORS
What is a Conjugate BASE
The original ACID with a proton REMOVED
What is a Conjugate ACID
The original BASE with a proton ADDED
What is an AMPHIPROTIC substance
A substance that can act as both an ACID and a BASE
What is the functional group of ALKANOLS
The hydroxyl group (-OH)
What is the functional group of ALKANOIC ACIDS?
Carboxyl group (-COOH)
Order of boiling points?
Highest to lowest: Alkanoic acids, alkanols, parent alkanes
State the intermolecular forces within ALKANES, ALKANOLS and ALKANOIC ACIDS
- Alkanes: Dispersion forces
- Alkanols: Dispersion forces and polar bonds
- Alkanoic acids: Polar bonds - hydrogen bonding
Define Esters
Esters are sweet-smelling, volatile organic compounds that contain the ester functional group (-COOC-)
Define Esterification
- The process which forms esters
- The reaction between an acid and an alkanol
- Endothermic
- Equilibrium
What sort of reaction is Esterification?
A CONDENSATION reaction (a water molecule is generated)
What is the purpose of adding SULFURIC ACID to esterification
- Acts as a CATALYST
- Increases yield: Acts as a DEHYDRATING AGENT to absorb the water and encourage forward reaction
Why do you heat the reaction flask during esterification?
- The higher the temperature, the fast the rate of reaction
- Esterification is an ENDOTHERMIC reaction and therefore an increment in heat will encourage the forward reaction
Describe the reflux apparatus
- A condenser placed vertically onto a boiling flask
- It cools any vapours that boil off so they can drip back into the flask
Explain the need for refluxng
- Allows the mixture to react at high temperatures without fear that the reactants/products will evaporate away
How to name esters
- Alkanol: “anol” –> “yl”
- Alkanoic acid: “oic acid” –> “oate”
What are esters used for?
- FLAVOURING: esters are produced to mimic flavours and scents
- COSMETICS: perfumes, nail polish remover
Esters Prac: Justification
- Boiling chips added to even out heatig
- Reflux was used to _____
- Addition of sulfuric acid ____
