Learning Outcome

Students will complete the following labs, observing the concentration of different substances.

Materials

Materials

Access to the lab simulation and video links:

CH₃COOH (vinegar)
NaHC0₃ (baking soda)
A kitchen scale
A thermometer (optional)
Three glasses or beakers

Pre-Lab Questions

Pre-Lab Questions

How does concentration affect the time and rate of a chemical reaction?

Lab 1

Lab 1 Instructions

Lab: Part 1

Visit the virtual stockroom at Chem Collective Virtual Lab.

Lab: Part 2

Visit the simulation: PhET Concentration Virtual Lab

Notice how many liters are in the container.
Add enough solid drink mix to the container (click and slide the drink mix) so that the solution in the container measures as close to 1.000 mol/L as you can get it. If you go too far over 1.000 mol/L, then you can add more H₂O. If you dilute it too much, then you can drain the container and add more drink mix.
When you have 1.000 mol/L, measure and record how much solution is in the container.
Slide the evaporation scale and record your observations.
Repeat this exercise using three other solutes in the simulation. Record your observations.

Lab 2

Lab 2 Instructions

Lab: Part 3

Watch the following video: Youtube Video
Based on your observations in the simulations, answer the following questions:
1. What type of reaction do you see?
2. Why is this reaction occurring?

Lab: Part 4

What reaction would occur if you added a constant amount NaHCO₃ to varying amounts of CH₃COOH?
What if the constant were CH₃COOH and the variable were NaHCO₃?

Label your glasses 1, 2, and 3.
In the first glass, pour 14.7868 mL of vinegar. In the second glass, pour 44.3603 mL of vinegar. In the third glass, pour 89.87206 mL of vinegar.
Put 4.8 g of baking soda in each glass.
If you have a thermometer, record the temperature of each glass.
Answer the following questions:
1. In which glass did you see the strongest chemical reaction?
2. Which glass reacted the fastest?
Record why the reactions occurred and what effect the concentration had on the chemical reaction.
Rinse out the glasses. Make sure they are still labeled 1-3.
Add 118.294 mL of vinegar to each glass.
In glass one, add 1.2 g of baking soda. In glass two, add 2.4 g of baking soda. In glass three, add 9.6 g of baking soda.
If you have a thermometer, record the temperature of each glass.
Answer the following questions:
1. In which glass did you see the strongest chemical reaction?
2. Which glass reacted the fastest?
Record why the reactions occurred and what effect the concentration had on the chemical reaction.

Post-Lab Questions

Post-Lab Questions

What are the main sources of error that might cause a discrepancy between predictions and observations in this lab, and how could you improve them?