Respuesta :
Explanation:tr
a) Molar mass of HF = 20 g/mol
Atomic mass of hydrogen = 1 g/mol
Atomic mass of fluorine = 19 g/mol
Percentage of an element in a compound:
[tex]\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{Molar mass of compound }}\times 100[/tex]
Percentage of fluorine:
[tex]\frac{1\times 19 g/mol}{20g/mol}\times 100=95\%[/tex]
Percentage of hydrogen:
[tex]\frac{1\times 1g/mol}{20 g/mol}\times 100=5\%[/tex]
b) Mass of hydrogen in 50 grams of HF sample.
Moles of HF = [tex]\frac{50 g}{20 g/mol}=2.5 mol[/tex]
1 mole of HF has 1 mole of hydrogen atom.
Then 2.5 moles of HF will have:
[tex]1\times 2.5 mol=2.5 mol[/tex] of hydrogen atom.
Mass of 2.5 moles of hydrogen atom:
1 g/mol × 2.5 mol = 2.5 g
2.5 grams of hydrogen would be present in a 50 g sample of this compound.
c) As we solved in part (a) that HF molecules has 5% of hydrogen by mass.
Then mass of hydrogen in 50 grams of HF compound we will have :
5% of 50 grams of HF = [tex]\frac{5}{100}\times 50 g=2.5 g[/tex]
