By N. Marlo Ballard, M.S.T. Instructions : Run the presentation in “ Slide Show ” format. Press the space button to advance the animations.

O H 1)Assign a color of gumdrop for oxygen atoms and hydrogen atoms = oxygen atom =hydrogen atom

O O O O O O HH HH HH H H HH HH 2) Construct a total of 6 separate water moleucles.

Now you have 3 hydroxide ions: O O O O O O HH HH HH H H HH HH 3) Pull one H off of 3 of the H 2 O molecules and place each H next to one of the 3 remaining H 2 O molecules. And 3 hyronium ions: In a solution like this one where: the number of H 3 O + = the number of OH - The pH is said to be about 7 The concentration of H 3 O + is about moles/liter

For the purpose of this exercise: Adding each H + molecule will increase the H + concentration by an order of magnitude of 10 1

O O O O O O HH H HH H H H H 4) Reassemble your atoms back to 6 H 2 O molecules. The starting pH is 7 (neutral) = m/l of H +. HHH

O O O O O O HH HH HH H H HH HH Now add 6 more Hydrogen atoms to the mixture HHH H H H pH 6 H + conc. = m/l pH 4 H + conc. = m/l pH 5 H + conc. = m/l pH 3 H + conc. = m/l pH 2 H + conc. = m/l pH 1 H + conc. = m/l 5) Utilizing the definition of an acid and a base from your lab manual, is the solution you just created an acid or a base ? An acid

For the purpose of this exercise: Adding each OH - molecule will decrease the H + concentration by an order of magnitude of 10 1.

O O O O O O O HH HH HH H H H HH 6) Now add 8 OH - (hydroxide) ions. The initial pH is 1 = the initial H + conc m/l. H pH 2 H + conc. = m/l pH 4 H + conc. = m/l pH 3 H + conc. = m/l pH 5 H + conc. = m/l pH 6 H + conc. = m/l pH 7 H + conc. = m/l O H H H OOO O H H H H H H HHH O O H H pH 8 H + conc. = m/l pH 9 H + conc. = m/l 7) Utilizing the definition of an acid and a base from your lab manual, is the solution you just created an acid or a base ? A base

8) Now that you have determined the pH for the solutions in questions 4 & 6, what characteristic of the solutions is pH based on? H + concentration H + concentration