1)Given the equilibrium reaction at constant pressure:
2HBr (g) + 17.4 kcal « H2 (g) + Br2(g)
When the temperature is increased, the equilibrium will shift to the
a.
right, and the concentration of HBr will decrease
b.
left, and the concentration of HBr will decrease
c.
right, and the concentration of HBr will increase
d.
left, and the concentration of HBr will increase
2)During distillation, liquids like petroleum distillates are separated according to their
a.
melting points
b.
boiling points
c.
triple points
d.
saturation points
3)Given the reaction: 2 Al + 3 H2SO4 à 3 H2 + Al2(SO4)3 the total number of moles of H2SO4 needed to react completely with 5.0 moles of Al is
a.
5.0 moles
b.
7.5 moles
c.
9.0 moles
d.
2.5 moles
4)In which group of elements do the atoms gain electrons most readily?
a.
18
b.
1
c.
16
d.
2
Thanks!!
My chemistry final is coming up and these are some questions I've gotten wrong on previous tests.someone please tell me the correct answers?
2016-05-30 6:03 pm
回答 (2)
2016-05-30 6:30 pm
✔ 最佳答案
(1)2HBr(g) + 17.4 kcal ⇌ H₂(g) + Br₂(g)
The forward reaction is endothermic. When temperature is increased, the equilibrium will shift to the right, because a higher temperature favors the endothermic reaction. Therefore, the concentrations of H₂ and Br₂ increase, while that of HBr decreases.
...... The answer is: a. right, and the concentration of HBr will decrease.
====
(2)
The process is the fractional distillation of petroleum. Fractional distillation is used to separate liquid fractions due to their differences in boiling point.
...... The answer is: b. boiling points
====
(3)
2Al + 3H₂SO₄→ 3H₂ + Al₂(SO₄)₃
According to the equation :
n(Al) : n(H₂SO₄) = 2 : 3
(5 mol) : n(H₂SO₄) = 2 : 3
2 × n(H₂SO₄) = 3 × (5 mol)
n(H₂SO₄) = 7.5 mol
...... The answer is: b. 7.5 mol
====
(4)
a. Electronic configuration : 2, 8, 8 (argon, a noble gas)
b. Electronic configuration : 1 (hydrogen)
c. Electronic configuration : 2, 8, 6 (sulfur, a Group VIA non-metal element)
d. Electronic configuration : 2 (helium, a noble gas)
...... The answer is: c. 16
2016-05-30 6:11 pm
Knowing the correct answers is USELESS. Learning HOW to find the answers yourself is the reason you take the class.
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