Water Properties Lab Report

Water Properties Introduction Water is a compound made up of 2 hydrogen atoms and 1 oxygen atom. Like other substances, it has its own properties. These properties are what make water unique and very important to living creatures. Water molecules are “​polar molecules” [Paragraph 2]. This is because of the polar covalent bond that bonds the hydrogen and oxygen atoms together. Having a polar covalent bond means that the shared electron spend more time on one atom than another, in this case, the electrons spend more time on oxygen. This gives oxygen atom a slight negative charge and gives hydrogen atoms a slight positive charge. [Notebook] Being polar molecules gave water its ​cohesion and adhesion ​properties. [Notebook] Cohesion is when water molecules stick together because of hydrogen bond (explained in the next paragraph). Adhesion is when water get attracted to any polar surfaces because of the molecules polarity. [Paragraph 11] This can create ​capillary action​, when water climbs up a small tube against the gravity due to adhesion and cohesion. [Paragraph 12] This is because of the water molecules that get attracted to polar surfaces above due to adhesion, and cohesion pulled the other water molecules up together. Since the water molecules have both positive and negative charges, the positively charged atom (hydrogen) of one molecule are attracted to the negatively charged atom (oxygen) of another water molecule because positive charges attract to negative charges. This is called “​hydrogen bond​,” an attractive force that keeps water molecules very tightly together. [Notebook] Hydrogen bond causes water to have ​high heat capacity ​or have a high specific heat index. It means that it takes a lot of heat for water to raise 1 degree celsius because for any substance to heat up, its molecules need to shake very fast. Hydrogen bond keeps the atoms very tightly together so there is not many space to shake, thus making it harder to raise temperature. [Notebook] Hydrogen bond also causes water to have ​high heat of vaporization​. It means that it also take a lot of heat to turn 1 gram of liquid water into gas water. This is because in order for any substance to turn from liquid to gas, the attraction force between the molecules must be broken. Since hydrogen bond is keeping the molecules tightly together, it takes more heat to break the hydrogen bond, thus increase the amount of heat needed to turn liquid water into gas water. [Notebook] Not only that hydrogen bond keeps the water molecules together, they also give water surface tension​. This is because the hydrogen bond at the surface of water is stronger than other part of water because it doesn’t have to bond to the water molecules above it so it can be attracted to water molecules beside or under it. [Notebook] 1

Water is a “​universal solvent​” [Paragraph 5] because it can dissolve far more substances than any other liquids. This is also because the water molecules being polar molecules. Water can dissolve any polar substances as the polarity of water molecule will easily break down the polar molecules of other substance, thus dissolving in water. [Notebook] One of the most unique property of water is that its ​density changes depending on its temperature​. [Paragraph 8] Warm water has higher density than cold water. Water in its liquid form is also denser than in its solid form, which is usually the other way around for most substances. This is because when water freezes, the hydrogen bond expands. This causes the water molecules to be separated and have less density than liquid water which its molecules are kept together very tightly because of hydrogen bond. The purpose of this lab was to investigate the properties of water. We will be testing some of the properties listed above to see if they actually apply in real life. The properties of water that we will be testing in this lab are water’s high heat capacity, surface tension, being a universal solvent, and capillary action.

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