Vanadium (IV) carbonate
1 answer:
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Answer:
0.269 g
Explanation:
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+
Data:
Half-life of (T(1/2)) = 138.4 days
Mass of PoCl4 = 561 mg (0,561 g) and molecular weight of PoCl4 = 350. 79 g/mol
Time = 338.8 days
Isotopic masses
= 209.98 g/mol
= 205.97 g/mol
Concepts
Avogadro’s number: This is the number of constituent particles that are contained in a mol of any substance. These constituted particles can be atoms, molecules or ions). Its value is 6.023*10^23.
The radioactive decay law is
N=Noe^(-λt)
Where:
No = number of atoms in t=0
N = number of atoms in t=t (now) in this case t=338.8 days
λ= radioactive decay constant
The radioactive constant is related to the half-life by the next equation
λ=
so
λ= =0,005008 days^(-1)
No (Atoms of in t=0)
To get No we need to calculate the number of atoms of in the initial sample. We have a sample of 0,561 g of PoCl4. If we get the number of moles of PoCl4 in the sample, this will be the number of moles of
in the initial sample.
This is:
= 0,001599 mol of PoCl4
This is the number of mol of in the initial sample.
To get the number of atoms in the initial sample we use the Avogadro’s number = 6.023*10^23
0,001599 mol of * 6.023*10^23 atoms/ mol of
= 9.632 *10^20 atoms of
Atoms after 338.8 days
We use the radioactive decay law to get this value
N=Noe^(-λt)
N=9.632*10^20 e^(-0,005008 days^(-1) * 338.8 days) =1.765*10^20
This is the number of atoms of in the sample after 338.8 days has passed
The number of atoms transformed is equal to the number of atoms of
produced.
The number of atoms of transformed is No - N
9.632 *10^20 – 1.765 *10^20 = 7.866*10^20
So, 7.866*10^20 is the number of atoms of produced
We can get the mass with the Avogadro’s number
(7.866*10^20 atoms of ) / ( 6.023*10^23 atoms of
/ mol of
= 0.001306 moles of
This number of moles have a mass of:
(0,001306 moles of )* (205.97 g of
/mol of
) = 0.269 g
Empirical formula is the simplest ratio of components making up the compound. the molecular formula is the actual ratio of components making up the compound.
the empirical formula is CH₂. We can find the mass of CH₂ one empirical unit and have to then find the number of empirical units in the molecular formula.
Mass of one empirical unit - CH₂ - 12 g/mol x 1 + 1 g/mol x 2 = 12 = 14 g
Molar mass of the compound is - 252 .5 g/mol
number of empirical units = molar mass / mass of empirical unit
=
= 18 units
Therefore molecular formula is - 18 times the empirical formula
molecular formula - CH₂ x 18 = C₁₈H₃₆
molecular formula is C₁₈H₃₆