Question

What is the percentage by mass of hydrogen in ethanoic acid?
Show workings bit by bit

Answer 1

Ethanoic acid has the molecular formula CH3COOH.

Let's find the molar mass of the component atoms:
- Carbon (C) has a molar mass of 12 g/mol.
- Hydrogen (H) has a molar mass of 1 g/mol.
- Oxygen (O) has a molar mass of 16 g/mol.

Now, let's find the molar mass of ethanoic acid:
- It contains 2 carbon atoms, 4 hydrogen atoms, and 2 oxygen atoms.
- Molar mass of ethanoic acid = (2 × 12) + (4 × 1) + (2 × 16) = 24 + 4 + 32 = 60 g/mol.

Next, let's calculate the mass of hydrogen in ethanoic acid:
- The mass of hydrogen = (Number of hydrogen atoms) x (Molar mass of hydrogen)
- The mass of hydrogen = 4 x 1 = 4 g.

Finally, let's find the percentage by mass of hydrogen in ethanoic acid:
- Percentage = (Mass of hydrogen / Molar mass of ethanoic acid) x 100
- Percentage = (4 / 60) x 100 = 0.0667 x 100 = 6.67%.

So, the percentage by mass of hydrogen in ethanoic acid is approximately 6.67%.