Chapter 2.3 (Exam 1) Chemical Reactions

Question 1

When do chemical reactions occur?

Answer 1

Chemical reactions occur when atoms collide with enough energy to combine or change their bonding partners

Question 2

Name an example of a chemical reaction.

Answer 2

Combustion of propane:

Propane reacts with oxygen (the reactants) and the atoms change partners to form CO₂ and H₂O (the products)

Question 3

Which type of chemical reaction is combustion classified as?

Answer 3

Combustion is an oxidation–reduction (redox) reaction—electrons are transferred between two molecules

Question 4

What is an oxidation–reduction (redox) reaction?

Answer 4

Electrons are transferred between two molecules: one molecule is oxidized, gaining O₂ and losing electrons, while the other is reduced, losing O₂ and gaining electrons

Question 5

Why must chemical reactions be balanced on both sides?

Answer 5

Matter and energy can neither be created nor destroyed

Question 6

What is energy?

Answer 6

Capacity to do work or the capacity for change

Question 7

What happens to energy during chemical reactions? How is this shown by the combustion of propane?

Answer 7

Energy usually changes form during chemical reactions

In propane combustion, the energy in propane is potential chemical energy in the covalent bonds; it changes to heat and light