al Science Unit Test Unit Test Active 21 22 23 24 25 Which argument best explains the charge of an atomic nucleus? An atomic nuc
1 answer:
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Answer:
6.24 x 10-3 M
Explanation:
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In this case, for the given dissociation, we have the following equilibrium expression in terms of the law of mass action:
Of course, water is excluded as it is liquid and the concentration of aqueous species should be considered only. In such a way, in terms of the change , we rewrite the expression considering an ICE table and the initial concentration of HBrO that is 0.749 M:
Thus, we obtain a quadratic equation whose solution is:
Clearly, the solution is 0.00624 M as no negative concentrations are allowed, so the concentration of BrO⁻ is 6.24 x 10-3 M.
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Answer:
Mass percent of nitrogen in the compound is 13,3%
Explanation:
Dumas method is an analytical method to determine nitrogen content in samples, thus:
CₐHₓNₙ + (2a+x/2) CuO → aCO₂ + ˣ/₂ H₂O + ⁿ/₂ N₂ + (2a+x/2) Cu
As the CO₂ is removed with KOH, in the mixture you have H₂O and N₂
At 25°C. the vapor pressure of water is 23,8 torr, that means that the pressure due to N₂ is:
726torr - 23,8torr = 702,2 torr.
Using gas law:
n = PV/RT
Where:
P is pressure (702,2torr≡ 0,924 atm)
V is volume (0,0318L)
R is gas constant (0,082atmL/molK)
And T is temperature (25°C≡298,15K)
Replacing, number of moles of N₂, n, are:
n = 1,20x10⁻³moles of N₂. In grams:
1,20x10⁻³moles of N₂× =<em> 0,0336 g of N₂</em>.
Thus, mass percent of nitrogen in the compound is:
×100= <em>13,3%</em>
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