Water, Water Everywhere! Essential Questions: What are the properties of Water? What are Mixtures, Solutions and Suspensions? Why is water important for living things? What is the pH scale?

Your turn! What do you know about the properties of water?

Introduction to Water Water makes up 70-95% of organisms. Consists of 1 Oxygen atom and 2 Hydrogen atoms per 1 water molecule. How is water bonded? Because of its bonding it can hold large molecules like proteins together. Carries substances via Osmosis. – Serves as material transportation – Blood, plant sap Cycles through the kidneys and eliminated out of the body

Five Major Properties of Water 1.Water is liquid at room temperature – boiling point is high at 100° C – low molecular weight – molecules are usually gaseous. Water resists temperature change. Because the boiling point is so high, It takes a lot of energy to heat water. ‏ Water exists in three phases: – Solid (ice) – Liquid (“water”) – Gas (vapor)‏

Five Major Properties of Water 2.Water has a high freezing point – Ice is less dense than water. (Thus, ice floats in water.)

Five Major Properties of Water 3.Water is the universal solvent for polar and ionic molecules (it can dissolve other liquids, solids, or gases) – Polar: Water has a slightly positive (+) end and a slightly negative (-) end. – Hydrophilic: means “water-loving”, molecules that interact with water, soluble in water – Hydrophobic: means “water-fearing”, insoluble in water

Five Major Properties of Water 4. Water is wet: – Hydrogen bonds hold separate water molecules together (polar areas attract) – Slightly negative (-) Oxygen end is attracted to the slightly positive (+) Hydrogen ends. – Cohesion: attraction of water molecules to each other. – Adhesion: attraction of water molecules to other types of molecules. Example: The meniscus in a graduated cylinder – Capillary action : cohesion and adhesion act together, pulling up water against gravity. Example: Transportation of water from the roots to the leaves of a tree

Five Major Properties of Water 5.Water has high surface tension – water is more attracted to itself (cohesion) than to the air around it – Sticks together (+ and – attract.) You will determine factors that affect Surface Tension in your Penny Mini-lab today!

Mixtures, Solutions & Suspensions A mixture is a combination of substances where both substances keep their original properties. – Physically mixed, not chemically mixed. Signs of Dehydration

Mixtures, Solutions & Suspensions Solution: one or more substances (solutes) are distributed evenly in another substance (solvent), like water – The more solute in a solvent, the higher the concentration – Homeostasis: Organisms regulate the concentration of water and other important substances in their bodies to maintain a certain stable concentration for life processes Signs of Dehydration

Mixtures, Solutions & Suspensions Suspension – mixture of water and non-dissolved particles – Example: Blood – tch?v=PgI80Ue-AMo tch?v=PgI80Ue-AMo Signs of Dehydration

pH Scale pH – a measure of how acidic or basic something is. Use pH paper (litmus paper) to test Acids range from pH of 0-6 – Acids form H+ ions in water – Example: Lemon (pH: 2)‏ Neutral is 7 – Example: Pure water and blood (pH: 7)‏ Bases range from pH of 8-14 – Bases form OH- ions in water – Example: Ammonia (pH: 12)‏ Buffers – weak acids and weak bases that react with strong acids or bases to prevent sudden changes in pH. Used to maintain homeostasis.

Homeostasis The ability or tendency of an organism to maintain internal equilibrium, or balance, internally.

Fight Club Science: Neutralization Reaction In the Movie, Fight Club, Brad Pitt’s Character puts a chemical burn (using Lye, pH of 13) on Edward Norton’s Character's wet hand. – Is lye an acid, a base or a neutral substance?

Fight Club Science: Neutralization Reaction In the Movie, Fight Club, Brad Pitt’s Character puts a chemical burn (using Lye, pH of 13) on Edward Norton’s Character's wet hand. – Is lye an acid, a base or a neutral substance? – Should he put water or vinegar to stop the burn? What is the pH of Water? What is the pH of Vinegar?

Fight Club Science: Neutralization Reaction In the Movie, Fight Club, Brad Pitt’s Character puts a chemical burn (using Lye, pH of 13) on Edward Norton’s Character's wet hand. – Is lye an acid, a base or a neutral substance? – Should he put water or vinegar to stop the burn? What is the pH of Water? What is the pH of Vinegar?

Penny Minilab!