11 the sugar fructose contains 400 c 67 h and 533 0 by mass...

(11) The sugar fructose contains 40.0% C, 6.7% H, and 53.3% O by mass. A solution of 11.7 g of fructose in 325 g of ethanol, C2H5OH, has a boiling point of 78.59°C. The boiling point of pure ethanol is 78.35°C, and Kb for ethanol is 1.20 °C/m. What is the molecular formula of fructose?

Transcript

00:01 Hello everyone now i'm going to discuss about this question in this question the given question is from qualitative property here the given is the here is the given question and here from this question it asks to find the what is the molecular formula of fructose now from the elevation in boiling point fast let's say what is elevation in boiling point here i have given the definition of elevation and boiling point and here is the formula for elevation in boiling point what is delta tb will be because to i into kb into m where kv is the constant of boiling point of elevation and delta tb is the elevation in boiling point and i is the ventor factor and kb is the boiling point constant and now after that if we the molality of the solution can be calculated as follows so the substitute 0 .24 degree c for delta t b and 1 .20 degree c for kb and in the so that we'll get m will be delta t y kb so to from if we put the value then we can calculate the molarity of the molecule which will be going to equal to 0 .2m now the number of moles of the fructose is calculated as follows so to calculate the number of moles of fruit toys we can use this method now substitute 0 .2 m of the solution and a 0 .3 to 5 kg for mass of the solvent of the solution so number of moles formula is equal to moliety of the solution into mass of the solvent so now calculate the number of moles of the fructose by using this formula so if you put this formula so if you put the mollative value and the mass of value then we'll get number of moles is 0 .065 mode now the molecular mass of the fructose can be calculated as follows so substitute 11 .7 gram of mass which is given and a 0 .6 moles are for the number of moles is given so molecular mass will be nothing but mass by number of moles so if you put all the values we'll get the molecular mass of the fruitage 180 gram per mole now now since the scale for the percentage is a hundred so it is the most covalent to calculate the mass of the elements present in the sample weighing 100 gram in the problem in the problem the composition of the compound is given in the percent the given compound or 40 percent carbon 353 .3 % oxygen and 6 .7 % hydrogen.

02:28 So 40 % carbon that means 40 gram of carbon in 100 gram of the compound similarly 67 .6 .7 % of h.

02:37 That means 6 .7 gram of hydrogen present 100 gram of compound...

Question

(11) The sugar fructose contains 40.0% C, 6.7% H, and 53.3% O by mass. A solution of 11.7 g of fructose in 325 g of ethanol, C2H5OH, has a boiling point of 78.59°C. The boiling point of pure ethanol is 78.35°C, and Kb for ethanol is 1.20 °C/m. What is the molecular formula of fructose?

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