Complete the statement.
During this chemical reaction, the car engine becomes ().

 - colder
 - warmer
To determine whether the car engine becomes warmer or colder, look for the text that describes the movement of thermal energy during the reaction.The gasoline used in cars today is a mixture of over 1,000 different substances. One of these substances is isooctane (C8 H18). In a car engine, isooctane reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2 O). During the reaction, a large amount of thermal energy is released into the surroundings. This thermal energy is used to power the car.The underlined text tells you that thermal energy is released into the surroundings. Because thermal energy moves out of the reaction and into the surroundings, the temperature of the surroundings increases.The surroundings include the car engine that the reaction takes place in. So, the car engine becomes warmer.