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No more coffee wasteMathophobia no moreDaylight Saving No MoreAnalysing how Brontë presents nature in 'Shall earth no more inspire thee'Understanding how Brontë presents nature in 'Shall earth no more inspire thee'RTI 11/5/25 IS vs Are, No More "Gonna" or "Finna" in writing, No More "Me and Lucy" in writing. Figurative Language and Context Clues AnalysisA shoemaker, by no fault of his own, had become so poor that at last he had nothing left but leather for one pair of shoes. So in the evening, he cut out the shoes which he wished to begin to make the next morning, and as he had a good conscience, he lay down quietly in his bed, commended himself to God, and fell asleep. In the morning, after he had said his prayers, and was just going to sit down to work, the two shoes stood quite finished on his table. He was astounded, and knew not what to say to it. He took the shoes in his hands to observe them closer, and they were so neatly made that there was not one bad stitch in them, just as if they were intended as a masterpiece. Soon after, a buyer came in, and as the shoes pleased him so well, he paid more for them than was customary, and, with the money, the shoemaker was able to purchase leather for two pairs of shoes. He cut them out at night, and next morning was about to set to work with fresh courage; but he had no need to do so, for, when he got up, they were already made, and buyers also were not wanting, who gave him money enough to buy leather for four pairs of shoes. The following morning, too, he found the four pairs made; and so it went on constantly, what he cut out in the evening was finished by the morning, so that he soon had his honest independence again, and at last became a wealthy man. Now it befell that one evening not long before Christmas, when the man had been cutting out, he said to his wife, before going to bed, "What think you if we were to stay up to-night to see who it is that lends us this helping hand?" The woman liked the idea, and lighted a candle, and then they hid themselves in a corner of the room, behind some clothes which were hanging up there, and watched. When it was midnight, two pretty little naked men came, sat down by the shoemaker's table, took all the work which was cut out before them and began to stitch, and sew, and hammer so skilfully and so quickly with their little fingers that the shoemaker could not turn away his eyes for astonishment. They did not stop until all was done, and stood finished on the table, and they ran quickly away. Next morning the woman said, "The little men have made us rich, and we really must show that we are grateful for it. They run about so, and have nothing on, and must be cold. I'll tell thee what I'll do: I will make them little shirts, and coats, and vests, and trousers, and knit both of them a pair of stockings, and do thou, too, make them two little pairs of shoes." The man said, "I shall be very glad to do it;" and one night, when everything was ready, they laid their presents all together on the table instead of the cut-out work, and then concealed themselves to see how the little men would behave. At midnight they came bounding in, and wanted to get to work at once, but as they did not find any leather cut out, but only the pretty little articles of clothing, they were at first astonished, and then they showed intense delight. They dressed themselves with the greatest rapidity, putting the pretty clothes on, and singing, "Now we are boys so fine to see, Why should we longer cobblers be?" Then they danced and skipped and leapt over chairs and benches. At last they danced out of doors. From that time forth they came no more, but as long as the shoemaker lived all went well with him, and all his undertakings prospered.A solution is a mixture in which one or more substances are uniformly distributed in another substance. Solutions can be mixtures of liquids, solids, or gases. For example, plasma, the liquid part of blood, is a very complex solution. It is composed of many types of ions and large molecules, as well as gases, that are dissolved in water. A solute (SAHL-YOOT) is a substance dissolved in the solvent. The particles that compose a solute may be ions, atoms, or molecules. The solvent is the substance in which the solute is dissolved. For example, when sugar, a solute, and water, a solvent, are mixed, a solution of sugar water results. Though the sugar dissolves in the water, neither the sugar molecules nor the water molecules are altered chemically. If the water is boiled away, the sugar molecules remain and are unchanged. Solutions can be composed of various proportions of a given solute in a given solvent. Thus, solutions can vary in concentra- tion. The concentration of a solution is the amount of solute dis- solved in a fixed amount of the solution. For example, a 2 percent saltwater solution contains 2 g of salt dissolved in enough water to make 100 mL of solution. The more solute dissolved, the greater is the concentration of the solution. A saturated solution is one in which no more solute can dissolve. Aqueous (AY-kwee-uhs) solutions—solutions in which water is the solvent—are universally important to living things. Marine microorganisms spend their lives immersed in the sea, an aqueous solution. Most nutrients that