IC 2 - Lesson 6-10

1. What happened when you mixed baking soda and road salt together? Based on the data table, which claim and supporting evidence are most accurate?

• a. Road salt, baking soda, and water when put together form a mixture. The white stuff in the baggie is a combination of baking soda and road salt.
• b. A new substance was formed when road salt, baking soda, and water were put together in a plastic bag.
• c. A new substance was formed when road salt, baking soda, and water were put together in a plastic bag. Before combining the substances, there were two white solids and one clear liquid. After combining the three substances, I observed a clear liquid and solid, and the bag became hot. We saw bubbles and the bag expanded.
• d. A new substance formed when road salt, baking soda, and water combined. When the substances were mixed together we noticed the bag expand and heat up. This tells us a gas was released. Although baking soda and road salt are both soluble in water, the white stuff in the baggie was not soluble in water.

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2. Which of the following observations does not indicate a chemical reaction has taken place?

• a. Temperature and/or color change
• b. A substance melts
• c. Gas is released - bubbles appear
• d. A precipitate was formed

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3. In the following equation, which is the reactant and which is the product? aluminum + copper chloride → copper + aluminum chloride

• a. Copper chloride is the reactant and copper is the product.
• b. Aluminum + copper are the reactants and aluminum chloride + copper chloride are the products.
• c. Aluminum + copper chloride are the reactants and copper + aluminum chloride are the products.
• d. Aluminum is the reactant and aluminum chloride is the product.

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4. Pavlo mixed two clear liquids together in a beaker in equal amounts. The mass of the two combined solutions and the beaker was 100g. After a few minutes, a yellow solid formed and settled to the bottom of the beaker. The mass of the beaker containing the yellow solid and the remaining liquid was 100g. Did a chemical reaction occur in Pavlo’s experiment? How do you know?

• a. A chemical reaction occurred because there was a change of color and a precipitate formed.
• b. Because the mass remained at 100g, a chemical reaction did not occur.
• c. A chemical reaction occurred because a liquid changed to a solid.
• d. A chemical reaction did not occur because there was no temperature change and no gas was released.

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5. In real life, substances can change into other substances, but only in a fairy tale could straw turn into gold. Why? What is the scientific reason that straw cannot be turned into gold?

• a. Gold can only be formed in the ground and straw is grown above ground.
• b. Gold is a naturally occurring pure substance and can not be created.
• c. When something new is made in a chemical reaction, it is made out of the materials that you start with. Straw does not contain any gold, so it is impossible to end up with gold as a new substance.
• d. Straw is a stalk of grasses like white, oats, rye, and barley that has been separated from the seed and dried. There is nothing left in the straw to react with for a chemical reaction to take place.

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6. Did a chemical reaction occur when magnesium was burned? Select the best explanation.

• a. A chemical reaction occurred when the teacher burned magnesium. While the two solids have the same solubility, the magnesium (the solid before burning) has a different color, hardness, density, and melting point than the solid after burning. The products of a chemical reaction are different substances from the reactants. The properties of the solids are different, so a chemical reaction occurred.
• b. A chemical reaction occurred when the magnesium was burned. Because the properties are different we know that a chemical reaction has taken place.
• c. The magnesium has the same solubility in water before and after the burning but all of the other properties have changed so a chemical reaction happened.
• d. A chemical reaction occurred when a strip of magnesium was burned. The strip of magnesium was a silver solid before the burning and now is a white powder with a different density and melting point.

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7. A chemical reaction describes what is happening and how substances interact with each other in the form of symbols instead of words in sentences. What does each symbol represent in the molecular formula?

• a. The symbols show the number and types of atoms that are in the reaction.
• b. Each formula shows symbols and numbers.
• c. Each formula shows how substances are combined with other substances to make new substances.
• d. Every formula is different depending on what substances are reacting with each other.

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8. When magnesium and oxygen interact together, it produces magnesium oxide, which is a new substance. Which of the following best represents this statement? Select the 2 answers that apply.

• a. magnesium + oxygen → magnesium oxide
• b. 2Mg + O 2 → 2MgO
• c. magnesium oxide → magnesium and oxygen
• d. MgO + MgO → 2MgO

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9. The chemical equation of the burning of magnesium shows we started with Mg and O and ended up with MgO. Which of these is considered the reactant and which is considered to be the product of the reaction? Were any new atoms introduced?

• a. The reactants are Mg and O. The product is MgO. The new atom is MgO
• b. The reactants are Mg and O. The product is MgO. No new atoms were introduced.
• c. The new atom of magnesium oxide is the product of the chemical reaction.
• d. The reactant is MgO and the products are Mg and O. No new atoms were introduced.

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10. Look at the symbols for magnesium, oxygen, and magnesium oxide. Which model best represents the chemical reaction of the burning of magnesium? Magnesium: Mg Oxygen: O 2 , Magnesium oxide: 2MgO

• a. Model 1 is the most accurate.
• b. Model 2 is the most accurate.
• c. Both models are the same.
• d. Neither model represents the chemical reaction.

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