EVALUATION OF THE EFFECTS OF SALT CONCENTRATIONS ON THE THERMODYNAMIC PROPERTIES OF WATERS IN LAKE VICTORIA.

Isaboke Ferdinard Nyanaro, Albert Getabu And Evans Okemwa. Department of Chemistry, Research and extension department, Kisii University. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 02 February 2019 Final Accepted: 04 March 2019 Published: April 2019 The presence of different cations in water does affect thermodynamic properties differentiary. Lake Victoria has many inflows (rivers) emanating from an agricultural areas. Consequently, it is expected that the will harbor a huge amount of cations. This research was focused on the salt effects on the thermodynamic properties of the waters of Lake Victoria. Where the mean of the wet season was acidic at 6.42± 0.11, close to neutral and exhibited little variability, thus showing high stability. Further observations were made on the of the dry season which had mean of 6.53±0.28 in this research. A SAMSUNG refrigerator (Model SR-L727EV) was used for freezing and a HACH heater (Model 240vac) were used for boiling purposes. Digital thermometer (Model 4445001) was used for temperature logging throughout the experiments. Analysis of variance was carried out to determine any significant differences of the cations concentrations on the water samples and on whether the cations significantly affected melting (point depression, boiling point elevation and vapor pressure deficit. It also was observed that cation concentration was significantly different and that direct addition of similar molar concentrations (0.2 moles) of the cations affected melting point, boiling point and vapor pressure significantly and differentially. Correlation models were developed that can be used to predict the effect of salt addition on thermodynamic properties.

The presence of different cations in water does affect thermodynamic properties differentiary. Lake Victoria has many inflows (rivers) emanating from an agricultural areas. Consequently, it is expected that the will harbor a huge amount of cations. This research was focused on the salt effects on the thermodynamic properties of the waters of Lake Victoria. Where the mean of the wet season was acidic at 6.42± 0.11, close to neutral and exhibited little variability, thus showing high stability. Further observations were made on the of the dry season which had mean of 6.53±0.28 in this research. A SAMSUNG refrigerator (Model SR-L727EV) was used for freezing and a HACH heater (Model 240vac) were used for boiling purposes. Digital thermometer (Model 4445001) was used for temperature logging throughout the experiments. Analysis of variance was carried out to determine any significant differences of the cations concentrations on the water samples and on whether the cations significantly affected melting (point depression, boiling point elevation and vapor pressure deficit. It also was observed that cation concentration was significantly different and that direct addition of similar molar concentrations (0.2 moles) of the cations affected melting point, boiling point and vapor pressure significantly and differentially. Correlation models were developed that can be used to predict the effect of salt addition on thermodynamic properties.

Introduction:-
Natural and anthropogenic activities in a given region largely determine the quality of surface [1] . Both of the said activities results in the water being polluted. Pollution is any chemical, physical or biological change in the quality of water that has a harmful effect on any living thing that drinks or uses or lives (in) it. If humans beings and animals drink polluted water it often has serious effects on their health. Water pollution can also make water unsuited for the desired use. Lake Victoria is shared between the three East African states and is in fact the largest tropical lake in the world with a surface area of 68,800 [3] .
Lake Victoria is relatively shallow, with a mean depth of 40 m. The people of the East African countries have high ecological regard for Lake Victoria waters. It (L.Victoria) is used for transport, recreation, fisheries, and as a water supply for drinking, industry and agriculture. 80% of its water is due to direct precipitation [5] Average evaporation The area around the lake is one of the world's most densely populated rural areas. Some of the most important towns and cities around the lake include Kisumu (population: 410,000), Kisii (population: 200,000), and Homa bay (population: 56,000) in Kenya; Kampala (population: 1.66 million), Entebbe (population: 80,000), and Jinja (population: 73,000) in Uganda; Mwanza (population: 707,000), Musoma (population: 134,000), and Bukoba (population: 86,000) in Tanzania.
The many anthropogenic activities including factories and plants in these cities discharge their waste directly into lake Victoria's waters and the rivers that flow into it.
The raw sewage that is being discharged also increases eutrophication, which sustains the water hyacinth [4] Strange changes in thermodynamic properties impact indirectly upon biota through loss of supporting habitat such as coral reefs [6] by changing the solubility of oxygen and calcium carbonate (calcite or aragonite) in water, or by influencing the extent to which metal contaminants [8] [2] and other toxins are assimilated by physiological processes.
Water quality depends on the variations on the thermodynamic properties. This is because they influences several other parameters and can alter the physical and chemical properties of water. In this regard they should be accounted for when determining conductivity and salinity, oxidation reduction potential (ORP), pH, dissolved oxygen and other dissolved gas concentrations, density, metabolic rates and photosynthesis production, and compound toxicity.
Water has the highest dielectric constant of all substances except hydrogen peroxide (H 2 O 2) and hydrogen cyanide (HCN). It has a high dissolving power because the water molecules reduce the forces of attraction between ions. The force between ions (F) is coulombic and the dielectric constant (ε) reduces this force according to: F = q1q2/r2ε , where q1 and q2 are the charges on two ions separated by a distance, r. For water at 25°C, ε = 78.
The high heat capacity and heats of fusion and evaporation provide immense thermo stating capacity in the critical temperature range that accommodates most life (-50 to 100 °C).

Figure 1:-Temperature & phases of water versus energy
Salts and any other polar compounds dissolve in water consequently increasing its density. The effect is greater when the concentration of solute increases. However, dissolved salts lower the temperature at which water reaches its maximum density. This is because dissolved salts inhibit the tendency of water molecules to form direct bonds with other water molecules. Dissolved salts have the effect of making the water molecules cluster and become more ordered, thus harder to pull apart and evaporate.

