Chemical Reactions Lesson One

Multiple Choice

Why is observing a color change important when identifying chemical reactions in everyday life, such as cooking?

• It shows that a new substance may have formed.

• It always means the food is cooked.

• It makes food look more appealing.

• It indicates the food is safe to eat.

Multiple Choice

Which of the following is NOT evidence that that a chemical reaction has occurred?

• produces light/heat
• production of a gas
• formation of a precipitate
• melting

Open Ended

How does the production of gas during the making of pizza dough provide evidence for a chemical reaction?

Multiple Choice

Which observation(s) might be used as evidence that a chemical reaction occurred?

• Color change
• Odor change
• Properties change
• All of the above

Multiple Choice

Which of the following situations is evidence of chemical change? 

• Boiling water produces steam
• Adding vinegar to baking soda makes foaming bubbles
• Sharpening a pencil
• Cutting paper

Multiple Choice

Which of the following best describes the difference between exothermic and endothermic reactions as explained in the text?

• Exothermic reactions absorb energy, while endothermic reactions release energy.

• Exothermic reactions release energy, while endothermic reactions absorb energy.

• Both exothermic and endothermic reactions absorb energy.

• Both exothermic and endothermic reactions release energy.

Open Ended

Analyze the graphs of exothermic and endothermic reactions. What does the difference in the energy of reactants and products indicate about the direction of energy flow in each reaction?

Multiple Choice

Equal amounts of four different substances (A-D) were added separately to equal amounts of an acid, and a thermometer was placed in the mixture. For which substance is the reaction the least endothermic?

• A. temperature falls by 3 $$\degree C$$    

• B. temperature rises by 5 $$\degree C$$

• C. temperature falls by 5 $$\degree C$$

• D. temperature rises by 3 $$\degree C$$

Multiple Choice

Equal amounts of four different substances (A-D) were added separately to equal amounts of an acid, and a thermometer was placed in the mixture. For which substance is the reaction the most exothermic?

• A. temperature rises by 3 $$\degree C$$    

• B. temperature falls by 5 $$\degree C$$   

• C. temperature falls by 3 $$\degree C$$    

• D. temperature rises by 5 $$\degree C$$  

Multiple Choice

Is photosenthysis an Exothermic or an Endothermic reaction?

• Endothermic
• Exothermic

Multiple Select

Which of the following factors can affect the rate of a chemical reaction, as described in the text?

• Surface area

• Temperature

• Concentration

• All of the above

Multiple Choice

What is the effect of a catalyst on the activation energy of a chemical reaction, as shown in the graph?

• It increases the activation energy needed for the reaction.

• It decreases the activation energy needed for the reaction.

• It has no effect on the activation energy.

• It stops the reaction from occurring.

Fill in the Blanks

Multiple Choice

In which experiment is the rate of reaction between hydrochloric acid and calcium carbonate slowest? 

• A
• B
• C
• D

Multiple Choice

What is the primary reason that endothermic reactions require an input of energy?

• To break bonds in the reactants

• To form new bonds in the products

• To increase the reaction rate

• To decrease the reaction rate

Multiple Choice

Four students performed four different investigations by combining different substances. Their results are shown in the table provided. In which experiment are new substances being formed?

• Experiment 1
• Experiment 2
• Experiment 3
• Experiment 4

Open Ended

How are chemical reactions used in art, and what are some examples of their application as described in the text?

Open Ended

Reflecting on what you learned about chemical reactions in the kitchen, how might you use this knowledge to identify chemical changes in other everyday activities?

Multiple Choice

What are some observable signs that a chemical reaction has occurred when making pizza?

• Color change, gas production, and formation of a precipitate

• Change in temperature only

• Change in shape only

• No observable signs