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Answer Key

Challenge #1: Safety Comes First

Read the MSDS on hydrochloric acid and answer the following questions before starting the laboratory activities. Have the teacher check your answers and sign your paper. Everyone

• Read Section VII (Spill or Leak Procedures) and describe the steps that must be taken if there is a spill of hydrochloric acid.
  Carefully neutralize the hydrochloric acid with sodium bicarbonate and flush down the drain with lots of water.
• Read Section VII (Spill or Leak Procedures) and describe the guidelines for disposing of hydrochloric acid.
  Carefully neutralize with sodium bicarbonate, soda ash, or lime and flush down the drain with lots of water.
• Read Section VIII (Special Protection Information) and Section IX (Special Precautions) on the MSDS for hydrochloric acid. List the Personal Protective Equipment you require before starting the lab:
  Chemical safety glasses
  Rubber gloves
  Smock or apron

Challenge #2: Lab Worksheet #1

(Station One: Let’s Concentrate At This Station!)
Hypothesis: If the concentration of hydrochloric acid increases then the rate at which chalk reacts will increase.
Observation Chart: students should observe that the reaction is faster when the concentration of hydrochloric acid is stronger. (3.0 %)

Conclusion:

1. Which beaker had the reaction that lasted the longest time? C
2. Which beaker had the reaction that lasted the shortest time? A
3. Which one of the three beakers had the strongest concentration of hydrochloric acid (HCl_(aq))? A
4. Write a statement to describe how the rate of a reaction is affected by changing the concentration of a substance.
   The rate of a chemical reaction is faster when the concentration of a chemical increases.