Litmus Paper, Blue

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.)... 

ACID A chemical compound whose aqueous solution turns blue litmus paper red, reacts with and dissolves certain metals to form salts, and reacts with bases to produce salts and water. They are capable of transfeiTing a hydrogen ion (proton) in solution. 

Place six pieces of red litmus paper and six pieces of blue litmus paper on a piece of filter paper. 

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. 

Litmus paper comes in two varieties—blue and red. Blue litmus paper is made by soaking the paper in a solution containing lichens... 

Chlorine (CI2) turns damp blue litmus paper red, then bleaches it. 

Perhaps no two classes of compounds are more important in chemistry than acids and bases. All acids have several properties in common They have a sour taste, and they all react with most metals to form hydrogen gas (Hj) and with baking soda to form carbon dioxide (CO2). All acids turn blue litmus paper red, and their solutions conduct electricity because acids form ions when dissolved in water. t 11 bases also share several common properties They have a bitter taste, their solutions feel slippery like soapy water, and they turn red litmus paper blue (the opposite of acids). Solutions of bases also conduct electricity because they too form ions in water. Acids are similar because they produce hydrogen ion, (aq), in water. Bases, on the other hand, all form hydroxide ion, 0 [ (aq), in water. These ions are responsible for the properties of acids and bases. 

A sample of 2.5 g (5.6 mmole) of 2,2 -bipyridinium pentachlorooxomolybdate-(V) is placed in a 100-mL, round-bottomed flask fitted with reflux condenser and a bent guard tube (filled with fused calcium chloride) to avoid entrance of moisture. About 20 mL of ethanol (98%) is added, and the materials are shaken. There is an immediate reddish-pink coloration. The mixture is heated at reflux for about 1 hour, until there is no more evolution of hydrogen chloride (tested with blue litmus paper). The mixture is then filtered through a dry sintered-glass Gooch crucible and washed twice with small quantities of ethanol. The product, a reddish-pink solid, is dried in a vacuum desiccator. Yield 1.5 g (71%). Anal. 

Turn blue litmus paper red Turn red litmus paper blue... 

Occurrence.— If red ants be made to pass over blue litmus paper and be at the same time irritated, they leaveared streak behind them, produced by the formic acid which they qect. By placing the hand on an ant hill, a tingling sensation is felt from the same cause, and the hand acquires the powerful and pleasant odour of formic acid. 

Which of the following aqueous solutions turns blue litmus paper to red ... 

The reduced heating test at a temperature of 110°C in the presence of a blue litmus paper, which should not redden in less than 10 hr. 

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. 

Litmus test (Vieille test). This test introduced by Vieille [88] consists in warming a sample of nitrocellulose (2.5 g) or smokeless powder in a hermetically sealed test tube (Fig. 2) in presence of a band of blue litmus paper inserted within the tube. The tube is kept in a thermostat warmed to 110°C. The temperature inside the test tube is 108.5°G In U.StS.R. the temperature of the thermostat is 106.5°C. The blue paper should not turn definitely red in less than 7 hr. 

Acids. — Acetone should not redden blue litmus paper. 

Colorless, rhombic crystals, or white, crystalline powder, easily soluble (1 1) in water, but difficultly soluble in alcohol. The aqueous solution first reddens blue litmus paper and then bleaches it. 

A clear, colorless liquid of specific gravity 1.029 to 1.035. The acid first reddens blue litmus paper, and then bleaches it. The liquid contains about 6 per cent of S02. 

Organic Acids. — On shaking 1 gm. of alphanaphthol with 100 cc. of water and filtering, the filtrate should not redden blue litmus paper. 

Free Acid. Vigorously shake together 20 cc. of chloroform and 10 cc. of water Tor half a minute after the chloroform has separated, draw off the aqueous layer with a pipette. The liquid should not redden blue litmus paper, nor should it. acquire an opaleseenee when overlaid ori a mixture of 2.5 ce. of water and 2.5 cc. of silver nitrate solution. 

Acids. — Blue litmus paper, when immersed in collodion, should not be reddened immediately. 

A clear, colorless, mobile liquid of specific gravity 0.720, boiling at 34 to 36° C. Ether should not redden moist blue litmus paper. Filter paper which has been moistened with ether should have no odor when dry. 

Residue. — On allowing 20 cc. of ether to evaporate spontaneously in a glass dish, the residue must have no odor, and should not redden or decolorize blue litmus paper and it must be completely volatilized on warming on the water-bath. 

Free Acids and Bases. — On diluting 10 cc. of glycerin with 50 cc. of water, the solution should not affect red or blue litmus paper. 

IGNITE A SULFUR CANDLE [OR A TINY HEAP OF FLOWERS OF SULFUR) ON A PIECE OF TIN. HOLD MOISTENED BLUE LITMUS PAPER OVER FLAME. SULFUROUS ACID FORMED TURNS IT RED. 

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. 

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