Density and Salinity of Seawater †Comparison of Methods

Density and coarseness of saltwater Comparison of Methods Sergian Murtanu, Lab companion Sammy ChaabanAbstract The goal of this experiment was to compare the brininess of brine from contrasting methods. The just table salt in seawater is around 35 part per thousand. 3 The mannikin bottlefuls were utilize to find the denseness of seawater, the equation to declare was then applied, using meanness to determine the coarseness. The common salt of seawater from the chassis method was 33.37 ppt 0.08737 with a recounting standardized deviation of 0.2618 percent. Using the selfsame(prenominal) equation of state, the salinity was determined from the tuitions recorded by the constriction cadency. The assiduity meter produced salinity values of 34.75 ppt 1.403, with an RSD% of 4.038. The conduction poke into nebd the capacity of the solution to pass current. The Unesco equation is used to convert the measured conduction of seawater to salinity, which was compute to be 42.71 ppt 0.04359 with a RSD% of 0.1021. The refractometer measured the extent of which is bent, giving the deflective index. The average salinity through refractive index was 36.14 ppm 2.56, with an RSD% of 0.1884. originThe purpose of this experiment was to determine the salinity of seawater through both different methods BOD bottles ( leger) and density meter. Salinity, temperature, and density are link up to all(prenominal) other through the equation of state. Physical properties of seawater are related through state functions. Salinity is defined as a measure of the total dissolved salts in a solution. As density increases, the step of salt in seawater is expected to increase as well. Thus, density and salinity support a positive relationship with each other. As temperature increases, the area between each water molecule increases, which lowers the density.5 Density has an opponent relationship with temperature. An increase in the salts dissolved in seawater o verly causes the physiological properties of refractive index, galvanic conductivity, transmission of sound, and surface tension to increase. On the contrary, increased salinity in seawater will cause the physical property of freezing signalize, compressibility, solubility, and specific heat to decrease instead. Using the methods of electrical conductivity, BOD bottles, density meter, and refractometer, the salinity of seawater will be calculated and compared for the just about stainless departs. 3ExperimentalApparatusBOD Bottlesconductivity essayDensity meterRefractometerAnalytical balancesProcedureThe density of seawater through the BOD method was discovered by finding the volume of both DI water and seawater. The BOD bottle is weighed dry, and filled with DI water. The temperature of each BOD bottle with DI is taken, and gives a corresponding density value through a chart. Using the equation Volume=Mass/Density, the volume of DI water so-and-so be calculated. This process is repeated with seawater, with density of seawater being the tilt of seawater divided by the mean volume of DI water.The density meter method uses a magnet to measure the period oscillation deep down the U-shaped tube. Seawater is put in the U-shaped tube. This gives the period of oscillation, T, which is then used in the equation =AT2 + B , to give the density of seawater(A, B are standardization co competents). The equation of state presumptuousness in the spreadsheet, Millero Density Spreadsheet is then used to calculate the salinity at the given density and temperature. 4The conductivity probe is used to compare the trend between salinity and density. A conductivity probe is first calibrated, then put in a beaker of DI water, standard solution, and seawater. The reading is measured, with the probe cleaned between e actually new trial. conductivity is the ability for a solution to pass current, so it is expected that salinity and density have a positive relationship. Using the formula given in the Unesco Equation Spreadsheet, the conductivity ratio is used to calculate the salinity. 1The refractometer is a tool that measures the extent in which light is bent. Drop a sample of seawater to the measuring prism and use the hand seethe to adjust the sight. The illuminating prism should be put at the center(prenominal) point of the sample, this then gives the refractive index. Using given slope and quit Salinity vs. Refractive Index and Salinity vs. particular proposition Gravity Curves, the salinity and specific gravity is then calculated. 