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Group 4 Chemistry

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Chemistry The chemistry experiment is aimed at testing whether the concentration of salt influences the pH level in the tested water types. The frequency of the opening and closing of the barnacles may be influenced by the salt concentration and the pH level of the water environment in which the barnacles live. Generally, seawater has a pH level of 7.7-8.3 while fresh water has a pH level of 7.0. The high pH level is a result of high concentration of OH ion in a sample. Seawater is a basic solution because the presence of basic salts in the water, such as Sodium Carbonate (Na2CO3) and Potassium Carbonate (K2CO3). Question Is there a correlation between water salinity and its pH level? Hypothesis If it is true that sea water has a higher pH level than fresh water does, then intertidal water will have a higher pH level than stream water does because of intertidal's higher salinity. Independent variable: salinity (g) Dependent variable: pH level Controlled variables: temperature of experiment environment (room temperature), amount of water for each evaporation procedure (5mL), hot plate temperature (550� C), pH meter starts at 7.0 at the beginning of the testing, same amount of water for pH testing (40 mL), ensure all testing water all free of large contaminants by filtering Materials 6 buckets 5 50mL beakers electronic balance hot plate 1 graduated cylinder 1 pH meter filter paper Procedure 1. ...read more.


This is a graph based on data in Table 1: There seems to be no correlation between the two sets of data because it's very difficult to draw a best fit line. By using Spearman's Rank correlation test (Appendix II), we discover that it is highly improbable that there's a correlation between salinity and pH level. Sources of Errors A primary source of errors occurs when we tried to evaporate the water to obtain salt. When there was a little bit of water left in the beaker, some salt began to splash out of the beaker, leaving white crystals around the container. Some salt may be lost because of this. Furthermore, because our group was sharing the hot plate with others, their splashing salt might come into our beakers, resulting unintentional gain of salt. Both loss and gain of salt can result in errors in the salinity. If I were to do this experiment again, I would use a paper towel to cover my beaker during heating. After the beaker is completely dried, I would scrape some salt that's stuck to the paper towel back into the beaker to ensure accuracy in the salinity. Another possible error is the remnants in the beaker after evaporation. Although we tried to avoid contaminants by filtering, there can still be some chemical compounds or micro-organisms in the water. ...read more.


4 0.06 14 7.58 8 -6 36 outermost of stream 1 0.05 15.5 7.05 23 7.5 56.25 outermost of stream 2 0.05 15.5 7.05 23 7.5 56.25 outermost of stream 3 0.04 18.5 7.05 23 4.5 20.25 midzone of stream 1 0.04 18.5 8.03 3 -15.5 240.25 midzone of sream 2 0.04 18.5 8.03 3 -15.5 240.25 east beach (intertidal) 5 0.04 18.5 7.58 8 -10.5 110.25 outermost of stream 4 0.03 21 7.05 23 2 4 outermost of stream 5 0.01 24 7.05 23 -1 1 midzone of stream 3 0.01 24 8.03 3 -21 441 midzone of stream 4 0.01 24 8.03 3 -21 441 midzone of stream 5 0.01 24 8.03 3 -21 441 innermost of stream 1 0.01 24 7.12 18 -6 36 innermost of stream 2 0.00 28.5 7.12 18 -10.5 110.25 innermost of stream 3 0.00 28.5 7.12 18 -10.5 110.25 innermost of stream 4 0.00 28.5 7.12 18 -10.5 110.25 innermost of stream 5 0.00 28.5 7.12 18 -10.5 110.25 d2 = 4867 To calculate the correlation coefficient (r) using formula r = 1- r = 1 - = - 0.08 degree of freedom = number of samples - 2 = 28 The correlation coefficient fails the 5% acceptance level, which means that there's most likely no correlation between salinity and pH levels. ...read more.

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