1. Water & pH Do Now: Draw a sketch of three water molecules that are hydrogen bonded together.

2. pH basics pH is a measurement of how acidic or basic (alkaline) solutions are. On the pH scale, acids have low values ( 7) Neutral pH (7) is not acidic or basic

3. Properties of Acids & Bases Acids tend to taste sour, and strong acids can react with many substances. Bases feel slippery, and can also cause burns!

4. Predictions about pH Take a guess: what do you think the pH of the following substances are? –Water –Soda –Coffee –Soapy water

5. The big question: What IS pH? What do the numbers mean? What makes some acids more acidic than others? pH = -log[H 3 O+ (mol/L)] –WHAT THE HECK????

6. Dissociation of Water – What pH is All About. Dissociation of water: water molecules constantly break into H+ and –OH and quickly reform

7. pH measures H+ ACIDSBASES Low pHHigh pH Lots of H + / H 3 O + Little H + / H 3 O + Little - OHLots of - OH Taste sour (i.e. lemon juice, vinegar) Feel soapy (i.e. bleach)

8. Acids add H+, Bases add -OH Acid Example: –H 2 SO 4 (sulfuric acid) Base Example –NaOH (sodium hydroxide, aka lye)

9. Monday’s Lab Question: What is the effect of (recently) living matter on pH change? We will add small amounts of acid to a sample of liver homogenate (think liver shake) and compare the pH changes to a control group. What should the control group be?

10. Hypothesis / Prediction Liver will (increase/decrease/have no effect on) how much the pH changes when acid is added to a sample. If liver (affects pH change the way we hypothesize), then the pH of the liver will change (more/less/the same as) the pH of the water

11. Homework Read pp. 41-42 Answer #2-4 p. 42