Chemistry Practicals PDF

## Experiment No. 2(D) **AIM**: To perform and observe the reaction between sodium sulphate and barium chloride solutions and also to identify the type of reaction involved. **APPARATUS AND CHEMICALS**: Beaker (250mL), test tubes, test tube stand, glass rod, barium chloride solution, sodium sulpha...

## Experiment No. 2(D) **AIM**: To perform and observe the reaction between sodium sulphate and barium chloride solutions and also to identify the type of reaction involved. **APPARATUS AND CHEMICALS**: Beaker (250mL), test tubes, test tube stand, glass rod, barium chloride solution, sodium sulphate solution, distilled water. **PRINCIPLE**: Both barium chloride and sodium sulphate dissolve freely in water to give colourless solutions (use only distilled water). On mixing the two solutions a curdy white precipitate of barium sulphate is obtained. This is because barium sulphate is insoluble in water and is white in colour. $BaCl_2(aq) + Na_2SO_4(aq) \longrightarrow BaSO_4(s) + 2NaCl(aq)$ Barium chloride Sodium sulphate Barium sulphate (White ppt.) Sodium chloride It is an example of double displacement reaction. This is because in this reaction one component each of both the reacting molecules get exchanged to form the products. **PROCEDURE:** 1. In a clean beaker take nearly 20 mL of sodium sulphate solution and label it. Note its colour and appearance. 2. In clean and dry test tube take nearly 10-15 mL of barium chloride solution and label it. Note its colour and appearance. Put it in the stand. 3. Add barium chloride solution to the sodium sulphate solution with constant stirring and observe the changes produced. 4. Record your observations in the notebook. **Note**: Alternatively you can take barium chloride solution in the beaker and add sodium sulphate solution to it. **OBSERVATION TABLE:** | S.No. | Experiment | Observation | |---|---|---| | 1. | Note the colour and appearance of barium chloride solution. | It is transparent and colourless. | | 2. | Note the colour and appearance of sodium sulphate solution. | It is transparent and colourless. | | 3. | Note the colour and appearance of the reaction mixture after mixing of the two solutions. | (a) The liquid is colourless and transparent. (b) The precipitate formed is white in colour. | **INFERENCE:** Both barium chloride and sodium sulphate solutions are transparent and colourless. On adding barium chloride solution to sodium sulphate solution, a curdy white precipitate is formed. It is due to the formation of insoluble barium sulphate. It is an example of double displacement reaction. ## Precautions: 1. Use only clean and dry test tube for the barium chloride solution. 2. Use only distilled water to wash the test tubes. ## Experiment No. 3 **AIM:** (a) To observe the action of zinc (Zn), iron (Fe), copper (Cu) and aluminium (Al) metals on the following salt solutions: (i) $ZnSO_4(aq)$ (ii) $FeSO_4(aq)$ (iii) $CuSO_4(aq)$ (iv) $Al_2(SO_4)_3(aq)$ (b) Arrange Zn, Fe, Cu and Al in the decreasing order of reactivity based on the above result. **APPARATUS AND CHEMICALS**: Test tubes, test tube stand, distilled water, four metals (Fe, Cu, Al and Zn), $FeSO_4$ solution, $CuSO_4$ solution, $Al_2(SO_4)_3$ solution, $ZnSO_4$ solution, sandpaper. **PRINCIPLE**: A more reactive metal displaces a less reactive metal from its salt solution. The reactivity of these four metals is in the order Al > Zn > Fe > Cu. As such aluminium will displace zinc, iron and copper. $2Al(s) + 3ZnSO_4(aq) \longrightarrow Al_2(SO_4)_3(aq) + 3Zn(s)$ $2Al(s) + 3FeSO_4(aq) \longrightarrow Al_2(SO_4)_3(aq) + 3Fe(s)$ $2Al(s) + 3CuSO_4(aq) \longrightarrow Al_2(SO_4)_3(aq) + 3Cu(s)$ Zinc will displace iron and copper from their salt solutions. But it will not displace aluminium from its salt solution. $Zn(s) + Al_2(SO_4)_3(aq) \longrightarrow$ No reaction $Zn(s) + FeSO_4(aq) \longrightarrow ZnSO_4(aq) + Fe(s)$ $Zn(s) + CuSO_4(aq) \longrightarrow ZnSO_4(aq) + Cu(s)$ Iron will displace only copper from its salt solution. $Fe(s) + CuSO_4(aq) \longrightarrow FeSO_4(aq) + Cu(s)$ Copper cannot displace Al, Zn and Fe. **PROCEDURE:** 1. Clean the metals with a sandpaper and cut into small pieces. 