Acids blue litmus testing

Oxidation, (i) Dissolve 5 g. of potassium dichromate in 20 ml. of dil. H2SO4 in a 100 ml. bolt-head flask. Cool and add 1 ml. of methanol. Fit the flask with a reflux water-condenser and warm gently a vigorous reaction soon occurs and the solution turns green. The characteristic pungent odour of formaldehyde is usually detected at this stage. Continue to heat for 3 minutes and then fit the flask with a knee-tube (Fig. 59, p. 100) and distil off a few ml. Test the distillate with blue litmus-paper to show that it is definitely acid. Then apply Test 3 p. 350) for formic acid. (The reflux-distillation apparatus (Fig. 38, p. 63) can conveniently be used for this test.)... 

Use a stirring rod to transfer 1 drop of hydrochloric acid (test tube number 1) to a piece of red litmus paper. Then transfer 1 drop of hydrochloric acid to a piece of blue litmus paper. 

Acidity in Explosives Test is one of the std tests for the detn of purity of expls and propellants. A rapid qualitative method consists of touching a sample with a strip of moistened indicator paper, such as blue litmus paper. 

SET UP APPARATUS AS SHOWN. INTO TEST TUBE A DROP MIXTURE OF Vi TEASPOON TABLE SALT AND i/l TEASPOON SODIUM BISULFATE. HEAT. HYDROGEN CHLORIDE PRODUCED TURNS MOISTENED BLUE LITMUS RED. ADD 2 ml WATER TO TEST TUBE B. SHAKE. RESULT IS WEAK HYDROCHLORIC ACID. 

LIGHT SULFUR IN BOTTLE CAP. LOWER BURNING SULFUR INTO JAR. WHEN JAR IS FULL OF FUMES, REMOVE SULFUR. ADD A FEW ml WA TER. SHAKE. AS S02 DISSOLVES IN WATER IT FORMS A WEAK ACID— SULFUROUS ACID, HjSO,. TEST FOR ACID WITH BLUE LITMUS PAPER. 

MIX CALCIUM ACETATE WITH AN EQUAL AMOUNT OF SODIUM Bl-SULFATE. PLACE IN DRY TEST TUBE. HEAT GENTLY. YOU GET SHARP ODOR OF ACETIC ACID. MOISTENED BLUE LITMUS PAPER AT MOUTH OF TUBE TURNS RED. 

Litmus test is used to determine the acidic or basic nature of a substance or a water solution. If blue litmus turns red when dipped in a liquid, the liquid is an acid. There will be no change of colour if the liquid is a base (or water). If red litmus turns blue when dipped in a liquid, then the liquid is a base. There will be no change of colour if the liquid is an acid (or water). 

Pour the mixture into a tray and test with litmus paper to determine whether it is acidic or basic. (An acid turns blue litmus red a base turns red litmus blue.)... 

Small Quantities or Solutions. Wear eye protection, laboratory coat, and nitrile rubber gloves. In the fume hood, add the sodium cyanide to a solution of 1% sodium hydroxide (about 50 mL/g of cyanide). Household bleach (about 70 mL/g of cyanide) is slowly added to the basic cyanide solution while stirring. When addition of the bleach is complete, the solution can be tested for the presence of cyanide using the Prussian blue test To 1 mL of the solution to be tested, add 2 drops of a freshly prepared 5% aqueous ferrous sulfate solution. Boil this mixture for at least 60 seconds, cool to room temperature, and then add 2 drops of 1% ferric chloride solution. The resulting mixture is made acid to litmus with 6 M hydrochloric acid (prepared by adding concentrated acid to an equal volume of cold water). If cyanide is present, a deep blue precipitate will form. (Concentrations of cyanide greater than 1 ppm can be detected.) If the test is positive, add more bleach to the cyanide solution, and repeat the test. Continue until no Prussian blue precipitate is formed. Wash the solution into the drain.4 6... 

Label three clean test tubes no. 1, no. 2, and no. 3. In test tube no. 1, place 2 mL of 1 M Na3P04 in test tube no. 2, place a small amount (covering the tip of a small spatula) of a detergent in test tube no. 3, place a small amount (covering the tip of a small spatula) of a fertilizer. Add 2 mL of distilled water to the solids in test tubes no. 2 and no. 3 and mix. Add 6 M HN03 dropwise to all three test tubes until the solutions test acid to litmus paper (blue litmus turns red when treated with acid). Mix each solution well and then add 10 drops of the (NH4)2Mo04 reagent to each test tube. Warm the test tube in a water bath maintained at 60-70°C. Compare the three solutions and record your observations (12). 

Black Pepper Oil, 47, 572, (S 1)5 Black Peppier Oleoresin, 391, 392 Blank Tests, 4 Blank Titration, Residual, 4 Bleached Starch, 159 Bleidner Apparatus, (S3)17 Blue Litmus Paper, 861 Bois de Rose Oil, 47, 576 Boric Acid-Potassium Chloride, 0.2 M, 848... 

Test the contents of both jars with red and blue litmus paper to see which solution is acid and which solution is alkaline. Place the jar of acid directly in front of you. Place the alkaline solution to the right and slightly behind the acid (unless you are left-handed). Now, with the dropper near the calcium hydroxide, add 3 drops of it to the acetic acid, stir with the spoon near the acetic acid, and test the new solution with blue litmus paper. Repeat this procedure over and over, counting the drops carefully, and noting the amount of change in... 

