Tie one iron nail with a wire and gently immerse it in copper sulfate solution in test tube B through a cork with holes [as shown in Figure 1.1(a)] for about 15 minutes [Fig. 1.1: (a) Iron nail dipped in copper sulphate solution; and (b) Iron nails and copper sulfate solutions are compared. From your observations, determine the changes in the colors of the copper sulfate solution and the iron nail.
Why does the color of a copper sulfate solution change when an iron nail is dipped in it? The change in the color of ____ litmus paper to _____ suggests that the aqueous solution of magnesium oxide is ________ in nature. Litmus test Place moist blue and red litmus papers near the opening of the test tube 4.
Which of the above metal(s) will not evolve hydrogen gas from dilute hydrochloric acid. b) Precipitation reaction between aqueous solution of barium chloride with aqueous solution of sodium sulphate. Take 3 ml of barium chloride in another test tube and mark it as B. Note the color of the two solutions in test tubes A and B before they are mixed.
R ESULTS AND D ISCUSSION
Bring a strip of filter paper dipped in Nessler's reagent K2[HgI4] near the tip of the funnel.
P RECAUTIONS
O BSERVATIONS
N OTE FOR THE T EACHER
Q UESTIONS
T HEORY
M ATERIALS R EQUIRED
To measure the change in temperature during chemical reactions and conclude whether the reaction is exothermic or endothermic.
P ROCEDURE
O BSERVATIONS AND C ALCULATIONS
Bring wet blue and red litmus papers successively to the mouth of the test tube. Attach a delivery tube through a stopper to the mouth of the test tube and pass the released gas through the freshly prepared lime water (Fig. 4.1). Take about 5 ml of 10% sodium hydroxide solution in another test tube and mark it as B.
NaOH in test tube B. Shake the mixture slowly but continuously and observe the change by dipping litmus paper in test tube B. Which litmus paper are you going to use for this?). Add HCl from test tube A and 10% NaOH in test tube B drop by drop until the reaction mixture in test tube B becomes neutral to litmus paper. Take a small piece of aluminum metal and place it in a clean and dry test tube.
Smell Gently blow the gas towards the nose with your hand 3. Litmus Bring moist blue and red. test litmus paper near the mouth of the test tube. Perform a combustion test by holding a lighted candle close to the mouth of the test tube. Samples: sodium carbonate (washing soda), sodium bicarbonate (baking soda), ammonium chloride, sodium chloride, etc., strips of red litmus paper, freshly prepared lime water, misc. hydrochloric acid, five test tubes, a test tube rack, a boiling tube, a thistle funnel, a double stopper, a delivery tube and a glass rod.
For performing the lime water test, take the solution of test tube A in a boiling test tube and set up the apparatus (delivery tube, thistle funnel, etc.) as shown in Fig.
P RECAUTION
Infer from the observations and rank the metals in the order of their decreasing reactivities. Clean the metals by rubbing them with a piece of sandpaper before dipping them in the salt solutions. Wash the test tubes after each series of observations of the interaction of a particular metal with the four salt solutions.
Some metals react with water to produce metal hydroxides or oxides and release hydrogen gas. Metals such as aluminium, zinc and iron do not react with either cold or hot water, but they do react with steam to form a metal oxide and hydrogen. The order of reactivity in different test tubes can be compared by carefully observing the rate of formation of bubbles of liberated hydrogen gas in the test tubes.
Remove the metal parts from the test tubes that did not react with the cold water in steps 2 and 3. Also compare the order of their reactivity by observing the bubbles of hydrogen gas released in the test tubes. Record your observation of strong, slow or no reaction with cold water or with hot water or steam in the table below.
A PPLICATIONS
Name the physical and chemical properties of the liberated sulfur dioxide gas based on observations. The lower end of the thistle funnel must be dipped in the acid taken in Woulfe's bottle, otherwise carbon dioxide will escape through the thistle funnel. While the gas is being collected in the glass, place a piece of cardboard over the mouth of the gas glass.
What happens to the burning magnesium strip when it is introduced into a jar filled with carbon dioxide. What is the chemical name of the compound formed when carbon dioxide gas is passed through lime water. These ions move through the solution in the electrolysis cell towards the pure copper strip (negative electrode).
Put a drop of ethanoic acid on (i) blue litmus paper and (ii) red litmus paper. Take 1 ml of ethanoic acid and add a pinch of sodium hydrogen carbonate to it. Count the number of drops of sodium hydroxide required to get a pink color in the reaction mixture. Do you see condensation of water vapors on the inner surface of the inverted funnel?
21.1: (a) Test tubes containing different soap solutions (b) Showing the shaking of the test tube. c) To compare the foaming capacity of different soap samples (a). Once the foam is formed, the length of the foam produced is measured immediately using a measuring scale [Fig. Was the length of foam formed the same in each of the test tubes containing the soap solution.
In this experiment it is advisable to measure the length of the foam produced immediately after its production. Water hardness is caused by the presence of calcium and magnesium salts (hydrogen carbonates, chlorides and sulfates) in the water. Scale is formed due to the formation of insoluble calcium or magnesium salts of the fatty acid used in soap making.
Mixture Tube Readings Length. water + soap) Initial length Final length of foam produced. Infer from your observations which solution of the soap sample produces the greatest length of suds (suds).
