Respuesta :
Answer:
The compound XF3 has a molar mass of 87.7 g/mol
The element x has an atomic mass of 30.7 u
This element can be P (phosphorus) and the compound will be PF3
Explanation:
Step 1: Data given
Compound XF3 has a mass % of 65% F
Step 2:
The sample has 65% mass percent, this is the ratio of the element (F) it's mass compared to the mass of the compound.
(Mass of F / mass of compound)*100% = 65 %
Step 3: Calculate molar mass of the compound
F has an atomic mass of 19u (Since there are 3x F the atomic mass is 3*19 = 57 u)
The compound XF3 has a molar mass of (X+57)g/mol
⇒ with X = the molar mass of compound x
Mass % of F = 65% = (3*19g/mol)/(X+57)g/mol
0.65 = (57/(X+57))
57 = 0.65*(X+57)
57 = 0.65X + 37.05
19.95 = 0.65X
X = 30.7 g/mol
This means the atomic mass of the element x is 30.7 u
To control this we can calculate the mass % of F
((3*18)/(30.7 + 3*18)) * 100% = 65%
The compound XF3 has a molar mass of 87.7 g/mol
The element x has an atomic mass of 30.7 u
This element can be P (phosphorus) and the compound will be PF3