plants need are in aqueous solutions in moist soil. Body cells exist in an aqueous solution of intercellu- lar fluid and are themselves filled with fluid; in fact, most chemical reactions that occur in the body occur in aqueous solutions. Copyright © by Holt, Rinehart and Winston. All rights reserved. Liquid water Solid water Ice (solid water) is less dense than liquid water because of the structure of ice crystals. The water molecules in ice are bonded to each other in a way that creates large amounts of open space between the molecules, relative to liquid water. FIGURE 2-12 solvent from the Latin solvere, meaning “to loosen” Word Roots and Origins CHEMISTRY OF LIFE 43 ACIDS AND BASES One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base? Ionization of Water As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change: one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into two ions of opposite charge: H2O ∏ H OH The OH ion is known as the hydroxide ion. The free H ion can react with another water molecule, as shown in the equation below. H H2O ∏ H3O The H3O ion is known as the hydronium ion. Acidity or alkalin- ity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution. If the number of hydronium ions in a solution equals the number of hydroxide ions, the solution is said to be neutral. Pure water contains equal numbers of hydro- nium ions and hydroxide ions and is therefore a neutral solution. Acids If the number of hydronium ions in a solution is greater than the number of hydroxide ions, the solution is an acid. For example, when hydrogen chloride gas, HCl, is dissolved in water, its mol- ecules dissociate to form hydrogen ions, H, and chloride ions, Cl, as is shown in the equation below. HCl ∏ H Cl These free hydrogen ions combine with water molecules to form hydronium ions, H3O. This aqueous solution contains many more hydronium ions than it does hydroxide ions, making it an acidic solution. Acids tend to have a sour taste; how- ever, never taste a substance to test it for acidity. In concentrated forms, they are highly corrosive to some materials, as you can see in Figure 2-13. Bases If sodium hydroxide, NaOH, a solid, is dissolved in water, it dissociates to form sodium ions, Na, and hydroxide ions, OH, as shown in the equation below. NaOH ∏ Na OH Copyright © by Holt, Rinehart and Winston. All rights reserved. Eco Connection onnection Acid Precipitation Acid precipitation, more commonly called acid rain, describes rain, snow, sleet, or fog that contains high levels of sulfuric and nitric acids. These acids form when sulfur dioxide gas, SO2, and nitrogen oxide gas, NO, react with water in the atmosphere to produce sulfuric acid, H2SO4, and nitric acid, HNO3. Acid precipitation makes soil and bodies of water, such as lakes, more acidic than normal. These high acid levels can harm plant and animal life directly. A high level of acid in a lake may kill mollusks, fish, and amphibians. Even in a lake that does not have a very elevated level of acid, acid precipitation may leach aluminum and magnesium from soils, poisoning water- dwelling species. Reducing fossil-fuel consump- tion, such as occurs in gasoline engines and coal-burning power plants, should reduce high acid levels in precipitation. Sulfur dioxide, SO2, which is produced when fossil fuels are burned, reacts with water in the atmosphere to produce acid precipitation. Acid precipitation, or acid rain, can make lakes and rivers too acidic to support life and can even corrode stone, such as the face of this statue. FIGURE 2-13 44 CHAPTER 2 This solution then contains more hydroxide ions than hydronium ions and is therefore defined as a base. The adjective alkaline refers to bases. Bases have a bitter taste; however, never taste a substance to test for alkalinity. They tend to feel slippery because the OH ions react with the oil on our skin to form a soap. In fact, commercial soap is the product of a reaction between a base and a fat. pH Scientists have developed a scale for comparing the relative con- centrations of hydronium ions and hydroxide ions in a solution. This scale is called the pH scale, and it ranges from 0 to 14, as shown in Figure 2-14. A solution with a pH of 0 is very acidic, a solution with a pH of 7 is neutral, and a solution with a pH of 14 is very basic. A solution’s pH is measured on a logarithmic scale. That is, the change of one pH unit reflects a 10-fold change in the acidity or alkalinity. For example, urine has 10 times the H3O ions at a pH of 6 than water does at a pH of 7. Vinegar, has 1,000 times more H3O ions at a pH of 3 than urine at a pH of 6, and 10,000 times more H3O ions than water at a pH of 7. The pH of a solution can be measured with litmus paper or with some other chemical indicator that changes color at various pH levels. Buffers The control of pH is important for living systems. Enzymes can function only within a very narrow pH range. The control of pH in organisms is often accomplished with buffers. Buffers are chemi- cal substances that neutralize small amounts of either an acid or a base added to a solution. As Figure 2-14 shows, the composition of your internal environment—in terms of acidity and alkalinity— varies greatly. Some of your body fluids, such as stomach acid and urine, are acidic. Others, such as intestinal fluid and blood, are