回18 ai To my knowledge, Homologous series can be expressed using the same general formula, I.e. CnHn, so I think as CnH2n+1OH and CnH2n(OH)2 are two different general formula, so they are not in the same homologous series. 路人純9Up, 想搵人Confirm 下
Q34(2) Mole ratio of the reactants to product is 3:2 in the forward reaction.Thus,increasing the pressure of the system shifts the equilibrium position to the right to reduce the volume of the gas and hence opposing the increase of pressure.In this sence,isn't (2) wrong? thx
higher pressure = higher concentration = higher rate. Just like higher temperature can increase both forward and backward rate. But forward rate increase more so the reaction shift right.
I have a few questions What I have learnt in textbook is that Mg can react with hot water and steam. Mg+steam=MgO+hydrogen gas Mg+hot water=magnesium hydroxide+hydrogen gad
Why my knowlegde is different from others? Different version of chemical knowledge? or mistakes made by the textbook? My textbook is HKDSE Chemidtry A modern view second edition by Aristo Education Press Ltd
I think although the carboxylic acid formed can form hydorgen bond with water,the long carbon chain make it barely soluble in water,thus forming white precipitate
Re 1AQ32(3),since the mole ratio of the reaactant to product is 2:2,which equals to 1:1,no matter how the equilibrium position shifts,it would produce the same volume of gases
1AQ1 The question said covalent compound is formed, how come the answer is not PCl3 which is a covalent compound, but GaCl3 which is an ionic compound?
For PCl3, P is Group V element while Cl is Group VII element. Different electronic configuration.
For GaCl3, it is covalent compound, with bitetrahedral structure. Similar example is AlCl3. It is not definitely that metal and non-metal will form ionic compound. There is actually no clear-cut.
1AQ14: What is the white fume when Cl2 is mixed with NH3 gas? Q16: Statement 1: Does "nitrogen" in this statement mean nitrogen atom, or nitrogen molecule? Thank you.
5** 操 Past Paper 正確方法 
【英文】一個暑假大幅進步的方法 
【2019 DSE】暑期的輕鬆温書安排
1A Q1 atom唔會有一樣既electronic arrangement,ion先有
回覆刪除Q9 NH4Cl 並唔系oxidizing agent，因為反應中oxidation number無變
Manganese(IV) oxide 先系反應中既oxidizing agent
MN 由+4變+3
Q18 (a)(i)佢地唔系都係同1group咩？
Q20 (3)geometrical isomerism指既應該系 cis-trans，而唔系enantiomer
回18 ai
刪除To my knowledge, Homologous series can be expressed using the same general formula, I.e. CnHn, so I think as CnH2n+1OH and CnH2n(OH)2 are two different general formula, so they are not in the same homologous series.
路人純9Up, 想搵人Confirm 下
1AQ1
刪除I aware some concept is outC, so I amend some of the option. Thanks
1AQ9
NH4+ + e ---> NH3 + H2
H is reduced from +1 to 0 so it is OA.
1AQ18 no, they belong to different group because they cant be represented by same general formula.
1AQ20
you are right. I change "geometrical" to "stereoisomer" Thanks!
re 1AQ9
刪除NH4+ + e ---> NH3 + H2
2MnO2+H2 --->Mn2O3+H20
but H2 is cancelled out in the process
by樓主
I agree that there's problem in wording. I try to use other word to correct it. thanks
刪除Q34(2)
刪除Mole ratio of the reactants to product is 3:2 in the forward reaction.Thus,increasing the pressure of the system shifts the equilibrium position to the right to reduce the volume of the gas and hence opposing the increase of pressure.In this sence,isn't (2) wrong?
thx
Re Q.34 (2)
刪除should be both forward and backward rate increase (?)
but forward reaction rate > backward reaction rate
1AQ34
刪除樓上 is correct, both rate increase
Can someone explain Q34(2),i still don't get it.
刪除Thx
higher pressure = higher concentration = higher rate. Just like higher temperature can increase both forward and backward rate. But forward rate increase more so the reaction shift right.
