[DSE化學2018]同學準備好DSE CHEM未?

想問2012practice paper1BQ8(direct methanol fuel cell)嗰兩條half equation係要自己deduce定有得背 ？
要deduce嘅話有無方法

有
fuel=有oxygen
咁黎手寫番條oxygen既式出黎先喇
O2+2H2O+4e- -->4OH-
我冇題目係手所以估係acidic medium
O2+2H2O+4H+ + 4e- -->4H2O
O2+4H+ + 4e- --> 2H2O
咁哩個收電子
姐係有個要放電子
姐係CH3OH係放電子
咪住先我唔知CH3OH放電子之後product出咩喎
再睇番題目,係fuel cell
咩係fuel呀?
姐係combustion
姐係overall equation我應該寫到條combustion既式
e.g CH3OH + 3/2O2 --> CO2 + 2H2O
2CH3OH+3O2-->2CO2+4H2O
我依家得CO2未有,姐係CH3OH出CO2
姐係CH3OH-->CO2
再用H+,H2O balance下
會出到 CH3OH +H2O--> CO2 +6H+6e-

好詳盡
唔該晒巴打

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

巴打aim入咩科

Cu science

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

巴打aim入咩科

Cu science

science既咩系有冇諗住

bio果方面
University chem太難 不了

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

想問2012practice paper1BQ8(direct methanol fuel cell)嗰兩條half equation係要自己deduce定有得背 ？
要deduce嘅話有無方法

有
fuel=有oxygen
咁黎手寫番條oxygen既式出黎先喇
O2+2H2O+4e- -->4OH-
我冇題目係手所以估係acidic medium
O2+2H2O+4H+ + 4e- -->4H2O
O2+4H+ + 4e- --> 2H2O
咁哩個收電子
姐係有個要放電子
姐係CH3OH係放電子
咪住先我唔知CH3OH放電子之後product出咩喎
再睇番題目,係fuel cell
咩係fuel呀?
姐係combustion
姐係overall equation我應該寫到條combustion既式
e.g CH3OH + 3/2O2 --> CO2 + 2H2O
2CH3OH+3O2-->2CO2+4H2O
我依家得CO2未有,姐係CH3OH出CO2
姐係CH3OH-->CO2
再用H+,H2O balance下
會出到 CH3OH +H2O--> CO2 +6H+6e-

好詳盡
唔該晒巴打

呢題我每年教到cell一定教埋呢題
2CH3OH + 3O2 -> 2CO2 + 4H2O
首先你要識抽返anode同cathode既reaction出黎先
根據oxidation number, CH3OH -> CO2
O.N. of C: -2 -> +4, so oxidation (anode)
O.N. of O: 0 -> -2, so reduction (cathode)

anode: CH3OH -> CO2
cathode: O2 -> H2O

用返平時普通bal redox既方法就得 (補H2O,H+,e-)

anode:CH3OH + H2O -> CO2 + 6H+ + 6e-
cathode: O2 + 4H+ + 4e- -> 2H2O

如果bal完唔sure啱唔啱 可以用O.N.驗算

因為C個O.N. total升左6, 所以anode條式會放6個e-就啱
O個O.N. total跌4(因為O2兩個O reduce), 所以cathode條式會收4個e-就啱

題目講明acidic medium所以唔洗用OH-去抵消d H+

syllabus學果7隻電池既equation全部都唔洗背
100%可以用呢個方法prove返出黎

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

industrial chem 話graph 揾order, x axis 同y axis 既scale 係咪可以唔同，例如x 係1格=0.2 y係1格=0.1

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

We can use a formula: rate=delta [X]/delta time at different time during the reaction
if rate varies at different time point, this is not a zero order in respect of xxx

graph不嬲都唔洗x y軸一樣scale
自己plot只要show清楚就ok

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

U chem都係9背
如果你肯背bio,咁chem既workload應該係哩個細10倍左右

有啲背得嚟又背唔到 食屎狗eg orbital
其實係唔鐘意計數嗰part(physical Chem)
Biochem/org chem都還可

巴打覺得dse會唔會考plot graph

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

We can use a formula: rate=delta [X]/delta time at different time during the reaction
if rate varies at different time point, this is not a zero order in respect of xxx

咁最多都係not zeroth
點prove 一定係1st / 2nd ?

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

We can use a formula: rate=delta [X]/delta time at different time during the reaction
if rate varies at different time point, this is not a zero order in respect of xxx

咁最多都係not zeroth
點prove 一定係1st / 2nd ?

但prove 2nd一定要用data ga wor?
用time against concentration都係得curve ma?
要用time against rate先睇到linear定curve?

