A science class is learning about exothermic reactions, which are reactions that transform chemical energy into heat. The students combine substance X and substance Y in a beaker. A chemical reaction between X and Y creates new substance Z. How could the students tell whether the reaction is exothermic? A. They could measure the change in mass of substance X and substance Y using a balance.
B. They could measure the increase in temperature of the mixed substances using a thermometer.
C. They could measure how long the chemical reaction lasts using a stopwatch.
D. They could measure the volume of substance Z using a graduated cylinder.