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

 - colder
 - warmer
To determine whether the solution becomes warmer or colder, look for the text that describes the movement of thermal energy during the reaction.Dutch chocolate is a special type of chocolate that has a dark color and a mild flavor. It is made by treating chocolate with a solution of water and sodium hydroxide (NaOH). When sodium hydroxide dissolves in water, sodium ions (Na+) and hydroxide ions (OH−) form in the solution. During this process, chemical energy is converted to thermal energy, which flows into the surroundings.The underlined text tells you that thermal energy flows 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 solution that the reaction takes place in. So, the solution becomes warmer.