Formation of a New Substance/Chemical Changes

A student stirs two liquids together and they turn into a solid. What type of change has happened and why?

• chemical, because a change instate of matter always means a chemical change
• physical, because it was stirred
• chemical, because a new substance was formed

A student has two 100 mL beakers of different clear liquids, both at room temperature. The student mixes them. Which of these reactions would NOT show a chemical change?

• The mixture’s volume is 200 mL.
• The mixture turns blue.
• The mixture heats up.

If a student is combining two substances and sees bubbles and fizzing, a ______ is probably taking place.

• chemical change
• physical change

What is the production of a precipitate?

• formation of solid particles out of a liquid
• formation of liquid drops from a gas
• formation of heat or light from a chemical change

A student mixes two clear liquids and the mixture slowly turns orange.Which conclusion can we draw about the clear liquids?

• They are both dangerous
• They formed a new substance
• At least one is an element

A man going camping chops a log to make firewood. Then he burns the firewood to roast his marshmallows.Which of these activities demonstrated a chemical change?

• Chopping the firewood
• Burning the firewood
• Neither are chemical changes

Someone boils water until it evaporates. What kind of change has happened and why?

• physical, because a new substance was not formed
• chemical, because the state of matter changed
• physical, because the identity of the substance was altered

Baking soda and vinegar are mixed,and immediately there are bubbles and fizzing. What does this show?

• formation of a gas
• formation of a precipitate
• formation of a new liquid

A half-eaten apple turns brown. How do we know that this is a chemical change?

• Change in color
• Change in temperature
• Change in state of matter

Someone accidentally dropped a test tube on the floor and it shatters. Is this an example of a chemical change?

• Yes, because heat energy was released
• Maybe, depending on how far the glass scattered
• No, because the identity of the glass wasn’t altered