Le Chatelier's Equilibirum

Le Chatelier's Equilibirum - teliers Equilibrium Prashanth...

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atelier’s Equilibrium Prashanth Rasanayagam Grade 12 IB Chemistry Ms. Varnes Monday, February 09, 2009
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Introduction In chemistry, Le Chatelier's Principle can be used to predict the effect of a change in conditions on a chemical equilibrium. Le Chatelier's Principle states that if a chemical system in equilibrium is subjected to a change in concentration of a reactant or product, temperature, volume, or total pressure the equilibrium will shift in the direction that will counteract or reverse the imposed change. The principle is used to manipulate the outcomes of reversible reactions, often to increase the yield of reactions. The principle is an empirical observation and has no general validity, because chemical systems with positive feedback exist. Le Chatelier’s Principle states that if equilibrium is subjected to a stress, the system will react to remove the stress. To remove a stress, a system can only do one of two things: form more products using up reactants, or reverse the reaction and form more reactants, using up products. This shift, in an attempt to counteract the change, will only reverse the change to a certain extent. Therefore, the intention of this investigation is to observe and record the effects of changing the concentration of reactants and products in systems that begin at equilibrium. Data Collection Table 1: Initial Observations of Reactants Reactant Observations Bromothymol Blue (BTB) Dark navy blue, opaque CuSO 4 Aqua marine - light blue, translucent Fe(NO 3 ) 3 Orange, translucent Pb(NO 3 ) 2 Colourless Na 2 SO 4 Colourless, translucent HCl (0.1/1.0 M) Colourless, transparent NaOH (1.0 M) Colourless, transparent NH 4 OH (0.1M) Colourless, transparent Table 2: Observations During/After Reaction for Tube 1 [Bromothymol Blue ( +HCL + NaOH)] Tube 1 During: Adding HCl (0.1 M) After: Adding NaOH
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Bromothymol Blue (BTB) Added 2 drops of HCl (0.1M): - turned light orange - solution is translucent After adding 2 drops of HCl(0.1M), added 1 drop of NaOH: - turned dark blue - solution is opaque Adding another drop of NaOH: - solution stayed the same Table 3: Observations During/After Reaction for Tube 2 [CuSO 4 (+ NH 4 OH + HCl) Tube 2 During: Adding NH 4 OH After: Adding HCl (0.1 M) Copper Sulphate (CuSO 4 ) Added 1 drop of NH 4 OH: - turned slightly lighter in colour - lighter blue solution Added another drop of NH 4 OH: - turned opaque Added 6 more drops of NH 4 OH: - solution stayed the same Added 2 more drops of NH 4 OH: - solution becomes divided into two layers - top layer is translucent - light blue precipitate collects at bottom for every addition of NH 4 OH, dark blue precipitate initially forms but disappears when After addition of all NH 4 OH,2 drops of HCl is added: - turned lighter blue - light blue precipitate collects at bottom Adding 3 more drops of HCl: - solution is opaque - light blue colour - precipitate still present Adding 4more drops of HCl: - translucent - precipitate no longer present
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mixing Table 4: Observations During/After Reaction for Tube 3
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This note was uploaded on 11/23/2009 for the course HIS HIS1d03 taught by Professor Dr.adams during the Fall '08 term at McMaster University.

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Le Chatelier's Equilibirum - teliers Equilibrium Prashanth...

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