215. What per cent of pure marble, CaCO3, is oxygen? 216. What per cent of gypsum (plaster of Paris), CaSO1+ 2 H2O, is sulphur? 217. What per cent of washing-soda, Na, CO2+10 H2O, is carbon? 2 218. In 118 lbs. of Glauber salts, Na2SO4 + 10 H2O, how many ounces of sulphur? 219. How many ounces of soda, Na,O+H2O, in 7 lbs. of borax, Na2B4O7+10 H2O? 2 220. What per cent of pure alcohol, C2H, O, is carbon? What per cent of pure white marble, Ca COs, is carbon? 221. What per cent of pure acetic acid (the acid of vinegar), is carbon, the formula being C2HO2? 222. How much acetic acid can be obtained from 12 lbs. of alcohol, C2 HO, if there is no waste? 2 223. How many grains of carbon in 1 oz. avoirdupois of oxalic acid, C2H204+2H2O? 224. How many milligrams of carbon in 3o of tartaric acid, CHO? 225. How many kilograms of carbon in 95% of white sugar, C12H22O11? 226. The formula of camphor is C10 H18 O. How many grams of carbon in 14kg of camphor? 227. In 20kg of oil of vitriol, H2SO4, how many grams of sulphur? 228. What per cent of oil of vitriol is water? what per cent sulphuric acid, SO,? 229. In 3.5% of black oxide of iron, FeO, how many milligrams of iron? 230. Red iron-rust consists of 70% iron and 30% oxygen. Find its formula. 231. The choking vapor of burning sulphur is equal parts 'sulphur and oxygen. What is its chemical form ula? 232. If the composition of copperas is sulphuric acid 28.9%, oxide of iron 25.7%, water 45.4%, what is its formula? SOLUTION. Water being 18, oxide of iron 72, and sulphuric acid 80, first seek multiples of 72 and 80, in the proportion of 25.7 to 28.9; that is, of .8892 to 1. But it is evident that 72 and 80 are in almost exactly that proportion. This gives FeSO+water; and the remaining question is to find a multiple of 18 which is to 152 as 45.4 is to 54.6; that is, which is .8314 of 152, or 126.3. But 7 × 18 = 126; and the addition of seven parts of water gives as the complete formula, 233. Spirits of turpentine is 11.76% hydrogen and 88.24% carbon. Give a chemical formula which will express that fact. Compare now with camphor, C10H1O. What per cent of oxygen combined with spirits of turpentine are required to make camphor? 234. Out of the ten digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, how many numbers each consisting of two figures can be formed? 235. How many odd numbers consisting of two figures can be formed with the ten digits? 236. With the digits 0, 1, 2, 3, 4, 5, how many numbers between 1000 and 4000 can be formed? 237. How many dominoes are there in a set numbered from double blank to double nine? 238. How many different amounts can be weighed with 1-lb., 2-lb., 4-lb., 8-lb., and 16-lb. weights? Volumes. Surfaces. Lengths. Circle and Sphere. Roots. Extreme and mean ratio II. SELECTED CONSTANTS. Constants. Diagonal of square in terms of side 1.4142136 Side in terms of diagonal Cube root of 2 Cube root of Square root of 20 Square root of 3 Square root of Square root of 30 Square root of 5 0.1505150 .7071068 9.8494850 1.2599210 0.1003433 .7937002 9.8996567 4.4721359 0.6505150 1.7320508 0.2385606 .5773503 9.7614394 Weights. |