The following mistakes were made when carrying out the experiment. What effect does each have on the calculated molar mass? Be specific. For example, too large because… Only part of the pipet was immersed in the boiling water, so the temperature in part of the pipet was less than that of the water bath. If the temperature was less than the water bath in some places because only part of the pipet was immersed in the boiling water, the molar mass calculated would become lower.
if you were to have a larger hole in your aluminum cap, you would be losing vapor to the room. If this is the case then you would have a falsely high weight of vapor. It seems that you take a known volume of vapor and condensed and weigh it b) Water vapors condensed under the aluminum foil before the final weighing. If Water vapors condensed under the aluminum foil before the final weighing, the final weight would be lower than the fact. There will have some error.
According to the Revell's lab experiment, aspirin, acetaminophen, caffeine recoveries are 60% or higher, <10% and <5%, respectively. The reason for such a low percent recoveries for acetaminophen is due to a formed solid is too fine to be filtered, and for caffeine is due to its low solubility in diethyl ether(1.8mg/ml) than in water (22mg/ml). Not only caffeine's solubility in water can affect its percent recoveries, but also it can affect other two compounds by contaminating with caffeine. For the TLC, expected approximate Rf values for aspirin, acetaminophen, and caffeine are 0.6, 0.3, and 0.1 , respectively. Procedures A.
During the process of TIG welding, an arc is formed between a pointed tungsten electrode and the area to be welded. As a result of the gas shield, a clean weld is formed. This prevents oxidization from occurring. The arc is started with a tungsten electrode shielded by inert gas and filler rod is fed into the weld puddle separately. A slower process than MIG, it produces a more precise weld and can be used at lower amperages for thinner metal and can be used on exotic metals.
The question is, how can you determine which liquids have a strong surface tension and which have a weak surface tension? An example of a liquid that has a unique, strong surface tension would be H20, water! Research suggests that water has a high surface tension because of their unique hydrogen bonds. Hydrogen bonds have, without a doubt, the strongest intermolecular attractions. According to Science Buddies in the article Measuring Surface Tension of Water with a Penny, water “molecules at the surface experience a net force pulling them inward” (2007).
The ideal gas constant value is 0.082057 (L x atm)÷(mol x K). The purpose of the experiment was to be able to measure the temperature and the mass of each gas tested, to configure a constant and determine which gas is the most “ideal”. To configure “R” the equation will be, R= PV ÷ nT. Based on our knowledge of an ideal gas, we hypothesized Pentane will have the most ideal behavior to real gas and Cyclohexane to be the least ideal. We expect Pentane to be the most ideal because it’s boiling point is the furthest away from the boiling point of water.
From Table 3, the IR spectrum for fluorene had two significant signals. One was a distinct peak at 1446.2 cm-1 that corresponds to a C=C group of theoretic IR spectrum. The other signal is a collection of shallow peaks at around 3000-3100 cm-1, which corresponds to an aromatic ring. These signals show that fluorene was synthesized and it is exact the same with IR spectrum in theoretic book. As the result of this, the sample was obtained was
Ethan D. Wilhelm September 10, 2012 Chemistry 121 section 8 Friday 9-12 Sarah Gains Unknown Substance Lab Purpose: The purpose of this lab was to identify an unknown substance B by finding enough of its physical properties that we could eliminate all substances it can’t be. We use micro lab to help us find the boiling point, freezing point and mass. Then we tested the solubility of the unknown substance in water, hexane, and Alcohol. With this information we were able to find the identity of the unknown substance B. Procedure: Throughout this lab we were finding the physical properties of substance B.
The percent error is much higher for the first order stopping potential than for the second. This may be due to the fact that the lamp was not fully heated when the measurements were taken. There was not a gauge anywhere to tell when the lamp was fully heated, so it was more of a guessing game than anything. Another source of error may have been the ambient light in the lab. This may have entered the detector during the experiment, skewing the data.
EXPERIMENT 6 Title Kinetics of Chemical Reaction – Iodination of Cyclohexanone Aim To determine the value of the rate constant, k and order of reaction, a, b and c, and also to suggest a mechanism which agrees with the rate equation that has been obtained. Background Theory The basis of the theory of absorbance is as follows: Io ―――――→ sample ―――――→I if Io = I, no absorbance occur Io > I, the sample absorbs certain amount of light wave Io < I, the sample emits certain amount of light of certain wave length. THE HALOGENATION (IODINATION) OF KETONES (CYCLOHEXANONE) This experiment examined the rate of iodination of cyclohexanone in an aqueous medium. To increase the amount of iodine in the solution, iodine is converted to a more soluble complex ion, I3- by the addition of excess iodide ion: I2 + I- →I3- One of the characteristic reactions of ketones is the substitution of a halogen for one of the hydrogen is adjacent to the ketone group. The net reaction is: This reaction has been studied extensively and occurs for a wide variety of ketones.