CBSE Class 10 Chemistry Acids Base and Salts Worksheet Set A

Question. What is brine?
Answer. Brine, salt water, particularly a highly concentrated water solution of common salt (sodium chloride).

Question. Give two important uses of washing soda.
Answer.Two important uses of washing soda are; It is used in the manufacture of soap and glass. It is used to remove the permanent hardness of water.

Question. Write an equation to show reaction between Plaster of Paris and water.
Answer.

Question. What do you understand by neutralization reaction. Give one example.
Answer. Neutralization reaction: Neutralization is a type of chemical reaction in which an acid reacts with a base to form salt and water.
Example: 1. Reaction between hydrochloric acid(HCl) and sodium hydroxide(NaOH) Hydrochloric acid reacts with sodium hydroxide to produce their salt sodium chloride(NaCl) and water.

Question. Why does an aqueous solution of an acid conduct electricity?
Answer. In an aqueous solution, acids dissociate to produce ions. These ions are responsible for the conduction of electricity.

Question. What is observed when carbon di oxide gas is passed through lime water
Answer. When carbon dioxide gas is passed through lime water, it turns milky or turbid due to the formation of calcium carbonate which is insoluble in water. Following is the chemical equation for the reaction
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O
However, when excess of carbon dioxide is passed through the solution, the turbidity disappears and a clear solution is obtained due to the formation of calcium bicarbonate, which is soluble in water.
Following is the chemical equation for the reaction
CaCO₃ + H₂O + CO₂ → Ca(HCO₃)₂

Question. What are strong and weak acids? Separate strong and weak acids from the following list-Hydrochloric acid, Citric acid, acetic acid , nitric acid, formic acid, sulphuric acid.
Answer. Strong acid is an acid that ionizes completely in aqueous solution. It always loses a proton (H+) when dissolved in water. Weak acid is an acid that ionizes partially in a solution. It gives off only a few of its (H+) atoms when dissolved in water.Strong acid- Hydrochloric acid, sulphuric acid, nitric acid Weak acid- formic acid, acetic acid, Citric acid

Question. Name the acids present in ant stings and give its chemical formulae. Also give common methods to get relief from the discomfort caused by the ant sting.
Answer. Formic acid (HCOOH) ) acid present in the ant sting. Rubbing baking soda and applying Calamine solution are common method to get relief from the discomfort caused by the ant sting.

Question. A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by-product of chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.
Answer.
The brine solution is electrolyzed during the chloralkali process. Brine is a sodium chloride solution in water. Brine solution decomposes into hydrogen gas, chlorine gas, and sodium hydroxide during electrolysis.2NaCl(aq)Sodium chloride+2H₂O(l)Water→2NaOH(aq)Sodium hydroxide+H₂(g)Hydrog en+Cl₂(g) Chlorine
The chloralkali process produces sodium hydroxide as a byproduct. It collects moisture and becomes sticky when left out in the open.
When sodium hydroxide is combined with carbon dioxide, sodium carbonate is formed. It is important to keep in mind that carbon dioxide is an acidic gas.
2NaOH(aq)Sodium hydroxide+CO₂(g)Carbon dioxide→Na₂CO₃(s)Sodium carbonate+H₂O(l)Water

Question. During summer season, a milkman usually adds a small amount of baking soda to fresh milk. Give reason.
Answer.A milkman adds a very small amount of baking soda so as to prevent spoilage of milk.
It leads to change in the pH which does not allow bacteria and enzymes to act and milk does not become sour due to fermentation.

Question. A stain of curry on a white cloth becomes raddish – brown when soap is scrubbed on it.
Which indicator can be used here? What type of indicator is it ?
Why did the stain becomes raddish – brown when soap is scrubbed on it ?
What happens when the cloth is washed with plenty of water ?
Answer. (i) turmeric indicator
(ii) Soap is base so turmeric gives raddish brown color in basic medium
(iii) When cloth is washed in plenty water ,the stain turns yellow. 

