Chemistry – Correlation between Salinity and pH level        Michelle Fan, Janice Liu, Tanya Tang


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).


Is there a correlation between water salinity and its pH level?


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                                                 (550º 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


6 buckets                                5 50mL beakers                        electronic balance                hot plate

1 graduated cylinder                1 pH meter                                filter paper

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  1. took 6 samples of water from 6 different locations: 3 from the intertidal area, and 3 from the stream area.
  2. used paper filter to filter out the dirt
  3. measured the mass of 5 empty beakers and record the measurements
  4. chose one water sample first and put 5ml of it into 5 different beakers and evaporated the water completely to get white particles
  5. measured the mass of each beaker with the leftover compounds; used the empty dry beaker’s mass to subtract from this mass to get the salinity
  6. repeated step 2 – 5 with the other ...

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