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Lab 16 |
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Print a copy of the Check-list for this lab. Initial each item on the Check-list as completed. Preparing a Boiling Water Bath How to use the Top Loading Balance Why do I have to wear safety goggles? You will mix various solutions and look for the formation of a solid. This solid is an insoluble salt. With the use of solubility rules, you will write the formulas of insoluble salts that you form. You will heat and cool a KNO3 solution and noting the temperature at which you first notice solid crystals of KNO3. This is the temperature at which the solution is saturated. You will construct a solubility curve for KNO3 using your data and the data obtained by other groups of students in the class. Solubility is defined as the number of grams of solute in 100 mL of solute. Goals:
Solubility in the ability for a substance to dissolve in water. Some compounds dissolve readily. Soluble ionic compounds form solutions that are strong electrolytes. Other compounds have limited solubilities and are said to be insoluble. To predict the solubility of ionic compounds, chemists have developed solubility rules. The solubility rules are listed below.
The solubility of a compound is the amount of that substance that dissolves in a given quantity of water (usually 100 mL) at a given temperature to give a saturated solution. In general, the solubility of a substance depends on temperature. Naturally occurring water always contains dissolved materials, especially ionic substances. Hard water contains metal ions, such as Ca2+ and Mg2+. These metal ions react with soaps to produce insoluble calcium and magnesium salts ("soap scum"). Read pages 159-162 before coming to lab. Answer the pre-lab question on page 163 before coming to lab. You are encouraged to complete part A. on pages 163, Q.1 on page 163, Q.2 on page 165 before coming to lab. The following problems are found in your Timberlake textbook on and are due at the beginning of the laboratory session. Note: you must use the unit-factor method where applicable, include units with your calculations, and show all of your work in order to obtain the maximum number of points.
Safety Precautions:
Solid wastes may be disposed of in the waste can. Liquid wastes, except for the silver and barium solutions, can be poured down the sink followed with large quantities of water.
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