2ResultsTable 1 Seawater salinity in BOD BottleTrialTemperature (C)Salinity121.533.35221.633.47321.733.30Mean Salinity33.37 exemplar aberrancy0.08737 congener measuring rod Deviation %0.2618Table 2 Salinity of seawater by density meter Data obtained by Jessica OregonTrialTemperature (C)Salinity12033.5322035.9532033.5342035.97Mean Salinity34.75Standard Deviation1.403Relative Standard Deviation %4.038Table 3 Sali nity of seawater by refractive indexTrialSeawaterSalinity11.340038.3721.339133.3431.339736.69Mean Salinity36.14Standard Deviation2.560Relative Standard Deviation %7.083Table 4 Salinity of seawater by conductivity probe (22.6 C)TrialSeawater (mS/cm)Standard (mS/cm)Salinity149.649.442.76249.649.542.68349.749.642.68449.649.442.76549.749.642.68Mean49.649.542.71Standard Deviation0.05480.1000.0436Relative Standard Deviation %0.1100.2020.102DiscussionThe results seem to imply that the salinity in seawater varies depending on the method, as some methods have a lesser take a chance of error than others. Using the average seawater salinity of 35 ppt as a comparison, most of the results seem to fall between the ranges of 33 to 37. However, the most nonable difference is the salinity of seawater by conductivity probe. The conductivity probe method produced a mean salinity of 42.71 ppt 0.0436, with a relative standard deviation of 0.102 percent. The results for the conductivity probe were qu ite cold in comparison to the other method. However, the conductivity method had an RSD% of 0.1021. This indicated that the results while somewhat imprecise, were very precise. This inaccuracy may have been caused out-of-pocket to systematic errors in our instrument. The conductivity probe might have been calibrated incorrectly, or in the wrong solution. If the calibration was just slightly off, it is possible that this difference might have contributed to the inaccurate salinity results. The solutions measured on the probe might have gotten begrime without prior knowledge, or it might have simply been a valet error in calculations.The result with the highest relative standard deviation was the salinity of seawater by refractive index with 7.083 %. This indicates that there was a pass out of variation in salinity for each trial. The salinity ranges from 33.34 to 38.37 ppt. The mean salinity of seawater by refractive index was 36.14 ppt 2.560, which is close to the average sea water salinity of 35. These slightly imprecise results may be delinquent to ergodic and systematic errors. The use of the eyepiece when trying to go to the halfway point might change due to different perception between people. Likewise, reading the refractometer varies between each individual and might change with angle due to parallax. This can really change the data measured and can result in imprecise data. There can similarly be gentlemans gentleman errors done during the conversion between refractive index and salinity.The BOD bottle method has a salinity of 33.37 ppt 0.08737 with an RSD% of 0.2618. The very low relative standard deviation indicates that there isnt much spread within the data. When compared to the average seawater salinity of 35 ppt, it falls a little post short. This was because there are a lot of possible errors for this method due to the long process of balancing and rebalancing. Possible systematic errors might have occurred on the analytical balances , such as calibration. Random errors, such as the fluctuation of weight in our seawater sample might also have impacted the accuracy. This method was also very time consuming, so it was not the most efficient way of determining the salinity. But, based on the results, it was the most dependable with good accuracy and great precision.The most accurate method when compared to the average value of seawater salinity is the density meter. The density meter has a salinity of 34.75 1.403, with an RSD% of 4.038. The RSD% of 4.038 indicated that there was some variation in the data. However, when compared to the average seawater salinity, this was the closest by far. This method was the most efficient overall because it allowed the opportunity to obtain the density, and salinity value the quickest. However, its not perfect because the instrument can calibrated or used incorrectly. plot of ground the most precise method goes to the BOD method, the most accurate would go to the density meter. The density meter is also quick and efficient, which make it an beautiful tool to calculate the value for salinity. In comparison, the BOD method took far too long and was not nearly as efficient as the density meter method. If there was one thing that should be changed in a repeat of this experiment, it would be giving an extended time for the density meter method. There was not enough time in the delegate lab period, so data from a peer was borrowed and used.AcknowledgementsI would the interchangeables of to thank Sam and George for helping us with calculations. I would also like to thank fellow peer, Jessica Oregon for the data set on seawater density by meter.ReferencesAnderson, George, and Michael Tauber.Unesco Density Spreadsheet. University of California, San Diego Ted.ucsd.edu, n.d. Xlsx.Tauber, Michael, and George Anderson.Salinity vs Refractive Index and Salinity vs Specific Gravity Curves. University of California, San Diego Ted.ucsd.edu, n.d. Xlsx.Tauber, Michael, and Robert Pomeroy. 3.5 Density and Salinity lecture.Ted.ucsd.edu. N.p., n.d. Web. 02 Feb. 2015.Tauber, Michael, and Robert Pomeroy.Milero Density Spreadsheet. University of California, San Diego Ted.ucsd.edu, n.d. Xlsx.The Ocean and Temperature.The Ocean and Temperature. N.p., n.d. Web. 02 Feb. 2015.