Chemical Changes

In a chemical reaction in which sodium and chlorine are chemically combined to form salt, which of the following are the reactants?

• sodium and chlorine

• sodium and salt

• salt and chlorine

• just salt

In a chemical reaction in which sodium bicarbonate and vinegar are chemically combined to form carbon dioxide, water, and sodium acetate, which of the following are products?

• sodium bicarbonate and water

• sodium acetate, water, and carbon dioxide

• sodium bicarbonate and vinegar

• carbon dioxide only

Which of the following is evidence that a chemical change has occurred?

• The reactants separate

• A strong odor

• A new substance is formed

• None of the above

Both physical and chemical changes affect matter, but physical changes are ______________ and chemical changes are ________________?

• reversible, irreversible

• permanent, reversible

• irreversible, reversible

• irreversible, permanent

An ice cube melts in a glass of water. Has a chemical reaction taken place? How do you know?

• Yes, a new substance was formed.

• Yes, a gas was given off.

• No, the color did not change.

• No, a phase change does not always indicate a chemical change.

Which of the following is an example of a chemical change?

• Rust forming on your bike.

• A popsicle melting in the sun.

• Rolling a ball of dough into a flat pizza.

• Boiling a pot of water.

Which of the following is an example of a physical change?

• Rust forming on your bike.

• Sugar turning into caramel

• Rolling a ball of dough into a flat pizza.

• Plants changing sunlight, water, and carbon dioxide into glucose and oxygen.

Which component represents a reactant in the diagram above?

• Carbon dioxide gas

• Baking soda

• Water

• Oxygen

Which component represents a product in the diagram above?

• Carbon dioxide gas

• Vinegar

• Air

• Baking Soda

Baking soda and vinegar chemically change. What evidence supports a chemical change?

• The baking soda dissolves

• A gas is produced

• A mixture is formed

• Color change