Evidence of Chemical Reactions

What are the substances at the beginning of a chemical equation called?

• Products

• Catalysts

• Reactants

• Solvents

In the equation 2Mg + O2 ---> 2MgO, what are the reactants?

• Mg and O

• MgO and O2

• Mg and O2

• 2Mg and O2

How can you tell if a chemical reaction has occurred?

• By observing changes such as color change, temperature change, gas production, or formation of a precipitate.

• By measuring the pH level of the solution.

• By checking the density of the substances involved.

• By observing the size of the reactants before and after the reaction.

What is an exothermic reaction?

• A chemical reaction that absorbs energy in the form of heat.

• A chemical reaction that releases energy in the form of heat.

• A chemical reaction that occurs at low temperatures.

• A chemical reaction that requires a catalyst to proceed.

Give an example of evidence of a chemical reaction.

• Sugar that is burned gives off an odor and turns brown and then black.

• Water boiling to form steam.

• Ice melting into water.

• Salt dissolving in water.

What does evidence of a chemical reaction indicate?

• A new substance has formed.

• The temperature has changed.

• The color of the substance has remained the same.

• The mass of the substance has decreased.

What is a chemical reaction?

• A process where reactants are transformed into products, resulting in the formation of new substances.

• A method of separating mixtures into their individual components.

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

• A process that only occurs in living organisms.

What is the phrase to know if a Chemical Reaction has taken place?

• California-Girls-Love-To-Party (CGLTP)

• Chemical-Reaction-Indicator (CRI)

• Substance-Change-Alert (SCA)

• Reaction-Formation-Check (RFC)

What does it mean if a gas is produced during a chemical reaction?

• It indicates that a new substance has formed, often observable as bubbles.

• It means the reaction is exothermic and releases heat.

• It suggests that the reactants are in a gaseous state.

• It implies that the reaction is reversible and can go in both directions.

What are products in a chemical reaction?

• The substances that are formed as a result of a chemical reaction.

• The starting materials that undergo change during the reaction.

• The energy released during the reaction.

• The catalysts that speed up the reaction.