SPAN 2101 : Span 1152 Study Guide For Test 1 Fall 2012

1-How many grams of NaCl would be needed to prepare 150.00 L of a 1.402 M NaCl solution?

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2- first a standardized solution of sodium hydroxide (NaOH) will be quantitatively diluted to about 0.1 M but not exactly 0.1M. The molarity of the dilute NaOH will be calculated! A similar quantitative dilution was done in experiment 3 when you diluted 5.0 M HCl to 0.50M HCl using a volumetric flask and pipet.

The second part of the experiment is very similar to the last part of experiment 6 where samples of the unknown were weighed out, dissolved in water, and titrated with the dilute NaOH using phenolphthalein as the indicator to determine the percent by mass of a compound in the unknown. The compound will be different than the compound used in experiment 6. The molecular formula of the compound will be provided during the final. You must know how to weigh by difference (Preweigh, tare sample and small container to zero, transfer sample to flask, and place the small container back on balance to get mass) and titrate the sample using the buret in order to do well.

Be sure to read the instructions for the practical toward the end the CHM151L lab manual and do the practice problem on the next page.

You will have 1.5 hours to do the practical. You may only use a calculator and a pencil on the practical. There is no talking during the practical such that students cannot help each other and the TA may only help you with equipment problems.

It would be a good idea to wash any glassware you might use the lab period before the lab practical. There will also be a help session before the lab practical.

At the end of the lab final you will wash all glassware used or any dirty glassware in your locker, wash your unknown vials and remove the labels, checkin your locker and return your key, and evaluate the lab.

Please put the following statements in the correct order relating to the day of the lab practical:
1 2 3 4 5 6 Wash all your glassware and unknown vials, checkin your locker, evaluate the lab, and check your grades.
1 2 3 4 5 6 Do at least 3 good trials (weigh and titrate sample) as time allows.
1 2 3 4 5 6 Start the lab practical by diluting the NaOH solution.
1 2 3 4 5 6 Before the day of the practical clean glassware, read the practical instructions and do the practice problem in the lab manual and complete the loncapa problems for the final.
1 2 3 4 5 6 Calculate the molarity of the dilute NaOH, the percent by mass of the compound in you unknown for each trial and then the median.
1 2 3 4 5 6 Come to the help session before the lab final.

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3-

A NaOH solution was prepared by diluting 5.00 mL of 2.205 M NaOH to a final total volume of 100.00 mL. What is the exact molarity of the dilute NaOH (use 4-5 significant figures)?

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4-For the problem above, select glassware and size from the list below to conduct the dilution.

A B C D E F G H <= Glassware used to transfer the 2.205 M NaOH to be diluted
A B C D E F G H <= Glassware used to measure the final volume of the diluted M NaOH.

5 10 15 20 25 50 100 250 500 1000 <= Volume of the glassware chosen to transfer the concentrated NaOH above
5 10 15 20 25 50 100 250 500 1000 <= Volume of the glassware chosen to contain the final dilute NaOH above.

Good Afternoon,

I am doing a laboratory report for the course entitled: Principles of Instrumental Analysis. It is a 4th year course and i have been tasked with the following analytical problem, "Determine the DEET composition in common bug sprays." In other words, I have to determine the concentration of DEET in a couple of bug sprays. The sprays and DEET are supplied. Secondly, I have to prepare a protocol for measuring the concentration of DEET in my samples and a GC:MS method for analysis of DEET. By the way, GC:MS is short for 'Gas chromatography–mass spectrometry' and as you may know it is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Basically, I need your help in giving me a layed-out protocol (such as we would see in a manual) of what I will do in the lab to answer the above analytical problem. You can think of it as a lab manual that you would write so that someone else could go in the lab and perform the experiment in your place.

It should have all of these components.

1. Brief (!) introduction of the problem (1 short paragraph)

2. Sampling – how much (be precise), in what form, how many, where, etc.

3. Sample preparation – list all reagents needed up front. Then list all steps and procedures you will use to prepare the samples for instrumental analysis. You should know what concentration ranges you are aiming for.

4. Standards preparation – list steps involved in preparing your standards used for calibration (if you need to do this).

5. Instrumental Analysis – list the procedure for running the instrument, including any blanks, standards. The sequence of runs (sample, standard, blank, etc) should be listed.

6. Data Analysis – how will you go from the raw data provided by the instrument to a value with a ± deviation on it.

Please refer to the above question. Can you give me a detailed layout of how I will determine the concentration of DEET in my samples before doing the GC:MS analysis? You do not need to determine the composition or synthesize DEET. You need to determine the concentration of DEET, in a couple of bug sprays. The sprays and DEET are supplied.

I'm not quite understanding. Thank you for your clarification once again.

Can someone please help me figure this out? We have to figure out an experiment to get at least 90% yield of compound B.

These are the topics covered that we can use to plan this experiment:

1) Basic Operations: Using a weighing balance; Separation, Density.
2)Separating the Components of Panacetin - Acid-Base Reactions, Stoichiometry Techniques: Separation, extractions
3) Identifying the Constituents of Panacetin: Key techniques: Recrystallization and Melting point
4)Synthesis of Salicylic acid . Key techniques: Reflux, Recrystallization, Melting point
5) Separation of Unknown by Chromatography-Concepts: Polarity, capillary action, Technique: Column and Thin layer chromatography
6)Dehydration of cyclohexanol to an cycloalkene. Key Concepts: Preparation, and Reactions Hydration, Halogenation & Hydro halogenation of Alkenes;
7)Polarimetric Analysis of Unknown Sugars. Key concepts: Stereochemistry Techniques: Optical rotation
8)Properties of organic compounds -Concepts: Solubility, Hydrogen bonding; Technique: Distillation
9)Preparation of 2-chloro-2-methylbutane–An Sn1 reaction - Key concepts: Nucleophilic Substitution reactions