A 1/5 mmol (yes, millimol... no, it isn't a typo_ sample of XeFn h as a mass of 0.311 g. What is the value of n?
The answer is 4, but why?
omg that should say 1.50 mmol
Given 0.311g sample = 1.50 mmole sample = 1.5x10^-4 mole sample
Sample mole weight = (0.311)g/(1.5x10^-4)mol = 207.33 g/mol
fwt(Xe) + n·fwt(F) = 207.33 g/mol
(131.3)g/mol + n·(19.0)g/mol = 207.33g/mol
(n·19)g/mol = (207.33 - 131.3)g/mol
n = [(207.33 - 131.3)g/mol]/(19)g/mol
n = 74.03/19 = 4
XeF4
thank you :D
You are most welcome...
DrReb(at)g.m.a.i.l.c.o.m
To find the value of n in XeFn, we need to use the molar mass of XeFn and the given mass of the sample.
Here's how you can calculate it step by step:
1. Start by finding the molar mass of XeFn. To do this, you need to know the atomic masses of xenon (Xe) and fluorine (F). The atomic mass of Xe is 131.293 g/mol, and the atomic mass of F is 18.998 g/mol.
The molar mass of XeFn is equal to the atomic mass of xenon plus the atomic mass of fluorine multiplied by n. So, the molar mass of XeFn can be written as:
Molar mass of XeFn = Atomic mass of Xe + (Atomic mass of F x n)
2. Calculate the molar mass of XeFn using the formula mentioned above:
Molar mass of XeFn = 131.293 g/mol + (18.998 g/mol x n)
3. Now, use the given mass of the sample (0.311 g) and convert it to moles. Recall that moles = mass/molar mass.
Moles of XeFn = 0.311 g / Molar mass of XeFn
4. Divide the moles of XeFn by the desired fractional value of moles (1/5 mmol). Since 1/5 mmol is equivalent to 1/500 mol, you need to divide the moles of XeFn by 1/500.
Moles of XeFn divided by (1/500) = (0.311 g / Molar mass of XeFn) / (1/500)
5. Simplify the equation by multiplying the numerator by the reciprocal of the denominator.
Moles of XeFn divided by (1/500) = (0.311 g / Molar mass of XeFn) x 500
6. Now, equate the simplified equation to 1. Since the sample is exactly 1/5 mmol, the moles of XeFn divided by (1/500) should be equal to 1.
(0.311 g / Molar mass of XeFn) x 500 = 1
7. Rearrange the equation to solve for the molar mass of XeFn:
Molar mass of XeFn = 0.311 g / 500
8. Substitute the value of the molar mass of XeFn into the molar mass formula from step 1 and solve for n:
131.293 g/mol + (18.998 g/mol x n) = 0.311 g / 500
9. Solve for n by subtracting the atomic mass of xenon from both sides, then dividing the result by the atomic mass of fluorine:
18.998 g/mol x n = (0.311 g / 500) - 131.293 g/mol
n = [(0.311 g / 500) - 131.293 g/mol] / 18.998 g/mol
By performing the calculations, the value of n is found to be approximately 4.
Therefore, the value of n in XeFn is 4.