Law of Conservations of Mass

Multiple Choice

The chemical formula for acetic acid is CH3COOH. How many hydrogen atoms are in one molecule of acetic acid?

• 3

• 4

• 5

• 6

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(Activate Learning) Engage

1. Bell Ringer: POD “Problem of the Day”

(Explicit Instruction)
2. “I Do”: Everyday Phenomenon – Teacher Demo (Glowstick)

(Interactive Practice) Explore
3. “We do”: Wayground walkthrough to review steps and expectations for the Virtual Lab

(Independent Practice)
4. “You do”: Complete Virtual Lab in SAVVAS

(Demonstration of Learning)
5. Exit Ticket: Conservation of Mass problem

(Closure)
6. Reread CO/LO and connect back to the Virtual Lab

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​FRIDAY

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​9/12/2025

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​CO: I will investigate a chemical reaction in a virtual lab to explore the relationship between reactants and products.

LO: I will describe my observations and explain my reasoning about the Law of Conservation of Mass using correct science vocabulary (reactants, products, mass, conservation) during the virtual lab and exit ticket.

Open Ended

What do you predict will happen to the mass of the glow-stick as the reaction continues?

Open Ended

What will you investigate in this activity?

Open Ended

How do you think the numbers of atoms before a reaction will compare to the numbers after the reaction?

Multiple Choice

Which of the following best describes the Law of Conservation of Mass?

• Mass is created during a chemical reaction.

• Mass is destroyed during a chemical reaction.

• Mass is neither created nor destroyed during a chemical reaction.

• Mass always increases during a chemical reaction.

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Open Ended

What pattern did you notice when analyzing the chemical reactions? How did the number of each type of atom before the reaction compare to the number of each type of atom after the reaction?

Open Ended

In a chemical reaction, matter is conserved. This means that no new atoms are made and no atoms are destroyed. Explain how your observations of the chemical reactions in this activity support this idea.

Open Ended

1. In your own words, what did you notice about the total mass of reactants compared to the total mass of products in the Virtual Lab?

2. A reaction starts with 45 g and 132 g of reactants. The products are 24 g, 73 g, and one unknown. What is the mass of the missing product?

Fill in the Blanks

Open Ended

Exit Ticket – Law of Conservation of Mass

1. What happened to the total mass in the Virtual Lab?
☐ Increased  ☐ Decreased  ☐ Stayed the same

2. Explain why you think that happened.
Sentence starter: The mass stayed the ______because_____

3a. Total mass of the reactants = 45 g + 132 g = ____ g
3b. Total mass of the known products = 24 g + 73 g = ____ g
3c. Missing product mass = Reactants − Products = ____ g