Module 2: Acids

Question 1

Name the 4 types of bases

Answer 1

• Metal Oxide
• Metal hydroxide
• Metal carbonate
• Ammonia (NH3)

Question 2

Name the common alkalis

Answer 2

• Magnesium oxide
• Barium oxide
• Magnesium hydroxide
• Sodium hydroxide
• Potassium hydroxide
• Ammonia

Question 3

Name common bases

Answer 3

• Aluminium hydroxide
• Sodium carbonate
• Aluminium oxide

Question 4

Name the acids you need to know

Answer 4

• HCL
• H2SO4
• HNO3
• H3PO4
• HCOOH (methanoic acid)
• CH3COOH (ethanoic acid)
• CH3CH2COOH (propanoic acid)

Question 5

Define acid

Answer 5

Releases H+ ions in an aqueous solution

Question 6

Define strong acid

Answer 6

Completely dissociates when dissolved in water.

Question 7

Define weak acid

Answer 7

Only slightly dissociates in water to give an equilibrium mixture

Question 8

Define a base

Answer 8

A substance which neutralises acids

Question 9

Define alkalis

Answer 9

A soluble base which releases OH- ions in an aqueous solution

Question 10

How do you determine state symbols?

Answer 10

• Metals are solid.
• Salts in solution are aqueous
• Any ion is aqueous
• Acids/alkalis are aqueous

Question 11

What do salts do In water?

Answer 11

Soluble salts e.g NaCl dissolve In water to form aqueous ions.

Question 12

How do you make up a standardised solution?

Answer 12

1. Weigh out an accurate mass of solid in a clean dry beaker.
2. Add deionised water to dissolve the solid and stir with a glass rod.
3. Transfer the solution into a volumetric flask using a funnel.
4. Rinse the beaker, stirring rod and funnel with deionised water and transfer the washings to the volumetric flask.
5. Add deionised water to the volumetric flask to make up to the graduation mark. Use a dropping pipette when close to the mark as going beyond the mark will result in an unknown concentration.
6. Stopper the flask and invert to mix thoroughly and ensure a homogenous solution.

Question 13

How would you carry out a titration between an unknown concentration of HCl and NaOH?

Answer 13

1. Pour hydrochloric acid into a beaker and measure out 25cm^3 of HCl using a pipette and a pipette filler.
2. Transfer to a conical flask.
3. Fill burette with NaOH and take the initial reading to two decimal places.
4. Add a few drops of methyl orange or phenolphthalein indicator.
5. Add NaOH until the indicator colour changes (in this instance it should be colourless to pink or orange to pink) as this indicates neutralisation.
6. Take final readings to 2 decimal places on burette. This is your volume required for neutralisation (titre value).