The formal definition of ocean salinity used by oceanographers is complicated and involves numerous chemical conversions...

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The formal definition of ocean salinity used by oceanographers is complicated and involves numerous chemical conversions to obtain Practical Salinity Units (psu). But the saltwater used in this lab contains only sodium and chlorine ions (from NaCl), so this lab will employ a far simpler definition: the mass of dissolved solids (ions) divided by the total mass of the saltwater sample (water+ ions) X 1000. Salinity (%)=[ mass of dissolved solids (g) / total mass of saltwater (g) | X 1000 This equation expresses salinity in parts per thousand (%), almost identical to psu. It is similar to the typical percentage (%) common in everyday life. Percentage (%) is simply parts per hundred; a bucket containing 100 apples, 99 red and I green, would have 1% green apples. This means the amount of green apples is one part per hundred (1/100). Parts per thousand is similar; replace the 100 in the denominator with 1000. For example, a bucket containing 1000 g total of saltwater, with 1 g of dissolved salt, will have a salinity of 1%. This means the amount of dissolved solids is 1 part per thousand (1/1000) by mass. The difficult part of determining salinity is measuring how many dissolved solids are in the sample of saltwater; this lab will use several different methods to calculate salinity. Three different water samples will be tested, one of a known salinity (35% about the salinity of the ocean) and two of unknown salinity (samples A and B). This lab will determine the salinity of the unknown samples using five different methods. Some of the methods are easier than others and some are more precise. Sample Known 35% Unknown A Unknown B Dish only 41.56 41.89 41.09 Dish + water 49.33 50.22 Salinity by Evaporation Water only 50.22 Dish + salt 41.85 42.10 41.59 Salt only Question: What is the salinity (in %) of the three water samples according to the evaporation method (hint: use the simple equation for salinity -[mass of salt/mass of saltwater] X 1000)? Question: Did any of the dissolved salt ions evaporate with the water? The formal definition of ocean salinity used by oceanographers is complicated and involves numerous chemical conversions to obtain Practical Salinity Units (psu). But the saltwater used in this lab contains only sodium and chlorine ions (from NaCl), so this lab will employ a far simpler definition: the mass of dissolved solids (ions) divided by the total mass of the saltwater sample (water+ ions) X 1000. Salinity (%)=[ mass of dissolved solids (g) / total mass of saltwater (g) | X 1000 This equation expresses salinity in parts per thousand (%), almost identical to psu. It is similar to the typical percentage (%) common in everyday life. Percentage (%) is simply parts per hundred; a bucket containing 100 apples, 99 red and I green, would have 1% green apples. This means the amount of green apples is one part per hundred (1/100). Parts per thousand is similar; replace the 100 in the denominator with 1000. For example, a bucket containing 1000 g total of saltwater, with 1 g of dissolved salt, will have a salinity of 1%. This means the amount of dissolved solids is 1 part per thousand (1/1000) by mass. The difficult part of determining salinity is measuring how many dissolved solids are in the sample of saltwater; this lab will use several different methods to calculate salinity. Three different water samples will be tested, one of a known salinity (35% about the salinity of the ocean) and two of unknown salinity (samples A and B). This lab will determine the salinity of the unknown samples using five different methods. Some of the methods are easier than others and some are more precise. Sample Known 35% Unknown A Unknown B Dish only 41.56 41.89 41.09 Dish + water 49.33 50.22 Salinity by Evaporation Water only 50.22 Dish + salt 41.85 42.10 41.59 Salt only Question: What is the salinity (in %) of the three water samples according to the evaporation method (hint: use the simple equation for salinity -[mass of salt/mass of saltwater] X 1000)? Question: Did any of the dissolved salt ions evaporate with the water?

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salinity mass of dissolved solids g total mass of saltwater g1000 sa... View the full answer