Introduction

In this article, we will see the cleaning capacity of soap in hard and soft water.

Basic Building Concept

1. Soaps are long-chain fatty acids made up of sodium and potassium salts.

2. The process of forming soap by heating fat with sodium or potassium hydroxide is known as saponification.

3. Soaps are made up of molecules whose one end is hydrophobic means water repellent, and the other end is hydrophilic means water-loving.

4. Hydrophobic part is soluble in oil or dirt part while the hydrophilic part is soluble in water.

5. When the soap is at the surface of clothes, it forms a cluster in which the ionic part(hydrophilic) is in the water, and the hydrophobic tail in the cluster is formed on clothes. This cluster is known as a micelle.

6. Soap in the form of a micelle can clean clothes because the dirt is collected in the micelle.

Aim

To study the cleaning capacity of soap in hard and soft water.

Materials Required

1. Tap water,

2. Distilled water,

3. Calcium hydrogen carbonate,

4. Calcium Chloride,

5. Calcium sulphate,

6. Soap Sample,

7. Spatula,

8. Physical balance,

9. Weight box,

10. Five test tubes,

11. Three beakers,

12. Four glass rods,

13. Measuring cylinder,

14. A measuring cylinder and three droppers

Theory

1. The water that does not contain magnesium and calcium compounds is called soft water, and the water that contains salts of magnesium and calcium in a large amount is known as hard water.

2. Hard water contains magnesium and sodium hydrogen carbonates, sulphates, and chloride.

3. When soap is dissolved in hard water, it does not form micelle, although it reacts with the hard water and forms scum. Scums are the sodium and magnesium salts of soap. The reaction of forming scum is

2C17H35COONa(aq) + Ca2+ (aq)→ (C17H35COO)2Ca(s) + 2Na+(aq)

Soap (sodium stearate)

2C17H35COONa(aq) + Mg2+ (aq)→ (C17H35COO)2Mg(s) + 2Na+(aq)

Soap (sodium stearate)

4. When sodium and magnesium ions react with soap, it does not form soap, and its cleaning property is also reduced.

Procedure

Step 1: Take three beakers and name them as A, B, and C.

Step 2: In beaker C, take 30 ml of water and add 1 gram of soap into it.

Step 3: In beaker A, take 20 ml of tap water.

Step 4: In beaker B, take 50 ml of distilled water.

Step 5: Place five beakers A, B, C, D, and E in a test tube stand,

Step 6: With the help of a dropper, pour 5ml of tap water in test tube A and 5ml of distilled water into each tubes B, C, D, and E.

Step 7: Add calcium hydrogen carbonate, calcium chloride, and calcium sulphate to beaker B.

Step 8: Mix this solution using a glass rod.

Step 9: Using a dropper add 5 ml of salt solution to test tube A.

Step 10: Measure the height of the solution and note it down.

Step 11: Place the thumb on the mouth of test tube A and shake it ten times.

Step 12: See whether the foam is formed in test tube A and record your observation.

Step 13: Measure the height of this solution immediately and record your observation.

Step 14: Repeat the steps from 7 10 11 with test tubes B, C, D, and E.

Observation

1. Volume of water in each test tubes = 5ml.

2. Volume of soap solution added to each test tube = 3ml.

Result

1. Maximum length of foam produced in water = …….

2. Formation of scum in water = …….

3. The water solution most suitable for washing clothes = ……..

Precautions

1. Small amount of soap should be used.

2. Equal volume of water should be used.

3. Measure the height of foam immediately after its formation.

4. Shake well in each test tube.

Conclusion

Hard water does not have the cleansing property because of the presence of sulphates and chlorides of calcium and magnesium.

In this way, we have seen the cleaning capacity of soap in hard and soft water.

Viva Questions With Answers

Q.1 What do you mean by soft water?

ANS. The water that does not contain magnesium and calcium compounds is called soft water.

Q.2 What do you mean by hard water?

ANS. The water that contains magnesium and calcium salts in a large amount is known as hard water.

Q.3 What do you mean by micelle?

ANS. When the soap is on the surface of clothes, it forms a cluster in which the ionic part(hydrophilic) is in the water, and the hydrophobic tail in the cluster is formed on clothes. This cluster is known as a micelle.

Q.4 What do you mean by scum?

ANS. When soap is dissolved in hard water, it does not form micelle, although it reacts with the hard water and forms scum. Scums are the sodium and magnesium salts of soap.

Q.5 Give the reaction of formation of sum?

ANS. 2C17H35COONa(aq) + Ca2+ (aq)→ (C17H35COO)2Ca(s) + 2Na+(aq)

Soap (sodium stearate)

2C17H35COONa(aq) + Mg2+ (aq)→ (C17H35COO)2Mg(s) + 2Na+(aq)

Soap (sodium stearate)

Q.6 What kind of ions are present in soft water?

AND. Sodium-ion.

Q.7 Which kind of water can clean clothes?

ANS. Soft water.

Q.8 Can you treat hard water into soft water?

ANS. Yes, we can transform hard water into soft water.

Q.9 How can hard water be turned into soft water?

ANS. Chemical treatment or boiling.

Q.10 What was the aim of our experiment?

ANS. To study the cleaning capacity of soap in hard and soft water.

Saquib Siddiqui

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.