2. Take 10 mL each of $ZnSO_4$, $FeSO_4$ and $CuSO_4$ solutions in three test tubes. Add 1-2 small pieces of aluminium to each test tube. Record your observations in the table. 3. Take 10 mL each of $Al_2(SO_4)_3$, $FeSO_4$ and $CuSO_4$ solutions in three test tubes. Add 1-2 small pieces of zinc to each test tube. Record your observations in the table. 4. Take 10 mL each of $Al_2(SO_4)_3$, $ZnSO_4$ and $CuSO_4$ solutions in three test tubes. Add 1-2 small pieces of iron to each test tube. Record your observations in the table. 5. Take 10 mL each of $Al_2(SO_4)_3$, $ZnSO_4$ and $FeSO_4$ solutions in three test tubes. Add 1-2 small pieces of copper to each test tube. Record your observations in the table. **A diagram shows 4 test tubes with metal strips in them, each one containing a different salt solution. The caption at the bottom of the diagram reads:** Fig. 2. Reaction of $ZnSO_4$, $Al_2(SO_4)_3$, and $CuSO_4$ solutions with zinc strips **OBSERVATIONS:** | Metal added | $Al_2(SO_4)_3$ sol. | $ZnSO_4$ sol. | $FeSO_4$ sol. | $CuSO_4$ sol. | |---|---|---|---|---| | Aluminium | - | Zn is displaced | Fe is displaced | Cu is displaced | | Zinc | No reaction | - | Fe is displaced | Cu is displaced | | Iron | No reaction | No reaction | - | Cu is displaced | | Copper | No reaction | No reaction | No reaction | - | **Inference:** The order of reactivity of these four metals is: Al > Zn > Fe > Cu **PRECAUTIONS:** 1. Use only distilled water for the experiment. 2. Add 1-2 drops of conc. $H_2SO_4$ to clear the solutions of metal salts (if needed). 3. Thoroughly clean the apparatus before the experiment. 4. Clean the metal pieces with sandpaper before the experiment. ## Experiment No. 4 **AIM**: To study the following properties of acetic acid (ethanoic acid) : (i) Odour (ii) Solubility in water (iii) Effect on litmus (iv) Reaction with sodium hydrogencarbonate. **APPARATUS AND CHEMICALS**: Test tubes, test tube stand, acetic acid, red and blue litmus papers or solution, sodium hydrogencarbonate etc. **PRINCIPLE**: When pure, it is a colourless liquid in summer but freezes to an ice-like solid (m.pt. 16.7°C) in winter. It has a typical vinegar like odour. It is miscible with water in all proportions. Acetic acid is a typical acid. It turns blue litmus red. It liberates $CO_2$ from carbonates and bicarbonates. For example, a brisk effervescence is produced when $NaHCO_3$ is added to acetic acid. $NaHCO_3(s) + CH_3COOH(l) \longrightarrow CH_3COONa(aq) + CO_2(g)$ The $CO_2$ so produced can be tested with lime water. It will turn lime water milky. $Ca(OH)_2(aq) + CO_2(g) \longrightarrow CaCO_3(s) + H_2O(l)$ On passing an excess of $CO_2$ the solution becomes clear. $CaCO_3(s) + CO_2(g) + H_2O(l) \longrightarrow Ca(HCO_3)_2(aq)$ **PROCEDURE:** 1. Take acetic acid in a clean and dry test tube. Observe its colour and smell. It is colourless and has a typical, strong vinegar like odour. 2. Take 2-3 drops of acetic acid in a clean and dry test tube. Add 3-5 drops of water and shake well. A clear solution is obtained. Thus acetic acid is miscible with water in all proportions. 3. Add 2-3 drops of blue litmus solution to 2-5 mL of acetic acid in a test tube the blue litmus solution will turn red. Repeat the experiment with red litmus solution. No change in colour is observed. 4. Add a pinch of solid sodium bicarbonate to 2-3 drops of acetic acid in a test tube. A brisk effervescence is produced with the liberation of colourless, odourless gas. Pass the gas through lime water. Lime water first turns milky and then becomes clear. The gas evolved is $CO_2$. Acetic acid liberates $CO_2$ from bicarbonates. **OBSERVATION TABLE:** | S.No. | Experiment | Observation | |---|---|---| | 1.| Smell: Smell the sample of ethanoic acid (acetic acid). | It has vinegar like odour. | | 2.| Solubility Test Try to dissolve 2-3 drops of ethanoic acid (acetic acid) in 3-5 drops of water. | It is freely soluble in water. | | 3.