Answer to Question #144790 in General Chemistry for Joshua

Question #144790
Terephtgalic acid is an important chemical used in the manufacture of polysters and plasticizers. It contains only C,H, and O. Combustion of 19.81 mg of terephthalic acid produced 41.68 mg CO2 and 6.45 mg H2O. The molar mass of terephthalic acid is 166 g. Calculate the empirical and the molecular formula of terephthalic acid.
1
Expert's answer
2020-11-22T11:13:47-0500

Chemical reaction:

CxHyOz+O2    CO2+H2OC_xH_yO_z+O_2\iff CO_2+H_2O


m(CxHyOz)(C_xH_yO_z)= 19.81 mg

m(CO2)(CO_2) = 41.68 mg

m(H2O)(H_2O) = 6.45 mg


mass of carbon:

4441.68mg44-41.68m g

12x=11.3672mg12- x=11.3672mg


mass of hydrogen:

186.45mg18 - 6.45mg

2x=0.7167g2-x=0.7167g


mass of oxygen:

m(oxygen) = m(terephtgalic acid) - m(carbon) - m(hydrgen) = 7.7261mg


(CxHyOz)=11.367212=0.71671=7.726116=(C_xH_yO_z) = \dfrac{11.3672}{12} = \dfrac{0.7167}{1} = \dfrac{7.7261}{16} = 0.9472647:0.7167:0.482881250.9472647:0.7167:0.48288125


need to devide each number by the smallest one:


1.96169286:1.48421584:1

n(CxHyOz)=166gn(C_xH_yO_z)=166g = 166g

41n=166g41n=166g

n=4n=4


need to multiply above ratio by 4, then we get molecular formula of terephtgalic acid:


8:6:4

C8H6O4C_8H_6O_4


Since all three coefficients have the common factor 2, divide the molecular formula by 2 to find the empirical formula:

C4H3O2C_4H_3O_2



Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be the first!

Leave a comment