Chemical Properties

A scientist is examining an unknown solid. Which procedure would most likely help determine a chemical property of the substance?

• heating it to find the temperature at which it melts

• exposing it to a flame to see if it catches on fire

• hitting it with a hammer to determine if it breaks or bends

• placing it in water to find out whether or not it dissolves

Which characteristic of a substance is considered a chemical property?

• its boiling point

• its reactivity

• its density

• its conductivity

Which statement best describes chemical properties of matter?

• Chemical properties, such as density, must be observed when a substance is in its natural state at room temperature and normal atmospheric pressure.

• Chemical properties, such as reactivity, must be observed when a substance is in its natural state at room temperature and normal atmospheric pressure.

• Chemical properties, such as combustibility, are generally observed as the identity of a substance changes and one or more new substances form.

• Chemical properties, such as boiling point, are generally observed as the identity of a substance changes and one or more new substances form.

Which use of iron is due to its chemical properties?

• producing colored sparks in fireworks

• changing from liquid to gas at 2,862°C

• conducting electricity and heat

• changing from solid to liquid if heated to 1,538°C

Which statement best describes what happens during a chemical change?

• Both the identity and the properties of a substance change.

• Some properties of a substance change, but its identity remains the same.

• The chemical properties of a substance change, but its physical properties remain the same.

• The physical properties of a substance change, but its chemical properties remain the same.

In a science demonstration, a teacher mixed zinc (Zn) with hydrogen chloride (HCl) in a flask and quickly attached a balloon over the mouth of the flask. Bubbles formed in the solution and the balloon inflated. What most likely occurred during this demonstration?

• The Zn and HCl both retained their identity.

• Either Zn or HCl, but not both, retained its identity.

• Evaporation of one of the substances occurred.

• One or more new substances formed.

Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation. Which statements correctly defend or dispute his conclusion?

• He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.

• He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.

• He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.

• He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.

In a science lab, Cash mixes two clear liquids together in a beaker. Bubbles are produced, and a white solid forms and settles to the bottom. He plans to heat the beaker over low heat and make more observations. Which statement is most likely correct?

• A physical change occurred, so if Cash heats it, the white solid will dissolve to form the original mixture of clear liquids.

• A physical change occurred, so even if Cash heats it, the white solid will remain.

• A chemical change occurred, so if Cash heats it, the white solid will dissolve to form the original mixture of clear liquids.

• A chemical change occurred, so even if Cash heats it, the white solid will remain.

What is the outcome of all chemical changes when two substances are combined?

• A new substance forms with identical properties.

• The two substances release an odor.

• The two substances change color.

• A new substance forms with different properties.

Which laboratory activity involves a chemical change?

• leaving a copper penny in vinegar until it turns green

• boiling saltwater for several minutes until only solid salt remains

• extracting iron filings from a sand mixture using a magnet

• crushing a rock with a hammer to extract mineral deposits