Anions are negatively charged ions such as halides (Cl–, Br–, I–), sulfates (SO42-), and carbonates (CO32-). In this video, we will discuss the test tube tests for these ions, which all relate to the required practical activity in this topic: use of chemical tests to identify the ions in unknown single ionic compounds covering the both metal ions (cations) and non-metal ions (anions).
Chromatography was introduced in the first topic on separating mixtures. In this video, we will look at the method of chromatography in more detail to prepare you for the required practical on chromatography. We will look at how to set up a paper chromatography experiment and explain in more detail how it is used to separate and tell the difference between coloured substances. You will also learn what an Rf value is and how to calculate it.
Clean drinking water is essential for life, and those of us in developed countries where clean drinking water flows from the taps may underestimate the difficulties that millions of people around the world have in accessing potable water. In this video, we describe the processes of treating ground water, sea water and waste water to make potable (clean drinking) water. Details for the required practical on analysis and purification of water samples are also covered.
Having learnt how to measure rates of reaction and interpret rate graphs, we now discuss the five main factors that affect the rate of a reaction: temperature, concentration, pressure, surface area and catalysts. In the second half of the video, we also look at the requirements for the required practical on this topic: investigating how changes in concentration affect the rates of reactions, with specific reference to a method involving a change in colour.
Every reaction involves energy changes. In this introduction to energy changes in reactions, you will learn about exothermic and endothermic reactions. We also cover details on how to investigate the variables that affect temperature changes in reacting solutions, using neutralisation as an example. This is the required practical for this part of the course.
In this video, you will learn how electrolysis of aqueous ionic compounds differs from the electrolysis of molten salts you have seen so far. The required practical on electrolysis is to investigate what happens when aqueous solutions are electrolysed using inert electrodes. So, in this video, you will learn the rules that will help you to predict which elements are formed at the cathode and the anode when electrolysing aqueous solutions.
Titration is an important method in Chemistry: using precise apparatus to accurately measure how much acid neutralised a given volume of alkali (or vice versa). In this video, you will learn how to set up a titration for your required practical, how to record measurements, and how to calculate the concentration of an unknown solution using titration (HT only).
Salts are very common chemical compounds consisting of a metal part and a non-metal part. They are usually made by reacting a metal, metal oxide or carbonate with an acid. In this video, we will detail the method needed for the required practical on making pure, dry samples of named soluble salts, from an insoluble oxide or carbonate.