Results The change in color of the blue litmus to red became less and less marked as you added more alkali to the acid. This shows that the addition of an alkali was making the solution less and less acid. Finally, you reached a point where the solution had no effect whatsoever on the color of the litmus paper. This was the end point, or point of neutralization. Enough alkali had been added so that the solution was definitely no longer acid it had been neutralized by the alkali. If you had continued to add alkali to the solution after reaching the end point, it would slowly have turned into an alkali, and you could have traced its progress by testing it with red litmus paper. The equation for the neutralization in this experiment is ... 

On the other hand, in some cases we may only have simply to test whether the solution is acid or alkaline. For this test a strip of litmus paper may be used. In acid solutions litmus turns to red, while in alkaline ones it shows a blue colour. The transition pH range lies around pH = 7. 

Experiment 52. — Dissolve a small piece of sodium hydroxide in an evaporating dish half full of water. Slowly add dilute hydrochloric acid, until a drop taken from the dish by means of a glass rod reddens blue litmus paper. Then evaporate to dryness by heating over a piece of wire gauze. Since the residue mechanically holds traces of the excess of hydrochloric acid added, it is necessary to remove this acid before applying any test. Heat the dish until all the yellow color disappears, then moisten the residue carefully with a few drops of warm water and heat again to remove the last traces of acid. This precaution is essential to the success of the experiment. Test a portion of the residue with litmus paper to find whether it has acid, basic, or neutral properties. Taste a little. Test (a) a solution of the residue for a chloride, and (b) a portion of the solid residue for sodium. Draw a definite conclusion from the total evidence. 

For,1 firework use the sulphuric acid content mu t be low especially if it is used in combination with chlorate. The acidity is tested with blue litmus paper to see whether the wash water of the sulphur changes its colour to red or not. /... 

Properties of Formic Acid (Section 100).—(a) Odor of formic acid.—Note the odor of the solution obtained in experiment 86 above, and test the solution with blue litmus paper. 

Illustration Take a piece of blue litmus paper and dip it in a test tube containing hydrochloric acid, observe the change in colour (it turns red). Take another piece of blue litmus paper and dip it in a test-tube containing nitric acid. Observe the change in colour (it turns red). Repeat the experiments with other acids in different test tubes (e.g. oxalic acid, acetic acid etc.). (In each case blue litmus turns red). 

Take another piece of blue litmus paper and dip it in a test-tube containing nitric acid. Observe the change in colour. (It turns red.)... 

Repeat the experiments with other adds in different test tubes (e.g. oxalic acid, acetic add etc.). (In each case blue litmus turns red.)... 

In the chemistry lab, litmus test paper is used. Litmus paper is made by soaking paper in a solution of litmus and then drying it to remove the water. Litmus papers are usually available in a slightly basic form (blue) and a slightly acidic form (red). 

Red and blue litmus paper is used for testing alkaline and acid solutions. For instance, if we had a solu-tion and wished to know whether it was a base or acid, we would take a piece of red or blue litmus paper and dip it in it. If the red paper turned blue it would indicate a base. If it remained red we would not know whether or not it was neutral or alkaline. Therefore, we would try it with blue litmus paper. If the blue litmus paper would turn red we would then under-... 

Put a drop of dilute hydrochloric acid, of dilute sulphuric acid, and of dilute nitric acid on each of three pieces of blue litmus paper. (1) What is the action of acids on blue litmus paper (2) What is a test for an acid Dip the end of a glass rod into the water into which you passed chlorine in Experiment 21 and touch a piece of blue litmus paper with it. (3) What change in color takes place hnmediatelyf (4) What kind of a compound or compounds does the water contain (5) What are the names of the substances formed by the action of chlorine on water (6) Write the equation for the reaction. Cautiously smell the solution. (7) Does it still contain chlorine (8) Did the reaction, the equation of which you have just written, proceed to completion (9) What is the evidence (10) What substances are present in chlorine water (11) Which of the substances is the bleaching agent in chlorine water (12) What are your reasons for ascribing the action to this compound rather than to the other substances present ... 

Directions Perform this experiment in the hood. Measure out into an evaporating dish 8 c.c. of water and add to it 10 c.c. of concentrated sulphuric acid. (Do not add the water to the acid.) While the solution is cooling set up an apparatus like the one for the preparation of chlorine, Experiment 21. Put 10 grams of sodium chloride into the test tube and pour the acid down the thistle tube. When the salt has become thoroughly moistened with the acid, heat the test tube with a low flame, holding the burner in your hand. To determine when the bottle has been filled, hold a piece of wet blue litmus paper at its mouth. Do not consider the bottle full when the first test is obtained but continue generating the gas until it overflows in some quantity. Collect four bottles full and cover them with glass plates. 

Directions (a) (1) What was the action on litmus paper of the solutions of acids studied in Experiment 44 Fill a perfectly dry test tube one-quarter full of glacial acetic acid (this is a pure substance and contains no water) and transfer a drop of it with a rod to a piece of blue litmus paper. (2) How does the result differ from that obtained with the acid solutions in Experiment 44 Add a drop of water to the acid on the litmus paper. (3) What happened (4) What property is exhibited by a solution of acetic acid which is not possessed by the pure substance itself (5) When acetic acid is dissolved in water is any new substance formed (6) What is the evidence (7) Do other acids when dissolved in water form the same substance (8) What is the evidence (9) What is the name of the substance (10) What is its chemical composition (11) How is it essentially different from other substances previously studied (12) Can it be obtained in a pure state out of solution (13) What happens to it when a solution containing it is evaporated (14) What is a test for it ... 

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