Exploring Reactions and Net Ionic Equations in AP Chemistry

This AP Chemistry lesson, led by Michael Farabaugh, covers Unit 4 topics including chemical reactions, physical vs chemical changes, balancing chemical equations, net ionic equations, and particle diagrams. The lesson begins with a review of a homework problem involving absorbance and concentration of cobalt solutions. It then explains the differences between physical and chemical changes, provides guidance on writing and balancing chemical equations, and details how to write net ionic equations. The lesson concludes with a discussion on using particle diagrams to represent chemical reactions.

What is the main focus of Unit 4 in this AP Chemistry lesson?

• Chemical Reactions

• Electrochemistry

• Organic Chemistry

• Thermodynamics

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

NGSS.HS-PS1-4

NGSS.HS-PS1-5

Where can students find more information about the online AP exam format?

• APstudents.org/resources

• APstudents.org/unit4

• APstudents.org/chemistry

• APstudents.org/exams2020

What is the approximate concentration of cobalt in a solution if the absorbance is 0.74?

• 0.013 moles per liter

• 1.3 moles per liter

• 0.130 moles per liter

• 0.0013 moles per liter

What is the approximate energy of one photon of light with a frequency of 6 x 10^14 Hz?

• 4 x 10^-19 joules

• 8 x 10^-19 joules

• 6 x 10^-19 joules

• 10 x 10^-19 joules

Tags

NGSS.HS-PS4-1

Which of the following is an example of a physical change?

• Rusting iron

• Baking a cake

• Melting ice

• Burning wood

What is a key indicator of a chemical change?

• Change in phase

• Change in temperature

• Formation of a new substance

• Change in size

What is the correct balanced chemical equation for the reaction between calcium hydroxide and hydrobromic acid?

• Ca(OH)2 + HBr → CaBr2 + H2O

• Ca(OH)2 + 2HBr → CaBr + 2H2O

• Ca(OH)2 + 2HBr → CaBr2 + 2H2O

• Ca(OH)2 + HBr → CaBr + H2O

Tags

NGSS.HS-PS1-7

Which of the following is a common mistake when writing net ionic equations?

• All of the above

• Using incorrect chemical formulas

• Balancing atoms but not charges

• Including spectator ions

Tags

NGSS.HS-PS1-7

What is the net ionic equation for the dissolution of calcium chloride in water?

• CaCl2 + H2O → Ca^2+ + 2Cl^- + H2

• CaCl2 + H2O → Ca(OH)2 + HCl

• CaCl2 → Ca^2+ + 2Cl^-

• CaCl2 → Ca + Cl2

Tags

NGSS.HS-PS1-7

In a particle diagram, what does the presence of excess reactant indicate?

• The product is in excess

• The reaction is incomplete

• There is leftover reactant

• All reactants are used up