A mixture that is made by dissolving one compound (solute) in another (solvent) is called a solution. The amount of solute that can be dissolved in a solvent at a given temperature is called solubility. For most substances, solubility increases with temperature. When the amount of solute dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a high temperature, and then slowly cooling the solution to room temperature. If a thin string is dipped into it and left in the solution, the sugar in excess of the solubility at room temperature will form sugar crystals around the string, making the sweet rock candy. The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees Celsius) is plotted in the graph below.A solution of sugar in water is NOT supersaturated when 300 g of sugar and 100 g of water are mixed at a temperature of:
Answer(s): D
One way to solve this problem is to draw a line through the graph along the 300 g of sugar per 100 g of water mark on the graph, as illustrated in the figure below.In the passage, a supersaturated solution was defined as one in which the amount of solute dissolved exceeds solubility at a given temperature. The line going through the 300 mark is above the solubility curve, at all temperatures listed in choices A, B, and C. At temperature D, however, 300 g sugar /100 g of water does not exceed solubility. Therefore, at 70 degrees Celsius, the solution is NOT supersaturated.
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a solution. The amount of solute that can be dissolved in a solvent at a given temperature is called solubility. For most substances, solubility increases with temperature. When the amount of solute dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a high temperature, and then slowly cooling the solution to room temperature. If a thin string is dipped into it and left in the solution, the sugar in excess of the solubility at room temperature will form sugar crystals around the string, making the sweet rock candy. The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees Celsius) is plotted in the graph below.In order for 250 g of sugar to completely dissolve in 100 g of water, the temperature of the solution would have to be at a minimum of:
Answer(s): C
You could use the strategy described in problem 1. If you draw a line through the 250 mark, you will see that it crosses the solubility curve at about 45 degrees Celsius. Below that temperature (choices A and B), the sugar will not dissolve completely. At 65 degrees (choice D) the sugar will dissolve. Choice D is incorrect because 65 degrees is above the minimum temperature required to dissolve the sugar.
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a solution. The amount of solute that can be dissolved in a solvent at a given temperature is called solubility. For most substances, solubility increases with temperature. When the amount of solute dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a high temperature, and then slowly cooling the solution to room temperature. If a thin string is dipped into it and left in the solution, the sugar in excess of the solubility at room temperature will form sugar crystals around the string, making the sweet rock candy. The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees Celsius) is plotted in the graph below.At 100 degrees Celsius the solubility of sugar in water would most likely be:
This question is asking you to extrapolate, make a prediction, based on the given data. The solubility of sugar in water increases, as the temperature increases. You can assume that the trend will continue. So, you can rule out choices A and B. Draw a line through the 100-degree Celsius mark, and extend the solubility curve to that mark, following the trend, as illustrated in the figure below. This should help you rule out choice C, since it will require the shape of the curve to change.
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a solution. The amount of solute that can be dissolved in a solvent at a given temperature is called solubility. For most substances, solubility increases with temperature. When the amount of solute dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a high temperature, and then slowly cooling the solution to room temperature. If a thin string is dipped into it and left in the solution, the sugar in excess of the solubility at room temperature will form sugar crystals around the string, making the sweet rock candy. The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees Celsius) is plotted in the graph below.In order to produce rock candy at 20 degrees Celsius from a solution of 300 g of sugar not completely dissolved in 100 g of water, the solution must be:
Answer(s): A
The question could be answered by going back to the passage. Rock candy is made by first completely dissolving the excess sugar, at a high temperature, then slowly cooling to room temperature Choices B, C, and D don't describe heating, followed by slow cooling.
A mixture that is made by dissolving one compound (solute) in another (solvent) is called a solution. The amount of solute that can be dissolved in a solvent at a given temperature is called solubility. For most substances, solubility increases with temperature. When the amount of solute dissolved in a solvent exceeds the solubility, the solution is called supersaturated. Rock candy can be made by dissolving as much sugar in water, as solubility would allow at a high temperature, and then slowly cooling the solution to room temperature. If a thin string is dipped into it and left in the solution, the sugar in excess of the solubility at room temperature will form sugar crystals around the string, making the sweet rock candy. The solubility (in grams of sugar per 100 grams of water) as a function of temperature (in degrees Celsius) is plotted in the graph below.How much sugar must be added to a solution of 50 g of sugar in 100 g of water at 45 degrees Celsius in order for the solution to be supersaturated?
You can solve this problem by drawing a line through the 45-degree Celsius mark. It intersects the solubility curve at about 250 g of solute per 100 g of solvent. In order for a solution to be supersaturated, the amount of sugar has to exceed solubility. Therefore, a total of more than 250 g is necessary. If a solution already contains 50 g of sugar, more than 200 grams are required.
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