Dale P. answered • 03/02/21
Ph. D in Chemistry with 4 years of undergrad tutoring experience
The formula for trifluoroacetic acid is CF3CO2H. It's molar mass is 114.02 g/mol.
To find the mass of the acid we can multiply 15.7 by (114.02/31.9988) to get 55.9 g of the acid.
I used a bit of a trick to simplify the problem. If we were to work the problem stepwise you would first determine the moles of oxygen by dividing 15.7 by 15.999 g/mol to get 0.981 moles of oxygen.
There are two oxygen atoms per molecule of acid so we need to divide the 0.981 moles by two to get moles of the acid or .491 moles of acid.
Then multiply the moles of acid by its molar mass to get the grams of acid or 55.9 g of acid.
The original equation just combined all these steps into 1 equation.
