Step that Indicator Up December 3 2, * 10 3  Objective:  SWBAT evaluate different indicators for accuracy  Catalyst:  What is the pOH of a solution with 4.1 * 10 5 M [H + ]?  __ NH 3 + __ HCl  __ NH 4 Cl  If I have 45 grams of HCl, how many moles of NH 4 Cl will I produce?

pH Math Review  Find the equation where the thing that you are looking for is BY ITSELF and the thing that you have is in the equation! EQUATIONS! pH= -log [H + ] [H+] = 10 -pH pOH= -log [OH - ] [OH - ]= 10 -pOH pH+pOH=14

Acid-Base Lab Safety  Always wear GOGGLES when handling acids and bases!  If you get an acid/base on your skin, rinse with water for at least 5 minutes  If you get an acid/base in your eyes, flush with water for at least 5 minutes  If you get an acid/base all over your body, use the safety shower

Lab Overview  Today, you will be participating in an extensive pH indicator lab.  It will test the knowledge and skills you have learned so far this week!  You must stay focused the entire time in order to be safe and smart!  Don’t forget to be a GOGGLE GANSTER!

Question  Which acid-base indicator is more accurate: cabbage juice or pH paper?

Pre-Lab Directions  Fill in all white blanks at top of lab sheet  Answer Pre-Lab Questions 1-3  Read over procedure as a group and fill in Materials and Safety Methods  Ask Mr. Jhaveri to check your work  If you are cleared, you may begin working

Main Steps of the Lab  Part I: Determine pH Using pH Paper  Use as little as possible!  Part II: Determine pH Using Cabbage Juice  Be careful – it’s smelly!  Part III: Compare Data to Accepted Values  Get sheet from Mr. Jhaveri  Part IV: Determine pH of Mixed Substances  Beware of the unkowns…ooooooh!

Any Questions???

Exit Question 1. Which indicator gave pH values closer to the accepted values? 2. Give an explanation for the pH value of the mixed substances (Part IV).