Chemical Reactions Everywhere

True or false: You can always tell if a chemical reaction has happened.

• True; chemical reactions always have visible signs.

• False; some reactions may not have obvious signs.

• True; all chemical reactions produce gas or heat.

• False; chemical reactions are always detectable by smell.

What is a chemical reaction?

• A process where substances (reactants) change into new substances (products) with different properties.

• A method of separating mixtures into their individual components.

• A physical change that alters the state of matter without changing its composition.

• A reaction that occurs only in the presence of a catalyst.

What is a product?

• A substance that is formed as a result of a chemical reaction.

• A type of chemical bond between atoms.

• A mixture of two or more substances.

• A process of combining elements to form compounds.

What is a precipitate?

• A gas that escapes from a liquid during boiling.

• A solid that forms from a solution during a chemical reaction.

• A liquid that evaporates when heated.

• A colorless solution that contains dissolved salts.

What is NOT evidence of a chemical reaction?

• Melting.

• Bubbling or fizzing.

• Color change.

• Temperature change.

What is oxidation?

• A chemical reaction where a substance combines with oxygen, often producing heat and light.

• A process where a substance loses electrons and increases its oxidation state.

• A reaction that occurs when a substance is cooled down rapidly.

• A method of separating mixtures using physical means.

Which of the following is NOT a chemical reaction?

• Burning wood

• Rusting iron

• Cutting a piece of paper in half

• Baking a cake

What is a reactant?

• A substance that undergoes change in a chemical reaction.

• A product formed after a chemical reaction.

• A catalyst that speeds up a chemical reaction.

• A mixture of two or more substances.

What is evidence of a chemical reaction?

• Color change, production of gas, temperature change, and formation of a precipitate.

• Change in smell only.

• Change in shape only.

• Increase in size only.

What is an example of a chemical reaction producing gas?

• Baking soda mixed with vinegar produces carbon dioxide gas.

• Mixing water and salt produces hydrogen gas.

• Heating sugar produces steam.

• Combining iron and sulfur produces a solid compound.