Short Answer Questions

Question. Why does distilled water not conduct electricity, whereas rain water does?
Ans. Water is a bad conductor of electricity but when it contains dissolved salt in it, the mixture conducts electricity. As distilled water does not contain any salts dissolved in it, it does not dissociate into ions, so it does not conduct electricity. But rain water has dissolved CO2 in it which forms carbonic acid.
CO₂ + H₂O ⎯⎯⎯→ H₂CO₃
This carbonic acid dissociates into ions which are responsible for electrical conductivity in rain water.
H₂CO3 + 2H₂O ⎯⎯⎯→ 2H3O+ + CO3₂^-

Question. Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9 respectively. Which solution is:
(i) neutral (ii) strongly alkaline (iii) strongly acidic
(iv) weakly acidic (v) weakly alkaline?
Arrange the pH in increasing order of H+ ion concentration.
Ans. (i) Neutral solution ‘D’ having pH value 7.
(ii) Strongly alkaline solution ‘C’ with pH value 11.
(iii) Strongly acidic solution ‘B’ with pH value 1.
(iv) Weakly acidic solution ‘A’ with pH value 4.
(v) Weakly alkaline solution ‘E’ with pH value 9.
The pH in increasing order of H+ ions 11, 9, 7, 4 and 1.

Question. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to the test tube A, while acetic acid (CH₃COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why ?
Ans. Fizzing will occur more vigorously in test tube A. Hydrochloric acid (HCl) is a strong acid whereas acetic acid (CH₃COOH) is a weak acid. Being a strong acid, HCl solution contains a much greater amount of hydrogen ions in it due to which the fizzing will occur more vigorously in test tube A (containing hydrochloric acid). The fizzing is due to the evolution of hydrogen gas which is formed by the action of acid on the magnesium metal of magnesium ribbon.

Question. A milkman adds a very small amount of baking soda to fresh milk.
(i) Why does he shift the pH of the fresh milk from ‘6’ to slightly alkaline?
(ii) What do you expect to observe when this milk comes to a boil?
(iii) Why does this milk take a long time to set as curd?
Ans. (i) On adding baking soda, he shifts pH of fresh milk from ‘6’ to slightly greater than 7 making it alkaline so that it is not quickly spoiled by the action of bacteria.
(ii) On boiling this milk, it becomes slightly bitter in taste due to changing of baking soda into Na₂CO₃ salt, which is bitter in taste.
(iii) As the bacteria that change milk to curd are less active in the alkaline medium, it takes longer to set as curd.

Question. Two solutions A and B have pH₃ and 5 respectively. Which of the two solutions has more hydrogen ion concentration and which one is more acidic? Give reason for your answer. 
Ans. pH of solution A = 3, pH of solution B = 5
Solution A is more acidic as solution A has more hydrogen ion concentration, because the pH of a solution is inversely proportional to the concentration of hydrogen ions in it. That is, a solution having low concentration of hydrogen ions has a higher pH value.

Question. State reason for the following:
(i) dry HCl gas does not change the colour of the dry blue litmus paper.
(ii) alcohol and glucose also contain hydrogen, but do not conduct electricity.
(iii) Conc. of H3O+ ion is affected when a solution of an acid is diluted.
Ans. (i) Dry HCl gas does not contain any hydrogen ions in it, so it does not show acidic behaviour. Dry HCl gas does not change the colour of dry blue litmus paper because it has no hydrogen ions [H+ (aq)] in it. However, when HCl gas dissolves in water, it forms hydrogen ions and hence shows acidic behaviour.
(ii) The aqueous solutions of glucose and alcohol do not show acidic character because their hydrogen does not separate out as hydrogen ions [H+ (aq) ions] on dissolving in water. Hence, they do not conduct electricity.
(iii) • An acid is a substance which dissociates on dissolving in water to produce hydrogen ions [H+ (aq) ions].
• Hydrogen ions do not exist as H+ ions in a solution, they attach themselves to the polar water molecules to form hydronium ions, H₃O+. H+ + H₂O → H₃O+
• When a solution of an acid is diluted, the number of [H₃O⁺] ions per unit volume decreases. Thus pH of the solution increases.