刪除ms
回覆刪除29. The systematic name should be heptana-2,4,6-triol
應該系叫heptane-2,4,6-triol
1AQ29
刪除Yes, you are right, some typo occur
P1AQ18
回覆刪除想問點解option C錯
Mass of A < mass of B
Mole of A present in 1g > mole of B
加上B 比A多一個O atom
Gum唔係A要多D O2去complete combustion?
Thx
yes, you are right, the answer is D
刪除1A Q23 option 3,
回覆刪除想問D GAS 係點來？
Thx
no gas, the answer is changed. haha
刪除1A Q36 "Both calcium and magnesium can react
回覆刪除with water." why false?
Magnesium can only react with steam
刪除Mg (s) + 2H2O(g) -> Mg(OH)2(aq) + H2(g)
Right !
刪除I have a few questions
刪除What I have learnt in textbook is that Mg can react with hot water and steam.
Mg+steam=MgO+hydrogen gas
Mg+hot water=magnesium hydroxide+hydrogen gad
Why my knowlegde is different from others? Different version of chemical knowledge? or mistakes made by the textbook?
My textbook is HKDSE Chemidtry A modern view second edition by Aristo Education Press Ltd
you are right according to the syllabus of DSE.
刪除for more information, check here
https://www.chemguide.co.uk/inorganic/group2/reacth2o.html
Q36 statement 1 is too controversial.
刪除Magnesium in fact reacts even with cold water, though very slowly.
1A Q5 why the ans is C, not B or D?
回覆刪除1AQ5
刪除electrode B is positive charged, Cl- go to B and discharged to Cl2.
1A Q33 why form precipitate
回覆刪除I think although the carboxylic acid formed can form hydorgen bond with water,the long carbon chain make it barely soluble in water,thus forming white precipitate
刪除樓上 is correct. The ratio of C and OH is 4:1 to make the molecule soluble
刪除1A Q23 why Zn and KMnO4/H+ would not form pale pink solution?
回覆刪除oh yes, the answer should be A. I forget why I type B at that moment.
刪除why not C
刪除MnO4- get electron instead of H+, so no gas is produced la
刪除1AQ32
回覆刪除why (3) is incorrect?the equilibrium position shifts to the right which produces less gases?
1AQ2
A should it be ionizes instead of dissociates?
Re 1AQ32(3),since the mole ratio of the reaactant to product is 2:2,which equals to 1:1,no matter how the equilibrium position shifts,it would produce the same volume of gases
刪除1AQ32 same to above =]
刪除1AQ2 Both ionize and dissociate can be used for acid
1AQ1
回覆刪除The question said covalent compound is formed, how come the answer is not PCl3 which is a covalent compound, but GaCl3 which is an ionic compound?
For PCl3, P is Group V element while Cl is Group VII element. Different electronic configuration.
刪除For GaCl3, it is covalent compound, with bitetrahedral structure. Similar example is AlCl3. It is not definitely that metal and non-metal will form ionic compound. There is actually no clear-cut.
1AQ14
回覆刪除option b said that Chlorine gas can turn moist pH paper white. Why is it right? I think chlorine gas can only turn moist LITMUS PAPER white
the OCl- is bleaching agent anyway, so it doesnt matter if it is pH meter or litmus paper
刪除1A Q3 點做?
回覆刪除let it be M2Ox
刪除M2Ox --> 2M
5g --> 4.44g
5/(2*65.4+16x)=4.44/(2*65.4)
x=1
so, M2O
可否每題都簡單講下點解ans係_?
回覆刪除just ask which one you dont understand coz difficult to type all
刪除1AQ14:
回覆刪除What is the white fume when Cl2 is mixed with NH3 gas?
Q16:
Statement 1: Does "nitrogen" in this statement mean nitrogen atom, or nitrogen molecule?
Thank you.
NH4Cl(Q14)
刪除Seems molecule(Q16)
1A Q10 why A
回覆刪除3MgCO3 + 2H3PO4 --> Mg3(PO4)2 + 3CO2 + 3H2O
刪除10g = 0.1186 mol
0.1186/3*2 = 0.08 mol, but H3PO4 only 0.06 mol, is limited.
CO2 volume = 0.06/2 *3 *24 = 2.16 dm3
Q31 how to calculate?
回覆刪除What is the explanation for Q2's answer
回覆刪除