AP Biology Discussion Notes Monday 9/12/2016

Goals for Today: 1. Be able to list and describe the Emergent Properties of water 2. Be able to describe and apply basic chemistry concepts Start here Tuesday

9/12 Question of the Day: What do we know about Water itself, or its relationship to living things?

What do we know about water? H2O, essential in life, universal solvent, earth ~70% water, solid liquid gas

Water is: A Polar-Covalent Molecule What is a Covalent bond? What would make it Polar? Sharing electrons, the fact that Oxygen is a more electronegative atom than hydrogen, so there is an unequal sharing of electrons.

Let’s Draw Water & its Polar Covalent bonds! Formula: Sharing electrons, the fact that Oxygen is a more electronegative atom than hydrogen, so there is an unequal sharing of electrons.

Water has: Hydrogen Bonding Hydrogen bonds are 1/20 the strength of the covalent bond, but serve to organize water in a particular way. A single H bond is weak Together H bonds are very strong This organization/Structure is what give water its emergent properties/ Interesting Functions!

Some Emergent Properties of Water Cohesive & Adhesive behavior Surface Tension Ability to moderate temperature High Specific Heat High Heat of Vaporization Expansion upon freezing Versitility as a solvent

Emergent Properties of Water: Cohesive behavior Water molecules stay close to each other because of hydrogen bonding

Emergent Properties of Water: Adhesive behavior Water molecules stick to the sides of a cell wall for instance helping counter the pull of gravity.

Emergent Properties of Water: High Surface Tension the measure of how difficult it is to stretch or break the surface of a liquid.

http://gizmodo.com/5935664/this-is-one-awesomely-perfect-and-refreshing-example-of-surface-tension

Bbc life episode 2 – minute 12:30-14:30 Breaks Surface tension, but makes this possible!

Emergent Properties of Water: Moderation of temperature Large bodies of water aborb heat and moderate costal temperature. Stable temperatures in the water and on land help sustain life. Moderation of temperature applies at the organismal level but also at the Ecosystem, biome or biosphere level.

Emergent Properties of Water: Heat vs Temperature Heat – Total kinetic energy of a given body of matter (need volume to calculate) Temperature – measure of heat intensity that represents the average kinetic energy (regardless of volume) vs

Emergent Properties of Water: Moderation of temperature Celsius scale: Freezing: Human body: Boiling: Comfortable Room Temp: 37 100 21-25

Emergent Properties of Water: Moderation of temperature calorie- the amount of heat it takes to raise the temperature of 1g of water by 1˚C (The amount of heat released when 1g of water cools 1˚C) Calories: 1000 calories (1 kilo calorie) Little “c” calories Big “C” calories are food calories

Emergent Properties of Water: Moderation of temperature High Specific Heat the amount of heat that must be absorbed (or lost) for 1g of that substance to change its temperature by 1˚C

Emergent Properties of Water: Moderation of temperature by Specific Heat Specific heat of water is 1cal/g ˚C Specific heat of Ethyl alcohol .6cal/g ˚C IF we added 100 calories to a given amount of water and 100 calories to the same amount of alcohol which would have a greater temperature change? Water will change its temperature less when it absorbs or loses a given amount of heat. In other words water acts as a heat reservoir. Hydrogen bonding responsible. Energy has to be used to break hydrogen bonds.

Emergent Properties of Water: Moderation of temperature (High) Heat of Vaporization the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state. This allows organsism’s bodies to remain at more stable temperatures because they can use water to cool themselves, like when we sweat. (Takes more heat away than other liquids would)

Emergent Properties of Water: Expansion upon freezing Why is this possible? (Try to think about the chemical properties that would make this possible, or why the solid of a substance can’t usually float on its liquid form. Solid water (ice) is 10% less dense than liquid water.

Emergent Properties of Water: Expansion upon freezing Ice floats in liquid water because hydrogen bonds in ice are more “ordered,” making ice less dense Water reaches its greatest density at 4°C If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth

Emergent Properties of Water: Expansion upon freezing Allows life in the oceans, lakes, and rivers, to persist despite extremely cold temeratures. Ice serves as an insulating layer and allows liquid water to persist underneath.

https://www.youtube.com/watch?v=HG17TsgV_qI

Emergent Properties of Water: The solvent of life – a *Near univeral solvent Solution – homogenous mixture of two or more substances Solvent – the dissolving agent in a solution Solute – the substance that is dissolved. What is the Rule for if something is soluble or not? ? LIKE disolves like!

Emergent Properties of Water: The solvent of life Water is a versatile solvent due to its polarity, which allows it to form hydrogen bonds easily When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a hydration shell

Emergent Properties of Water: The solvent of life Hydrophilic – water loving or POLAR molecules Hydrophobic – water fearing or Non-Polar

Questions? About properties of water? About your chemistry review?

Second Notebook

9/12 Species of the Day Northern Cardinal: Cardinalis cardinalis

9/12 Species of the Day Northern Cardinal: Cardinalis cardinalis

9/12 Species of the Day Northern Cardinal: Cardinalis cardinalis

Species of the Day 9/12 Northern Cardinal: Cardinalis cardinalis What properties of water are most beneficial to this cardinal?