chem about acid

As there are a number of acids to learn in chemistry, you should know how to deduce them.

First, bromine water is an oxidizing agent. It would be decolourised when reacting with reducing agent. Therefore, you should think about a gas that satisfied the above situation.

The answer will then come to your mind immediately. That is concentrated sulphuric acid. Concentrated sulphuric acid is not acting as an acid in this case, it will not give hydrogen gas but sulphur dioxide gas due to its oxidizing properties.

2H2SO4 (l) + Zn (s) ---> ZnSO4 (aq) + 2SO2 (g) + 2H2O (l)

SO2 formed is the reducing agent.

Then, you can start to write the ionic-half equation.

SO2 (g) + 2H2O (l) ---> SO4 2- (aq) + 4H+ (aq) + 2e- --------------(1)

Br2 (aq) + 2e- ---> 2Br- (aq) ----------(2)

Since both equation have the same charge, you can simply combine them.

The combined equation is as follows: (no need to write the electrons anymore as they will be cancelled at both sides together finally)

SO2 (g) + 2H2O (l) + Br2 (l) --> SO4 2- (aq) + 4H+ (aq) + 2Br- (aq)



Note: writing ionic-half equation & the combined equation afterwards should include STATE SYMBOLS.



Hope my explanations help.

The acid is concentrated sulphric acid.
Zn + conc. H2SO4-->SO2(g)+ZnSO4(aq)+2H2O
And then,SO2 is passed to Bromine water.
SO2 act as reducing agent.
H2O+SO2 + Br2 --> 2Br- + SO3(2-) + 4H+

二氧化硫維基百科，自由的百科全書（重定向自So2）說明編輯　二氧化硫
圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/9/93/Sulfur-dioxide-3D-vdW.png/150px-Sulfur-dioxide-3D-vdW.png
英文名Sulfur dioxide（美國）、Sulphur dioxide（英國）IUPAC英文名Sulfor dioxide 識別CAS號7446-09-5RTECS號WS4550000 性質化學式SO2摩爾質量64.054 g mol−1外觀無色氣體密度0.002551 g/L熔點−72.4 °C (200.75 K)沸點−10 °C (263 K)在水中的
溶解度9.4 g/100 mL (25 °C)pKa1.81 危險性NFPA 704
圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/NFPA_704.svg/75px-NFPA_704.svg.png
3 警示性質
標準詞R23, R34安全建議
標準詞S1/2, S9, S26,
S36/37/39, S45閃點不易燃 相關化學品相關化學品三氧化硫、硫酸若非註明，所有數據都依從國際單位制，以及來自標準狀況（25 °C, 100 kPa）的條件。二氧化硫（化學式：SO2）是最常見的硫氧化物。無色氣體，有強烈刺激性氣味。大氣主要污染物之一。火山爆發時會噴出該氣體，在許多工業過程中也會產生二氧化硫。由於煤和石油通常都含有硫化合物，因此燃燒時會生成二氧化硫。當二氧化硫溶於水中，會形成亞硫酸（酸雨的主要成分）。若把SO2進一步氧化，通常在催化劑如二氧化氮的存在下，便會生成硫酸。[1] 這就是對使用這些燃料作為能源的環境效果的擔心的原因之一。
二氧化硫可通過燃燒硫獲得：[編輯]製備
圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/6/62/Sulfur-dioxide-resonance-2D.png/500px-Sulfur-dioxide-resonance-2D.png
二氧化硫的三種共振結構