Chemical equilibrium- LeChâtelier\'s Priniciple lab. Please help. I need all the

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Chemical equilibrium- LeChâtelier's Priniciple lab. Please help. I need all the blanks filled in. I've got the other parts. Any help is greatly appreciated.  

reverse reaction will increase or decrease until a new position of equilibrium is restored. In other words, the reaction mixture will cither "shift in concentration toward products" or "shift in concentration toward reactants" in order to regain a chemical equilibrium. Mathematically, when a system is not at equilibrium, the ratio of products over reactants as expressed in Equation 2 no longer is equal to Keg, and the reaction will proceed so that when the reaction is again at equilibrium, that ratio will again equal Keq. Possible perturbations to equilibrium include changing the concentrations of one or more of the chemicals in the vessel, changing the volume or pressure in a container in which gases are among the reactants or products, and changing temperature. Temperature changes can cause a shift in equilibrium because temperature changes either add or remove heat from a reaction. Look at the exothermic reaction for the formation of gaseous hydrogen chloride in Equation 3a 112(g) + Cl2(g) 2HCl(g) H =-184 kJ Eq. 3a In exothermic reactions, heat is released during the process and another way to write the reaction is given in Equation 3b where heat is explicitly shown as a product of the reaction H2(g) + Cl2(g) 2HCl(g) 184kJ Eq. 3b + If heat is added to the reaction shown in Equation 3a or b, the reaction will shift to the left to relieve the stress of the added 'product' of the reaction and if the reaction is cooled in some manner, the reaction will shift to the right to produce more heat and restore the equilibrium. A thorough explanation of the effect of heat would include thermodynamic properties, which may be covered in the associated lecture course but is not necessary for the understanding of these experiments. A frequent example in general chemistry textbooks of an application of LeChâtelier's Principle in gaseous systems is the equilibrium of dinitrogen tetroxide with nitrogen dioxide, a temperature dependent equilibrium (Equation 4). Of the two gases in Equation 4, one gas is brown and the other is colorless. This reaction is reversible and at equilibrium some of cach gas is present Depending on whether more of the brown gas is present or more of the colorless gas is present the intensity of the color of the mixture will change in the reaction chamber. This reaction will be observed in this experiment. N2Odg) + 57.2 kJ 2NO2(g) Eq. 4 Examine the net ionic equation of a reaction that will be thoroughly investigated during this experiment (Equation 5) Fe" (aq) + SCN' (aqjs FeSCN2+ (aq) Stressing the equilibrium of this reaction by adding more iron(III) ions will cause the reaction to shift toward products (the right), because a shift towards the products will cause a reduction in the iron(IIl) ions lessening the stress, restoring equilibrium. Removing some iron(II) will cause the reaction to shift toward reactants (the left) in order to produce more iron(II) and restore equilibrium. In that spec ies can be removed from a reaction by adding something else that causes a side reaction 46

Explanation / Answer

For the reaction,

2NO2(g) <==> N2O4(g)

NO2 = deep red color

N2O4 = colorless

at room temperature : the color remained deep red due to NO2

Hot water bath : when heated NO2 forms N2O4 and the color changes to colorless. The reaction is endothermic in nature.

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For the reaction,

Fe3+ + SCN- <==> FeSCN2+

Fe3+ = dark brown

SCN- = yellow

FeSCN2+ = reddish

At room temperature : the color is dark yellow, formation of complex is seen. The forward reaction occurs and is exothermic in nature.

Hot bath : The color becomes lighter, so backward reaction occurs. Bakcward reaction is endothermic as only after addition of heat reaction occured.

After adding Fe(NO3)3 : color darkens

Excess Fe3+ reacts with more SCN- to form complex FeSCN2+. Reaction shifts to the right handside.

After adding SCN- : color darkens

Excess SCN- reacts with more Fe3+ to form complex FeSCN2+. Reaction shifts to the right handside.

After adding AgNO3 : color becomes light

Excess Ag+ reacts with more SCN- to form complex Ag(SCN)+. So a decrease of free SCN- on the left handside, pushed the reaction to the left handside. Reaction shifts to the left handside to form more SCN- species.

After adding NaOH : color becomes lighter

Excess OH- reacts with free Fe3+ to form Fe(OH)3, reducing Fe3+ concentration in solution. Reaction shifts to the left handside to generate more Fe3+.

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