🧪 Chemical Science End of Unit Assessment 🧪

Box Y:

• color
• odor
• flammability
• state of matter

Box Z

• amount of substance present
• structure of the substance′s molecules
• way the substance looks

Based on Figure 1, which data is the student trying to produce by conducting the investigation?

• A. the components that produce rust
• B. the types of metal that rust the fastest
• C. the amount of rust that forms every 10 days
• D. the amount of mass lost during the rusting process

Y

• A. test tube 1 only
• B. test tube 4 only
• C. both test tubes 1 and 4

Z

• A. formed a new shape
• B. changed in temperature
• C. formed a new substance

A solid, yellow substance formed when Mr. Simon poured two colorless liquids together at room temperature. Which statement best explains why this demonstrates a chemical reaction?

• A The color of the liquids changed to yellow.
• B One of the liquids dissolved in the other liquid.
• C One of the liquids changed from a liquid to a solid.
• D The yellow substance is a solid at room temperature.

Caitlin’s model has an error. What can Caitlin do to correct her model?

• Erase a hydrogen atom from the reactant molecule that has two hydrogen atoms.
• Add another hydrogen atom to the product molecule that has one hydrogen atom.
• Change the reactants to three molecules of one hydrogen atom and one oxygen atom.
• Change the product to one molecule of four hydrogen atoms and two oxygen atoms.

Scientists have found copper artifacts that were used as tools about 8,000 years ago. Later they found tools from the Bronze age (about 5,000 years ago) that were made from an alloy made from copper and tin. Copper is a soft, bendable metal. Tin is harder than copper, but is brittle, which means that it breaks easily. Bronze is harder and stronger than copper and not as brittle as tin. Describe the advantage of using bronze to make tools instead of copper.

• Bronze is a newer and improved metal.
• Bronze would be harder and more durable than copper. It wouldn’t get scratched and broken as easily as copper.
• Copper is more popular to use in coins and making statues. Bronze is better for hand tools.
• Bronze would be less expensive because it is made from a mixture of copper and tin.

Ms. Hawk set up a demonstration to show what happens when the metal zinc is added to a test tube containing hydrochloric acid. Students noticed that the test tube felt warmer after adding the zinc and the zinc decreased in size even though it is not soluble in hydrochloric acid. Which of the following indicates a chemical reaction has taken place? Select all that apply.

• The test tube feeling warmer is evidence of a chemical reaction.
• The piece of zinc gets smaller over time but is not soluble in hydrochloric acid.
• The students did not see any bubbles near the zinc so there was no chemical reaction

Select the best comparison of boiling water to electrolysis.

• When liquid water boils, the water undergoes a phase change from liquid to gas, but it’s all still water. Electrolysis is a chemical reaction. The atoms in the water molecules rearrange to form separate hydrogen gas and oxygen gas.
• When water boils, heat is added to water to make it change from a liquid to a gas. In electrolysis, electricity is added to water to make the water change from the liquid phase to the gas phase.
• Electrolysis happens when electricity is placed in water so that battery acid separates into hydrogen and oxygen gasses. When boiling water, heat breaks the water molecules into two atoms - hydrogen and oxygen.
• Boiling water is a phase change where heat is added to the water. The water molecules start to move faster and faster until they separate into water vapor which is a gas form. Electrolysis causes the water to heat up so much that it separates into oxygen and hydrogen.