Question

Select all of the chemical changes and chemical properties from the list below.

a. Copper is left outside and begins to turn green, like the Statue of Liberty.
b. An electric lamp is turned on and the bulb gives off light and heat.
c. Milk is left on the counter for 3 days and begins to make a terrible smell.
d. Food coloring turns white frosting red.
e. Hydrochloric acid is poured on magnesium and begins to bubble.
f. Sugar is dissolved in sweet tea.

Answer 1

Chemical changes and properties from the list include copper turning green when exposed to air, indicating a reaction to form copper carbonate, milk souring due to bacterial fermentation, and magnesium reacting with hydrochloric acid to produce hydrogen gas. The other events listed represent physical changes where no new substances are formed.

Step-by-step explanation:

To identify which items from the list represent chemical changes and chemical properties, we look for signs of new substances being formed, such as color change, gas production, or energy transfer. The following items from the list indicate a chemical change or a chemical property:

• a. Copper is left outside and begins to turn green, like the Statue of Liberty. This is a chemical change because copper reacts with elements in the air to form a green patina, mostly comprised of copper carbonate. The green color indicates a new substance is formed.
• c. Milk is left on the counter for 3 days and begins to make a terrible smell. This represents a chemical change because the milk is undergoing a process called souring, where bacteria ferment the lactose, turning it into lactic acid, which is a new substance with a distinct smell.
• e. Hydrochloric acid is poured on magnesium and begins to bubble. The bubbling is evidence of a chemical change, as it indicates the production of hydrogen gas from the reaction between the acid and the metal.

The other examples from the list are: b. An electric lamp is turned on and the bulb gives off light and heat. - This is a physical change because it's a result of electrical energy converted to light and heat, not a chemical reaction within the bulb's material. d. Food coloring turns white frosting red. - This is a physical change because the food coloring is simply mixing with the frosting changing its color but not its chemical composition. And f. Sugar is dissolved in sweet tea. - Dissolving is a physical change, since it's a matter of sugar particles dispersing throughout the tea while still retaining their chemical identity.