Reaction Basics
These are the substances present at the beginning of a chemical reaction.
What are reactants?
This reaction is: A + B → AB
What is a synthesis reaction?
This law states that matter is not created or destroyed during a chemical reaction.
What is the Law of Conservation of Mass?
A reaction causes the surroundings to become warmer.
What is an exothermic reaction?
This describes how fast or slow a chemical reaction occurs.
What is reaction rate?
Cutting a piece of aluminum foil in half is this type of change.
What is a physical change?
This reactionis: AB → A + B
What is a decomposition reaction?
A sealed container has a mass of 125 g before a reaction. What should its mass be after the reaction?
What is 125 g?
A reaction causes the surroundings to become cooler.
What is an endothermic reaction?
This substance speeds up a chemical reaction without being used up.
What is a catalyst?
Bubbling, formation of a new solid, odor change, and temperature change can all provide this.
What is evidence that a chemical reaction occurred?
This reaction is: A + BC → AC + B
What is a single-displacement reaction?
Baking soda and vinegar react in an open container and the measured mass decreases. Why?
What is gas escaped from the container?
A reaction starts at 22°C and ends at 31°C. What type of thermal-energy reaction occurred?
What is exothermic?
This substance slows down a chemical reaction.
What is an inhibitor?
Two clear liquids are mixed and a solid forms. This new solid is called this.
What is a precipitate?
A reaction starts with one compound and produces two simpler substances. Identify the reaction type.
What is a decomposition reaction?
Iron rusts and the rust has more mass than the original iron. Where did the extra mass come from?
What is oxygen from the air?
Trial A changes from 20°C to 27°C. Trial B changes from 20°C to 16°C. Which trial absorbed thermal energy from the surroundings?
What is Trial B?
Students want to determine whether temperature affects reaction rate. Name one variable they should keep constant.
What is amount of reactant, type of reactant, container size, concentration, or another reasonable controlled variable?
Water turns pink and bubbles form when a bath bomb is added. Identify one physical change and one piece of evidence of a chemical change.
Physical change: the water changing color
Chemical evidence: gas/bubbles forming
A metal is placed into a compound and replaces another element in that compound. Identify the reaction type.
What is a single-displacement reaction?
Explain what happens to atoms during a chemical reaction.
The atoms are rearranged into new combinations, but the number and type of atoms are conserved.
A bath bomb causes water to cool from 24°C to 18°C. Explain what happened to thermal energy.
The reaction absorbed thermal energy from the surroundings, making the water cooler, so it was endothermic.
Group A’s bath bomb changes the temperature by 8°C but fizzes for 20 seconds. Group B’s changes the temperature by 3°C but fizzes for 75 seconds. Which design is better?
It depends on the design goal or criteria. Group A is better for a larger temperature change, while Group B is better for a longer reaction.