ch.4 notes

ch.4 notes - 9/23/2009 What!are!the!Goals!(Chapter!4)?

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9/23/2009 1 What are the Goals (Chapter 4)? Learn about aqueous solutions. Understand what electrolytes, nonelectrolytes strong electrolytes and weak electrolytes are. Learn about solubility and precipitation . Learn about ionic equations and spectator ions. Introduce acid " base reactions. Understand concentrations of solutes in solutions and dilution (qualitative and quantitative). Learn to use solutions and concentrations for stoichiometry problems. Solutions A solution is a homogenous mixture which is composed of two or more components the solvent - the majority component and on o mor solute one or more solutes - the minority components
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9/23/2009 2 Solutions Most common solutions are liquids where a solid, liquid or gas (the solute ) is dissolved in the liquid solvent. Some are solids where both the solvent and the solute are solids. Steel is an example Solutions Gas-Solid solution: Hydrogen in palladium
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9/23/2009 3 Solutions Common laboratory solvents are usually organic liquids such as acetone, hexane, benzene or ether – also water (not organic). Water is the most important solvent. The oceans cover ~ ¾ of the surface of the planet and every cell is Solutions in water are termed aqueous solutions and species (solutes) are written as E ( aq ) . mainly composed of water. Solutions Aqueous Solutions Water is one of the “best” solvents as it can dissolve many molecular and ionic substances. The properties of solutions which contain molecular and ionic solutes are very differen and give insigh into different and give insight into the nature of these substances and solutions.
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9/23/2009 4 Solutions Ionic Solutions An ionic substance, such as NaClO 4 , contain ions – + inthis case Na and ClO 4 - . The solid is held together through electrostatic forces between the ions. In water, the solid dissolves and the particles move away from each other and diffuse through the solvent. This process is termed Ionic Dissociation Solutions Ionic Solutions In an ionic solution, there are therefore charged particles – the ions – and as the compound is electrically neutral, then the solution is neutral. When a voltage is applied to the solution, the ions can move and a current flows through the solution. The ions are called charge carriers and whenever electricity is conducted, charge carriers are present.
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9/23/2009 5 Solutions Molecular Solutions A molecular solution does not conduct electricity as there are no charge carriers present. The bonding in a molecule is covalent and involves the sharing of atoms and there is no charge separation. Solutions Electrolytes A solute that, when dissolved, produces a solution that conducts is termed an electrolyte, which may be strong or weak. A strong electrolyte is one which is fully dissociated in solution into ions A weak electrolyte is one which is only partially dissociated.
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9/23/2009 6 STRONG ELECTROLYTES - dissolve and dissociate 100% in water - give a LARGE number of ions in solution ! GOOD conductors - solutions of well soluble ionic compounds like: NaCl, KBr, NH 4 NO 3 , Na 2 SO 4
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This note was uploaded on 05/11/2010 for the course CHEM 1201 taught by Professor Cook during the Spring '08 term at LSU.

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ch.4 notes - 9/23/2009 What!are!the!Goals!(Chapter!4)?

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