Physical and Chemical Changes + Specific Heat

Essay by rmassenaHigh School, 10th grade October 2014

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The specific heat of a substance is crucial in determining the amount of energy in the substance lost when the substance is being heated or cooled. The specific heat of an object it the amount of energy required to raise 1 gram of the substance 1 degree Celsius. In order to find the specific heat of a substance, you need other values such as the change in temperature, mass, and amount of energy gain/lost, and plug them into the equation q=mcΔt and solve for c, specific heat. Most substances have different specific heats which causes them to heat up and cool down at faster or slower rates. Liquid Water (H2O (L)) has a very high specific heat, indicating that it is very difficult to heat up or cool down. The equation q=mcΔt only works when there is a change in temperature and most of the time no phase change.

When there is a phase change and no change in temperature you use a different equation, q=mHF or q=mHV. The equation q=mHF is used for when a substance is being melted, frozen, or crystallized. In contrast, the equation q=mHV is used for when the substance is being boiled or is condensing. Using any of these 3 equations, you can find any variable that is present in one of them. For example, you can find energy gained/lost, mass, specific heat of a substance, or the change in temperature of the substance with just the equation q=mcΔt.

The words heat and temperature are used in this lab and being able to explain the difference between them is required. Heat is defined as the transfer of energy when something is being heated, energy from something with a great energy flows to a substance with lesser energy. Something being cold is simply just a...