問: 在 2N H3 (g) + H2 S O4 (aq) ---> (NH4)2 S O4 (aq) 中, 150g Ammonia 可 produce 多少 Ammonium sulphate ?
答: mass of (NH4)2 S O4 / 14x2+4x2+32+61x4 = 150 / 2(14+3) <---Ammonia sulphate的實重/moler mass = Ammonia的實重/moler mass mass of (NH4)2 S O4 = 582g
標準答案15行 v.s 以上2行
問: A sample of impure Cu of 28.5g is dissolved in conc. H NO3. The mixture is heated to dryness to give Cu (NO3)2. On strong heating,31.8g of CuO form. Calculate the percentage by mass of Cu in the sample.
答: Let the percentage by mass of Cu in the sample be x%. (28.5)(x%) / 63.5 = 31.8 / 63.5+16 <---Cu的實重/moler mass = CuO的實重/moler mass x% = 89.1%
小弟也是讀Chem的 有錯請講 先找錯一下,(NH4)2 S O4 (aq)---->是Ammonium sulphate NH3是Ammonia NH4+ ion是Ammonium ion 我的做法是: no. of mole of Ammonia [NH3(g)]=150/(14+3) By the equestion, 2mole of the NH3(g) produce 1mole of (NH4)2 S O4(aq) [這就是說1mole的NH3(g)produce 0.5mole的 (NH4)2 S O4(aq) Therefore,no. of mole of (NH4)2 S O4(aq)=no. of mole of NH3(g) x1/2=150/(14+3) x1/2 The mass of Ammonia sulphate produce=150/(14+3) x2 x(14x2+1x8+32.1+16x4)=583(cor. to the 3 sig. fig.) 當然,樓主的方法也行,只是我582.79411....進位583而已作者: zadomen 時間: 12/3/2012 01:46 PM 提示: 作者被禁止或刪除 內容自動屏蔽作者: 梓 時間: 12/3/2012 04:42 PM 唔同人出題→唔同既Marking 簡單黎講睇Marking係完全幫唔到你去清Concept 去到AL更會發現計完數睇Marking 你係睇唔明個Marker想講咩，就算你計岩都好 Marking就用黎睇答案就好 唔好理條友寫乜，總之答岩就得
BTW，我唔係幾明樓主點解要將所有Step係一條式 我望完你條式，我係自己會忍唔住落手計一次 你呢種速算係MC度用就冇所謂 不過LQ個D就分返開晒堆Step 由計no. of mole個度開始做起 就算你最尾答案錯都有返Step分 你一條式黎計，到最尾錯答案就真係一分都冇
