Evaporation is a process where liquid is converted to vapor with the purpose of separating it from a dissolved solid or from a liquid that is higher in boiling point in experiments or investigations on how to separate soluble solid in liquids (Holland, 2005). Evaporation technique was chosen for the experiment because it is easy and simple to execute compared to other methods of separation such as distillation.
Distillation is an investigative technique used in separation of mixtures based on conditional and differences required to change the components phases of the mixture. It can be applied in a mixture of liquids, and the mixture of soluble solutes and solvents like in this experiment. During the distillation process, the water is heated into the gas phase of the vapor leaving the salts deposits, then condenses back into liquid form that is then collected. The process is then repeated again to improve the water purity (Porteous, 2010). This method was obtained because pure water can be obtained
This technique is a process of solid crystals formation from a solution. This technique is a technique of separating solids and liquids in which transfer of solute from a solution to a solid crystalline which pure occurs (Jones, 2002). This method was chosen because pure solutes can be obtained.
Modifications made, and justification for the changes
1. In evaporation, I applied some heat from flames to the containers holding solution of water and salt. I applied the heat to increase the rate of evaporation instead of leaving it open in the air and under the sunshine that is slow.
2. I used ice in the condenser to condense maximum amount of vapor. Moreover, I re-distilled the condensed water to get maximum dissolved salts again.
3. In crystallization, I left the crystallization process to proceed slowly undisturbed instead of fast cooling. This was to prevent impurities from getting attached to the salts and also to get bigger crystals.
Ways to ensure the accuracy
To ensure accuracy, I ensured that the same amount of solvent and solution was used in the three experiments. Moreover, an equal amount of time was applied on all the experiments to get accurate results. Lastly, I ensured that the salts and the water had no impurities that could affect their boiling points.
Ways to ensure reliability
Reliability in the techniques was determined by the experiments producing consistent results. To ensure reliability, I started with the evaporation method which the results were salt and water, distillation and crystallization also produced consistent results of salt and water.Ways to ensure validity
Validity indicates the extent to which the applied technique in the separation process separated the components it was intended to separate. To ensure the validity, I ensured that salt and water which were the components of the solution that was to be separated were the end products.
The process requires a lot of heat energy which might be expensive. However, solar heat is slow and evaporates small quantities of the solution. The method is suitable in situations where salt is the only product needed. However, collection of water vapor is difficultDistillation
The distillation process desalinate water removes dangerous heavy metals like mercury, arsenic and lead, and the soluble salts that harden the water such as magnesium, calcium and phosphorous. Therefore, it is preferable for distillation of drinking water. However, this process is ineffective in separation of soluble salts that has lower boiling points than water such as synthetic chemicals, chlorine solutions, herbicides and pesticides (Porteous, 2010). Moreover, it requires large source of heat which is costly. Lastly, the distillation process strips water its natural trace elements; hence the hydrogen composition in water increases and makes water acidic (Porteous, 2010).
The process is complex compared to the evaporation method. It is also unsuitable where water is to be collected as an end product. However, it is advantageous since pure salts can be obtained for usage (Jones, 2002).
b) Suggestions of possible improvements
Alternative sources of heat could be used such as the use of solar energy to reduce high costs incurred in the evaporation and distillation process. Despite the fact that solar energy cannot produce a high amount of energy needed to heat the large amount of the solution for a longer duration of time, it is the best cost-wise.
Given that some dissolved salts have lower boiling points than the water hence difficult to separate them from water, the boiling point of water can be lowered by lowering the gas pressure above the liquid.
The distillation process strips water its natural trace elements, hence making water to be acidic due to increased proportion of hydrogen. To avoid water being acidic, beneficial salts can be added into the water for human consumption such as calcium that is good in formation of bones.
Holland, C. D. (2005). Fundamentals and modeling of separation processes: absorption, distillation, evaporation, and extraction. Englewood Cliffs, N.J: Prentice-Hall.
Jones, A. G. (2002). Crystallization process systems. Oxford: Butterworth-Heinemann.
Porteous, A. (2010). Saline water distillation processes. London: Longman.