r eactions in a queous s olutions : m etathesis r eactions and n et i onic e quations experiment 21...
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REACTIONS IN AQUEOUS SOLUTIONS: METATHESIS REACTIONS AND NET IONIC EQUATIONSExperiment 21Page 227
Dr. Scott Buzby, Ph.D.
OBJECTIVES
To become familiar with writing equations for metathesis reactions
Understand the difference between molecular, ionic and net ionic equations
Determine the solubility of a salt by using solubility rules
Study the effect of temperature on solubilty
DEFINITIONS Solubility
The property of a substance to dissolve in another substance to form a homogenous solution
Solute – The substance being dissolved Solvent – The substance doing the dissolving Aqueous solution – A solution where water is the solvent Homogenous solution – A stable mixture that is uniform
in composition where the solute will not settle out, no matter how long the solution sits, and it cannot be removed by physical means (ex. filtering)
Saturation The point at which no more solute can dissolve in a
solution and additional amounts of it will appear as a precipitate.
Precipitate the formation of a solid in a solution
Electrolyte any substance containing free ions that make the
substance electrically conductive (ionic solution)
METATHESIS REACTION
An aqueous chemical reaction in which the cations (+ Ions) and anions (- ions) appear to change partners
In order for a net change in the solution to occur (i.e. a reaction), ions must be removed from the solution by the formation of a precipitate a weak electrolyte or nonelectrolyte a gas that escapes from solution
BXAYBYAX
METATHESIS REACTION CON’T.
Formation of a Precipitate
Formation of a Gas
Formation of a Weak Electrolyte
)()(3)(3)( saqaqaq AgClNaNOAgNONaCl
)(2)()(2)( 22 gaqaqaq SHNaClSNaHCl
)(2)()()( laqaqaq OHNaClNaOHHCl
IONIC AND NET IONIC EQUATIONS
Molecular Equation
Ionic Equation
Net Ionic Equation
)()(3)(3)( saqaqaq AgClNaNOAgNONaCl
)()(3)()(3)()()( saqaqaqaqaqaq AgClNONaNOAgClNa
)(sAgClClAg
PROCEDURE
Part A: Metathesis Reactions Mix the solutions in small test tubes and record
your observations (precipitate, gas bubbles, heat, nothing) on the report sheet
Write out the three reactions according to your observations
Skip reactions 6 - 9 & 14 - 15
PROCEDURE CON’T.
Part B: Solubility, Temperature and Crystallization Prepare the solution as per instructions on Pg. 231 Cool the solution to ~10°C by dipping beaker into ice
water (DO NOT add ice to solution) and stirring carefully
Observe shape of crystals and filter COLD solution into an evaporating dish
Evaporate filtrate to half of its volume using a Bunsen burner and a ring stand (additional crystals should form)
Filter HOT solution into 100mL beaker and compare shape of crystals with first batch
Cool the filtrate to ~10°C with ice while stirring to obtain a third batch of crystals and compare shape with other two batches.
HOMEWORK – DUE NEXT WEEK Part A
Report Sheet – Pages 233 – 236
Part B Solubility Graph – Page 235 Questions – Pages 235 – 236
Questions Page 236
Pre-lab Experiment #22 – Page 243