Introduction: This should include relevant background information (both from and outside of the lab) necessary to understand the concepts behind the experiment and to help illustrate the purpose of the experiment. This should include a discussion about the theory behind the experiment. You should also include the objective, or purpose of the experiment. The purpose is a brief statement (two sentences maximum) of what you intended to accomplish in the experiment. Usually, the object of the experiment is to analyze, measure, or synthesize some compound. The entire introduction should be at least half of a page or SO in length. For this lab you will need to discuss Beer's Law and how spectroscopy works.
Experimental: This section is a detailed description of exactly how the experiment was actually
performed (i.e. including any changes you or your instructor made from what was written in the lab manual). It should be detailed enough that another chemist could reproduce the experiment exactly as you did it. References to previous work by other individuals can be included i.e. you could say something like "the boiling point was determined using the procedure given on page 23 of the Chem 2101 Lab Manual (Morante, Ho and Ackroyd, 2013)". Any departures from the lab manual should be detailed, i.e. spills, leaks, etc. The exact quantities of materials used must be included, i.e. masses or volumes of reagents. (I.e. if the lab manual says about 3 grams and you actually used 2.7483 grams, then report
2.7483 grams in this section.) Note: it is not sufficient to simply copy the procedure from the lab manual, you must write the procedure in your own words. Also, do not simply recopy the point-form procedure from your lab notebook, it must be in paragraph form. Be sure you think through as you write this, understanding what you are doing (and why!) at each step. Separate each part into its own section.
These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction
of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice.
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Each chemical reaction has a typical condition of equilibrium at a specified temperature. If two reactants are mixed, then they react to form products till a state is reached where the quantities of reactants and products will remain the same. At this position, the reactants and products are to be said in chemical equilibrium and will remain the same, till the system is changed somehow. This condition is known as equilibrium state and it is associated with a number called the equilibrium constant, Keq which is the expression of the necessary condition particularly the concentrations of reactants and products for a specific reaction at a given temperature.
In this experiment, I studied the equilibrium properties of the reaction between the iron(III) ion and thiocyanic acid (HSCN). The equilibrium involving iron (III) ion and thiocyanic acid is shown below:
Fe³+ (aq) + HSCN (aq) <--> FeSCN²+ (aq) + H+ (aq)
According to the general law, Keq for this reaction is given from the blow formula involving the concentrations of all components.
After mixing the solution of Fe3+ and HSCN, a deep red FeSCN2+ complex ion is formed. The intensity of the color of the solution is directly related to the concentration of FeSCN2+ complex, which can be estimated using a spectrophotometer. Beer’s Law is very useful and applicable in spectrophotometry which relates the absorbance with the concentration of the solution. A straight-line relationship observed in a dilute solution between the color intensity (measured as Absorbance) and the concentration of colored complex FeSCN2+. Beer’s law is expressed as follows:
A = ɛbC
A = absorbance
ɛ = molar absorptivity coefficient
b = cell path length (in cm)
C = concentration of the colored substance
For the purpose of this experiment, the inference of Beer’s Law is that the concentration of the red complex ion FeSCN2+ in solution will be proportional to the absorbance of the given solution.
In the first part of this experiment, a very small amount of HSCN was converted completely to the colored FeSCN2+ complex ions by means of the addition of an excessive amount of Fe3+ ions. By applying the Le Châtelier’s principle it can be assumed that the equilibrium will shift strongly to the right converting virtually all the initial HSCN to the FeSCN2+ ion. Both the Fe3+ and HSCN solutions were prepared using 0.50 M HNO3 in order to maintain a sufficient H+ ion concentration to prevent the formation...