Need help with my writing homework on Chemistry: Cooling of Water. Write a 1500 word paper answering; Since this experiment involves a lot of measuring of reagents, the hands and eyes stand the most risk of being splashed on with the chemicals.
In this light, the use of gloves and wearing eye protection is advised. It is also advisable to wear close to the laboratory since spilled chemicals can pour on the feet. These measures involve clothing, but it is necessary to exhibit proper laboratory conduct. Measuring of reagents should be done from the working surface and not in the air. this reduces the chances of chemicals falling.
What temperature changes are noted, when NaOH, NaNO3, KNO3, and (NH4)2SO4 are dissolved in water? This question formed the basis of the experiment involving ionic substances as solutes, and water as the solvent.
Water, in its pure state, shows specific cooling behavior. It is characterized by a heat capacity of 4.2Jg-1K-1. Owing to this high heat capacity, it means that for the temperature of an aqueous solution to be raised by one unit (0C or K, which gives the same change), a lot of energy will be required (Reger, Goode, and Ball). Similarly, for the temperature of an aqueous solution to fall by one unit, a lot of energy has been released to the surrounding.
Water is a di-ionic molecule made up of a hydroxyl ion (OH-), and a hydrogen ion (H+) also referred to as a proton. The oxygen of water has a pair of dissociated electrons which gives it a partial negative charge. Oxygen, being more electronegative than hydrogen, gives the hydrogen a partial positive charge. Due to these properties, water exists as a dipole. Different water molecules form hydrogen bonds amongst themselves, between the partial negative of one molecule, and partial positive charge of another molecule. The presence of partial charges in a water molecule makes it possible for ionic substances to dissolve in water.
When an anionic compound is added to water, it goes into solution. This process is accompanied by temperature change where either the temperature rises or falls. When an ionic substance is dissolved in water, the process is referred to as hydration. In a case whereby hydration is accompanied by a temperature increase of the solution, the process is exothermic. When the reverse is true, the hydration process is characterized as endothermic (Reger, Goode, and Ball).