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  1. Pour limewater into one of the test tubes and seal with a rubber stopper.
  2. Carefully pour a small amount of hydrochloric acid into the remaining test tube.
  3. Add a small amount of sodium carbonate to the acid and seal the test tube with the rubber stopper.
  4. Connect the two test tubes with a delivery tube.
  5. Observe what happens to the colour of the limewater.
  6. Repeat the above steps, this time using sulfuric acid and calcium carbonate.


The clear lime water turns milky meaning that carbon dioxide has been produced.

When an acid reacts with a carbonate a salt, carbon dioxide and water are formed. Look at the following examples:

  • Nitric acid reacts with sodium carbonate to form sodium nitrate, carbon dioxide and water. 2 HNO 3 + Na 2 CO 3 2 NaNO 3 + CO 2 + H 2 O
  • Sulfuric acid reacts with calcium carbonate to form calcium sulfate, carbon dioxide and water. H 2 SO 4 + CaCO 3 CaSO 4 + CO 2 + H 2 O
  • Hydrochloric acid reacts with calcium carbonate to form calcium chloride, carbon dioxide and water. 2 HCl + CaCO 3 CaCl 2 + CO 2 + H 2 O

Acids and bases

  1. The compound NaHCO 3 is commonly known as baking soda. A recipe requires 1.6 g of baking soda, mixed with other ingredients, to bake a cake.
    1. Calculate the number of moles of NaHCO 3 used to bake the cake.
    2. How many atoms of oxygen are there in the 1.6 g of baking soda? During the baking process, baking soda reacts with an acid to produce carbon dioxide and water, as shown by the reaction equation below: HCO 3 - ( aq ) + H + ( aq ) CO 2 ( g ) + H 2 O ( l )
    3. Identify the reactant which acts as the Bronsted-Lowry base in this reaction. Give a reason for your answer.
    4. Use the above equation to explain why the cake rises during this baking process.
    (DoE Grade 11 Paper 2, 2007)
  2. Label the acid-base conjugate pairs in the following equation: HCO 3 - + H 2 O CO 3 2 - + H 3 O +
  3. A certain antacid tablet contains 22.0 g of baking soda (NaHCO 3 ). It is used to neutralise the excess hydrochloric acid in the stomach. The balanced equation for the reaction is: NaHCO 3 + HCl NaCl + H 2 O + CO 2 The hydrochloric acid in the stomach has a concentration of 1.0 mol.dm - 3 . Calculate the volume of the hydrochloric acid that can be neutralised by the antacid tablet. (DoE Grade 11 Paper 2, 2007)
  4. A learner is asked to prepare a standard solution of the weak acid, oxalic acid (COOH) 2 2H 2 O for use in a titration. The volume of the solution must be 500 cm 3 and the concentration 0.2 mol.dm - 3 .
    1. Calculate the mass of oxalic acid which the learner has to dissolve to make up the required standard solution. The leaner titrates this 0.2 mol.dm - 3 oxalic acid solution against a solution of sodium hydroxide. He finds that 40 cm 3 of the oxalic acid solution exactly neutralises 35 cm 3 of the sodium hydroxide solution.
    2. Calculate the concentration of the sodium hydroxide solution.
  5. A learner finds some sulfuric acid solution in a bottle labelled 'dilute sulfuric acid'. He wants to determine the concentration of the sulphuric acid solution. To do this, he decides to titrate the sulfuric acid against a standard potassium hydroxide (KOH) solution.
    1. What is a standard solution?
    2. Calculate the mass of KOH which he must use to make 300 cm 3 of a 0.2 mol.dm - 3 KOH solution.
    3. Calculate the pH of the 0.2 mol.dm - 3 KOH solution (assume standard temperature).
    4. Write a balanced chemical equation for the reaction between H 2 SO 4 and KOH.
    5. During the titration he finds that 15 cm 3 of the KOH solution neutralises 20 cm 3 of the H 2 SO 4 solution. Calculate the concentration of the H 2 SO 4 solution.
    (IEB Paper 2, 2003)

Questions & Answers

what is the relationship between the strength of intermolecular Force and boiling point
Onias Reply
inversely proportional
what is atom?
Ice_ Reply
what is Boyle's law
Nqabisa Reply
what is field
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Khayalethu Reply
what is intermolecular forces
Mandy Reply
type of intermolecular force
Are forces that act between stable molecules And we have two type's of intermolecular forces * polar and non-polar
what is intramolecular force
Thantsha Reply
what are the bonding atom
datuali Reply
what is atom
fused atom
building blocks of matter
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Dennis Reply
what do you think will happen to semi metal when place in boiling water
dill ute
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Itumeleng Reply
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maneo Reply
Transverse waves move perpendicular to the surface... and longitudinal waves move parallel to the surface. Does it make sense to u?
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what is the formula to calculate a longitudinal wave
Keaton Reply
what is Snell's law
Leekat Reply
Snell's law (also known as Snell-Descarteslaw and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, air.

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Source:  OpenStax, Siyavula textbooks: grade 11 physical science. OpenStax CNX. Jul 29, 2011 Download for free at http://cnx.org/content/col11241/1.2
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