Introduction to Solutions



Introduction to Solutions | |

Solutions are _________________________________ mixtures of two or more substances. They can exist as

________________________, ________________________, or ___________________ depending upon their components.

All solutions are comprised of two basic components: a ________________________________ and one or more ____________________________. The solvent is the substance present in the ________________________

proportion. For example in sugar water the sugar is the __________________________ and the water is the

____________________________.

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Saturated, Unsaturated and Supersaturated

Solutions can be described as saturated, unsaturated, or supersaturated. Saturated solutions are defined as solutions in which the _____________________________ amount of solute has been dissolved in the solvent at a given temperature. Unsaturated solutions are defined as those in which ______________________________ the maximum amount of solute has been dissolved in the solvent at a given temperature. Supersaturated solutions generally arise when saturated solutions are cooled. Under these conditions it is possible for ________________ solute than is normally able to dissolve at a given temperature to be present in solution. Notice that if we had three beakers of sugar water in which one was saturated, one was unsaturated, and one was supersaturated, they would all appear as _______________________, __________________________ _____________________. To distinguish amongst them a bit more solute(sugar) could be added to each. If the solution was unsaturated the additional sugar should _____________________________ (perhaps with some stirring). If the solution was saturated the additional sugar should simply ________________________________ on the bottom of the beaker. If the solution was supersaturated the additional sugar would cause the whole system to _____________________________.

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Solubility

Solubility is defined as the amount of substance needed to make a ___________________________________

__________________________________________________. Two common ways of recording solubility are:

1)

2)

The term soluble is vague. Everything is soluble to some extent and everything has an upper limit on its solubility. As a consequence scientists have agreed on a standard. A solute is considered soluble if____________________

__________________________________________ . Use the solubility table on the back of your periodic table to determine whether the following ionic compounds are considered soluble or not.

|a) MgSO4 __________________ |b) Mg(OH)2 _________________ |c) CaS __________________ |

|d) CaSO3 __________________ |e) CuCl2 _________________ |f) CuCl __________________ |

Two other terms you are likely to encounter when dealing with solutions are miscible and immiscible. Miscible refers to ______________________________________________________________________________

__________________________________. An example of two miscible liquids would be _________________ and __________________________. Immiscible refers to _______________________________________

___________________________________________________________. An example to two immiscible liquids would be _______________ and _________________________.

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Solubility Curves and Factors That Affect Solubility

Consider the solubility curve shown below.

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As mentioned the solubility of a solute is dependant on ______________________________. Notice that with few exceptions, the solubility of solid ionic solutes _____________________________ as temperature ______________________________. Liquid solutes generally behave in the same manner. If the solute is a gas like NH3, however, increasing temperature __________________________ solubility. Pressure has no effect on the solubility of _____________________________ or ____________________________ but increasing pressure will ____________________________ the solubility of ___________________.

Solubility curves can be used in many ways. Try the questions below.

a) What is the solubility of NH4Cl at 90oC? ___________________________________________________

b) 20 g of KClO3 is dissolved in 100 g of water at 50oC. Is the solution saturated, unsaturated, or supersaturated? ________________________________

c) 30 g of KCl is dissolved in 50 g of water at 50oC. Is the solution saturated, unsaturated, or supersaturated? ___________________________________

d) 18 g of Ce2(SO4)3 dissolved in 200 g of water at 10oC. Is the solution saturated, unsaturated, or supersaturated? ___________________________________

e) A saturated solution of KNO3 was prepared at 70oC. The solution was then cooled to 50oC. What mass of KNO3 precipitates out? _______________________________

Factors such as grinding the solute or mixing the solute and solvent will not affect the _____________________ of a solute, but will increase the ___________________ at which dissolving occurs because it increases the ______________________________________ of solute exposed to the solvent.

Making Solutions

Remember that there are three main types of compounds: _____________________, ____________________

__________________________ and ______________________________________________. See if you can remember their basic characteristics by completing the table below.

| |Ionic |Polar Covalent |Non-polar Covalent |

|Are e- transferred or shared? If | | | |

|shared, equally or unequally? | | | |

|Is the charge distribution symmetrical | | | |

|or assymetrical? | | | |

|Examples | | | |

| | | | |

| | | | |

In order to make a solution rather than a suspension or mechanical mixture you must remember the basic rule:

| |

| |

OR

|Non-polar solutes dissolve in |Polar solutes dissolve in |Ionic solutes dissolve in |

|___________________________ |___________________________ |___________________________ |

|solvents. |solvents. |solvents. |

Conductivity of Solutions

1. In order to conduct a solution must contain ____________________.

2. ______________________ substances (ie: substances made up of a _____________________ and a __________________________) will conduct electricity as long as they are either ________________ or dissolved in water.

3. _________________________ and _________________________ form ions when dissolved in water and therefore conduct electricity.

4. ___________________________ substances (ie: substances made up of two ____________________) do not conduct electricity because they do not form _________________ when they dissolve.

5. Compounds whose formulas start with carbon (organic compounds) usually do NOT form ______________ when they dissolve in water and therefore do not conduct electricity. Exceptions are organic acids that end in “COOH” like acetic acid (CH3COOH).

6. The greater the concentration of _____________________ the greater the conductivity.

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Since solubility is dependent on temperature, the temperature should always be recorded along with the solubility.

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