[DSE化學2019]同學準備好DSE CHEM未?

Sor囉 渣嘛科科都要追
開始覺得時間唔夠用了 每日做一做三個elective既卷 加多份core 又差唔多過完一日

書有講架

medical use of aspirin人地syllabus寫到明要識
其實肯睇住syllabus溫已經知一課分開邊幾個section 會有明確方向
例如reaction rate分做rate definition, measuring rate, rate factors, gas molar volume等等
equilibrium就分做equilibrium characteristics, equilibrium constant, equilibrium position factors等等
再配合by topic pastpaper練習 其實每課常考內容同考法都唔難掌握
至於細緻位就每年都有 例如問microscale experiment既優點, hygroscopic substances, gas density, number of stereoisomers等等 呢d係要你讀chem過程去慢慢累積 唔係淨睇syllabus就知咁簡單

想問下 dse程度黎講點define NH3做一隻soluble base

dissolve in water form OH-

also react with acid to form salt and water only

eqm when temp change Kc will change
但果刻Qc都會變?
chhange of Qc係咪同change of Kc相同? 因為條式一樣

溶落水再measure pH / 溶落HCl measure pH

change of Qc 其實冇乜意思

Qc 係指未係eqm既時候去計d濃度
計黎係幫你判斷個eqm 會shift 去左定右

唔洗諗得咁複習
temperature直接改變Kc
當然你要計Qc都會一齊變 但已經不重要

yes
concept上 一日未attain equilibrium都係叫Qc
attain左equilibrium就叫Kc

initial rate黎 assume你S2O32-落好少
不過iodine clock通常係用黎compare initial rate under different concentration 多過搵exact initial rate

assume你S2O32-用量少
咁出現blue color所需既iodine都會好少
反映出黎既rate嚴格黎講未必係exact既initial rate
但以實驗簡易程度黎講已經足夠
同埋因爲每次trial個color change會正比返每次個initial rate 咁就可以compare濃度改變對initial影響

呢d自己上網查啦

舊人lm

門生好耐無見
幾時得閒去你間U食個tea

你叫到親自煮又點話

好 遲d考完黎聚下

呢d其實幾主觀 無話一定要咁寫
我自己覺得寫white smoke通常指dense white fume果種