Evidence and Analysis:
The literature Ksp for calcium hydroxide is 5.02×〖10〗^(-6), which is a relatively large Ksp value. This goes against the “rules of solubility” that labels calcium hydroxide as insoluble. According to the “rules of solubility”, calcium hydroxide should not be soluble in water; however, our results reveal that it does have some degree of solubility at standard conditions. We know this because we started with an initial concentration of calcium hydroxide and no concentration of either calcium or hydroxide ions. However, when this reaction reached equilibrium, we found a concentration of calcium hydroxide to be 1.1×〖10〗^(-2) M, concentration of calcium ions to be 1.3×〖10〗^(-2) M, and concentration of hydroxide ions to …show more content…
This value is comparable to the CRC Ksp, which is 5.02×〖10〗^(-6). Our calculated value is slightly larger than the literature value because of our experimental error. Some of this error came from the different methods that we chose to separate the solid calcium from the hydroxide solution. The three methods that we used were decanting, separation by centrifuge, and filtration with filter paper. According to the CRC Handbook, the expected concentration at 20 degrees Celsius of dissolved calcium hydroxide is 2.025×〖10〗^(-2)M. During our experiment we found that filtration yielded the most accurate results, followed by separation by centrifuge, and then by decanting. Using filtration, we got measured concentrations of 0.017 M using the pH probe and 0.019 using titration. Using separation by centrifuge, we got measured concentrations of 0.024 M using the pH probe and 0.026 using titration. Using decanting, we got a wide range 0.017-0.026 M using the pH probe and 0.020-0.028 M using titration. This wide range on the decanting method suggests that this method is very inconsistent and is less precise than the other methods. Also, with our observations we noticed that the centrifuge solution was clearer than the cloudy decanted solution, suggesting that decanting is less …show more content…
When we completed our lab, we had to determine the Ksp and the concentration of Calcium Hydroxide. Before doing this lab, we actually practiced these calculations. We also learned in lecture about using different indicators for different chemical reactions. For this lab, we used a different indicator called Bromothymol Blue. We used this in substitute of our usual Phenolphthalein due to where we were measuring when it got to equilibrium. One example of real life application for solubility has to do with purification of water. In areas with high pollution, water can be easily contaminated by harmful cations. Due to this environmental issue, different water filtration strategies must be used. One involves using seashells which causes these cations to precipitate as solids and to be easily filtered through different filters. This relates to our lab, because we tested different ways to filter Calcium Hydroxide to see which would be more helpful. This seashell technique helps make filtering much
The literature Ksp for calcium hydroxide is 5.02×〖10〗^(-6), which is a relatively large Ksp value. This goes against the “rules of solubility” that labels calcium hydroxide as insoluble. According to the “rules of solubility”, calcium hydroxide should not be soluble in water; however, our results reveal that it does have some degree of solubility at standard conditions. We know this because we started with an initial concentration of calcium hydroxide and no concentration of either calcium or hydroxide ions. However, when this reaction reached equilibrium, we found a concentration of calcium hydroxide to be 1.1×〖10〗^(-2) M, concentration of calcium ions to be 1.3×〖10〗^(-2) M, and concentration of hydroxide ions to …show more content…
This value is comparable to the CRC Ksp, which is 5.02×〖10〗^(-6). Our calculated value is slightly larger than the literature value because of our experimental error. Some of this error came from the different methods that we chose to separate the solid calcium from the hydroxide solution. The three methods that we used were decanting, separation by centrifuge, and filtration with filter paper. According to the CRC Handbook, the expected concentration at 20 degrees Celsius of dissolved calcium hydroxide is 2.025×〖10〗^(-2)M. During our experiment we found that filtration yielded the most accurate results, followed by separation by centrifuge, and then by decanting. Using filtration, we got measured concentrations of 0.017 M using the pH probe and 0.019 using titration. Using separation by centrifuge, we got measured concentrations of 0.024 M using the pH probe and 0.026 using titration. Using decanting, we got a wide range 0.017-0.026 M using the pH probe and 0.020-0.028 M using titration. This wide range on the decanting method suggests that this method is very inconsistent and is less precise than the other methods. Also, with our observations we noticed that the centrifuge solution was clearer than the cloudy decanted solution, suggesting that decanting is less …show more content…
When we completed our lab, we had to determine the Ksp and the concentration of Calcium Hydroxide. Before doing this lab, we actually practiced these calculations. We also learned in lecture about using different indicators for different chemical reactions. For this lab, we used a different indicator called Bromothymol Blue. We used this in substitute of our usual Phenolphthalein due to where we were measuring when it got to equilibrium. One example of real life application for solubility has to do with purification of water. In areas with high pollution, water can be easily contaminated by harmful cations. Due to this environmental issue, different water filtration strategies must be used. One involves using seashells which causes these cations to precipitate as solids and to be easily filtered through different filters. This relates to our lab, because we tested different ways to filter Calcium Hydroxide to see which would be more helpful. This seashell technique helps make filtering much