Question. Illustrate any three chemical properties of acids. With examples. 
Ans. Chemical properties of acids:
(i) Acids react with metals to form H2 gas.
Zn + 2HCl ⎯⎯⎯→ ZnCl₂ + H2↑
(ii) Acids turn blue litmus into red.
(iii) Acids react with bases to form salt and water (neutralization reaction).
HCl + NaOH ⎯⎯⎯→ NaCl + H₂O
Acid Base Salt Water

Question. Write balanced equations for the following reactions:
(i) Dilute sulphuric acid reacts with zinc granules.
(ii) Dilute hydrochloric acid reacts with magnesium ribbon.
(iii) Dilute sulphuric acid reacts with aluminium powder.
(iv) Dilute hydrochloric acid reacts with iron filings.
Ans. (i) Zn(s) + H₂SO₄ (aq) ⎯⎯⎯→ ZnSO4 (s) + H₂ (g) dil.
(ii) Mg (s) + 2HCl (aq) ⎯⎯⎯→ MgCl2 (s) + H₂ (g)
(iii) 2Al (s) + 3H₂SO₄ (aq) ⎯⎯⎯→ Al₂ (SO4)₃ (s) + 3H₂ (g)
(iv) Fe (s) + 2HCl (aq) ⎯⎯⎯→ FeCl2 (s) + H2 (g)
These reactions show that metals when react with dilute acids, they form salt of that acid and H₂ gas.

Question. Compounds like alcohols and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it. 
Ans. Take solutions of glucose, alcohol, HCl acid and H2SO4 acid in separate beakers. Fix two nails on a cork and place the cork in a 100 ml beaker. Connect the nails to the two terminals of a 6 volt battery through a bulb and a switch, as shown in the figure.
(i) Now take enough dil. HCl in the beaker so that the nails are immersed in the acid. Switch on the current.
(ii) Now repeat this experiment with dilute H2SO4 acid. You will observe that the current gets conducted through each of the acid solutions as the bulb glows in each case with acid solution. In case (i) and (ii) acid breaks up into its ions to conduct electricity. Acids produce H+ ions and their acid radical ions.

(iii) Repeat the experiment separately with glucose and alcohol solutions. With glucose and alcohol solutions, the bulb does not glow showing that these substances do not break into
their ions and so do not conduct electricity through their solutions. So glucose and alcohol, though have hydrogen atoms in their molecules but do not give H+ ions in their solutions to conduct electricity.
Result: This activity proves that only acids produce H+ ions in their aqueous solutions.

Question. You are provided with three test tubes C, A and B which contain distilled water, acidic solution and basic solution. If you are given blue litmus paper only, how will you identify the contents of each test tube? 
Ans. • First take three strips of blue litmus paper and dip one in each test tube.
• The liquid in test tube A turns blue litmus to red. It means test tube A contains acid because (acid turns blue litmus to red).
• If other two test tubes do not change the colour of blue litmus paper, it shows that one of them contains a base and the other contains distilled water.
• Now put the blue litmus paper which is turned red by the acid of test tube A in the remaining two test tubes.
• If the liquid of test tube B turns that red litmus paper to blue again, it shows that it is a base.
• The liquid in test tube C does not turn the colour of either blue litmus or red litmus thus is distilled water.

Question. (a) You are given two solutions A and B. The pH of solution A is 6 and pH of solution B is 8.
(i) Identify the acidic and basic solution.
(ii) Which solution has more H+ ion concentration? Give reason for your answer.
(b) Why is HCl a stronger acid than acetic acid? Explain. 
Ans. (a) Solution A: pH = 6 Solution B: pH = 8
(i) A is acidic solution whereas B is basic solution.
(ii) Solution A has more H+ ion concentration because higher the hydronium ion concentration, lower is the pH value.
(b) HCl is a stronger acid than acetic acid because strength of acid depends on the number of H+ ions produced. When same concentration of HCl and acetic acid are taken then these two produce different amounts of hydrogen ions. HCl produces more H+ ions and is said to be a strong acid while acetic acid gives less H+ ions, therefore said to be a weak acid.

