Salinity Experiment

Topics: Sodium chloride, Water, Concentration Pages: 2 (345 words) Published: August 5, 2001
Salinity Experiment

Aim
To determine a method of measuring a soil sample's salinity level in order to measure 3 samples' salinity level.

Hypothesis
I think that by running a current through a salt solution and measuring the resultant amperage, a pattern in the recordings will help find a soil sample's salinity level.

Variables
Controlled  Amount of solution (100 mL), supplied voltage (4V), amount of soil (50 gm) & water (150 mL) in soil sample's solution. Independent  Amps recorded by ammeter.
Uncontrollable  Impurities dissolved into water.

Materials
Power pack; copper electrodes; ammeter; 8 different concentrations of salt solution (NaCl)  0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 mols; beakers; filter papers; funnel; wires; retort stand; scales; 3 soil samples; distilled water.

Method
1) Pour 100 mL of 0.1 mol NaCl solution onto beaker, place electrodes in solution and run 4V through the circuit as shown in the following diagram

2) Record amperage from ammeter.
3) Repeat steps 1 & 2 for 0.5, 1, 1.5, 2, 2.5, 3, 3.5 mols NaCl solution. 4) Observe results for a pattern linking salt level and amperage. 5) Mix soil and water to dissolve salt from soil.
6) Filter mixture to remove soil.
7) Run current through sample as in step 1.
8) Record amperage.
9) Repeat steps 5-8 for other soil samples.
10) Compare these results to the previous results to find salinity levels of dirt samples.

Results

Table of Results for NaCl solutions.
Concentration (mols)Amperage (mA)
0.185
0.5115
1.0150
1.5200
2.0230
2.5295
3.0370
3.5425

Graph of results for NaCl solutions.

Table of results for soil samples
Sample IDAmperage (mA)
1  In front of science room40
2  Oval10
3  Backyard15

Explanation of Results
The amperage of the soil samples is very low compared to that of the NaCl solutions'. This means that there is very little to no traces of salt in the chosen soil samples.