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HW #2: Seawater Salinity The salinity of seawater is the ratio of the total mass (in grams) of salt per 1 kg (1000 g) of seawater, and is expressed in units of parts per thousand (ppt, or %) which is approximately the same as practical salinity unit (psu). A 1 kg sample of seawater that has a salinity of 34 % thus contains 34 g of salt. 1. The average salinity of the oceans is 35 %. The total mass of the oceans is about 1.4 x 10²1 kg. If the oceans completely evaporated, how much salt (kg) would be left behind? Show all of your work and box your answer (use extra paper if needed):

HW #2: Seawater Salinity The salinity of seawater is the ratio of the total mass (in grams) of salt per 1 kg (1000 g) of seawater, and is expressed in units of parts per thousand (ppt, or %) which is approximately the same as practical salinity unit (psu). A 1 kg sample of seawater that has a salinity of 34 % thus contains 34 g of salt. 1. The average salinity of the oceans is 35 %. The total mass of the oceans is about 1.4 x 10²1 kg. If the oceans completely evaporated, how much salt (kg) would be left behind? Show all of your work and box your answer (use extra paper if needed):

Applications and Investigations in Earth Science (9th Edition)
Applications and Investigations in Earth Science (9th Edition)
9th Edition
ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Chapter1: The Study Of Minerals
Section: Chapter Questions
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HW # 2: Seawater Salinity and Constant Proportions The salinity of seawater is the ratio of the total mass (in grams) of salt per 1 kg (1000 g) of seawater, and is expressed in units of parts per thousand (ppt, or %) which is approximately the same as practical salinity unit (psu). A 1 kg sample of seawater that has a salinity of 34 % thus contains 34 g of salt. 1. The average salinity of the oceans is 35 %. The total mass of the oceans is about 1.4 x 10²1 kg. If the oceans completely evaporated, how much salt (kg) would be left behind? Show all of your work and box your answer (use extra paper if needed): The dissolved constituents that make ocean water saline are composed of about six major ions as well as traces of various other ions (see Fig. 1 below). Even though the salinity of seawater varies in different parts of the globe and at different depths, the relative proportions of these ions in seawater is basically constant everywhere. Thus, if you know the concentration of only one of the major ions in seawater in a particular sample, you can calculate the total salinity of that sample! Read through the example on the following page... Copyright 1999 John Wiley and Sons, Inc. All rights reserved Sulfate 7.72% Magnesium 3.68% Calcium 1.17% Potassium 1.1% Bicarbonate 0.4% Bromine 0.19% All other ions 0.05% Chloride 55.07% Sodium 30.62% Figure 1: Major dissolved ions in seawater.
Transcribed Image Text:HW # 2: Seawater Salinity and Constant Proportions The salinity of seawater is the ratio of the total mass (in grams) of salt per 1 kg (1000 g) of seawater, and is expressed in units of parts per thousand (ppt, or %) which is approximately the same as practical salinity unit (psu). A 1 kg sample of seawater that has a salinity of 34 % thus contains 34 g of salt. 1. The average salinity of the oceans is 35 %. The total mass of the oceans is about 1.4 x 10²1 kg. If the oceans completely evaporated, how much salt (kg) would be left behind? Show all of your work and box your answer (use extra paper if needed): The dissolved constituents that make ocean water saline are composed of about six major ions as well as traces of various other ions (see Fig. 1 below). Even though the salinity of seawater varies in different parts of the globe and at different depths, the relative proportions of these ions in seawater is basically constant everywhere. Thus, if you know the concentration of only one of the major ions in seawater in a particular sample, you can calculate the total salinity of that sample! Read through the example on the following page... Copyright 1999 John Wiley and Sons, Inc. All rights reserved Sulfate 7.72% Magnesium 3.68% Calcium 1.17% Potassium 1.1% Bicarbonate 0.4% Bromine 0.19% All other ions 0.05% Chloride 55.07% Sodium 30.62% Figure 1: Major dissolved ions in seawater.
Example: Total salt in seawater is 30.62 % sodium (Na). This is equivalent to saying that if you had 100 g of total salt from a sample of seawater, it would contain 30.62 g of sodium. Say you measured the sodium concentration in a sample of seawater to be 10.5 % (remember this means there are 10.5 g of sodium in 1 kg of this sample of seawater). What is the total salinity of the sample? 10.5 g sodium 100 g total salt 1 kg seawater 30.62 g sodium X -= 34.4 g total salt per kg seawater or 34.4% *Note that the above math was set up so that the units 'g sodium' cancelled out to leave 'g total salt/kg seawater', which is the definition of salinity. 2. Given a sample of water with the same salinity as the sample in the above example, calculate the total mass (in grams) of chloride in a 1 kg sample of the seawater. Show all work for credit, and box your answer: 3. Calculate the salinity of a sample of seawater that has a chlorinity (chloride concentration) of 18.2%. Show all word for credit, and box your answer: 4. (a) List and briefly describe ONE way that surface seawater salinity can increase in a particular location, and ONE way that surface salinity can decrease. (b) What happens to the proportion of sodium ions to chloride ions in a sample of seawater when the total salinity increases?
Transcribed Image Text:Example: Total salt in seawater is 30.62 % sodium (Na). This is equivalent to saying that if you had 100 g of total salt from a sample of seawater, it would contain 30.62 g of sodium. Say you measured the sodium concentration in a sample of seawater to be 10.5 % (remember this means there are 10.5 g of sodium in 1 kg of this sample of seawater). What is the total salinity of the sample? 10.5 g sodium 100 g total salt 1 kg seawater 30.62 g sodium X -= 34.4 g total salt per kg seawater or 34.4% *Note that the above math was set up so that the units 'g sodium' cancelled out to leave 'g total salt/kg seawater', which is the definition of salinity. 2. Given a sample of water with the same salinity as the sample in the above example, calculate the total mass (in grams) of chloride in a 1 kg sample of the seawater. Show all work for credit, and box your answer: 3. Calculate the salinity of a sample of seawater that has a chlorinity (chloride concentration) of 18.2%. Show all word for credit, and box your answer: 4. (a) List and briefly describe ONE way that surface seawater salinity can increase in a particular location, and ONE way that surface salinity can decrease. (b) What happens to the proportion of sodium ions to chloride ions in a sample of seawater when the total salinity increases?
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