signs of a chemical reaction

Evidence of a chemical reactions is anything that shows - 

• a new substance has formed
• a solid dissolved in a liquid
• interaction between 2 gases
• a change in the state of matter

One of the signs of a chemical reaction taking place is:

• Bubbles are produced 
• Reactants are not combining
• Products are not forming
• Color is not changing

Which of the following describes a precipitate?

• a liquid forms when a block of metal is heated
• a solid forms when one liquid is poured into another
• a gas forms when a solid is placed in a liquid
• bubbles form when an acid is poured on a rock

Which is NOT an indication of a chemical change?

• temperature change
• formation of a precipitate
• shape change
• production of light

You know you a chemical reaction has occurred if 

• there is a precipitate.
• there is a color change.
• there is a temperature change.
• All of these answers are evidence.

A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?

• The level of the substance in the beaker is higher after the other liquid is added.
• A yellow solid forms and then settles to the bottom of the beaker.
• Small white crystals are left behind in the flask that held the first liquid.
• The mass of the combined liquids is greater than either original liquid.

Dissolving salt is a

• Chemical change

• Physical change

The glow stick reaction is a

• Chemical change

• Physical change

The production of carbon dioxide gas when baking soda and vinegar reacted indicated a _____________.

• Chemical change

• Physical change

In a chemical reaction, no new atoms are created, and no atoms are _________________.

• Destroyed

• Created