Review the trend in values of the van’t Hoff factor i as a function of concentration (Table 13.4). Use the following data to calculate the van’t Hoffweight) (for which ΔT =−3.05°C) and a Na₂SO₄ concentration of 5.00% (by weight) (for which ΔT = −1.36°C). Are these values in line with your expectations based on the trend in the values given in Table 13.4? Speculate on why this trend is seen.

Data given in Table 13.4

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TABLE 13.4 Freezing Point Depressions of Some lonic Solutions AT fp (calculated, °C) m AT fp Mass % (mol/kg) (measured, °C) NaCl 0.00700 0.0120 0.500 0.0860 1.00 0.173 2.00 0.349 Na₂SO4 0.00700 0.00493 0.500 0.0354 1.00 0.0711 2.00 0.144 -0.0433 -0.299 -0.593 -1.186 -0.0257 -0.165 -0.320 -0.606 -0.0223 -0.160 -0.322 -0.649 -0.00917 -0.0658 -0.132 -0.268 ATfp, measured ATfp, calculated 1.94 1.87 1.84 1.83 2.80 2.51 2.42 2.26