What is the Rf values relationship to the molecular weight of a pigment in Chromatography?
440553
Because you mention Rf values, I assume you're asking specifically about Thin-Layer Chromatography.  Actually the molecular weight is a fairly minor factor in the Rf value.  Intermolecular interactions between the pigment in question and the solid phase and the mobile phase are the most important.  So it really comes down to the selection of the mobile phase, how polar, how acidic or basic in relation to the analyte (your pigment in this case).  pH of the mobile phase is critically important in that your pigment may ionize to a greater or lesser extent depending upon the pH, and this drastically changes the intermolecular interactions.  Stationary phase selection is also important.
55652
light density or intensity? if you're talking about intensity then it depends on distance. that's an inverse square relationship.
41822
Simple one will be \nSunlight + Carbon dioxide (CO2) + Water (H2O)--> Glucose (C6H12O6) + Oxygen (O2).\nor \n6CO2 +12 H2O (light energy and chlorophyll) ---> C6H12O6 + 6O2\nRemember to use subscript whenever necessary.
773889
Suspected trick question.  The volumes included are irrelevant.  You know the molecular weight (66000 Da) and you know how many micromoles you need total in each solution.  What does it matter if the one micromole is in 1 ml or 10K gallons?  You know it only contains one micromole.  Divide the molecular weight by 10^6 and you're done.  (or you have not stated the problem correctly)
391970
The higher the frequency. the shorter the wavelength. The lower the frequency, the longer the wavelength.\n\nIt is an indirectly proportional relationship.
976936
CrCl = (Urine Cr x Urine Vol) / (Serum Cr x 1440)
920352
Did you measure the absorbance of a standard in addition to the unknown sample?\n\nIf so, you could plug the values into (As / Au) = (Cs / Cu)\nWhere\nAs = Absorbance of the Standard\nAu = Absorbance of the Unknown\nCs = Concentration of the Standard\nCu = Concentration of the Unknown?\n\nAlternatively, did you get a value for the molar absorptivity of PNP at the wavelength you used? \nIf so, you could plug it into\n\nA = (epsilon)(b)(c)\n\nWhere\nepsilon is the molar absorptivity,\nb is the length of the path through which the light passed,\nc is the concentration of the chromogenic substance.\n\nAnd you could rearrange that to solve for c.\n\nHope it helps
48684
C- longer wavelength.  Red is the long (low fequency) end of the spectrum, and violet is at the short end (high frequency).
983043
A=ebc\n\nWhere A is absorbance (no units, since A = log10 P0 / P )\n\ne is the molar absorbtivity with units of L mol-1 cm-1,\n\nb is the path length of the sample - that is, the path length of the cuvette in which the sample is contained. We will express this measurement in centimetres.cm\n\nc is the concentration of the compound in solution, expressed in mol L-1\n\nNow, you know why there is no unit for "A".
487877
The UV-VIS spectrum is due to the electronic transitions of the molecule. This is characteristic of a compound. Qualitative and quantitative estimations of compounds are possible by this non destructive technique. \n\nThe absorption (A) of a solution at a particular wavelength is given by Beer-Lambert's law ect = A where c is the concentration of the compound , t is the thickness of the cell and e is the molar extinction coefficient characteristic of the compound at a given wavelength. This principle is used for quantitative measurements. \n\nCary 5E is a high resolution spectrophotometer to study the electronic spectrum of solutions, single crystals and powder samples (in nujol mull) in the range of 3150-185 nm. This is a double beam instrument controlled by a microprocessor. Base line correction, repetitive scan, kinetics, derivative and concentration modes are possible. Diffuse reflectance is available for solid samples. VT accessory in the range 5-90 degrees Centigrade is available\n\nThis principle is used for quantitative measurements.
979643
Assuming you meant the MASS or the number of moles of Calicum, and assuming your asking the ratio of Ca+2 to CN-  it would be 1/2 the molar mass of CN-, or equal to the number of moles of substance.\n\nFor example, if you had 1 mole of CaCN2, you would have 1 mole of Ca+2 and 2 moles of CN-.  If you know the number of moles you can find mass, and if you know the mass you can find number of moles.\n\nI'm not sure what your looking for here, but if you maybe re word it some I will be able to help.
929369
I sure hope you have more information than you're giving us.  Typically profs will narrow the choices to one example of each major class of organic compound.  If you have the whole universe of canidates to choose from, you will need a lot more than these simple test.\n\nTLC:  In one of your textbooks or handouts, you should have a short list of organic candidates vs their Rfs.  Assuming you are using silica gel or alumina plates, ethyl acetate is about twice a strong a chromatographic mobile phase as dichloromethane (DCM) (see linked pdf, p. 15).  The fact that your unknown moved at all in ethyl acetate but hardly at all with DCM lets you know that your compound is fairly polar.  This is not an alkane or a fatty acid/ester.\n\nSolubility:  Not soluble in water?  It's not a saccharide, short-chain acid, alcohol or phenol.  Not soluble in base means it's definitely not a carboxylic acid or a phenol.  Soluble in acetone means it's not a fat or long-chain fatty acid.\n\nSo, what are we left with?  Ethers, ketones, esters and aldehydes.  I suggest you look in the chromatographic tables you have for one of these compounds that has the same Rf values and melting point you've quoted us.\n\nGood luck.
131302
it has a relative molecular mass of 40 g/mole
391994
Each color is obtained by using a different chemical or mixture of chemicals.  Many dyes and pigments involve heavy metal compounds, such as iron and copper.  For instance, iron oxide (rust) is used in some paints.  The color of a particular compound is determined by the frequencies of light it absorbs.
159204
The speed of light in a vacuum is the reference for refractive index.  Thus for any color, the RI for vacuum is 1.
832640
If you mean by TLC or HPLC, that would depend on the stationary phase and the eluting solvent.  Sorry - not enough info.
671842
Lamda = h/p\ntherefore p = h/lamda\nnow lamda = c/n (n= frequency) and (c = velocity of light   as photons travel at the speed of light)\ntherefore p = hn/c.\nAll conditions satisfied without the use of mass