Question. A cloth ‘strip dipped in onion juice is used for testing a liquid ‘X. The liquid ‘X changes itsodor. Which type of an indicator is onion juice? The liquid ‘X turns blue litmus red. List the observations the liquid ‘X
will show on reacting with the following :
(a) Zinc granules
(b) Solid sodium carbonate
Write the chemical equations for the reactions involved.
Answer. Olfactory indicator
(a) Colorless and odourless gas is evolved with bubbles-
Zinc+Acid = Zinc salt +H₂
(b)Brisk effervescence /colorless and odourless gas evolved.
Sodium chloride+ Acid=Sodium Salt of acid + water + carbon dioxide

Question. Complete and balance the following chemical equations :
(i) NaOH(aq) + Zn(s) →
(ii) CaCO₃(s) + H₂O(l) + CO2(g) →
Answer. (i) NaOH(aq) + Zn(s) →NaZnO₂ (s) +H₂(g)
(ii) CaCO₃(s) + H₂O(l) + CO₂(g) → Ca(OH₃)₂

Question. To a solution of sodium hydroxide in a test tube, two drops of phenolphthalein are added.
(i) State the colour change observed.
(ii) If dil HCl is added dropwise to the solution, what will be the colour change?
(iii) On adding few drops of NaOH solution to the above mixture the colour of the solution reappears. Why?
Answer.(i) When few drops of phenolphthalein are added to a dilute solution of sodium hydroxide a pink colour is produced.
(ii) It turns colourless
sodium hydroxide, NaOH is a strong basic in nature. so, when few drops of phenolphthalein is added to sodium hydroxide, solution turns deep pink.
(iii) if few drops of NaOH is added to again to the solution, solution becomes basic in nature and hence, pink colour of Phenolphthalein reappears.

Question. Five solutions A,B,C,D and E when tested with universal showed pH as 4,1,11 ,7 and 9 respectively.
Which solutions is-
(a) Neutral ? (b) strongly alkaline ? (c) strongly acidic (d) weakly acidic (e) weakly alkaline
(f) arrange the pH in increasing order of hydrogen ion concentration .
Answer. Solution
pH↑[H+]conc.↓
[H+]conc.↑ Acid Strength↑
B→ Strongly Acidic
A→ Weakly Acidic
D→ Neutral [pH=7]
E→ Weakly Alkaline
C→ Strongly Alkaline
So, [H+]conc. is B>A>D>E>C

Question. Out of HCl and CH₃COOH ,which one is weak acid and why?
Answer. HCI, being a strong acid dissociates into H+ and CI− ions. These ions conduct electricity in the solution resulting in the glowing of the bulb. On the other hand, the CH₃COOH is a weak acid. It does not dissociate into ions completely in solution.

Question. The pH and hydrogen ion concentration of some solutions

How is the hydrogen ion concentration and pH related to each other.
On the basis of above table , arrange the following in the decreasing order of H⁺ concentration . Pure water, tomato juice , milk of magnesia , sea water
A solution of pH 2 is fill in two separate beaker and few drops of methyl orange and phenolphthalein are added into separate solution. How will the color of the indicators change?
Answer. (i) pH is inversely proportional to the hydrogen ion concentration.
(i) The decreasing order of H+ concentration is
Tomato juice > Pure water > Sea water > Milk of magnesia
(iii) The solution of pH 2 is acidic in nature. So, the colour change is
Methyl orange: red; phenolphthalein: colourless

pH is quite useful to us in a number of ways in daily life. Some of its applications are:Control of pH of the soil : Plants need a specific pH range for proper growth. The soil may be acidic, basic or neutral depending upon the relative concentration of H* and OH-. The pH of any soil can be determined by using pH paper. If the soil is too acidic, it can be corrected by adding lime to it. If the soil is too basic, it can be corrected by adding organic manure which contains acidic materials. Regaining shine of a tarnished copper vessel by use of acids : A copper vessel gets tarnished due to formation of an oxide layer on its surface. On rubbing lenion on the vessel, the surface is cleaned and the vessel begins to shine again. This is due to the fact that copper oxide is basic in nature, which reacts with the acid (citric acid) present in lemon to form a salt (copper citrate) which is washed away with water. As a result, the layer of copper oxide is removed from the surface of the vessel and the shining surface is exposed.Self-defence by animals through chemical warfare : Stings of bees and ants contain methanoic acid. When stung, it causes lot of pain and irritation. This can be cured by rubbing the affected area with mild base like baking soda.

