Formic acid is responsible for the sting of ant bites. By mass, formic acid is 26.10% C, 4.38% H, and 69.52% O. The molar mass of formic acid is 46.02 g/mol. Find the molecular formula of formic acid and draw its Lewis structure.
Solution 91E Step 1 of 5 The mass percentage can be used to obtain the ratio between the elements involved in forming a compound. Step 2 of 5 Since we know the mass percentages, it is reasonable that in 100 g of compound we have 26.10 g of C 4.38 g of H 69.52 g of O Now we can calculate the number of moles for each element moles of C= Mass of C/(Atomic mass of C)= 26.10 g/ (12.01g/mol)=2.17 moles of H= Mass of H/(Atomic mass of H)= 4.38 g/ (1.008g/mol)=4.35 moles of O= Mass of O/(Atomic mass of O)= 69.52 g/ (16.00g/mol)=4.35 Step 3 of 5 Since the C has the lower number of mole, we can use this number as reference to know the ratio between these three elements. We have to divide all the numbers of moles obtained in the step 2 for the lowest value. So we obtain a C:H:O ratio that is 1:2:2. Thus we have on atom of C, 2 atoms of H and 2 atoms of O. Thus the empirical formula is CH O2 2