Calculating Gram Formula Weight (GFW)
This page provides exercising is calculating gram formula weights (GFWs). You will need your periodic table, scratch paper, and perhaps a calculator. Follow these steps to answer correctly:
- Determine the number of each element type present in the given chemical formula.
- Multiple the gram atomic weight (GAW) of each present element by the number of atoms for that element, determining in step 1.
- Add each of these products together - this is the GFW.
Example: CO2
- 1 carbon atom and 2 oxygen atoms
- 12.011 g × 1 carbon atom and 15.9994 g × 2 oxygen atoms
- 12.011 g + 31.9988 g = 44.010 g
- To begin-press "New Compound" and a chemical formula will appear to the right of the table.
- Calculate the GFW, enter it in the answer cell and press "Check Answer."
- The results on the problem and a running total will appear in the second table.
- If you get a problem "incorrect", you should redo it and recheck your answer.
- For ease of presentation, all GFWs are presented to four significant figures, even though the GAWs are often known to greater precision than that.
- Pressing the "Show Answer" will display the solution and you will no longer be able to submit an answer for that problem.
