Determination of Calcium and Chloride Ion Concentration in Water Sample, Lab Report Example

Introduction

The purpose of this laboratory experiment is to determine the concentration of calcium and chloride ions that are present in water samples using titration methodology. It is necessary to do so because understanding the availability of these ions in water have public health implications. Typically, the water we drink is not pure and it is essential to understand the amount of these ions that are present in these water samples to determine if they will cause us detriment in some way. An understanding of molality and molarity is essential for this experiment. Molality impacts the freezing point of a solution. Furthermore, this knowledge can be utilized in conjunction with a knowledge of molarity to determine the number of molecules of a particular molecule that is present in a mixture. This is practical because it allows us to identify concentrations. One of the most useful applications for these calculations are determining the dosage of medications, as a failure to take a correct dose can result in disability or death. In this particular experiment, this theory is only practically useful if a color change is observable for the titration. It is sometimes difficult to be clear when this type of color change occurs, so the results may not always be accurate.

To understand this experiment, it is useful to have knowledge of certain vocabulary. For example, the rate is the speed at which a chemical reaction proceeds. A titration utilizes a chemical with a known concentration to determine the unknown concentration of a known substance. A freezing point is a property that defines the temperature at which distinct chemicals are able to freeze.

Materials and Procedures

The materials used are as follows:

– Thermometer

– Thermometer clamp

– Stirrer

– Burner

– Napthalene

The first step of this process is to ensure that the naphthalene melts. Then, the rubber stopper which has the thermometer and copper wire will be inserted into the test tube and placed into the naphthalene. Then, the stirring wire was moved up and down to ensure that the temperature is constant throughout the sample. When the beaker is boiled, the water will be removed from under the test tube. The temperature of the naphthalene was then recorded every 30 seconds once it reached 90 degrees Celsius. The temperature of the naphthalene will be taken until it drops to 65 degrees Celsius. A cooling curve that depicts the temperature of naphthalene will be plotted.

Three 250 mL Erlenmeyer flasks will filled with distilled water and numbered. The buret was cleaned with standard 0.05 M silver nitrate solution. The buret was then filled with the standard silver nitrate solution. 1 mL of potassium chloride indicator solution will be added to each sample flask. The initial volume of the silver nitrate will be recorded. A small amount of calcium carbonate will be added to each flask. Add the silver nitrate from the buret to each sample, once at a time, while stirring the flask. When one drop of permanent red color forms, silver nitrate will stop being added. The final volume in the buret will be recorded. The volume of silver nitrate needed to turn the solution red will be recorded. The concentration of chloride ion and mean concentration of chloride ion will then be determined. To determine the concentration of calcium ion in the water, the protocol will be repeated using .05 M Na2H2EDTA solution in the buret and a combination of Mg/EDTA solution and Eriochrome Black T indicator solution for the titration. No changes were made to the procedure.

Results and Discussion

For the determination of chloride ion in water, he results demonstrated that there was an average use of 2.05 mL of silver nitrate needed to cause a color change in the solution. There was an average of 0.103 moles and the concentration of the sample was 0.003. For the determination of calcium ion in water, the average volume of EDTA used was 14 mL and this was an average of 0.70 moles. The average concentration of the sample was 0.02. This means that there is a low concentration of these ions in water. Next time, it may be more useful to complete more trials, as the numbers received were not precise.

Conclusion

The concentration of the chloride ion and calcium ion was approximately equal, which shows that there are low concentrations of these molecules present in water. These results were not precise, but the average of the trials could be potentially accurate. It is therefore important to utilize more trials in the future to ensure that the results are valid. This is an important implication for the real world because it shows us that there is some of these chemicals present in our drinking water. However, it is likely not enough to cause physical harm. While the concentrations that are present in our own water likely vary, it is important to be knowledgeable about the contents of our drinking water so that we can remain healthy.

Works Cited

Experiment 27: Determination of Chloride Ion and Calcium Ion in Water Samples. Print.