# Problem: Terephthalic acid is an important chemical used in the manufacture of polyesters and plasticizers. It contains only C, H, and O. Combustion of 19.81 mg terephthalic acid produces 41.98 mg CO2 and 6.45 mg H2O. If 0.250 mole of terephthalic acid has a mass of 41.5 g, determine the molecular formula for terephthalic acid.

###### FREE Expert Solution

We’re being asked to determine the molecular formula of a terephthalic acid composed of C, H, and O given the combustion analysis.

Recall that in combustion analysisa compound reacts with excess O2 to form products

For a compound composed of C, H, and O, the reaction looks like this:

CxHyOz + O2 (excess)  x CO2y H2O

This means we need to do the following steps:

Step 1: Calculate the mass of C and H in the compound.

Step 2: Calculate the mass of O in the compound.

Step 3: Determine the lowest whole number ratio of C, H, and O to get the empirical formula.

Step 4: Use the empirical mass to calculate the molecular formula

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###### Problem Details

Terephthalic acid is an important chemical used in the manufacture of polyesters and plasticizers. It contains only C, H, and O. Combustion of 19.81 mg terephthalic acid produces 41.98 mg CO2 and 6.45 mg H2O. If 0.250 mole of terephthalic acid has a mass of 41.5 g, determine the molecular formula for terephthalic acid.