Physical and Chemical Changes

Front

Why are lighting a match and baking a cake considered chemical changes?

Back

They create new substances.

Front

Which of these changes involves a chemical change in matter?

• evaporation of water
• grinding of rock
• melting of ice
• rusting of iron

Back

rusting of iron

Front

Which change should be categorized as a chemical change? Options: iron becomes rusty, a gold bar is melted, lake water evaporates, a granite rock is polished.

Back

iron becomes rusty

Front

Which event is an example of a chemical change?

• fog rising off a river
• wood burning in a fireplace
• ice cream melting in the sunshine
• grinding peppercorn into pepper flakes

Back

wood burning in a fireplace

Front

Which statement BEST describes the formation of rust?

Back

Rust results from a chemical reaction between iron and water.

Front

Which is an example of a chemical reaction?

• Vinegar added to baking soda forms a gas.
• Water evaporates into air.
• Sugar dissolves in water.
• Corn kernels are crushed to form flour.

Back

Vinegar added to baking soda forms a gas.

Front

A chemical change happens when:

• glass breaks into pieces.
• dough bakes in an oven.
• ice cream melts into a liquid.
• electricity flows through a wire.

Back

dough bakes in an oven.

Front

When a person chews, saliva from the mouth mixes with starches in food. These starches begin to turn into sugars. Changing starches into sugars is BEST described as:

Back

a chemical change.

Front

Which part of digestion is mainly a chemical change? Options: Teeth break food into small pieces, Throat muscles push food toward the stomach, Stomach acids dissolve food into nutrients, Intestinal cells transport nutrients into the blood.

Back

Stomach acids dissolve food into nutrients

Front

Why does the temperature of a cold pack with separate liquid and powder sections drop when squeezed?

Back

A chemical change occurs.