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1. A sample was spotted on two different TLC plates:
a) One plate was placed in a chamber containing methanol, and after developed it showed one spot with an Rf value of 0.97. The other plate was placed in a chamber containing hexane, and after developed it showed two spots, one with an Rf value of 0.54 and one with an Rf value of 0.37. Explain how this occurred.
b) One plate was placed in a chamber containing hexane, and after developed it showed one spot with an Rf value of 0.05. The other plate was placed in a chamber containing ethyl acetate, and after developed it showed two spots, one with an Rf value of 0.15 and one with an Rf value of 0.46. Explain how this occurred.
Describe how you would make 4 liters of a 0.075 M phosphate buffer at pH of 7.15 without using a pH meter, if the only materials
A student tried to make a buffer of pH 4.0 using sodium acetate and acetic acid. The initial pH of the buffer solution was 3.9. How should the student adjust the pH to the desired value?
A bottle of wine consists of an 11 weight percent solution of ethanol (C2H5OH) in water. If the bottle of wine is chilled to -20oC, will the solution begin to freeze? Kfp for water is 01.86 oC?m-1
A compound is constituted by mass of 52.1% carbon and 13.1% hydrogen, the rest being oxygen. Given that a volume of 5.33 L of this gas has a mass of 11.5 g at 13 °C and 110 kPa, find the molecular formula for this compound.
Show, with the aid of a form of the Nernst equation that when using a pH sensitive glass electrode and reference electrode that the measured potential is proportional to pH.
42 grams of a mystery powder was heated from 36.0 degrees celcius to 65.0 degrees celcius. the powder absorbed 5895 j of energy. what is the specific heat of the powder?
If 24.60 mL of a standard 0.3871 M NaOH solution is required to neutralize 43.87 mL of H2SO4, what is the molarity of the acid solution?
A buffer solution contains 0.71 mol of boric acid (H3BO3) and 0.53 mol of sodium dihydrogen borate (NaH2BO3) in 4.00 L. The Ka of boric acid (H3BO3) is Ka = 5.8e-10. pH of buffer solution
Calculate the wavelength (in nanometers) of a photon emitted by a hydrogen atom when its electron drops from the n = 5 state to the n = 3 state
The solubility of CO2 in water at 25°C and 1 atm is 0.034 mol/L. What is its solubility under atmospheric conditions? (The partial pressure of CO2 in air is 0.0003 atm.) Assume that CO2 obeys Henry's law.
calculate the average moles of ascobic acid in the pipetted sample used for titration d)Calculate the average moles of ascobic acid in the crushed tablet.
What is the minimum mass of sulfur dioxide necessary to produce 200. grams of sulfuric acid in the reaction?
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