Water
H₂O makes Earth special
71% of Earth's surface is covered in water, and 96% of its water is found in the oceans. Without water, Earth would likely be another boring rock in the sky.
Polar bears, naturally found at the North Pole, are sort of bipolar. The meter is defined as 1/10,000,000 of the distance between the North and South Pole.
Water is the standard polar solvent
Polarity is the "the state of having two opposite or contradictory tendencies, opinions, or aspects." In chemistry, polar molecules have one end that is positively charged and one side that is negatively charged.
The electronegativity of elements has been charted. Oxygen loves electrons and has one of the strongest electronegativities. In the process of "Oxidation", Oxygen often steals electrons from whatever it can; this includes important biological molecules and leads to the process of aging.
Because of their specific electron and proton configurations, each element has an "electronegativity" and an "electron affinity". This indicates how strongly those elements pull on electrons. When electrons are shared between atoms in a molecule, the more electronegative elements pull on those electrons and create an uneven distribution of charge. This creates the polarity that water is famous for.
As a polar solvent, water separates other polar and charged substances (like this NaCl salt) and helps them dissolve.
Life as we know it requires a polar solvent. Our blood is 90% water and helps transport polar salts, minerals, and proteins.
Hydrogen bonding is responsible for a lot of water's unique properties
When oxygen pulls electrons away from hydrogen, it creates partial positive and partial negative poles. These partial poles are represented by the Greek lowercase delta, 𝛿. The 𝛿+ from hydrogen in one water molecule will react with the 𝛿- from oxygen in another water molecule. This interaction is known as a "hydrogen bond." Most of the unique and significant properties of water, including many of its life sustaining properties, can be attributed to hydrogen bonding.
For most substances, the density of solid > liquid > gas. Why does solid water float on water? Hydrogen bonding!
Ice floats, and that's abnormal
Density of Ice (0°C): 0.919 gram/cm³
Density of Water (25°C): 0.997 gram/cm³
Density of Steam (100°C): 0.000596 g/cm³
Hydrogen bonding can only occur at specific angles. When water freezes, it locks water molecules into a specific shape that is actually less dense than liquid water. This abnormal property allows ice to float.
The density of water is the basis for the metric "gram" standard
When scientists measure mass, they often use the "gram" as their reference unit. What exactly is a gram? Originally, the gram was based on the mass of 1 cubic centimeter of water at 4°C. Water is so important to our species, that we compare all other masses to water.
Water has a relatively high boiling point, and is the standard for the Celsius scale
It takes a lot of energy to break the hydrogen bonds that keep water molecules together. Because of these hydrogen bonds, water exists as a liquid for a large range of temperatures. This prevents our blood from boiling or freezing even with large variations in air temperature. The Celsius scale is based on these important temperatures for water.
0 °C = Water freezes
100 °C = Water boils
Water has an abnormally high specific heat, allowing it to absorb more thermal energy without a significant rise in temperature
Why is the temperature at the beach so much lower than the temperature inland? A big part of those temperatures is based on the specific heat of water. Specific heat is the amount of energy that a substance can absorb before it changes temperature. Metals have low specific heat, and will get hot quickly when exposed to heat; water has a relatively large specific heat (primarily because of hydrogen bonding) and requires much more energy to warm up. The energy from the sun is easily absorbed by the ocean, while the concrete in urban areas is more likely to radiate into its surroundings.
4.187 Joule = 1 calorie
The amount of energy needed to raise 1 gram of water by 1 °C is called a "calorie".
1000 calories = 1 kCal = 1 Calorie
Our evolutionary ancestors came from aquatic life. Water's high specific heat prevents big temperature changes in the ocean. Ice's unique density allows it to float above liquid water, which creates an insulating barrier for the water below it. Lakes freeze from the top down, allowing life to survive until warmer seasons arrive.
Water's high specific heat and its unusual density allowed aquatic live to thrive.
Our "fishapod" ancestors from 375 million years ago bridged the gap between sea and land life thanks to the unique freezing properties of water.
Cohesion is responsible for water forming distinct drops. Adhesion is responsible for those drops sticking to leaves in the morning.
Hydrogen bonding gives water cohesive and adhesive properties
Cohesion and adhesion allow water molecules to attach to other water molecules and other surfaces. Plants took advantage of these unique properties to transport water large vertical distances energy-free with transpiration, allowing them to grow tall.
All of the water on the globe can be condensed to the big sphere; the tiny sphere of fresh water is far smaller in volume.
Fresh water is vital for human life, but we don't have as much as we think we do.
Dihydrogen Monoxide warnings might falsely give the public the impression that water is dangerous. Jokes aside, our access to potable water is dwindling and may prove to be a massive socioeconomic issue in the future. Global climate change has shifted weather patterns and made some areas more dry (California) while others are flooding (New Orleans, Miami, and even New York City). Water is the standard for life, and we need to treasure it.
Dihydrogen Monoxide is known to the CDC as a hazard capable of asphyxiation or tissue damage. DHMO is a constituent of many known toxic substances, diseases and disease-causing agents, environmental hazards and can even be lethal to humans.
Water OC (17 pts)
Water is vital to life and one of our first clues we search for when scanning our universe for other life-forms. Use the Scale of the Universe tool to demonstrate the size of various objects in our universe to appreciate the uniqueness of our water planet.
Identify these objects by taking a snapshot and adding the pictures to your site. Include a note on your prefix chart the approximate scale of your selected objects.
(3 pt) Create a prefix chart in Google Sheets. Embed your sheet as an iframe.
1 pt: Create the appropriate chart with correct names/symbols/factors/common names
1pt: Include your "Scale of the Universe" objects in your scale,
1pt: Embed the chart as an iFrame
Surface Tension Activity (10 pts)
Collect data for the activity in a Google Sheets and embed it here. (2 pts)
Record a 30 second (or less) clip of yourself performing the experiment/activity and embed the video here. (4pts)
Explain your results from both parts of the experiment in terms of cohesion and surface tension. (4 pts)