To determine the average concentrations of salt from different points along an estuary by analyzing the densities and residue of the water.



I think that the density and the residual percentages are going to be higher as the estuary samples are closer to the ocean.



1. 2-liter samples of estuary water from five locations along an estuary.


2. 2-liter sample of tap water


3. graduated cylinder


4. electric balance


5. 10 plastic cups




1. Drive out to an estuary and collect five samples of estuary water from five different points along the estuary.


*There are two parts to this experiment*


Part one- Determine the actual amount of saltwater mix by calculating the densitites of the five samples.


1. Weigh the graduated cylinder on the electric balance.


2. Using the graduated cylinder, measure 150mL of each reference sample. Weigh them seperatly on a balance scale. Then subtract the graduated cylinder weight to obtain the mass of each sample.


3. Find the density of each sample by dividing the mass by the volume. Then calculate the average density for all the samples.


4. Next, find the actual percentage of saltwater for each sample. Once you have determined the seperate and combined densities of the freshwater and saltwater in your sample and know the samples total volume, the percentage of fresh river water (x) and saltwater (y) can be calculated as follows:

[(volume of x)(density of x)] + [(volume of y)(density of y)]= total (volume)(density)


Part two- Measure how much residue is in each of the samples.


1. Reduce 2 liters of an estuary location sample by boiling it. Allow it to cool and pour into a plastic cup. Place another cup alongside and fill it with distilled water until the volumes in both cups are the same.


2. Then weigh both cups on a electric scale and subtract the mass of the distilled water from the mass of the sample water. Repeat for each of the samples and record your results.