Chemical Changes and Energy

Energy is the ability to do work or produce heat Heat is commonly measured in joules or calories. One calorie is equivalent to 4.184 joules. 

The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius is the specific heat of the substance. Liquid water has a high specific heat of 4.184 J/(g C). By contrast, the specific heat of iron is 0.449 J/(g-°C). When the temperature of a substance changes, the amount of heat absorbed or released is given by the following equation. 

In the equation, = the heat absorbed or released, c = the specific heat of the substance, m = the mass of the sample in grams, and AT is the change in temperature in °C. 

A silver bar with a mass of 250.0 g is heated from 22.0°C to 68.5°C. How much heat does the silver bar absorb  

The temperature change is the difference between the final temperature and the initial temperature. 

Energy enables you to live, move from place to place, and stay comfortably warm or cool. Almost all of the energy you use comes from chemical reactions, including those that take place in your own body. 

Visit the Chemistry Web site at chemistrymc.com to find links about energy and chemical change. 

Each time the roller coaster zooms up and down the track, its energy changes back and forth between kinetic energy of motion and potential energy of position. 

Does a temperature change occur when a chemical reaction takes place  

Measure about 5 ml 5M NaOH solution and pour it into a large test tube. Determine the temperature of the solution. 

Ozone (03) in the atmosphere may react with nitric oxide (NO). 

From the following data, calculate the AG° in kJ for the reaction at 25 °C and determine whether the reaction is spontaneous. 

If AS = 75.8 J/K, what is the lowest temperature at which the reaction will be spontaneous  

Calculate the standard heat of vaporization, A//vap, for tin(IV) chloride, SnCl4. 

Given the following data at 298 K, calculate AS for the given reaction. 

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Electrochemistry is the study of the relationship between electrical energy and chemical change. It involves oxidation-reduction reactions to produce electricity, or electricity to cause an oxidation-reduction reaction. 

The branch of chemistry studying relationships between electrical energy and chemical change. 

The branch of chemistry dealing with heats of reaction and closely related subjects is called thermochemistry. The more general study of the relations between energy and chemical change, including such questions as the electrical potential that can be obtained from an electrolytic cell and tfie amount of work that can be done by chemical... 

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