The coldest seawater ever recorded (in a liquid state) was in a stream under an Antarctic...

 

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The coldest seawater ever recorded (in a liquid state) was in a stream under an Antarctic glacier in 2010; it measured -2.6 °C (27.3 °F). On average, water in the world's oceans has a salinity of about 3.5% (35 g/L, or 599 mm). This means that every kilogram (roughly one liter by volume) of seawater contains approximately 35 grams (1.2 ounces) of dissolved salts (predominantly sodium (Na) and chloride (CI) ions). Figure a provides information on the amounts of various cations and anions in seawater with an average density of 1.025 g/ml. Sea Salts Seawater Sulfate- 7.7% (2.7g) Calcium- 1.2% (0.42g) Potassium- 1.1% (0.39g) Chloride 55% (19.25g) Sodium 30.6% (10.7g) Magnesium 3.7% (1.3g) -Minor constituents 0.7% (0.25g) Water 96.5% (965g) Salt 3.5% (35g) A Figure a Cations and anions in Ocean Water Figure by illustrates the salinity of the oceans on Earth in grams of dissolved material (solute) per kilogram of seawater (solution) or parts per thousand (ppt). Salinity (ppt) more than 371 37 36 35 34 less than 34 © 2017 Pearson Education, Inc. Figure b Salinity of Seawater in the Earth' s Oceans Because most of the dissolved minerals in seawater is sodium chloride, we can make the assumption that seawater having a salinity of 35 g/kg contains 35 grams of NaCl per one kilogram of seawater. Use the information provided in the figures to answer the following questions: a. Calculate the freezing point of a sample of seawater having the highest salinity. Calculate the freezing point of a sample of seawater having the lowest salinity. Use a Van't Hoff Factor of 1.9 in your calculation. Assume the two samples contain water as the solvent and NaCl as the solute. b. Figure c is a proposed graph of the freezing temperature of saltwater versus the amount of salinity. A student claims that saltwater having a salinity of 280 g NaCl/kg of saltwater freezes at -20°C. Is this claim accurate? Explain. Freezing point (°C) -10 POT 198 -15- -20 100 300 400 200 Salinity (g/kg) ▲ Figure e Salinity of Saltwater Versus the Freezing Point of Seawater c. Use the information provided in Figure b and redraw the graph in Figure c using a range of salinity values from six different oceans. The y-axis should be the freezing point of water, and the x-axis should be the salinity of seawater in units of grams of NaCl/kg of seawater. Does Figure e provide an accurate view of the freezing point of the oceans? The coldest seawater ever recorded (in a liquid state) was in a stream under an Antarctic glacier in 2010; it measured -2.6 °C (27.3 °F). On average, water in the world's oceans has a salinity of about 3.5% (35 g/L, or 599 mm). This means that every kilogram (roughly one liter by volume) of seawater contains approximately 35 grams (1.2 ounces) of dissolved salts (predominantly sodium (Na) and chloride (CI) ions). Figure a provides information on the amounts of various cations and anions in seawater with an average density of 1.025 g/ml. Sea Salts Seawater Sulfate- 7.7% (2.7g) Calcium- 1.2% (0.42g) Potassium- 1.1% (0.39g) Chloride 55% (19.25g) Sodium 30.6% (10.7g) Magnesium 3.7% (1.3g) -Minor constituents 0.7% (0.25g) Water 96.5% (965g) Salt 3.5% (35g) A Figure a Cations and anions in Ocean Water Figure by illustrates the salinity of the oceans on Earth in grams of dissolved material (solute) per kilogram of seawater (solution) or parts per thousand (ppt). Salinity (ppt) more than 371 37 36 35 34 less than 34 © 2017 Pearson Education, Inc. Figure b Salinity of Seawater in the Earth' s Oceans Because most of the dissolved minerals in seawater is sodium chloride, we can make the assumption that seawater having a salinity of 35 g/kg contains 35 grams of NaCl per one kilogram of seawater. Use the information provided in the figures to answer the following questions: a. Calculate the freezing point of a sample of seawater having the highest salinity. Calculate the freezing point of a sample of seawater having the lowest salinity. Use a Van't Hoff Factor of 1.9 in your calculation. Assume the two samples contain water as the solvent and NaCl as the solute. b. Figure c is a proposed graph of the freezing temperature of saltwater versus the amount of salinity. A student claims that saltwater having a salinity of 280 g NaCl/kg of saltwater freezes at -20°C. Is this claim accurate? Explain. Freezing point (°C) -10 POT 198 -15- -20 100 300 400 200 Salinity (g/kg) ▲ Figure e Salinity of Saltwater Versus the Freezing Point of Seawater c. Use the information provided in Figure b and redraw the graph in Figure c using a range of salinity values from six different oceans. The y-axis should be the freezing point of water, and the x-axis should be the salinity of seawater in units of grams of NaCl/kg of seawater. Does Figure e provide an accurate view of the freezing point of the oceans?

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