Part B The coldest seawater cw:r rn rded (in a liquid state) \\ a stre m under a

Question

Part B The coldest seawater cw:r rn rded (in a liquid state) a stre m under an Artarctic glacier in 2010: it rmeasured-2.6 uC (27.3 'F). For a solution of water with a salinity of 280 g NaClykg, what is the calculated freazing point? Express the temperature in degrees Celsius to one decimal place. On average, water in the world's oceans has a salinity of about 3.5% (35 g/L, or 0.60 This means that every kilogram (roughly one liter by vclurme) af seawaler contains approximalely 35 grarms (12 ounces) of dissolved salts (predominanty sodlum (Na and chloride (CI lons Figure 1 (Figure 1) provides information on the amountsof vanous cations and anions in sawater with an average density of 1.025 gm Hinta ? Figure 2 (Finura 2 illustrates the salinity of the ooaans on Earth in grams of dissolvod material (snlutr) per kilagram af saawatrr (solution) or parts per thausand ippt). Because moe of the dissolved minerals in seawater is sodium chloride, we can make the assumpton that seawater having a salinity of 35 gjkg contalns 35 g of NaCl per one klogram of seawater. My Answers Give Ue Use the information provided in the figures to answer the following quesions. Part C Use the information provided in Figure 2 and redraw the graph in Figure 3 using a range of salinity values from sk different oceans. The y axis should be the freezing point of water, and tha x axis should be the salinity of seawaber in units of grams of NaCI per klogram of seaeNaCl/kg Select Plot: World's Oceans from tha list under add graph and use a minimum ot hree data points to construct the graph. You can detine the freezing point for each salinity to tao dacimal place8 Sketch a graph of the freezing point of the world's oceans. Hints Figure 3 of3 +add graph add points de graphi graph infot?alp alinity (e NacI/swater) 31 32 33 34 35 36 338 39 40 1.7 1.8 -15 2.0 25 100 200 300 Salinity (g/kg) 2.3

Explanation / Answer

Part B :
Tf = i * m * Kf
for water Kf = 1.86oC/m ; i = 2
converting salinity to molality =(280 gm / 58.44 g/mol) / Kg of water = 4.7912 mol NaCl / Kg H2O
Tf = 2 * 4.7912 * 1.86 = 17.8234oC
Tf = 0 - 17.8 = -17.8oC

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