Lab 3_ Separations of Components of a Solid Misture (3)

Using recrystallization techniques, a student attempts to purify 0.50 g of compound H. Based on the solubility of H in the chosen solvent at collection temperature, the maximum percent recovery is 82%. The student obtains 0.396 g of purified crystals. What is their percent recovery? Group of answer choices 41% 64% 79% 82% 97% none of these

II. b) What is the difference between liquid-liquid, solid-liquid and solid-phase extraction? Complete the table below and sort the following examples in the correct column: Steeping tea, washing an organic phase (workup), brewing beer, chemical desalting of crude oil, activated carbon sugar decolorization. liquid-liquid solid-liquid solid-phase Phase that contains analyte before extraction? Phase that contains analyte after extraction? Example(s)

Analytical chemistry is a particular field within the broader spectrum of the chemical sciences, in which many times the focus of analytical experiments is to develop new methods to analyze compounds, either structurally or by determining concentrations of compounds. One of the processes analytical chemists use to determine the exact concentration of a working solution is called standardization. In your own words, describe the differences between a primary, secondary, and tertiary standard, and describe the underlying concept behind the standardization process. Why is it done?

PAPER CROMATOGRAPHY • Define chromatography • Demonstrate an understanding of the process of chromatography • Describe the steps involved in a chromatography investigation Explanation Coloured inks are often made up of several different inks. Each colour of ink will get carried a different distance by the water, allowing you to see all of the different inks. Try this with different colours to see what actually goes into a colour. This technique is called chromatography and can be used in chemistry to find out what is in an unknown mixture. II. Materials .Felt tip pens (non-washable) . Kitchen roll .A bowl or cup . Water • Scissors III. Health and safety • Make sure that you thoroughly clean any equipment after the experiment before using for food IV. Procedure Method 1 1. Take a sheet of kitchen roll and draw a simple picture with a non-washable felt tip pen. 2. Place the sheet over an empty bowl. This is to keep the paper from getting too wet. 3. Carefully add a few drops of water…

2 K₂Cr₂O7 (aq) + 8 H₂SO4 (aq) + 3 C₂H5OH(aq) --> 2 Cr₂(SO4)3 (aq) + 2 K₂SO4 (aq) + 3 CH3COOH (aq) + 11 H₂O (1) The above reaction is what occurs in a breathalyzer test. The ethanol (MM = 46.08 g/mol) reacts with the dichromate ion in potassium dichromate (MM = 294.20 g/mol) to produce the green chromate ion in chromium sulfate (MM = 392.21 g/mol). The sample is analyzed in a hand-held spectrophotometer, and the amount of light transmitted is converted into an electrical signal. The signal is then converted to an absorbance value which is proportional to the amount of ethanol in a sample. Calculate the grams of chromium sulfate formed from 0.0250 g ethanol. Enter the value with no units.

150 140 130 120 110 100 90 80 70 60 50 40 30 XCIO3 10 -Ce₂(506)s D Đ 10 20 30 40 50 60 70 80 90 100 Temperature (°C) According to the solubility curve graph above, a solution containing 10 g of NH3 at 90°C can be described as- unsaturated b insoluble supersaturated Time left for this assessment: d saturated 42:16 Grams of solute per 100 g H₂O B NaNO3 KNO3) NH Ka

In Lab 2, if the mass of Fe, NaCl and SiO2 recovered are 1.5g. 2.3g and 2.5g. The initial mass of the mixture before separation is 6.5g. Calculate the percent recovered of the mixture. O 23.8% O 23.1% 96.9% 103.2%

Need to find percent recovery of crude caffine and purified caffine

Need help to calculate for percentage % recovery

A student performs a crystallization on an impure sample of biphenyl. The sample weighs 0.5 g and contains about 5% impurity. Based on his knowledge of solubility, the student decides to use benzene as the solvent. After crystallization, the crystals are dried and the nal weight is found to be 0.02 g. Assume that all steps in the crystallization are performed correctly, there are no spills, and the student lost very little solid on any glassware or in any of the transfers. Why is the recovery so low?

