Question

Which expression gives the mass percent of carbon in methanoic (formic) acid, HCOOH?

12/29 x 100
12/46 x 100
2/46 x 100
16/46 x 100

Answer 1

12/46 * 100

Step-by-step explanation:

To solve this problem, the atomic masses of the individual elements present in the mix must be taken into consideration.

The atomic mass of carbon is usually 12 a.m.u , the atomic mass of hydrogen is 1 a.m.u while the atomic mass of oxygen is 16 a.m.u

These are the three elements present in methanoic acid. Now, we can calculate the molar mass of the acid.

This is : 1 + 12 + 2(16) + 1 = 46g/mol

Now, to express the percentage of the carbon present, we simply place the atomic mass of the carbon over the total mass and multiply by 100. This is thus 12/46 * 100