Science Assessment

Students should know that:

1. When energy is released from a chemical reaction, the products of the reaction have less chemical energy than the reactants; when energy is taken in from the surroundings the products of the reactants have more chemical energy than the reactants.
2. The amount of energy released or taken in during a chemical reaction depends on the specific reactants and the amounts of each reactant present in the system. Increasing the amounts of reactants increases the amount of energy released or taken in and decreasing the amounts of reactants decreases the amount of energy released or taken in.
3. The production of light or sound or an increase in temperature or motion in the surroundings is evidence that energy was released during the chemical reaction. In the case where the temperature of the surroundings increases, some chemical energy was converted to thermal energy and that thermal energy was transferred to the surroundings.
4. One way to determine the relative amount of energy released during two chemical reactions is to compare the change in temperature of the surroundings that accompanies each reaction.  The larger the increase in temperature of the surroundings, the more energy was released during the reaction.
5. A decrease in the temperature of the surroundings during a chemical reaction is evidence that energy from the surroundings was taken in and thermal energy was converted to chemical energy.  Additionally, light and sound can also be taken in from the surroundings but this may be difficult to observe.
6. Energy released during a chemical reaction can be used to drive/power a variety of processes.  For example, energy released during chemical reactions that occur inside of a battery can be used to power a flashlight and energy released during chemical reactions that occur inside an animal’s body can be used to contract muscles that the animal uses to move.

Boundaries:

1. At this level, students are not assessed on the idea that there is a relationship between chemical energy and the configuration of the atoms in molecules of a substance.  This knowledge is covered under the advanced chemical energy idea.
2. Students are not assessed on the definitions of the words “reactants” and “products” but they should understand reactants and products to be the starting and ending substances of a chemical reaction.
3. For this idea, dissolving is considered a chemical change (because the configuration of and interactions between atoms change). Therefore, item contexts may include the dissolution of ionic solids (e.g. cold packs).
4. Students are not expected to know that the energy that can be released from or absorbed by a chemical reaction system depends on other conditions such as temperature or type of solvent.
5. Students are not expected to quantify how much chemical energy is stored in any particular chemical reaction system. For example, students are not expected to use tables of bond energies or do calculations involving such data.  The sub-ideas above describe semi-quantitative relationships.