Page 2 2. A 0.9527 g sample containing only KCI and CaCl2 yielded 3.9802 g of dried Hg2Cl2. Calculate the percent of each halogen compound in the sample. KCI = K* + CIr; CaCl2 = Ca2+ + 2C-; 2CI- + 2Hg* = Hg2Cl2 CI 35.453; K 39.0983; Ca 40.078; Hg 200.59

A group of third-year students, who had been growing chilli peppers at home, decided to bring samples to their Pharmacology practical where they would be measuring capsaicin, to determine which of them had grown the hottest peppers. The three students ground a sample of their peppers in 100 µl of distilled water, centrifuged the solution and then transferred the supernatant into a collection tube. One student used 70 % ethanol from a wash bottle on their bench instead of using distilled water as the extraction fluid. Samples of the collected supernatants were added to a 96 well test plate along with a range of serially diluted capsaicin standards. The students used a FlexStation which automatically added 20 µl aliquots of each supernatant onto separate wells containing 80 µl of cultured cells, which had been transfected with the capsaicin sensitive TRPV1 ion channel and preloaded with the ratiometric calcium indicator dye FURA-2 prior to the class. The FlexStation was programmed to…

I need help understanding how to do this, can you please show me how you get the CFU/mL

11c

A titrimetric method for the determination of calcium in limestone was tested by analysis of an NIST limestone containing 30.15% CaO. The mean result of four analyses was 30.26% CaO, with a standard deviation of 0.085%. By pooling data from several analyses, it was established that s   = 0.094% CaO.a. Do the data indicate the presence of a systematic error at the 95% confidence level?b. Do the data indicate the presence of systematic error at the 95% confidence level if no pooled value for s was available?

An environmental chemist working for the Environmental Protection Agency (EPA) was directed to collect razor clams from a heavily-contaminated river superfund site and analyze them for their Cd?+ content using graphite furnace atomic absorption spectrometry (GFAAS). The chemist dried the clams at 95 °C overnight and ground them in a scientific blender, resulting in approximately 50 g of homogenized dry weight. A representative 98.75 mg sample was taken from the approximately 50 g of dry material and dissolved in 100.0 mL of 0.1 M HCI to create a sample solution. Using the method of standard additions, the chemist prepared five standard solutions in 100.0 mL volumetric flasks, each containing 5.00 mL aliquots of the sample solution. Varying amounts of a 75.0 ppb (ug/L) Cd? + standard were added to each of the flasks, which were then brought to volume with 0.1 M HCI. The Cd? + content of the solutions was then analyzed using GFAAS, resulting in the. absorbance data given in the table.…

professor Scimemi has accepted you as a Master’s student and you are involved in a project that studies the cellular basis of neuropsychiatric diseases. For your electrophysiology recordings you have to make a recording solution containing (in mM): 119 NaCl, 2.5 KCl, 2.5 CaCl2, 1 MgCl2, 26.2 NaHCO3, 1 NaH2PO4, 22 glucose. You need 800 ml of it. How much KCl do you need to weigh out? Hint: we only care about KCl here. (MW KCl is 74.55 g/mol

16. The combustion of gasoline (octane) in a car engine can be represented by the following equation: 2C3H18(1) + 2502(g) a. What mass of oxygen is used up to burn a full tank of 36.00 kg of gasoline? Text --> 16CO2(g) +18H20(g) b. Why might a vehicle that is calibrated to run perfectly at sea level run poorly at higher elevations? Text Тext According to the Canadian Automobile Association, the average Canadian drives 20,000 km/yr. C. Assuming that distance, how many more kg of carbon dioxide are added to the atmosphere each year by a Toyota Tacoma (fuel economy of 12.8 L/100 km) than a Toyota Prius (4.52 L/100 km)? The density of gasoline is 0.719 kg/L.