Oysters Lessons 1-6 Mid-Unit Test Review

In a lab in Lesson 2 we investigated what would happen to the water when we increased the amount of carbon dioxide in the air. To do so, we designed a system similar to what is pictured here. What type of system did we design, and why is that important for understanding why the water changed color?

• We created a closed system, so we know that adding carbon dioxide to the air inside the cup is responsible for the water changing color; the only new thing in the system was the carbon dioxide, so we know it is what must be going into the water.
• We created an open system, which is important because it is the closest thing to the ocean and the atmosphere in the real world, which we are trying to study in the classroom.

The data we collected in class in Lesson 2 could be modeled like the picture here, where the increasing carbon dioxide from the baking soda and vinegar moved into the water, which decreased the pH. Our classroom investigation was designed to simulate the real world, where the oceans are getting more acidic (decreased pH). Using the model pictured here, and our investigative design with the cups from class, describe how we could change our investigation design so that the water wouldn’t get as acidic as it did. Choose the option that best represents a solution in the real world.

• Decreasing the amount of baking soda would make fewer carbon dioxide molecules go into the air. This would be like reducing CO2 emissions.
• Adding water to the cup would change the water to carbon dioxide ratio, changing the decrease in pH. This would be like adding water to the ocean.
• Removing the lid from the cup system would allow some of the carbon dioxide to escape the system. This would be like removing the atmosphere from the earth.

In automobiles, gasoline (C8H18) mixes with oxygen and burns in order to provide the energy they need to move. When they do, carbon dioxide (CO2) is released. What chemical equation is the most accurate model for the reaction?

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The CO2 that goes into the atmosphere can end up going into the ocean. Which chemical reaction model below could be used to predict what will happen to the CO2 once it is in the ocean?

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Which of the following models best illustrates how carbonic acid reacts in the water:

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This pH strip starts as a yellow-green color. After dipped in a liquid, we can determine that the pH of the substance tested is approximately...

• 1

• 6

• 11

Based on the color of the pH test strip, the substance that was tested is most likely a(n)...

• acidic substance

• basic substance

• neutral substance

Choose the chemical formula that best represents the substance tested on this pH strip.

• HCN

• H2O

• NaOH

Which equation in this set is balanced?

• A

• B

• C

Which equation in this set is balanced?

• A

• B

• C