ACIDIC 9.3

Question 0

Esterification general word formula

Answer 0

Alkanoic acid + alkanol Ester + water

Question 1

Formation of HYDRONIUM equation

Answer 1

H+ + H2O —-> H3O+

Question 2

General properties of ACIDS

Answer 2

• Corrosive
• Conduct electricity in solutions
• Neutralised by BASES
• Turns BLUE litmus RED

Question 3

General properties of BASES

Answer 3

• Caustic
• Neutralised by ACIDS
• Mainly insoluble in water (aqueous bases are ALKALIS)
• Usually metal hydroxides or metal oxides
• Turns RED litmus BLUE

Question 4

Common ACIDS

Answer 4

• Acetic acid (vinegar)
• Citric acid (lemon juice)
• Carbonic acid (fizzy drinks)

Question 5

Common BASES

Answer 5

• Sodium hydroxide (drain cleaners)
• Ammonia (household cleaners)
• Sodium bicarbonate (baking powder)

Question 6

Common NEUTRAL substances

Answer 6

• Pure water

- Milk

Question 7

What is an INDICATOR?

Answer 7

A substance that changes colour in solution depending on whether the solution is ACIDIC/BASIC

Question 8

What do you sprinkle over damp soil to test it’s pH?

Answer 8

Barium sulfate and then indicator

Question 9

Identify Acetic Acid

Answer 9

• Ethanoic acid
• CH3COOH
• WEAK

Question 10

Identify Citric Acid

Answer 10

• C6H8O7

Question 11

Identify Hydrochloric Acid

Answer 11

• HCL

- Strong

Question 12

Identify Sulfuric Acid

Answer 12

• H2SO4
• Strong
• Batteries

Question 13

When is an acid classified as STRONG

Answer 13

When it ionises completely in solution

Question 14

When is an acid classified as WEAK?

Answer 14

When it doesn’t ionise completely in solution (therefore equilibrium)

Question 15

Outline how acids are used as PRESERVATIVES

Answer 15

• Ethanoic acid (vinegar) is used in “pickling”
• Kills bacteria (sulfurous acid)
• Citric acid (natural preservative)

Question 16

Outline how acids are used as FLAVOURINGS

Answer 16

• Carbonic acids is added to soft drinks

- Ethanoic acid (vinegar) is added as flavouring

Question 17

Examples of Natural ACIDS

Answer 17

• Hydrochloric acid (HCl)
• Citric acid (C6H8O7)
• Ethanoic acid (CH3COOH)

Question 18

Examples of Natural BASES

Answer 18

• Ammonia (NH3)

- Calcium carbonate (CaCO3)

Question 19

Results of the comparison of the pH of strong and weak acids practical

Answer 19

• 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

Question 20

Outline the previous ideas of acids

Answer 20

• Lavoisier stated that acids contained OXYGEN
• Davy stated that acids contained HYDROGEN
• Arrhenius stated that acids produced H+ ions when in water

Question 21

Outline the bronsted-Lowry theory of acids and bases

Answer 21

• Acids are proton DONORS

- Bases are proton ACCEPTORS

Question 22

What is a Conjugate BASE

Answer 22

The original ACID with a proton REMOVED

Question 23

What is a Conjugate ACID

Answer 23

The original BASE with a proton ADDED

Question 24

What is an AMPHIPROTIC substance

Answer 24

A substance that can act as both an ACID and a BASE

Question 25

What is the functional group of ALKANOLS

Answer 25

The hydroxyl group (-OH)

Question 26

What is the functional group of ALKANOIC ACIDS?

Answer 26

Carboxyl group (-COOH)

Question 27

Order of boiling points?

Answer 27

Highest to lowest: Alkanoic acids, alkanols, parent alkanes

Question 28

State the intermolecular forces within ALKANES, ALKANOLS and ALKANOIC ACIDS

Answer 28

- Alkanes: Dispersion forces - Alkanols: Dispersion forces and polar bonds - Alkanoic acids: Polar bonds - hydrogen bonding

Question 29

Define Esters

Answer 29

Esters are sweet-smelling, volatile organic compounds that contain the ester functional group (-COOC-)

Question 30

Define Esterification

Answer 30

- The process which forms esters - The reaction between an acid and an alkanol - Endothermic - Equilibrium

Question 31

What sort of reaction is Esterification?

Answer 31

A CONDENSATION reaction (a water molecule is generated)

Question 32

What is the purpose of adding SULFURIC ACID to esterification

Answer 32

- Acts as a CATALYST | - Increases yield: Acts as a DEHYDRATING AGENT to absorb the water and encourage forward reaction

Question 33

Why do you heat the reaction flask during esterification?

Answer 33

- 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

Question 34

Describe the reflux apparatus

Answer 34

- A condenser placed vertically onto a boiling flask | - It cools any vapours that boil off so they can drip back into the flask

Question 35

Explain the need for refluxng

Answer 35

- Allows the mixture to react at high temperatures without fear that the reactants/products will evaporate away

Question 36

How to name esters

Answer 36

- Alkanol: "anol" --> "yl" | - Alkanoic acid: "oic acid" --> "oate"

Question 37

What are esters used for?

Answer 37

- FLAVOURING: esters are produced to mimic flavours and scents - COSMETICS: perfumes, nail polish remover

Question 38

Esters Prac: Justification

Answer 38

- Boiling chips added to even out heatig - Reflux was used to _____ - Addition of sulfuric acid ____