- How important is water to life?
Water is an important substance to life. 3/4 of Earth surface is water. Human and other living organisms need water to stay alive. Most number of cells are surrounded by water. Human body consists 70% of water.
- How is the quality of water on Earth?
Its getting worse due to the heavy pollution. Human activities are the main reason that effect the water quality for example: human and factory wastes flow directly into rivers.
- What is the pH scale?
pH scale is a measure of the acidity of a solution.
Five Main Facts
- Water is an important substance to sustain life.
- Cohesion happens when two substance is hold together by hydrogen bond.
- A substance that produces hydrogen ions in a solution is called acid.
- A substance that reduce hydrogen ions in a solution is called base.
- Anything that moves has kinetic energy which is the energy of motion.
Diagram
This diagram represents a hydrogen bonds between water molecules. The part that has been charged of a water molecule are attracted to oppositely charged parts of the neighbor molecules. A molecule can hydrogen-bond to multiple partners. This bond is constantly changing over time.
Summary
Water is an important substance to life. Three quarters of Earth's surface is covered by water. It is one of the most important thing for human and other living organisms to sustain their life. Water surrounded most cells and cells themselves are 70%-95% water. Albeit water is important to life, it's being polluted.
A liquid that is a mixture made up of two or more substances is called a solution. Solvent is a substance that can dissolve other substances and what is dissolved is called solute. Scientists tried to find an universal solvent and they found that nothing works better than water. However, water is not an universal solvent because there are things and substances that water can not dissolve.
Video
http://www.youtube.com/watch?v=ERy18NwemVc
10 Key Terms
- Cohesion: the binding together of like molecules, often by hydrogen bonds.
- Adhesion: the attraction between different kinds of molecules.
- Surface tension: a measure of how difficult it is to stretch or break the surface of liquid.
- Kinetic energy: the energy of motion.
- Solution: a liquid that is a completely homogeneous mixture of two or more substances.
- Solvent: the dissolving agent of a solution.
- Solute: a substance that is dissolved in a solution.
- Aqueous solution: a solution in water is the solvent.
- Hydrophilic: having an affinity for water.
- Hydrophobic: having an aversion to water; actually repel water.
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