Figure 3.04. Halite saturation composition graph. Mixtures of water and halite (NaCl) in Figure 3.03 are shown on a graph of weight percent NaCl vs. temperature. Click on the graph to see a larger, interactive version with more information.
What do you know about the chemical composition of the brines for the three mixtures to the right of the line that are saturated with halite? Assume chemical equilibrium. Please make a choice from the following list and press "Enter":
Yes! All H2O-NaCl solutions saturated with halite have the same composition (at the same temperature), regardless of how much excess halite is present.
Because all the brines for the mixtures to the right of the dashed line are saturated with halite, all these brines have the same concentration of NaCl. That concentration is given by the dashed line. Adding more salt to a saturated solution just adds to the pile of undissolved crystals. The brine composition doesn't change. Because each of the mixtures to the right of the dashed line has a bulk composition with a different weight percent NaCl, the ratio of undissolved halite to brine must be different for each. This ratio can be determined graphically from the NaCl weight percent of the bulk composition relative to the NaCl weight percents of the halite and the brine. The relationship between the proportions of halite and brine follows the "Lever Rule". No. All H2O-NaCl solutions with halite remaining at equilibrium are saturated with halite and have the same composition (weight percent NaCl) at the same temperature, regardless of how much excess halite is present.
Because all the brines for the mixtures to the right of the dashed line are saturated with halite, all these brines have the same concentration of NaCl. That concentration is given by the dashed line. Adding more salt to a saturated solution just adds to the pile of undissolved crystals. The brine composition doesn't change. Because each of the mixtures to the right of the dashed line has a bulk composition with a different weight percent NaCl, the ratio of undissolved halite to brine must be different for each. This ratio can be determined graphically from the NaCl weight percent of the bulk composition relative to the NaCl weight percents of the halite and the brine. The relationship between the proportions of halite and brine follows the "Lever Rule".