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

We can use a formula: rate=delta [X]/delta time at different time during the reaction
if rate varies at different time point, this is not a zero order in respect of xxx

咁最多都係not zeroth
點prove 一定係1st / 2nd ?

但prove 2nd一定要用data ga wor?
用time against concentration都係得curve ma?
要用time against rate先睇到linear定curve?

未必得
因為呢d問題個重點係要指出data之間既關係 同埋化學意義
例如rate is independent of concentration -> zeroth order
你純粹指出個數學關係 應該答唔到佢個point

想問2012practice paper1BQ8(direct methanol fuel cell)嗰兩條half equation係要自己deduce定有得背 ？
要deduce嘅話有無方法

有
fuel=有oxygen
咁黎手寫番條oxygen既式出黎先喇
O2+2H2O+4e- -->4OH-
我冇題目係手所以估係acidic medium
O2+2H2O+4H+ + 4e- -->4H2O
O2+4H+ + 4e- --> 2H2O
咁哩個收電子
姐係有個要放電子
姐係CH3OH係放電子
咪住先我唔知CH3OH放電子之後product出咩喎
再睇番題目,係fuel cell
咩係fuel呀?
姐係combustion
姐係overall equation我應該寫到條combustion既式
e.g CH3OH + 3/2O2 --> CO2 + 2H2O
2CH3OH+3O2-->2CO2+4H2O
我依家得CO2未有,姐係CH3OH出CO2
姐係CH3OH-->CO2
再用H+,H2O balance下
會出到 CH3OH +H2O--> CO2 +6H+6e-

好詳盡
唔該晒巴打

呢題我每年教到cell一定教埋呢題
2CH3OH + 3O2 -> 2CO2 + 4H2O
首先你要識抽返anode同cathode既reaction出黎先
根據oxidation number, CH3OH -> CO2
O.N. of C: -2 -> +4, so oxidation (anode)
O.N. of O: 0 -> -2, so reduction (cathode)

anode: CH3OH -> CO2
cathode: O2 -> H2O

用返平時普通bal redox既方法就得 (補H2O,H+,e-)

anode:CH3OH + H2O -> CO2 + 6H+ + 6e-
cathode: O2 + 4H+ + 4e- -> 2H2O

如果bal完唔sure啱唔啱 可以用O.N.驗算

因為C個O.N. total升左6, 所以anode條式會放6個e-就啱
O個O.N. total跌4(因為O2兩個O reduce), 所以cathode條式會收4個e-就啱

題目講明acidic medium所以唔洗用OH-去抵消d H+

syllabus學果7隻電池既equation全部都唔洗背
100%可以用呢個方法prove返出黎

原來唔洗背
唔該晒

practice paper係出過plot graph再搵Ea的
但實戰2012至今都未出過

我認為主要係因為paper 2時間太短
考plot graph唔practical 同埋試卷處理方面比較煩

不過絕對係可以考的 遲早會出現
亦有機會唔洗真係plot 但問你會點利用佢d data去搵order/Ea
要你講返你會點plot同預計幅graph會點咁

姐係點

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

U chem都係9背
如果你肯背bio,咁chem既workload應該係哩個細10倍左右

有啲背得嚟又背唔到 食屎狗eg orbital
其實係唔鐘意計數嗰part(physical Chem)
Biochem/org chem都還可

orbital都叫背咩
spdf 不過你都係睇好D DSE先
advanced chem考曬試再睇都未遲

入到先再揀 首先要入到

即係佢可以問你how to show that the reaction is first order by graph
你要答plot rate against concentration
a straight line passing through the origin is obtained (and rate is directly proportional to concentration) -> 1st order

咁可唔可以用differential嘅概念

你想點答先

We can use a formula: rate=delta [X]/delta time at different time during the reaction
if rate varies at different time point, this is not a zero order in respect of xxx

咁最多都係not zeroth
點prove 一定係1st / 2nd ?

但prove 2nd一定要用data ga wor?
用time against concentration都係得curve ma?
要用time against rate先睇到linear定curve?

未必得
因為呢d問題個重點係要指出data之間既關係 同埋化學意義
例如rate is independent of concentration -> zeroth order
你純粹指出個數學關係 應該答唔到佢個point

明白 thx bada

有冇巴打有啲教你basic chem嘅網站推介，我而家讀engine中學冇讀過chem而家上到一舊舊

有冇巴打有啲教你basic chem嘅網站推介，我而家讀engine中學冇讀過chem而家上到一舊舊

chemguide幾好 簡潔無廢話
http://www.chemguide.co.uk/
亦可以試下買大專chem書睇下 general chem已ok