Question. When black copper oxide placed in a beaker is treated with dilute HCl, its colour changes to
(a) white
(b) dark red
(c) bluish green
(d) no change.
Answer.C

Question. P is an aqueous solution of acid and Q is an aqueous solution of base. When these two are diluted separately, then
(a) pH of P increases while that of Q decreases till neutralisation.
(b) pH of P decreases while that of Q increases till neutralisation.
(C) pH of both P and Q decrease.
(d) pH of both P and Q increase.
Answer.A

Question. Which of the following acids is present in bee sting?
(a) Formic acid
(b) Acetic acid
(c) Citric acid
(d) Hydrochloric acid
Answer.C

Question. Sting of ant can be cured by rubbing the affected area with soap because
(a) it contains oxalic acid which neutralises the effect of formic acid.
(b) it contains aluminium hydroxide which neutralises the effect of formic acid
(c) it contains sodium hydroxide which neutralises the effect of formic acid
(d) none of these
Answer. C

Read the following passage and answer the questions given :-

An indicator is special chemical that changes its colour to indicate the presence of a chemical substance It is used to confirm the presence of an acid , a base or a neutral solution .indicators show different colours in acidic and basic medium .These are dyes or mixture of dyes which are used to indicate he presence of acid and bases . Some examples are litmus solutions, methyl orange , phenolphthalein and universal indicator . There are some substances whose odour changes in acidic or basic medium . these are called olfactory indicators . Onion and vanilla extract are examples of such i6ndicators .

Question. What are indicators ? What is the use of any indicator ?
Answer.  An indicator is special chemical that changes its colour to indicate the presence of a chemical substance.

Question. What are olfactory indicators ? Give two examples .
Answer. There are some substances whose odour changes in acidic or basic medium . these are called olfactory indicators . Onion and vanilla extract are examples of such indicators .

Read the following passage and answer the questions given :-

The primary reason behind the toxic foam is high phosphate content in the waste water because of detergents used in dying industries , dhobi ghat and house holds. Yamuna’ s pollution level is so bad that parts of it having labelled dead as there is no oxygen in it or aquatic life to survive .

Question. Predict the pH value of the water of river Yamuna if the reason for froth is high content of detergents dissolved in it.
10-11
5-7
2-5
7
The table provides the pH value of four solutions P,Q,R and S

Solutions   pH value
P                    2
Q                    9
R                    5
S                    11

Question. Which of the following correctly represents the solutions in increasing order or their hydronium ion concentration ?
P>Q>R>S
P>S>Q>R
S<Q<R<P
S<P<Q<R
Answer. High content of phosphate ion in river Yamuna may lead to
Decreased level of dissolved oxygen and increased growth of algae
Decreased level of dissolved oxygen and no effect on growth of algae
Increased level of dissolved oxygen and increased growth of algae
Decreased level of dissolved oxygen and decreased growth of algae

Long Answer Questions

Question. (a) The blue colour of crystals of a substance changed on heating in a closed test tube but the colour was regained after sometime on cooling. Name the substance and write its chemical formula. Explain the phenomenon involved.
(b) Write name and chemical formula of two such compounds whose one formula unit is associated with 10 and 2 water molecules respectively. 
Ans. (a) The substance is Copper sulphate crystals (CuSO₄ . 5H₂O) which are blue in colour. When copper sulphate crystals are heated strongly, they lose all the water of crystallisation and form anhydrous copper sulphate (which is white):
CuSO₄ . 5H₂O Heat⎯⎯⎯→ CuSO₄ + 5H₂O
Hydrated copper Anhydrous copper Water
sulphate (Blue) sulphate (White) (goes away)
Thus, on strong heating, blue copper sulphate crystals turn white due to the loss of water of crystallisation.
The dehydration of copper sulphate crystals is a reversible process. So when water is added to anhydrous copper sulphate, it gets hydrated and turns blue due to the formation of hydrated copper sulphate.
 CuSO₄ + 5H₂O ⎯⎯⎯→ CuSO₄ . 5H₂O
Anhydrous copper Water Hydrated copper
sulphate (White) sulphate (Blue)
(b) Chemical formula of two such compounds whose one formula unit is associated with 10 and 2 water molecules respectively—
• Washing soda — Na₂CO₃ . 10H₂O
(Sodium Carbonate Decahydrate)
• Gypsum — CaSO₄ . 2H₂O
(Calcium Sulphate Dihydrate)

