Most cold packs utilize water and ammonium chloride or ammonium nitrate to create endothermic reactions. Endothermic reactions require energy and obtain it by absorbing heat from the environment.Know More
While the majority of commercial cold packs use ammonium nitrate or ammonium chloride, many types of salts create endothermic reactions. Instant cold packs maintain water and ammonium salt in separate sections, with a thin barrier in-between. Breaking the barrier allows the salt and water to mix, dissolving the salt. As the ammonium salt dissolves, it absorbs heat from the air around it, lowering the temperature of the water to its freezing point. Once the water reaches its freezing point, it becomes less effective at dissolving the salt, meaning that some salt remains. Eventually the water begins to warm, allowing more salt to dissolve and then cooling the water again. In this way, cold packs retain their cool temperature for an extended period of time.
Endothermic reactions do not just occur in cold packs. Mixing an acid, such as vinegar or citric acid, with baking soda, a base, absorbs heat and cools its container for a short amount of time. Because endothermic reactions are those that absorb energy rather than releasing it, photosynthesis is also an endothermic reaction as it requires the absorption of energy in the form of sunlight.Learn more about Chemistry
The chemical reaction for the burning of sugar by the body is shown through the chemical equation C12H22O11(s) + 12 O2(g) -----> 12 CO2(g) + 11 H2O(l). In this equation, C12H22O11 is the sugar, which burns by reacting with the oxygen to create carbon dioxide and water.Full Answer >
A chemical reaction can be shown to be endothermic if it absorbs heat and causes a decrease in the temperature of its surroundings. Illustrative lab experiments performed in schools to demonstrate endothermic reactions often use the reaction occurring between vinegar and baking soda or the reaction between barium hydroxide and ammonium nitrate. The latter reaction, if taking place in a flask resting in a small amount of water, will absorb enough heat from the water to cause it to freeze.Full Answer >
There are a few telltale signs that can help indicate that a chemical reaction has taken place; these include the creation of one or more new substances and a noticeable energy change from the reaction site. However, telling whether a chemical reaction has actually taken place is not always very easy to observe.Full Answer >
The chemical reaction for fermentation is expressed as the chemical equation: C6H12O6 ? 2 C2H5OH + 2 CO2. Showing the alcoholic fermentation of glucose as chemical formula C6H12O6, this one glucose molecule is converted into two ethanol molecules expressed as 2C2H5OH and two carbon dioxide molecules expressed as 2CO2.Full Answer >