the reagent used to prepare the standard. Reagents used as standards are divided into primary reagent and secondary reagent. A primary reagent can be used to prepare a standard containing an accurately known amount of analyte. A primary reagent must have a known stoichiometry‚ a known purity (or assay) and be stable during a long term storage both in solid and solution form. The purity of a secondary reagent in a solid form or the concentration of a standard prepared from a secondary reagent must
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although somewhat lanky silhouette‚ his tousled red hair and his several days beard of the same tone caused her some emotion she tried to hide. He kept his eyes straight ahead pretending not to have seen Nancy‚ performance that caused her some tension. Lucas stared around like looking for site in several seats‚ but finally sat down beside
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negative result because biuret reagent is blue to begin with. If a solution is pinkish purple‚ or purple‚ then the test for protein is positive. The test solution for starches is yellowish brown. If any substance that is yellowish brown when mixed with iodine‚ then the test for starches is negative. If the solution turns purple‚ or a dark purplish black‚ then the test for starches is positive. If DI water‚ and sucrose are tested for proteins using biuret reagent‚ then they will show a negative
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minutes. Cool and filter the mixture. Add enough fresh 2M HCl to wash the residue and then bring the volume of the filtrate to 5ml. Place 1ml each of the filtrate to 2 test tubes as follows: 1. To 1ml of the filtrate‚ add a few drops of Mayer’s Reagent. Result: Light brown solution with
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two new σ bonds are formed. • Alkenes are electron rich‚ with the electron density of the π bond concentrated above and below the plane of the molecule. • Because alkenes are electron rich‚ simple alkenes do not react with nucleophiles or bases‚ reagents that are themselves electron rich. Alkenes react with electrophiles. Electrophilic Addition Energy Diagram: • The mechanism of electrophilic addition consists of two successive Lewis acid-base reactions. In step 1‚ the alkene is the Lewis
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film American Gangster tells the story of Harlem gangster Frank Lucas and his rise to power in the late 1960s. However‚ underneath the plot of the film‚ American Gangster is an excellent case for a striving sociologist to dive headfirst into as it can have several models in the academic field of sociology. The Structural Functional Theory‚ the Symbolic Interactionist Theory and Conflict Theory can be used to explain the rise of Frank Lucas‚ who became one of the most high-profile American gangsters of
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contain protein and which do not? How do you know? Egg white and pepsin contained protein as indicated by the appearance of a purple color in solution‚ whereas sugar and distilled water did not‚ as indicated by no color change from the blue biuret reagent. Questions A. Which of the test tubes are the positive and negative controls? The experiment illustrated that: The Positive controls were Test tube #1 Egg white and #2 Pepsin. The Negative controls were Test tube #4 Distilled water and #3
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–NH2 to give a purple colour. There are three samples in the experiment: sample A‚ Sample B and Sample C. The sample A contains 2 distilled water and ninhydrin reagent. There are egg white and ninhydrin reagent in sample B. Succinylated egg white and ninhydrin reagent were in sample C. Because distilled water cannot react with ninhydrin reagent‚ the sample A was as a blank in the experiment. We measured the absorbance of the egg solution at 570nm. In sample B‚ the native egg white was added. The data
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Title: Double Replacement Reactions (Data and Calculations) Objective: Classify the chemical reaction through observation‚ which each reagent produce when mixed with another reagent. After careful observation‚ be able to prove each observation using the net ionic equation. Background: First‚ a double-replacement reaction is when two cations in different compound switch anions‚ AX + BZ → BY. If either compounds are insoluble a precipitate occurs‚ and if there is no precipitate formed there is
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Materials: * Test tubes * Solutions : ( A‚B‚C‚D‚E‚F‚ and G) * Reagents: ( Iodine‚ Biuret‚ Benedict‚ Ethanol) * Spatula * Heating plate * A test tube cleaning brush * Tray * Beaker * Distilled water * Pipette ( comes with reagents since they are in bottles) Method/Procedure: Step #1: poor the solution into four different test tubes Step #2: In the first test tube put a few drops of a reagent called "biuret". If the solution turns purple‚ then the solution contains
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