Methodology:-
Six (6) locations were identified and marked along the river mouths of Sondu miriu, Nyamasaria, Kisiani, Kibos rivers mouths as known by the locals along the lake. From each sampling location, three (500mL) water samples were collected from the surface, between 5-10m deep. The samples were packed in plastic bottles and labeled (SI -S6) depending on the station and were stored in the refrigerator. Solutions of lower concentrations were prepared daily by a suitable dilution of the Lake Victoria waters. All tests were carried out at Kenya marine fisheries and research institute situated near Lake Victoria this enabled us to take advantageof the same meteorological conditions in the research site.
A SAMSUNG refrigerator (Model SR-L727EV) was be used for freezing and a HACH heater (Model 240vac) were used for boiling purposes. A HACH digital thermometer (Model 4445001) was used for temperature logging throughout the experiments. A Portable WTW Multi-meter (Model Profiline 197i) was used for the determination of the electrical conductivity (EC) and total dissolved solids (TDS). Other data were acquired from the national meteorological organization50ml of the water sample were measured into a beaker followed by addition of 5ml of conc. HNO 3. Then solution was slowly boiled in a hot plate until the volume reduced to 10-20 ml.
The contents were the Transferred by filtering into a 50ML volumetric flask and the filter paper washed three times with deionized water. Distilled water was added to the mark and the sample was ready for AAS analysis.
For each element, three standards were identified for calibration of the curve for analysis.
In addition, for pH readings, no sample preparation was required, only calibration of the pH heater was done then the samples were read.

Freezing Point Temperature
Temperature Probe was connected to the Vernier computer interface. The computer was prepared for data collection by opening the file -17 Freezing Ocean Water‖ from the Earth Science with Vernier folder. A 400 mL beaker was 1/3 full filled with ice, followed with 100 mL of water as shown in Figure 2. 5 mL of fresh water was put into a test tube and a utility clamp was used to fasten the test tube to a ring stand. The test tube was clamped above the water bath and the Temperature Probe was placed into the water inside the test tube. When everything was ready, data collection was started. Then the test tube was lowered into the ice-water bath. Soon after lowering the test tube, 5 32 spoons of salt was added to the beaker and stirred with a spoon continuously to stir the ice-water bath. Slightly, but continuously, the probe was moved during the first 10 minutes of data collection. The probe was kept in and not above the ice as it formed. When 10 minutes had gone by, moving the probe was stopped and allowed it to freeze into the ice. Stirring the ice-water bath was continued and more ice cubes was added as the original ice cubes got smaller. Observations were made and recorded as the water froze. When 15 minutes had passed, data collection was stopped. On the displayed graph, analysis was done on the flat part of the curve to determine the freezing temperature of fresh water.
The mouse pointer was moved to the beginning of the graph's flat part and Pressed and held down as it is dragged across the flat part to select it.
The Statistics button was clicked and the mean temperature value for the data selected was listed in the statistics box on the graph. This was the value for the freezing temperature of fresh water. The value was recorded it in the data table. This data was saved by selecting Store Latest Run from the Experiment menu. The Temperature Probe was not removed from the ice. The test tube was placed into a beaker of warm water to melt the ice, and the Temperature Probe was removed ∆T for the FP of each solution was calculated and added to the FP of pure water. The value was recorded in the data table. The difference between the measured value from the lab and the calculated value from the formula was calculated. This error was also recorded in the data table

Boiling Point Elevation
Boiling point apparatus were assembled (ring stand, ring, wire gauze, clamp, slotted rubber stopper, and thermometer). The thermometer was set up so that the temperatures above 100 ˚ C were easily read. The thermometer was supported in the middle of the liquid being heated, and that it was not rested on the bottom of the beaker in contact with the burner flame.
Water samples from the lake were measured separately and accurately (100ML) and labeled S1, S2, S3, S4, S5, and S6; for use in the boiling point study.
Using a graduated cylinder, exactly 100mL of distilled water (pure water) was measured and transferred to the 250 beaker. Heating the water was started bringing it to a gentle boil. When the water was gently boiling, its temperature was determined.
Note: The boiling point of water varies with atmospheric pressure, but should be very near 100 ˚ C. If the temperature as read on thermometer differs from 100˚C. This error should be kept in mind when reading the temperatures of the experimental solutions during the rest of this experiment. The flame was turned off and then very slowly and carefully 100ML of S1-sample was added the to a 250ML beaker. The flame was restarted bringing the solution to a gentle boil. The boiling point was recorded after making any adjustments based on error noted when measuring the temperature of the boiling distilled (pure) water. The procedure was repeated for S2, S3, S4, S5 and S6 samples.

Of water from different sampling sites.
The of water from five sites sampled in the inner winam gulf, Lake Victoria are presented in table 4.1, and appendix 2. The mean of the wet season was acidic at 6.42± 0.11, close to neutral and exhibited little variability, thus showing high stability. Similar observations were made on the of the dry season which had mean of 6.53±0.28 .The latter showed slightly higher variability compared to that of the wet season.
Values of water samples during wet and dry seasons were graphically represented.
33 The values from figure 8, during the wet season ranges from 6.21 to 6.59 whereas during the dry season it ranges from 5.75 to 7.44. If the pH of water is too high or too low, the aquatic organisms living within it will die. can affect the solubility and toxicity of chemicals and heavy metals in the water. The majority of aquatic creatures prefer a pH range of 6.5 to 9.0, though some can live in water with pH levels outside of this range.

Concetrations of selected cations in water from different sampling sites.
The concentrations of selected cations in water samples ( , , and ) are presented in table 1. The most dominant cation was followed by at all sampling sites during the wet season.