AP Biology Discussion Notes Monday 9/14/2015

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

Question of the Day 9/14: What do you know about water?

What we know about water:

Names Practice

Second Notebook

Polar-Covalent Molecule What is a Covalent bond? What would make it Polar?

Let’s Draw Water & its Polar Covalent bonds!

Hydrogen Bonding Hydrogen bonds are 1/20 the strength of the covalent bond, but serve to organize water in a particular way. This organization is what give water its emergent properties!

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 Surface Tension – the measure of how difficult it is to stretch or break the surface of a liquid.

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.

Emergent Properties of Water Moderation of temperature 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)

Emergent Properties of Water Moderation of temperature Celsius scale: Freezing: Human body: Boiling:

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

Emergent Properties of Water Moderation of temperature 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 Specific heat of water is 1 cal/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 higher temperature change? Water will change its temperature less when it absorbs or loses a given amount of heat.

Emergent Properties of Water Moderation of temperature High Heat of Vaporization – the quantity of heat a liquid must absorb for 1 g 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.

Emergent Properties of Water 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. - Expansion upon freezing

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.

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.

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 yellow chemistry review?