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# Regents Chemistry Review: Solutions Topic

Solute = a substance that dissolves (for example sugar)

Solvent = a substance is able to dissolve a solute ( for example water)

Solution = solute and solvent together ( for example sugar in water)

There are two tables that will be used for the solutions chapter. Table G provides solubility guidelines for various substances in 100 grams of water. Notice, that the solubility changes with temperature (x axis).

Let's take a look at an example. Let's say we have 20 grams of NaCl dissolved in 100 grams of water at 10 °C. We can see that this point is below the curve shown for the NaCl. This would be an unsaturated solution = more solute can be still dissolved.

If we are on the solubility line, then the solution is saturated = maximum amount of solute has been dissolved. If we are above the solubility line, then we have a supersaturated solution = more than the maximum amount of solvent got dissolved). Table F provides solubility guidelines for various compounds in water. If the compound is soluble, it will dissolve in water. If the compound is insoluble, it will not dissolve in water. The chart on the let shows all of the soluble compounds with a few exceptions at the bottom. For example, any compound that contains group1 ions such as Na+ is soluble. The chart on the right shows all the soluble compounds with exceptions as well. For example, MgCO3 would be insoluble.

Calculations

There are different ways to describe the concentration of a solution. These are: molarity, parts per million or percent by mass. All of the needed formulas for these are given in Table T on the Reference Table.

Molarity = moles of solute/ liters of solution

Parts per million = (mass of solute/ mass of solution)*1000000

Percent by mass = (mass of part/mass of whole)* 100

Facts to remember

• Higher concentration of ions in a solution, better conductor of electricity

• When solute is dissolved in pure solvent (such as dissolving sugar or NaCl in water), the boiling point increases and the freezing point decreases.

Prepare for the Chemistry Regents Exam: HERE