A compound consisting of C, H and O only, has a molar mass of 331.5g/mol. Combustion of 0.1000g of this compound caused a 0.2921g increase in the mass

ankarskogC

ankarskogC

Answered question

2020-10-23

A compound consisting of C, H and O only, has a molar mass of 331.5g/mol. Combustion of 0.1000g of this compound caused a 0.2921g increase in the mass of the CO2 absorber and a 0.0951 g increasein the mass of the H2O absorber. What is the empirical formula ofthe compound?
What is ment by absorber ? product?

Answer & Explanation

sweererlirumeX

sweererlirumeX

Skilled2020-10-24Added 91 answers

In combustion analysis, the amounts of carbon dioxide and waterproduced are determined by measuring the mass increase in thecarbon dioxide and water absorbers, respectively. Typicallythe absorbers are chemicals that absorb or react with carbondioxide or water. For example, a carbon dioxide absorber maybe NaOH (which reacts with carbon dioxide to form NaHCO3). The water absorber may be Mg(ClO4)2, a dessicant (drying agent). Because there was a mass increase of the CO2 absorber of 0.2921 g and a mass increase of 0.0951g of the water absorber, thenthe amount of CO2 produced from the combustion is 0.2921g and the amount of H2O produced is 0.0951 g.
To determine the empirical formula, calculate the grams of C from CO2, the grams of H from H2O, and the amountof O will be determined by taking the total mass of the substancecombusted (0.1000g) and subtracting the amount of C and H. Therefore:
gram C=(0.2921 g CO2)(1 mo44g)(1 mo Cmo CO2)(12 g C1 mo C)=0.07966 g C
gram H=(0.0951 g H2O)(1 mo H2O18 g H2O)(2 mo H2Omo H2O)(1.008 g Hmo H)=0.01065 g H
gram O=0.1000 g(0.07966 g+0.01065 g)=9.69×103 g
moles O=(9.69×103 g)(1 mo O16 g O)=6.056×104 mo O
Calculate the moles of H and C by dividing by their respective molecular weights to find:
mos H=0.01057 mo H
mo C=6.638×103 mo C
As the number of moles of O is the smallest, divide mole C, mole Hand mole O by mole O to obtain:
mole C/mole O = 10.96
mole H/mole O = 17.45
mole O/ mole O = 1
So have C10.96H17.45O must be whole numbersso multiply coefficients by 2 to obtain the empirical formula of C22H35O2
As the empirical formula weight is about 331 g/mole and the actualmolecular weight is 331.5 g/mole, the empirical formula of thiscompound is also the molecular formula.

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