Barking Dog Lab

20 Points

Purpose:  To use your knowledge of writing and balancing equations to predict the products of two reactions.

Materials:

Ringstand                                 Pneumatic Trough                     Rubber Stopper

Erlenmeyer Flask                      Test Tubes                               Glass tubing

Aluminum Foil              Matches                                   6.0 M HCl

 

Procedure:

  1. Obtain an Erlenmeyer flask attached to a ring stand with a stopper and tube attachment.  Also obtain a small piece of Aluminum Foil.
  2. Put your SAFETY GOGGLES ON!  DO NOT TAKE THEM OFF DURING THE ENTIRE LAB! OTHER GROUPS WILL STILL BE WORKING!
  3. Measure out 20.0 mL of 6.0 M HCl and pour it into the flask.  BE VERY CAREFUL AS ACID WILL BURN SKIN.  IF YOU GET ANY ACID ON YOU, BE SURE TO RINSE IMEDIATELY WITH WATER AND PUT BAKING SODA ON THE AFFECTED AREA.
  4. Fill your test tubes HALF-WAY with water and set them up in the Pneumatic Trough so that they are upside down.

 

 

  1. When you are ready, crumple the Al foil into a light ball and put it in the Erlenmeyer flask.  PUT THE STOPPER ON FIRMLY! Put the hose UNDER THE WATER when you put the stopper in place The pressure inside the flask will build and you donít want the stopper to pop off!  (If it does pop off, donít panic!  Just be sure to rinse off any acid that might get on you and call me over immediately!  If the rubber stopper pops off, it rarely splashes acid, but please be careful and be prepared.)
  2. After a few seconds, the reaction will take place.  It happens RAPIDLY so work quickly.  Remember:  Put the hose UNDER THE WATER when you put the stopper in place. When the reaction begins, collect the bubbles under the test tubes.  When the bubbles are all collected, lift the test tubes (one at a time) out of the Pneumatic Trough and light a match underneath the mouth of the test tube.  Donít turn the test tubes over (so their mouths are pointing up) or else youíll lose all the Hydrogen and have nothing to light. DONíT LIGHT THE HOSE COMING FROM THE ERLENMEYER!
  3. Throw your matches in the pneumatic trough BEFORE putting them in the trash can.  We donít want any trash can fires!
  4. Woof!

 

Pre-Lab Questions: Answer these before doing the lab.  Bring them to class with you.  No need to copy the questions

  1. Should the Aluminum foil be crumpled up tight, loose or left as a flat sheet?
  2. Should you put the stopper on firmly or lightly?
  3. How many mL of acid are you going to add to the Erlenmeyer flask?
  4. How much water should you put in the test tube? 
  5. Where should you put the hose from the Erlenmeyer immediately after you put the stopper in place?
  6. How should you hold the test tubes so that you can light them?
  7. What should you do if the stopper pops off and/or you are splashed with acid.
  8. After youíre done with your matches, where should you put them BEFORE they go in the trash can?

 

 

Questions:

  1. What type of reaction is occurring in the Erlenmeyer Flask? (Synthesis, Decomposition, Single Displacement, Double Displacement or Combustion).

 

  1. Write out a BALANCED equation for the reaction in the Erlenmeyer flask.  (You need to know that Aluminum has an oxidation number of +3.  Hydrogen is +1.  Chloride is Ė1.  The formula for hydrochloric acid is HCl)

 

  1. What are the reactants in this equation?

 

  1. What are the products in this equation?
  2. Look at your balanced equation (from Question #2).  If you had 4 moles of Aluminum for this reaction, how many moles of Hydrogen would you produce? (Realize that equations are balanced in moles, so an equation simply tells you the ratio of moles of reactant to moles of product)

 

  1. What type of reaction is occurring in the test tube?  (Synthesis, Decomposition, Single Displacement, Double Displacement or Combustion).

 

  1. Write out a BALANCED equation for the reaction in the test tube.  (Just inside the test tube, no aluminum or HCl is in

 

  1. What are the reactants in this equation?

 

  1. What are the products in the equation?

 

  1.  Look at the balanced equation (from Question #7).  If you had 2 moles of oxygen, how many moles of water would be produced?

 

  1. Why do you think I asked you to fill the test tube half-way with water.  Why not all the way full?

 

What is due for this lab?

Turn in the pre-lab questions and the questions only. 

   NEATNESS  COUNTS