Statement of purpose/ context
Relevant scientific theory, formula, evidence from literature and/or literature values (and appropriate documentation)
The purpose of this experiment was….
This lab relates to the things we have been learning in class because....
I have observed that... which has led to this investigation.
The temperature at which a liquid turns into a gas is called the boiling point. At standard temperature and pressure, the boiling point of water is 100⁰C. The primary difference between liquid and gaseous water is the distance in between the individual water molecules. In liquid water, the molecules are relatively close to each other and is held together by intermolecular forces. In gaseous water, the molecules are farther apart and interact very little. In order for liquid water to become gaseous water, the water molecules must have enough energy to overcome the intermolecular forces that hold them together. When water is heated, the molecules become more energetic and vibrate more and more. Eventually, they vibrate so quickly that they overcome the intermolecular attraction and are free to escape. This is what happens at the boiling point of water.
The boiling point of water can change under certain conditions. For example, the boiling point of water is dependent on pressure. Water that is at pressures higher than standard pressure (1 atm) will boil at higher temperatures. Water that is at pressure below standard pressure will boil at lower temperatures. This effect is observed when cooking at altitude, where water boils at temperatures below 100⁰C. The boiling point of water can also change if substances is added to the water. This phenomenon is known as boiling point elevation. When a substance such as salt is dissolved in the water, the ions surround the water molecules. These ions make it harder for the molecules to escape and thus more energy is needed to boil the water. Consequently, the boiling point of a salt and water mixture is higher than 100⁰C. The increase in the boiling point of the water is proportional to the quantity of salt added.