A compound with a percent composition by mass of 87.5% N and 12.5% H was recently discovered. What is the number of moles of Hydrogen in this compound? Atomic Mass: N = 14.01, H = 1.008
Actually, you can't find the number of mols until you have a mass; however, the data does provide a way to find the empirical formula.
Take a 100g sample.
That's 87.5 g N and 12.5g H.
mols N = 87.5/14.01 = about 6.25
mols H = 12.5/1.008 = about 12.5
The ratio is NH2 for the empirical formula. There are two mols hydrogen for every mole of N.
To find the number of moles of hydrogen in the compound, we need to use the percent composition and atomic masses.
Step 1: Percent Composition by Mass
The compound is composed of 12.5% hydrogen (H). This means that for every 100g of the compound, 12.5g is hydrogen.
Step 2: Calculate the mass of Hydrogen
If 12.5% of the compound's mass is hydrogen, and we have 100g of the compound, we can calculate the mass of hydrogen:
Mass of Hydrogen = (12.5/100) * 100g
Mass of Hydrogen = 12.5g
Step 3: Convert the mass of Hydrogen to moles
To calculate the number of moles of hydrogen, we need to use the atomic mass of hydrogen (H).
Atomic mass of hydrogen (H) = 1.008g/mol
Number of moles of Hydrogen = Mass of Hydrogen / Atomic mass of Hydrogen
Number of moles of Hydrogen = 12.5g / 1.008g/mol
Using a calculator, we can determine the number of moles of hydrogen in the compound:
Number of moles of Hydrogen ≈ 12.40 mol
So, there are approximately 12.40 moles of hydrogen in the compound.
To find the number of moles of hydrogen in the compound, we need to know the mass of the compound. The percent composition by mass tells us the relative proportion of each element in the compound.
First, we need to calculate the mass of nitrogen (N) in the compound using the percent composition by mass. Let's assume we have 100 grams of the compound:
Mass of nitrogen (N) = (percent composition of N / 100) * mass of compound
= (87.5 / 100) * 100 (since we assumed 100 grams of the compound)
= 87.5 grams
Next, we can calculate the mass of hydrogen (H) in the compound:
Mass of hydrogen (H) = (percent composition of H / 100) * mass of compound
= (12.5 / 100) * 100 (since we assumed 100 grams of the compound)
= 12.5 grams
Now, we can calculate the number of moles of hydrogen using the mass and molar mass of hydrogen:
Number of moles of hydrogen = Mass of hydrogen / molar mass of hydrogen
= 12.5 grams / 1.008 g/mol (molar mass of hydrogen)
= 12.4 moles (rounded to the nearest tenth)
Therefore, there are approximately 12.4 moles of hydrogen in this compound.