Question. Write the chemical name of Na2CO3.10H2O and Na₂CO₃. Write the significance of 10H₂O. Mention the term used for water molecules attached with a salt. With the help of chemical equation, explain the method of preparation of both Na₂CO₃.10H₂O and Na₂CO₃. Also list two uses of Na2CO₃.10 H₂O.
Ans. • Chemical name of Na2CO₃.10H2O: Sodium Carbonate Decahydrate (Washing soda)
• Na2Co₃ : Sodium Carbonate (Soda ash)
• 10H₂O is the water of crystallization of sodium carbonate. Water of crystallization is the fixed number of water molecules present in one formula unit of a salt. Thus ‘10’ water molecules are present in one formula unit of sodium carbonate.
Washing soda is produced by Solvay process, by the reaction of ammonical brine with CO₂ gas.
NaCl + NH₃ + CO₂ + H₂O Heat⎯⎯⎯→ NaHCO₃ + NH4 Cl
NaHCO₃ on heating produces Na2CO3 (Sodium carbonate, called soda ash) which on recrystallization produces washing soda.
2NaHCO₃ Heat⎯⎯⎯→ Na2CO₃ + CO₂↑ + H₂O
Na2CO3 + 10H₂O Crystallisation⎯⎯⎯→ Na2CO₃.10H₂O
(Washing soda)
Washing soda is a basic salt.
Some important uses of washing soda:
(i) Washing soda is used in the glass, soap and paper industries.
(ii) It is used in the manufacture of borax compound.
(iii) It is used as a cleansing agent for domestic purposes.
(iv) It is used for removing permanent hardness of water.

Question. (a) Define a universal indicator. Mention its one use. 
(b) Solution A gives pink colour when a drop of phenolphthalein indicator is added to it. Solution B gives red colour when a drop of methyl orange is added to it. What type of solutions are A and B and which one of the solutions A and B will have a higher pH value?
(c) Name one salt whose solution has pH more than 7 and one salt whose solution has pH less than 7.
Ans. (a) Universal indicator is a mixture of many different indicators which gives different colours at different pH values of the entire pH scale.
It shows different colours at different concentrations of hydrogen ions in a solution.
(b) Solution A gives pink colour when a drop of phenolphthalein indicator is added, therefore A is a base.
Solution B gives red colour when a drop of methyl orange is added to it, therefore B is an acid.
Hence, solution A will have less concentration of hydrogen ion than B.
Thus, A will have pH more than 7 because pH value of
— an acid solution < 7;
— a base solution > 7; and
— a neutral solution = 7.
(c) — The salts of strong acids and weak bases give acidic solution having pH less than 7. Example, NH4Cl, Ammonium Chloride will have pH less than 7.
— The salts of weak acids and strong bases give basic solution having pH more than 7. Example, Na2CO3, Sodium Carbonate will have pH more than 7.

Question. Write an activity to show the reaction of acids with metal carbonates and metal hydrogen carbonate salts. 
Ans. Take two test tubes. Mark them as ‘A’ and ‘B’. Take about 0.5 gm of sodium carbonate in the test tube ‘A’ and 0.5 gm of sodium hydrogen carbonate in test tube ‘B’. Add about 2 ml of dilute HCl acid to both of these test tubes. Pass the gas produced in each case through lime water as shown in the figure. Lime water in each case will turn milky due to the production of CO₂ gas in each of the test tubes. 

Reactions occurring in the above activity:
Test tube ‘A’ Na2CO₃ (s) + 2HCl (aq) ⎯⎯⎯→ 2NaCl (aq) + CO₂ (g) + H₂O (l)
Test tube ‘B’ NaHCO₃ (s) + HCl (aq) ⎯⎯⎯→ NaCl (aq) + CO₂ (g) + H₂O (l)
On passing the gas evolved through the lime water:
Ca(OH)₂ (aq) + CO₂ (g) ⎯⎯⎯→ CaCO₃ (s) + H₂O
lime water white ppt.
(milkiness)
But on passing excess CO₂ gas through the lime water, milkiness disappears due to the formation of soluble CaHCO₃
CaCO₃ + CO₂ + H₂O ⎯⎯⎯→ Ca(HCO₃)₂ (aq)
Calcium hydrogen-carbonate
This activity shows that metal carbonates and metal hydrogen carbonates react with acids to form salt, CO₂ and water.