IGCSE化学paper2重要考点

考试倒计时仅剩3天考前焦虑？

不必惊慌！

该会的你都会了！

6月12号paper 2会考哪些内容呢？我这里提供下考试的重点topic，没复习好的可要抓紧时间了。

来，上点干货，这些是考试重点内容：

atomic structurereactivity of metals

chemical test

organic

acid base and salt

calculation

energy change

bond energy

chromatography

elements, compounds and mixtures

the periodic table

rate of reaction

electrolysis

redox

equilibrium

gas in atmosphere

group 7

state of matter

group 1

titration

dot and cross digram

bonding and structure

crude oil

ammonia

formula equation

group 2

alkene

今天，我主要来说说chemical test部分。

按照大纲要求：

（1）describe tests for these gases:

• hydrogen   【‘pops’ with a lighted splint】

• oxygen      【relights a glowing splint】

• carbon dioxide   【gives a white ppt. with limewater】

• ammonia    【turns damp red litmus paper blue】

• chlorine      【bleaches damp litmus paper】

（2）describe how to carry out a flame test

【1. The technique is first of all to clean the end of a piece of platinum or nichrome wire by dipping it into clean hydrochloric acid and then placing it in a roaring Bunsen flame. This procedure should be repeated until the wire no longer produces a colour in the flame.2. The end of the wire should then be dipped into fresh hydrochloric acid and then into the solid sample under test.3. The end of the wire should then be placed into a non-roaring, non-luminous Bunsen flame.】

（3）know the colours formed in flame tests for these cations:• Li+ is red• Na+ is yellow• K+ is lilac

• Ca2+ is orange-red

• Cu2+ is blue-green

（4）test of cations

• NH4+ using sodium hydroxide solution and identifying the gas evolved 【放出的气体是NH3】

• Cu2+, Fe2+ and Fe3+ using sodium hydroxide solution 【Cu(OH)2, Fe(OH)2, Fe(OH)3颜色分别是blue, green, red-brown】

（5）test of anions• Cl–, Br– and I– using acidified silver nitrate solution 【AgCl, AgBr, AgI颜色分别是white, cream, yellow】

• SO42– using acidified barium chloride solution  【BaSO4是white precipitate】

• CO32– using hydrochloric acid and identifying the gas evolved. 【CO2 is released】

来，我们看道真题：