TABLE VIII. — FOODS OF ANIMAL ORIGIN Important Ash Constituents in the One-hundred Calorie Portion of Edible Material 1 1 From Sherman, Chemistry of Food and Nutrition, pp. 338-341. APPENDIX B REAGENTS A mole, or gram-molecule, of a substance is the molecular weight in grams. An equivalent weight, or gram-equivalent, of a substance is the quantity which is chemically equivalent to one gram-atom (1.008 grams) of hydrogen. A molar solution of any substance contains one mole of the substance per liter. A twice-molar solution (2 M) contains twice this quantity per liter, a half-molar solution (M/2) half the quantity per liter, and so on. A normal solution of any substance contains one equivalent weight of the substance per liter. A twice-normal solution (2 N) contains twice this quantity per liter, a half-normal solution one half this quantity per liter, and so on. H2SO4 36.5 grams Equivalent weight 36.5 grams Molar solution (M) contains 36.5 grams hydrogen chloride gas per liter. This is also the normal solution (N) of hydrogen chloride. A twice-molar solution (2 M, also 2 N) contains 73 grams hydrogen chloride per liter. Molecular weight 98 Mole 98 grams Equivalent weight 49 grams A molar solution of sulphuric acid contains 98 grams pure sulphuric acid per liter. This solution is twicenormal, 2 N. A half-molar (M/2) solution of sulphuric acid contains 49 grams per liter. This is a normal solution. Al2(SO4)3 Molecular weight 342. Since there are two atoms of aluminium, each equivalent to three atoms of hydrogen, the mole of aluminium sulphate is equal to six equivalent weights. The equivalent weight is, therefore, 57. A molar solution (M) of aluminium sulphate is a six times normal (6 N) solution. A normal solution (N) is one-sixth molar (M/6). Reagents for General Use Acetic Acid, 2 N. Dilute 115 cc. glacial acetic acid to one liter. Dilute 340 cc. concentrated ammonium hydroxide (sp. gr. 0.90) to one liter. Ammonium Oxalate, N/2 (M/4). 35 grams crystals, (NH4)2C2O4 . H2O, to one liter. Barium Chloride, N (M/2). 122 grams crystals, BaCl2. 2 H2O, to one liter. Calcium Chloride, N (M/2). 56 grams anhydrous calcium chloride or 110 grams crystals, CaCl2 . 6 H2O, to one liter. Calcium Hydroxide, Saturated. Slake a lump of quicklime, weighing about half a pound, by pouring upon it as much warm water as it will absorb and allowing it to stand for about ten minutes. Put the slaked lime in a two-liter bottle, fill the bottle with distilled water, and shake well, allow to settle, and decant the clear liquid. By refilling the bottle with water many batches of limewater may be prepared from the same portion of lime. Calcium Sulphate, Saturated. About 2.5 grams crystals, CaSO4. 2 H2O, to one liter. Copper Sulphate, N/2 (M/4). 62 grams crystals, CuSO4. 5 H2O, to one liter. Ether. Fehling-Benedict Solution. 17.3 grams copper sulphate crystals, CuSO4. 5 H2O 173 grams sodium citrate 100 grams sodium carbonate, anhydrous, or 270 grams sodium carbonate crystals, Na2CO3. 10 H2O U to one liter Ferric Chloride, N (M/3). 90 grams crystals, FeCl3 . 6 H2O, to one liter. Hydrochloric Acid, Concentrated. About 13 N. Specific gravity I.20. Hydrochloric Acid, Dilute, 2 N. Specific gravity 1.035. Dilute 170 cc. concentrated hydrochloric acid to one liter. Iodine. 20 grams potassium iodide to one I gram iodine Jliter Lead Acetate, N (M/2). 190 grams crystals, Pb(C2H3O2)2. 3 H2O, to one liter. Litmus. Heat 10 grams commercial cubes with about 200 cc. water. Filter. Wash the residue several times with hot water. Make up to one liter. Magnesium Chloride, N (M/2). 102 grams crystals, MgCl2. 6 H2O, to one liter. Mercuric Chloride, N/5 (M/10). 27 grams to one liter. Millon's Reagent. Treat mercury with twice its weight of concentrated nitric acid (in a porcelain dish under the hood). Warm gently towards the last. When all is dissolved, add the liquid to twice its volume of water. Allow to settle a few hours and decant the clear liquid. Nitric Acid, Concentrated. About 16 N. Specific gravity 1.42. Specific gravity 1.065. Dilute 130 cc. concentrated nitric acid to one liter. Phenolphthalein. 5 grams in one liter of alcohol (or of 60 per cent alcohol). Potassium Ferrocyanide, N (M/4). K4Fe(CN)6.3 H2O, to one liter. 106 grams crystals, Potassium Hydroxide, 50 per cent. 770 grams to one liter. Potassium Permanganate, M/10. 16 grams to one liter. liter hot water and filter. Dissolve in one Sodium Carbonate, N (M/2). 53 grams anhydrous, or 143 grams crystals, Na2CO3. 10 H2O, per liter. Sodium Hydroxide, 30 per cent. 400 grams to one liter. Sodium Hydroxide, 2 N. sticks to one liter. About 85 grams sodium hydroxide Sodium Phosphate, N (M/3). 119 grams crystals Na2HPO4. 12 H2O to one liter. |