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Method:

  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.

Observations:

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 reduction
Lesego Reply
reduction is the gain of electrons of an atom ; compound or molecule. reduction is also the decrease of the oxidation number of an atom ; compound / molecule.
Omphile
What does Redox reactins mean?
kholeka Reply
Reaction in which there is transfer of electrons between elements
sibahle
how to calculate a vector
sakhumzi Reply
state Faraday's law in word
Emkay Reply
which rules do you have to follow to identify oxidation numbers
sessy Reply
there are 7 of them > look them up on siyavula textbook physics
Omphile
Where can I get a Siyavula textbook?
Thimna
if possibly ther was a way to send a document I told hv sent it to you
Mhleli
go to siyavula on Google where u can download the textbook
Tatenda
Why do vectors have arrows?
vanessa Reply
vector quantity has both direction and magnitude so arrows illustrate the direction of the vector
Mhleli
how to calculate net electric field at a point
Bazel Reply
what are controlled variables
Link Reply
Independent variables in an experiment which influence the outcome results
Boss
Such as temperature when dealing with ohms law
Boss
variables whose amount is determined by the person doing the experiment
Clemencia
how to calculate exodation number
Cphiwe Reply
Calculate relative atomic mass
Lindo Reply
what is chemical bonding?
Lefa Reply
Chemical Bonding is a mutual attraction between two atoms resulting from the simultaneous attraction between their nuclei and the outer elections
Sydney
How would you go about finding the resistance of an unknown resistor using only power supply, a voltmeter and a known resistance
Lebona
who is the scientist who discovered electromagnetism
Zivele Reply
what happens to the galvanometer when the switch is closed ?
Zivele
how do we identify an oxidising or reducing agent in a reaction?
Zivele
hey
Banele
@zivele in your products the element with an oxidation number less than 0 is a reducing and the one with an oxidation number greater than 0 is oxidising
sessy
what is electricity
Vihanga Reply
Formula for concentration
Kabelo Reply
c=m/MV
Zipho
if given number of moles and volume , can use c=n/V
sibahle
Chemistry term three topic is stressing me out, I really need a huge help
Ziyanda
on what
Olebogeng
during a snooker competition ,a 200g ball A m moving with velocity va collide head on with a identical ball B that was at rest.A after the collision ball A remains at rest wile ball B moves on with a velocity of 4m/s? With what speed was ball a moving before the collision
mathew Reply

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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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