By now you should have a fairly good idea of what happens to the atomic size, ionization energy, and electron affinity as you move around the periodic table. Ultimately, you should be able to use this knowledge to predict the relative reactivity of different substances. The lab today will challenge your prediction skills.
We will be considering three substances today: Potassium, Calcium, and Zinc. We are trying to determine which of these substances is most reactive when combined with water. You will need to decide how you will determine what is most and what is least reactive and take data and observations accordingly.
PLEASE HAVE YOUR GOGGLES ON AT ALL TIMES!!!
Begin the lab by washing all of the glassware. You should have 3 Erlenmeyer Flasks (at least 500mL), a pair of forceps, 3 pieces of pH tape and a pair of flame resistant gloves.
Once your glassware is clean, fill each flask with 200mL of water.
Select a person to garner the chemicals. Make sure that you record the mass of each substance. Get only 1 substance at a time. Obtain the substance, test the reactivity, dispose of the waste, and obtain the next substance. Please wait for your teacher to give you the OK before getting the potassium.
GARNERING THE SUBSTANCES
MASS OF SUBSTANCE (g)
TESTING THE REACTION
You will be graded on both a lab write up (using the lab report rubric) and the following questions.
1) What is the problem/question of this lab?
2) What is your hypothesis? Make sure that your hypothesis is testable (i.e. how will you determine which is most reactive…time? …precipitate formed?…relative difference in color?…heat produced?
3) Justify your hypothesis using all that you know about chemistry so far. Please be thorough.
Questions to consider for the lab—Include as Appendix A in your Lab Report (4pts each)
1) How do you know when a chemical reaction has taken place?
2) Write the electron configuration for each of the following metals (you may use the shortcut):
3. Why do you think that the Potassium must be stored under mineral oil?