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Free course Water for life. Question 26 What are the formulas for each of these four molecules? Figure 21 The unbalanced equation for the reaction between hydrogen and oxygen to give water: a diagrammatic representation; b ball-and-stick model.
Note that the oxygen molecule comprises two oxygen atoms linked by a double bond. If carbonic acid were added to this system, some of it would be converted to bicarbonate and hydrogen ions. In biological reactions, however, equilibrium is rarely obtained because the concentrations of the reactants or products or both are constantly changing, often with a product of one reaction being a reactant for another.
To return to the example of excess hydrogen ions in the blood, the formation of carbonic acid will be the major direction of the reaction. However, the carbonic acid can also leave the body as carbon dioxide gas via exhalation instead of being converted back to bicarbonate ion, thus driving the reaction to the right by the chemical law known as law of mass action.
These reactions are important for maintaining the homeostasis of our blood. The outer electron shell dictates how readily and what type of chemical bonds a particular atom will form. The formation of compounds is often visually outlined in chemical equations which show the reactants participating in chemical reactions to form products. Improve this page Learn More. Skip to main content. Module 2: Chemistry of Life. Search for:. Chemical Reactions and Molecules Learning Outcomes Identify the components of simple chemical reactions.
In Summary: Chemical Reactions and Molecules The outer electron shell dictates how readily and what type of chemical bonds a particular atom will form. Try It. Views Read Edit Edit source View history. Reading room forum Community portal Bulletin Board Help out! Policies and guidelines Contact us. Add links. General Chemistry. Synthesis reactions always yield one product. Reversing a synthesis reaction will give you a decomposition reaction.
This is the most well-known example of a synthesis reaction—the formation of water via the combustion of hydrogen gas and oxygen gas. One example is the electrolysis of water passing water through electrical current to form hydrogen gas and oxygen gas.
Hydrogen peroxide slowly decomposes into water and oxygen because it is somewhat unstable. The process is sped up by the energy from light, so hydrogen peroxide is often stored in dark containers to slow down the decomposition.
Carbonic acid is the carbonation that is dissolved in soda. It decomposes into carbon dioxide and water, which is why an opened drink loses its fizz. Decomposition, aside from happening spontaneously in unstable compounds, occurs under three conditions: thermal, electrolytic, and catalytic. Thermal decomposition occurs when a substance is heated.
Electrolytic decomposition , as shown above, is the result of an electric current. Catalytic decomposition happens because a catalyst breaks apart a substance. An example is lead nitrate mixed with potassium iodide, which forms a bright yellow precipitate of lead iodide.
Note that the lead iodide is formed as a solid. The previous equation is written in molecular form, which is not the best way of describing the reaction. Each of the elements really exist in solution as individual ions, not bonded to each other as in potassium iodide crystals. If we write the above as an ionic equation , we get a much better idea of what is actually happening. Notice the like terms on both sides of the equation.
These are called spectator ions because they do not participate in the reaction. They can be ignored, and the net ionic equation is written. For example, when hydrochloric acid and sodium hydroxide react, they form water and sodium chloride table salt.
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