In the Dumas Method, the volatile sample
1 answer:
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Answer:
5.42g, 71.77%
Explanation:
First, we have to write out the balanced chemical equation. The unbalanced equation can be written as “SO2+O2 -> SO3” and to balance it, we can see that having two mols of SO2 and two mols of SO3 will make each side have the same amount of mols per element on each side. So the balanced chemical equation is “2SO2 + O2 -> 2SO3”
Now, we want to solve for the theoretical yield in grams of SO3. To do this, we have to use dimensional analysis. We convert g SO2 into mols SO2 using the molar mass of the elements. Then we convert mols of SO2 into mols of SO3 using the balanced equation. Once we’ve done that, we can convert mols of SO3 into grams of SO3.
You should know how to look up the molar mass of elements on the periodic table by now. Find the masses and set up the terms so they cancel like so:
Doing the math, we get 5.42g so3 as the theoretical yield. This is the most amount that you could ever get if the world was a perfect place. But alas, it isn’t and mistakes are gonna happen, so the number is going to be less than that. So the best we can do, is to figure out the percent yield that we got.
In a lab scenario, this was calculated to be 3.89 g as stated by the problem. The percent composition formula is
and plugging the numbers into it, we get:
make sure to follow the decimal/significant figure rules of your instructor, but only round at the end. My professor didn't care too much thankfully, but some professors do
Answers:
1. CO₂ < Ar < N₂ < He;
2. Cl₂ < CO₂ < Ar < N₂ < H₂
Step-by-step explanation:
Graham’s Law applies to the diffusion of gases:
The rate of diffusion (r) of a gas is inversely proportional to the square root of its molar mass (M).
If you have two gases, the ratio of their rates of diffusion is
1. Order of diffusion rates
According to Graham's Law, the lightest gases will have the highest diffusion rates and the heavier gases the slowest.
The molecular masses of the gases are:
Ar 39.95; CO₂ 44.01; He 4.00; N₂ 28.02
Putting them in order,we get
44.01 > 39.95 > 28.02 > 4.00
CO₂ > Ar > N₂ > He
Thus, the relative rates of diffusion are
CO₂ < Ar < N₂ < He
2. Order of molecular speeds
A postulate of the Kinetic Molecular Theory is that at a given temperature, the average kinetic energy of the molecules is directly proportional to the Kelvin temperature.
KE = ½ mv² ∝ T
mv² ∝ T Divide each side by m
v² ∝ T/m
If T is constant.
v² ∝ 1/m Take the square root of each side
v ∝ 1/√m
This is an inverse relationship, so the molecules with the smallest molecular mass should have the highest average speeds.
The molecular masses of the gases are:
N₂ 28.02; H₂ 2.016; Cl₂ 70.91; CO₂ 44.01; Ar 39.95
Putting them in order. we get
70.91 > 44.01 > 39.95 > 28.02 > 2.016
Cl₂ > CO₂ > Ar > N₂ > H₂
Thus, the relative molecular speeds are
Cl₂ < CO₂ < Ar < N₂ < H₂