Rewrite of Virtual Titration Lab (Unit 2 Lesson 8)

Procedure (Day 2)

  • On page 3 of the lesson in the LMS click on “Go to Virtual Titration Lab”
  • On left of the Titration Lab homepage click on “Go to Lab”
  • Click on the Assessment button and at bottom right click on the proceed button.
  • For the second titration should be with unknown base. If you are doing this as one titration a day you will have to go through the unknown acid again. You should have Potassium Hydroxide (in flask) and Nitric acid(in buret) as your reactants and Phenolphthalein as your indicator. The concentration of the base (KNO3) should be 0.10M (adjust the concentration until you get it to 0.10M) Hit the enter button.
  • Setting up lab
  • From right hand side of the top shelf move buret to the clamp on the stand
  • From bottom shelf move funnel to top of buret
  • From top shelf move white square tile to bottom of stand
  • From right hand side of bottom shelf move flask to sit on tile
  • Apparatus is set up. On left, click on go to reagent rack
  • Filling the reagents
  • Filling Flask (Flask will have the solution with unknown concentration in it)
  • Since Base is our unknown move that NaOH to the table, remove stopper and place on table.
  • Move bottle so that it is in front of flask and let go. Bottle will tip and have arrow.
  • When you click on the arrow, you begin pouring the liquid. Pour
  • 15, 20 or 25 mL into flask. Numbers to the left of the flask let you know how much has been poured into flask.
  • Close the bottle and place it back on the shelf
  • Take phenolphthalein from top shelf and place on table. Move dropper to above flask and it will lock in place with an arrow. You want 3- 5 drops of indicator (phenolphthalein) in flask. Click to stop dropper. Put dropper back in bottle and return it to shelf.
  • Filling buret (Buret will have your solution with known concentration)
  • Move the acid HNO3 to the table, remove stopper and place on table.
  • Move bottle so that it is in front of funnel. Let go and bottle will tip with arrow.
  • When you click on the arrow to the left there is an area that shows the buret reading. The buret starts at 50 at the bottom and the top is 0. You want to fill until the buret read between 0 and 3. Be careful you can overfill and you will have to start all over.
  • Remove the bottle, close it and put it back on the bottom shelf.
  • Filling in what we know
  • In the second table below
  • For the unknown write NaOH, For its volume - write the volume that is shown in the table to the right of our titration apparatus.
  • For the known write HNO3 and for its concentration write 0.15M
  • Titration
  • On the buret click on the stopcock. (the blue handle to the right of the body of the buret)
  • A table appears which shows how you filled the apparatus. If you couldn’t find the volume of the acid or the concentration of the base you can get them from this table. You can click on Proceed if you have your table with the information that I said to have there.
  • You want to close the green window that is on the buret. Note that there is a circle that surrounds the stopcock. This circle will open the stopcock a certain amount depending on which color you click on. The dark blue is a continuous run -1.0 mL continually running. The light blue is slow flow – 1.5 mL each drop but only one drop at a time. The dark green is .5 mL each drop. The light green is 0.05 mL each drop.
  • For your first drop you should be safe with a light blue. Your pH is about 13.25. You want to add so that you can pinpoint when it turns pink and does not change back. So after your first only add by dark green. To the right of the titration there is a graph of the pH. Your titration is over when the pH reaches 7.0. When you get to the end it will change rapidly. Continue adding by dark green until pH is about 12.5 then switch to light green additions. You should be shaking the flask every so often. Especially as you get nearer to the end. You need to record the number of mL of HNO3 that was added to reach a pH of 7. When you look at the graph there you see that the line is going straight down. That is why you have to be adding the minimum amount towards the end of the titration.
  • Completion of lab. (Day 2)
  • Write the balanced equation for the reaction of your known acid and base.
  • Find the concentration of your unknown using the formula below the table
  • Once you have completed both equations (one for each day), both tables and both calculations submit the lab by dropbox on page 5 of the LMS lesson.

Virtual Titration

Day 1 Table

Balanced Equation

HCl + NaOHNaCL+ H2O

Table / Solution / Mole ratio / mL used / Molarity
HCL(acid) / 18ml
NaOH(base) / 0.20M / 34ml

Calculation of concentration of unknown

____Concentration of known*_____mL of known used* moles unknown =____M unknown concentration

____mL of unknown that you started with moles known

Day 2 Table

Balanced Equation

HNO3 + KOH ______+ ______

Table / Solution / Mole ratio / mL used / Molarity
Unknown(base)
Known(acid)

Calculation of concentration of unknown

____Concentration of known*_____mL of known used* moles unknown =____M unknown concentration

____mL of unknown that you started with moles known