User:Atcovi/Science/AP Bio Lab Summary

Water is arguably the most important key to life. Our human bodies are made up of 60-70% water and without water, we wouldn't be able to live. Water is plentiful on the Earth, being the most abundant resource and the 3rd most abundant resource in the universe. Water's imbalance in electronegativity with the oxygen atom being more electronegative than the two hydrogen atoms makes it a polar molecule. Water's polarity gives away to many special properties that make water unique compared to other liquids.

Water is the "universal solvent", which means that water can dissolve any water that is made up of polar molecules (hydrophilic). In station 1, an ice cube, made up of polar molecules as it is water in solid form, was added into a beaker of water and the temperature was recorded. The temperature significantly decreases in the first minute from 25° C to 23.1°. This is because the ice is being dissolved during this period, thus the temperature decreases. At about 90 seconds in, the temperature reaches its lowest degree (22.8° C) until it starts to climb back up. After 90 seconds, the temperature goes from 22.8° C to 23.5° C. This is because the ice has been completely dissolved and now the water is returning back to its original temperature, albeit slowly.

Water is adhesive, meaning it sticks to other platforms that are not similar to itself. This is evident in station 2, as it took 14.57 seconds longer for water to be removed from an individual's hand than for ethanol to be removed from an individual's hand. This is because the water molecules were sticking to the hand (adhesion), making it harder for the fan to remove all the water.