Question:
Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as pure water at 20.0 degrees C (18 torr). The volume of the mixture is 1.7 L and its total pressure is 0.987 atm. Determine the number of moles of hydrogen gas present in the sample.
A. 0.272 mol
B. 0.04 mol
C. 0.997 mol
D. 0.139 mol
E. 0.0681 mol
Answer:
The correct option is;
E. 0.0681 mol
Explanation:
The equation for the reaction is
Zn + HCl = H₂ + ZnCl₂
Vapor pressure of the liquid = 18 torr = 2399.803 Pa
Total pressure of gas mixture H₂ + liquid vapor = 0.987 atm
= 100007.775 Pa
Therefore, by Avogadro's law, pressure of the hydrogen gas is given by the following equation
Pressure of H₂ = 100007.775 Pa - 2399.803 Pa = 97607.972 Pa
Volume of H₂ = 1.7 L = 0.0017 m³
Temperature = 20 °C = 293.15 K
Therefore,
Therefore, the number of moles of hydrogen gas present in the sample is n ≈ 0.0681 moles.
The solution for this problem would be:
We are looking for the grams of magnesium that would have
been used in the reaction if one gram of silver were created. The computation
would be:
1 g Ag (1 mol Mg) (24.31 g/mol) / (2mol Ag)(107.87g/mol) =
0.1127 grams of Magnesium
Answer:
k= 1.925×10^-4 s^-1
1.2 ×10^20 atoms/s
Explanation:
From the information provided;
t1/2=Half life= 1.00 hour or 3600 seconds
Then;
t1/2= 0.693/k
Where k= rate constant
k= 0.693/t1/2 = 0.693/3600
k= 1.925×10^-4 s^-1
Since 1 mole of the nuclide contains 6.02×10^23 atoms
Rate of decay= rate constant × number of atoms
Rate of decay = 1.925×10^-4 s^-1 ×6.02×10^23 atoms
Rate of decay= 1.2 ×10^20 atoms/s
<span>Uranium has an atomic weight of 238.03 g/mol.
We have 1.32x10^20 atoms of uranium.
We must convert this to moles by dividing Avogadro's number 6.022x10^23 atoms/mol.
(1.32x10^20atoms)/(6.022x10^23atoms/mol)
2.19x10^-4moles of Uranium
Now multiply this by the atomic weight of Uranium.
2.19x10^-4mol*238.03g/mol
Grams of Uranium = .0522g</span>
Answer:
Explanation:
1) alkali metals and halogens as alkalis have 1 electron they need to get rid of in order to gain a full outer shell of electrons and the halogens have to gain 1 electron.
2) they have the same number of electrons on the outer shells
3)they usually have high melting points
4) low or no reactivity
5) group 7
