Chemistry

1. The density of acetic acid is 1.05 g/mL. What is the volume of 650 gof acetic acid? Show calculations

volume = mass/density = 650/1.05 = 619 mL


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2. Which of the following liquids are likely to be miscible with water:1-propanol (CH3CH2CH2OH), carbon tetrabromide(CBr4), pentane (C5H12), and sulfuric acid (H2SO4)?

1-propanol and sulfuric acid are likely to be misciblewith water.
(1-propanol and sulfuric acid can be miscible with water because theirmolecules can form hydrogen bonds with water.)


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3. To prepare 1.000 kg of 5.5% by mass KCl(aq), one may dissolve X grams KCland Y grams of water

x + y = 1000 ...... (1)
[x/(x + y)] * 100% = 5.5% ...... (2)

Put (1) into (2):
[x/1000] * 100% = 5.5%
0.1x = 5.5
x = 55

(1):
55 + y = 1
y = 945


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4. Which group of the periodic table of elements forms only 1+ ions, 2+ions?
a) group 1A b) group 2A c) group7B d) group 7A e) group 8A

a) Group 1A elements form only 1+ ions.

b) Group 2A elements form only 2+ ions.


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5. What is the molarity of 10.00% by mass sulfuric acid? The molar mass of H2SO4is 98.08 g/mol. Assume, that the densityof the solution = 1.00g/mL

Consider 1 L (1000 mL) of the solution:
Mass of the solution = volume * density = 1000 * 1.00 = 1000 g
Mass of H2SO4 in the solution = 1000 * 10.00% = 100 g
No. of moles of H2SO4 in the solution = 100/98.08 = 1.02mol
Molarity of H2SO4 = 1.02/1 = 1.02 mol/L


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6. The products of the complete combustion of a hydrocarbon are carbon dioxideand water. Write a balanced chemical equation for the combustion of pentane, C4H10.

Pentane is C5H12. The equation for the complete combustionof pentane is:
C5H12 + 8O2 → 5CO2 + 6H2O

C4H10 is butane. The equation for the complete combustionof C4H10 is:
2C4H10 + 13O2 → 8CO2 + 10H2O

答案寫得不錯.
不過別幫懶人做功課嘛!
他不懂, 教他解題的方向就好了, 為甚麼要把答案雙手奉上予伸手黨?
知識+ 的原意不是這樣的吧?