Introduction
In this experiment, we study the law of conservation of mass. The law of conservation of mass remarks that mass is neither created nor destroyed in a chemical reaction.
Aim
To prove the law of conservation of mass holds true in a chemical reaction.
Requirements
1. Barium chloride,
2. Sodium sulphate,
3. Distilled water,
4. Two beakers each of volume 100ml,
5. One beaker of volume 150ml,
6. Physical balance,
8. Polythene bag,
9. Two watch glasses,
10. A glass rod.
Theory
1. The law of conservation of mass holds true in a chemical reaction, i.e., in a chemical reaction, the mass of reactants is always equal to the mass of the product obtained
2. Mass can not be created or destroyed.
3. We can prove the law of conservation of mass by taking the example of sodium sulphate and barium chloride.
4. Their reaction will be
BaCl2 + Na2SO4 → BaSO4 + 2NaCl.
Colourless Colourless White precipitate
5. The ionic equation is
Ba²+ (aq) + SO4²- → BaSO4
According to the law of conservation of mass, the mass of barium chloride and sodium sulphate (reactants) and the mass of barium sulphate and sodium chloride (product) are equal.
Procedure
1. Take 50 ml of water in each of the two beakers of volume 100 ml.
2. Weigh two watch glasses using the physical balance.
3. Weigh 3.6g of barium chloride (BaCl2.2H2O) in one of the watch glasses.
4. Add this barium chloride to one of the beakers of volume 100 ml and name it A.
5. Again, weigh 8.05g of sodium sulphate (Na2SO4.10H2O) in another watch glass and add this barium chloride to another beaker of volume 100ml and name it B.
6. Using polythene and spring balance, weigh the beaker of volume 150 ml and name it C.
7. Mix Barium chloride and sodium sulphate using a glass rod in this beaker.
8. A white precipitate starts forming in the beaker as you mix the content. This white precipitate appears due to the formation of barium sulphate (BaSO4).
9. Weigh this beaker C to find out the weight of barium sulphate.
10. Now, compare the masses of reactants and products.
A B C
Observation
1. The Mass of 50 mL of distilled water (assuming density as 1g /cc) = 50.0 g.
2. The Mass of barium chloride = 3.6 g.
3. The Mass of BaCl2 solution, A = 53.6 g.
4. The Mass of sodium sulphate= 8.05 g.
5. The Mass of Na2SO4 solution, B =58.05 g.
6. The Total mass of reactants (BaCl2 and Na2SO4) = (53.6 + 58.05)g = 111.65 g.
7. The Mass of an empty beaker of volume 150 ml,m1 =………………….g.
8. The Mass of reactants before precipitation, m2= m1+ 111.65 g = ……………………g.
9. The mass of product after precipitation, m3 =……………………. g.
Result
On the basis of comparison, we have found that in a chemical reaction, the mass of the reactants is equal to the mass of the product. Therefore it is proved that the law of conservation of mass holds true in a chemical reaction.
Precautions
1. Measure the mass of materials accurately.
2. While taking measurements, the spring balance should be held vertically.
3. Make sure that the pointer of the spring balance is at zero before taking the reading.
4. Chemicals should be used in small amounts.
5. Mix the reactants slowly by stirring.
Conclusion
In this way, we have proved the law of conservation of mass holds true in a reaction.
VIVA Questions With Answers
Q.1 What is the formula of barium sulphate?
ANS. BaSO4
Q.2 What is the formula of barium chloride?
ANS. BaCl2
Q.3 What is the formula of sodium sulphate?
ANS. Na2SO4
Q.4 What was the aim of our experiment?
ANS. To check whether the law of conservation of mass holds true or not in a chemical reaction.
Q.5 What do you mean by the law of conservation of mass in a chemical reaction?
ANS. It means the mass of reactants is equal to the mass of the product.
Q.6 Can we use CaCl2 instead of BaCl2 in a reaction?
ANS. Yes. On reaction with Na2SO4, it will form a white precipitate of CaSO4.
Q.7 What kind of reaction is involved in this experiment?
ANS. Double displacement and precipitation reaction.
Q.8 Who discovered the law of conservation of mass?
ANS. Antoine L. Lavoisier
Q.9 Can mass be created or destroyed?
ANS. No
Q.10 Does the law of conservation of mass also work in a nuclear reaction?
ANS. No, it only works in a chemical reaction.
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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