Lab #27: The Effect of Concentration on Reaction Rate Purpose – to see how concentration affects reaction rate Experiment – pipet 5 mL of solution 2 Solution 1 & water Pour the contents of one test tube into the other and begin the timer. Swirl the test tube consistently. Stop the timer once a noticeable reaction takes place. Repeat for various concentrations (see table) TRIAL Volume of Solution 1 and H 2 O Volume of Solution 2 Reaction Time(sec) 1 5 mL + 5 mL5 mL 2 4 mL + 6 mL5 mL 3 3 mL + 7 mL5 mL 4 2 mL + 8 mL5 mL

Analysis: Properly graph your data Results: Write a statement that includes how reaction rate is effected by the concentrations…make sure to include actual data to support your statement.

How the Iodine Clock Reaction Works (no notes!) 3HSO IO H 2 O  3SO I - + 3H 3 O + sol. 1 sol. 2 watercolorless ions STEP 1: Rate-determining step IO I - + 6H 3 O +  3I 2 + 9H 2 O sol. 2dark blue STEP 2: I 2 + HSO H 2 O  2I - + SO H 3 O + dark blue sol. 1colorless ions STEP 3: As long as there are HSO 3 - ions in the test tube that can react with the I 2, no visible color change will occur.