thermochemistry

thermochemistry - Hydrocarbons and Heat Most hydrocarbons...

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Hydrocarbons and Heat Most hydrocarbons are used as fuels. Knowing how much energy a fuel provides, can tell us if it is useful for a certain application. For example, the amount of energy a food releases when burned, can tell us about it’s caloric content (fats release lots of energy). Heat energy released during combustion can be measured with a calorimeter. A “bomb calorimeter” is shown. It includes water in a heavily insulated container, a stirrer, valve, bomb chamber, ignition wires, & a thermometer (pg 577).
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Exothermic and Endothermic changes An alternative to the bomb calorimeter is a “coffee cup” calorimeter, where two nested polystyrene cups take the place of the container In either case, the change in heat of the water tells us about the reaction of the chemicals. An increase in water temperature indicates that the chemicals released energy when they reacted. This is called an “exothermic” reaction. In an “endothermic” reaction, water temperature decreases as the chemicals absorb energy. We will see that heat is measured in Joules (J) or kiloJoules (kJ). Before we do any heat calculations, you should know several terms …
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Specific heat capacity balloon demo The heat needed to the temperature of 1 g of a substance by 1 ° C. Symbol: c, units: J/(g ° C). Heat capacity
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thermochemistry - Hydrocarbons and Heat Most hydrocarbons...

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