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Experimental Design and Methods in Chemistry

Determine Molar Absorptivity

A red-colored complex PbX4 prepared from Pb with ligand X() shows promise as a means to determine trace levels of lead in the environment. The analyst prepares five standard solutions (A, B, C, D, and E) of PB: 30, 60, 90, 120, and 150 ppm, respectively. 5 ml of each solution is mixed with 5 ml of 0.10 M X. The transmittance of

Structures

Methyl Orange is an acid-base indicator. In dilute solution, at a pH greater than 4.4, it is yellow. At pH=3.2, the solution appears red. Draw a structure of the species that is formed at the lower pH of the acid proton that adds to the azo nitrogen atom adjacent to the aromatic ring containing the -SO3 group. Why does the proto

Relative Retention

Retention times for several organic compounds separated on a gas chromographic column are given below: Compound tR(seconds) Air 75 Pentane 190 Heptane 350 2-Pentene 275 a. Calculate the relative retention of 2-Pentene with respect t

Mass Density of Certain Volume

The mass of a certain volume of an unknown liquid at 25 degrees Celsius was determined to be 24 mg. The mass of an equal volume of water at the same temperature was measured as 201 mg. Calculate the density of the unknown liquid at 25 degrees Celsius.

Laboratory Questions

A laboratory has four hoods each of which is 39 inches wide. When the hood door is open to a height of 8 inches and the hoods are operating, the average air velocity through the hood is 170ft/min. a. Evaluate the total ventilation rate for this room assuming that there are no other exhausts. b. The laboratory is designed for

Calculating Absorptivity

I have tried to play with all the numbers in this question, but nothing seems to be working. Nitrite ion, NO-2 is used as a preservative for bacon and other foods. It has been the center of controversy since it is potentially carcinogenic. Here is an abbreviated procedure for the determination: Step 1: 50.0 mL of unk

Understanding Beer's Law

What is Beer's law? Use Beer's law to mathematically determine the unknown concentration values. How do the values derived from Beer's law compare to those derived from the graph?

Identifying different solutions.

If I had 5 solutions that are not labeled (the solutions are ethanoic acid, calcium hydroxide, potassium bromide, sodium chloride and nitric acid) is there a way of identifying which one is which without using an indicator?