Summary Notes.docx

**S2 Science** **Environmental Chemistry - Summary Notes** 1. **Acids and Alkalis** pH is a measure of how much Hydrogen (H+) is in a solution. This means how acidic or alkaline it is. Cleaning products such as bleach are usually alkalis. Some foods and drinks can be acidic. The...

**S2 Science** **Environmental Chemistry - Summary Notes** 1. **Acids and Alkalis** pH is a measure of how much Hydrogen (H+) is in a solution. This means how acidic or alkaline it is. Cleaning products such as bleach are usually alkalis. Some foods and drinks can be acidic. They should be dissolved in water before testing. 2. **pH indicators** Some chemicals change colour to show the pH of a solution - pH indicators. Universal indicator and pH paper turn red in acids, green in neutral solutions and dark blue in alkalis. Some vegetables such as red cabbage make good pH indicators Dilution causes acids to become weaker -- pH increases towards 7. Dilution causes alkalis to become weaker -- pH decreases towards 7. pH probes can also be used to measure the pH of a solution. This is the most accurate method of measuring pH as it gives an exact digital readout. 3. **Fertilisers** In order to increase the production of plants we need to add nutrients to the soil. Fertilisers are substances that we add to soils that contain one or more of the elements - *Potassium*, *Nitrogen* or *Phosphorus*. Most fertilisers are made by the **reaction** of an **acid** and an **alkali**.  4. **Rocks** **The whole earth is made of rocks & minerals.** **A mineral is composed of the same substance throughout** **-- one single chemical.** **A rock is made up of 2 or more minerals.** **1. Igneous - formed when hot liquid rock (magma) cools and hardens.** Metal Ores are rocks containing **compounds of metals** **Unreactive metals such as gold are found in the Earth's crust uncombined.** **Other metals such as copper or iron need to be extracted by:** **1. heating alone** **2. heating with carbon** Copper can be extracted from malachite by first heating then heating again with carbon. 5. **Displacement Reactions** 6. **Corrosion**