Acid- base Reaction


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Acid- base Reaction

  1. 1. An acid (from the Latin acidus/acēre meaning sour) is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger. Chemicals or substances having the property of an acid are said to be acidic. Common examples of acids include acetic acid (in vinegar), sulfuric acid (used in car batteries), and tartaric acid (used in baking). As these three examples show, acids can be solutions, liquids or solids. Gases such as hydrogen chloride can be acids as well. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
  2. 2. Tartaric acid is a white crystalline diprotic organic acid. It occurs naturally in many plants, particularly grapes, bananas, and tamarinds; is commonly combined with baking soda to function as a leavening agent in recipes, and is one of the main acids found in wine. Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate).
  3. 3. A base in chemistry is a substance that can accept hydrogen ions (protons) or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions (OH−) quantitatively. The Brønsted-Lowry theory defines bases as proton (hydrogen ion) acceptors, while the more general Lewis theory defines bases as electron pair donors, allowing other Lewis acids than protons to be included. The oldest Arrhenius theory defines bases as hydroxide anions, which is strictly applicable only to alkali. Examples of common bases are sodium hydroxide and ammonia. Metal oxides, hydroxides and especially alkoxides are basic, and counteranions of weak acids are weak bases.
  4. 4. Sodium Hydroxide, commonly known as caustic soda, lye, or sodium hydrate, is a caustic compound which attacks organic matter. (caustic soda is sodium hydroxide, caustic potash is potassium hydroxide and silver nitrate is lunar caustic.) Ammonia is a chemical compound that consists of one nitrogen atom and three hydrogenatoms tightly bonded, which gives it the chemical symbol NH3. It can take the form of a strong-smelling liquid or gas.
  5. 5. There are three common definitions for acids: the Arrhenius definition, the Brønsted-Lowry definition, and the Lewis definition. Arrhenius definition -states that acids are substances which increase the concentration of hydronium ions (H3O+) in solution. Lewis definition -the modern-day definition of Lewis acid, as given by IUPAC is a molecular entity (and the corresponding chemical species) that is an electron-pair acceptor and therefore able to react with a Lewis base to form a Lewis adduct, by sharing the electron pair furnished by the Lewis base.
  6. 6. Brønsted-Lowry definition -it is an expansion: an acid is a substance which can act as a proton donor. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, and these two definitions are most relevant. The reason why pHs of acids are less than 7 is that the concentration of hydronium ions is greater than 10−7 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acids thus have pHs of less than 7. By the Brønsted-Lowry definition, any compound which can easily be deprotonated can be considered an acid. Examples include alcohols and amines which contain O-H or N-H fragments.
  7. 7. An acid–base reaction is a chemical reaction that occurs between an acid and a base. Several concepts that provide alternative definitions for the reaction mechanisms involved and their application in solving related problems exist. Despite several differences in definitions, their importance becomes apparent as different methods of analysis when applied to acid–base reactions for gaseous or liquid species, or when acid or base character may be somewhat less apparent. The first of these scientific concepts of acids and bases was provided by the French chemist Antoine Lavoisier, circa 1776.
  8. 8. Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution; 26 August 1743 – 8 May 1794; French pronunciation: [ twan lɔʁɑ də lavwazje]), the "father of modern chemistry",[1] was a French nobleman prominent in the histories of chemistry and biology. He named both oxygen (1778) and hydrogen (1783) and helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. He was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same.
  9. 9. What You Need: Baking Soda, Paper, Water, Light Bulb (heat source), Paintbrush or Swab, Measuring Cup, Purple Grape Juice (optional)
  10. 10. Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs. Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda. In colloquial usage, its name is shortened to sodium bicarb, bicarb soda, or simply bicarb. Grape juice is obtained from crushing and blending grapes into a liquid. The juice is often sold in stores or fermented and made into wine, brandy, or vinegar.
  11. 11. The incandescent light bulb, incandescent lamp or incandescent light globe produces light by heating a filament wire to a high temperature until it glows. The hot filament is protected from oxidation in the air with a glass enclosure that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposits metal vapor onto the filament, extending its life. The light bulb is supplied with electrical current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections. Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near hydrophilic surfaces. Under nomenclature used to name chemical compounds, Dihydrogen monoxide is the scientific name for water, though it is almost never used.
  12. 12. 1. There are at least two methods to use baking soda as an invisible ink. Mix equal parts water and baking soda. 2. Use a cotton swab, toothpick, or paintbrush to write a message onto white paper, using the baking soda solution as 'ink'. 3. Allow the ink to dry. 4. One way to read the message is to hold the paper up to a heat source, such as a light bulb. The baking soda will cause the writing in the paper to turn brown. 5. A second method to read the message is to paint over the paper with purple grape juice. The message will appear in a different color.
  13. 13. If you are using the heating method, avoid igniting the paper - don't use a halogen bulb. Baking soda and grape juice react with each other in an acid-base reaction, producing a color change in the paper. The baking soda mixture can also be used more diluted, with one part baking soda to two parts water. Grape juice concentrate results in a more visible color change than regular grape juice.