Introduction to Chemical Reactions Answers

Which best explains why a firework being ignited is an example of an exothermic reaction and not an endothermic reaction?

For a science project, Janet performs four experiments that are supposed to show a chemical reaction. She displays her results in a table.

Which is an example of a chemical reaction?

Pedro wants to create a chemical reaction between oil and water. He adds oil to a beaker of water and notices that the liquids do not mix. He then shakes the beaker and the drops of oil become suspended through the water for a few moments before returning to their separate layers.

When vinegar and baking soda react, the mixture becomes cold to the touch and a gas and a new liquid substance are formed.

Which of these most likely represents a chemical change?

Which best describes what happens to the atoms in a chemical reaction?

Cherylanne mixes together Chemical A and Chemical B in a test tube, forming Chemical C. The mixture instantly turns cool to the touch. She then adds Chemical D, and the reaction becomes hot and explodes.

What must occur in order for a chemical reaction to be specifically classified as endothermic instead of exothermic?

Reggie and Charlotte are baking oatmeal cookies. They dip the baked cookies in melted chocolate. The chocolate cools to form a hardened coating. Reggie argues the entire chocolate-covered cookie has undergone a chemical change. Charlotte disagrees, saying only the original oatmeal cookie has undergone a chemical change, not the chocolate coating.