| Litmus test (a) Add 2-3 drops of blue litmus solution to 2-5 mL of acetic acid in a test tube. (b) Add 2-3 drops of red litmus solution to 2-5 mL of acetic acid in a test tube. | Blue colour of litmus changes to red. No change in colour is produced. | | 4.| Reaction with sodium hydrogencarbonate (sodium bicarbonate) (a) Add a pinch of sodium hydrogencarbonate to 2-3 drops of acetic acid in a test tube. (b) Pass the gas produced through lime water. | A colourless, odourless gas is produced with a brisk effervescence. Lime water first turns milky and on passing more gas, it becomes clear. | **INFERENCE:** * Acetic acid has vinegar like odour. * Acetic acid is miscible with water in all proportions. * Acetic acid is acidic in nature. * Acetic acid liberates $CO_2$ when treated with sodium hydrogencarbonate. **PRECAUTIONS:** 1. Clean the apparatus thoroughly before the experiment. 2. Lime water used should be fresh. ## Experiment No. 5 **AIM:** To study the comparative cleaning capacity of a sample of soap in soft and hard water. **APPARATUS AND CHEMICALS**: Three test tubes (20 mL), dropper, test tube stand, three beakers (100 mL): three glass rods, a measuring cylinder (50mL), a measuring scale, underground water, hard water, distilled water, soap solution. **PRINCIPLE:** Hardness of water is generally due to the presence of salts of calcium and magnesium (hydrogencarbonates, chlorides and sulphates) in water. These salts are soluble in water. When soap is added to hard water, it reacts with the salts to form a scum, which is insoluble and floats on top of the water surface. The scum is formed due to the formation of insoluble calcium or magnesium salts of the fatty acid used in the soap formation. The soap in solution then becomes ineffective. $Ca(HCO_3)_2(aq) + 2Na^+ stearate(aq) \longrightarrow Ca(stearate)_2(s) + 2NaHCO_3(aq)$ **A diagram shows the reaction of calcium bicarbonate and sodium stearate, with products.** $MgCl_2(aq) + 2Na^+ stearate(aq) \longrightarrow Mg(stearate)_2(s) + 2NaCl(aq)$ As shown above the salts of calcium and magnesium show similar reactions. Therefore, the presence of calcium and magnesium salts in water precipitates the soap thereby reducing its cleansing power and foaming capacity. **PROCEDURE:** 1. Take three 100 mL beakers and label them as A, B and C. 2. Take 20 mL of distilled water in beaker A. In beaker B take 20 mL of underground water. In beaker C take 20 mL of hard water. 3. Put 10 drops of soap solution in each beaker with a dropper and stir the content of each beaker with separate glass rods. 4. Place three test tubes in a test tube stand and label them as tube A, B and C. **A diagram shows three test tubes labeled A, B and C, each containing a different type of water with soap solution. The caption at the bottom of the diagram reads:** Fig. 1. Test tubes containing different samples of water and soap solution 5. Pour 3 mL of the above solution in the corresponding test tubes. 6. Take test tube A and shake it ten times by placing thumb on its mouth. 7. Foam or lather will be formed by shaking the test tube. Measure the length of the foam produced immediately with the help of a measuring scale. 8. Similarly, repeat steps 6 and 7 with the remaining two samples. **A diagram shows a hand shaking a test tube, with the caption:** Fig. 2. Showing the shaking of the test tube **OBSERVATIONS AND CALCULATIONS:** | SI. No. | Mixture (water + soap) | Test tube readings | Length of the foam produced = $l_2 - l_1$ (cm) | |---|---|---|---| | 1. | Distilled water (soft water) | Initial length $l_1$ (cm) Final length, $l_2$ (cm) | | | 2. | Well water or underground water | | | | 3. | Hard water | | | **RESULT AND DISCUSSION:** Find out from the observations that which sample of water produces the maximum length of foam (lather). For cleansing purpose, the foam needs to be produced which depends on free availability of soap. In hard water it is trapped due to scum, this makes the hard water unsuitable for washing. **PRECAUTIONS :** (i) Stir the mixture carefully so as to avoid spilling of soap solution. (ii) Shake every tube for equal number of times and in a similar manner. (iii) Measure the length of the foam produced immediately after its production.