Solutions, Acids & Bases

The Water Molecule How many protons does a water molecule have? How many electrons? What is the overall charge of a water molecule? 8 O Oxygen H Hydrogen

The Water Molecule How many protons does a water molecule have? 10 How many electrons? What is the overall charge of a water molecule? 8 O Oxygen H Hydrogen

The Water Molecule How many protons does a water molecule have? 10 How many electrons? 10 What is the overall charge of a water molecule? 8 O Oxygen H Hydrogen

The Water Molecule How many protons does a water molecule have? 10 How many electrons? 10 What is the overall charge of a water molecule? – 10 = 0 8 O Oxygen H Hydrogen

Polarity Draw a water molecule e-

Polarity Oxygen has _____ protons, while Hydrogen only has _____ proton. Oxygen’s greater attraction for electrons causes the Oxygen to have a slightly ______________ charge, while Hydrogen maintains a slightly _____________ charge. 8 O Oxygen H Hydrogen

Polarity Oxygen has _____ protons, while Hydrogen only has _____ proton. Oxygen’s greater attraction for electrons causes the Oxygen to have a slightly ______________ charge, while Hydrogen maintains a slightly _____________ charge. 8 O Oxygen H Hydrogen negative positive

Polarity Key: Why is a water molecule polar? There is an uneven charge between the positive hydrogen and negative oxygen.

Polarity Draw Hydrogen bonds between one water molecule and another.

Hydrogen Bonds In terms of a water molecule explain what a hydrogen bond is: The attraction of the positively charged hydrogen atom of one water molecule to the negatively charged oxygen of another water molecule.

Hydrogen Bonds Cohesion: The ability for water molecules to stick to themselves.

Hydrogen Bonds How does cohesion explain why some insects can walk on water?

Hydrogen Bonds Adhesion: The ability for water molecules to stick to other materials.

Hydrogen Bonds How does adhesion change the way you read this graduated cylinder? Why?

Hydrogen Bonds What is capillary action in plants? Water clings to the inside of plant roots and climbs, just like water will climb up a paper towel if you put half of it in water.

Solutions and Suspensions Mixture: A combination of two or more substances that are physically mixed, not chemically combined. Example: Soil, salsa, trail mix, milk, cereal, sugar water

Solutions and Suspensions Solutions: A mixture formed when one substance dissolves in another EVENLY. Example: Salt water

Solutions and Suspensions Solutions: A mixture formed when one substance dissolves in another EVENLY. Example: Salt water A. Solute: Substance dissolved in a solution Salt = Solute

Solutions and Suspensions Solutions: A mixture formed when one substance dissolves in another EVENLY. Example: Salt water A. Solute: Substance dissolved in a solution B. Solvent: Substance that does the dissolving Salt = Solute Water = Solvent

Solutions and Suspensions Suspensions: A mixture of water and non-dissolved materials. Example: Blood, aerosol sprays, milk

Apply What You Know Solution or Suspension? Salt and Water Sand and Water Milk Kool-Aid Chicken Noodle Soup

Acids, Bases, and pH A. The ______ scale is used to measure the strength of acids and bases. B. Complete the table: pHExamplesCharacteristics Acids Neutral Bases pH 1-7 Lemon, vinegar, soda, aspirin Sour, burns, dissolves things 7 Pure WaterNot acidic, not basic! 7-14 Soap, baking soda, ammonia Bitter, slippery H+ OH- H2O

Acids, Bases, and pH C. Buffer: Weak acids or bases that neutralize strong acids or bases. Why are buffers important? When acids and bases are added to the body, the blood “buffers” preventing a pH change.

Buffers in the Body pH of blood MUST be between 7.35 and 7.45 Removing CO2 from the blood helps increase the pH Removing HCO3- from the blood helps lower the pH Buffers (Bicarbonate) maintain this acid-base balance in the blood.

pH Lab Each lab station is doing 2 experiments! (3 people per tray) Check assignment on back wall

pH Lab Overview 4 drops of each sample Put on white scratch paper Dip a small strip of pH paper in each sample Compare the color to the chart Add 4 drops cabbage juice Color the box & record Answer questions

General Lab Rules Stay at your lab table unless you are the designated person to get supplies. Read ALL DIRECTIONS CAREFULLY!!!! Wash your trays with hot, soapy water. Clean your lab station & push in stools. Your lab should look cleaner than when you started! Have fun!