1. Polystyrene can be prepared in the laboratory by heating a mixture of styrene and kerosene under reflux. The structure of styrene is C6H5CH=CH2
6a.). What characteristic in the structure of styrene enables it to act as a monomer?
6b.). Write the chemical equation for the polymerization.
6c.).Suggest ONE reason why polystyrene should be expanded before it is used to make disposable lunch boxes.
6d.). State whether you agree with the following statement. Explain your answer." Landfilling is better than incineration for the disposal of polystyrene wastes."
2. : In each cases, state an advantage of using material B over A:
(i) Make Water Pipes A:PVC B: Iron
(ii) Make lenses A: Perspex B: Glass
(iii) Make shopping bags A: Polythene B:Paper
MC:3. What is the volume (measured at r.t.p) of carbon dioxide formed during the complete buring of 8.5g carbon in air?(Relative atomic mass:C=12.0; molar volume of any gas at r.t.p. =24.0 dm3 mol-1)
A. 34 dm3
B. 17 dm3
C. 12dm3
D. 3 dm3
MC4. When 0.2 g of calcium is treated with excess dilute hydrochloric acid, what volume of gas at room temperature and pressure will be produced?(Relative atomic mass: Ca=40.0; molar volume of gases at r.t.p. is 24 dm3 mol-1)
A. 20 cm3
B. 60 cm3
C 100 cm3
D 120 cm3
MC5. When 25 cm3 of 0.25 M NaHCO3(aq) reacts with 30cm3 of 0.1 M HCl(aq), what is the volume of CO2(g) formed at r.t.p.?(Molar volume of gases at r.t.p. is 24 dm3 mol-1)
A. 150 cm3
B. 144 cm3
C. 78 cm3
D. 72 cm3
MC6. Hydrazine, N2H4, is commonly used as a rocket fuel. It reacts with ammonia to produce a large volume of gases from a small volume of liquid hydrazine. 4NH3(g)+ N2H4(l) ---> 3N2(g) + 8H2(g) What is the total volume (measured at r.t.p.) of gaseous products formed if 12 g of N2H4 are ignited? (Relative atomic masses: H=1.0, N= 14.0; Molar volume of any gas at r.t.p.= 24.0 dm3 mol-1)
A. 27 dm3
B. 72 dm3
C. 99 dm3
D. 132 dm3
急plz
Chemistry化學問題幾條(急).pLZZZZ help
2011-07-30 12:09 am
回答 (3)
2011-07-31 12:09 am
✔ 最佳答案
1.:6a.)
The molecule has C=C double bonds.
6b.)
n C6H5CH=CH2 → -(-CH(C6H5)-CH2-)n-
6c.)
In the expanded polystyrene, the trapped gas is good heat insulator to keepwarm.
6d.)
Yes, landfilling for the disposal of polystyrene wastes does not cause airpollution, but incineration would for the disposal of polystyrene wastes wouldcause the formation of air pollutants (e.g. toxic carbon monoxide).
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2. :
(i)
PVC is softened for hot water, but iron is not.
(ii)
Glass has a higher transparency than perspex. / Perspex is scratched more easilythan glass.
(iii)
In disposal, paper is biodegradable, but polythene is non-biodegradable.
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MC:3.
C + O2 → CO2
No. of moles of C = 8.5 g/12 = 8.5/12 mol
No. of moles of CO2 formed = 8.5/12 mol
Volume CO2 formed = (8.5/12) x 24 = 17 dm³...... answer : (B)
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MC4.
Ca + 2HCl → CaCl2+ H2
No. of moles of Ca reacted = 0.2/40 = 0.005 mol
No. of moles of H2 gas formed = 0.005 mol
Volume of H2 formed = 0.005 x 24000 = 120 cm³...... answer : (D)
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MC5.
NaHCO3 + HCl →NaCl + H2O + CO2
No. of moles of NaHCO3 added = 0.25 x (25/1000) = 0.00625 mol
No. of moles of HCl added = 0.1 x (30/1000) = 0.003 mol
Mole ratio NaHCO3 : HCl = 1 : 1
Hence, HCl is the limiting reactant.
No. of moles of HCl reacted = 0.003 mol
No. of moles of CO2 formed = 0.003 mol
Volume of CO2 formed = 0.003 x 24 = 72 cm³...... answer : (D)
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MC6.
4NH3(g)+N2H4(l) → 3N2(g) + 8H2(g)
No. of moles of N2H4reacted = 12/(14x2 + 1x4) = 0.375 mol
Total no. of moles of gaseous products = 0.375 x (3 + 8) = 4.125 mol
Total volume of gaseous products = 4.125 x 24 = 99 dm³...... answer : (C)
參考: micatkie
2011-07-30 2:37 am
Please do your homework yourself.
you can ask want you don't know, but should not abuse due to your laziness.
you can ask want you don't know, but should not abuse due to your laziness.
2011-07-30 12:12 am
收錄日期: 2021-04-13 18:07:34
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