Stages in analysis 5A Qualitative: Type of chemicals present in sample Quantitative: How much of each chemical is present in the sample Standard procedure = agreed method of working Safe - Effective - Accurate Sample taken...
Brief intro Changing the temp. of tubes containing nitrogen compounds: Heating-> nitrogen dioxide (NO2) gas forms->Colour of solution changes to dark brown Cooling-> nitrogen tetroxide (N2O4) gas forms->Colour of solution gets paler ...
Brief intro Reactions take place->atoms rearranged + bonds broken/made->energy is given out (exothermic) or taken in (endothermic). It is important to understand energy changes so that chemists can control how fast a reaction happens: Too fast=...
The Alkanes – a family of hydrocarbons 2A Physical properties 1) Oily 2) insoluble 3) less dense than H2O, mainly gasses 4) Insoluble - doesn’t mix with H2O States: Gas: 4 carbon atoms Liquid: 4 – 17 carbon atoms Solid:...
C3.3 Why do we need chemicals such as alkalis and chlorine and how do we make them? Long before industrialisation, alkalis were used in everyday life. Alkalis are very important chemicals as they NEUTRALISE acids to make salts. Traditional sources of alkali included...
C3.4 What can we do to make our use of chemicals safe and sustainable? A large number of industrial chemicals exist and have a range of uses, these uses include consumer products. There is too little data on the safety of these chemicals to judge whether they are...
Brief Intro Natural resources are converted into useful products. Bulk chemicals produced on a large scale b/c there is a larger demand for them. Fine chemical are produced on a smaller scale. They’re used as feedstock’s (reactants bought by other...
C3.2 Where does salt come from and why is it so important? Salt (SODIUM CHLORIDE) is very important for the food industry (as a preservative and also to add flavour), as a source of chemicals (a use includes cleaning products) and to treat roads in winter (as salty...
C3.1 What were the origins of minerals in Britain that contributes to our economic wealth? GEOLOGISTS are scientists who study rocks and the processes that formed them. They try to explain the past history of the Earth by modelling processes that can be observed...
C2.3 Why does it help to know about the molecular structure of materials such as plastics and fibres? MOLECULAR STRUCTURE OF MATERIALS It is possible to produce a wide range of different polymers with properties that make them suited to a particular use. The...
C2.4 What is nanotechnology and why is it important? NANOSCIENCE refers to the study of materials that are 1-100 nanometres in size, which is roughly about the same size as some molecules. NANOTECHNOLOGY is the science of building on a very tiny scale. It is the...
C2.2 Why is crude oil important as a source of new materials such as plastics and fibres? The materials that we use are chemicals or mixtures of chemicals and include metal and include metals, polymers and ceramics. Materials can be obtained or made from living things...
C1.3 What choices can we make personally, locally, nationally or globally to improve air quality? Motor vehicles and power stations that burn fossil fuels are two major sources of atmospheric pollution, so we need to look at how emissions from these sources can be...
C2.1 How do we measure the properties of materials and why are the results useful? Different materials behave in different ways because they have different PROPERTIES. Solid materials can differ in one or more of the following ways: Melting point Strength in tension...
C1.2 What chemical reactions produce air pollutants? What happens to these pollutants in the atmosphere? Many atmospheric pollutants are made by the burning of fossil fuels. This happens in power stations and in the engines of vehicles. POWER STATIONS: Most power...
C1.1 Which chemicals make up air, and which ones are pollutants? How do I make sense of data about air pollution? The Earth is surrounded by a thin layer of gasses called the ATMOSPHERE. It is about 15km thick. Air forms part of the atmosphere - it is a mixture of...
C6.2 Planning, carrying out and controlling a chemical synthesis Chemical synthesis is the procedure used to make useful compounds – this often involves a number of chemical reactions. There are a number of different stages to any chemical synthesis of an inorganic...
C6.1 Chemicals and why we need them Chemicals are all around us and we depend on them daily – chemical synthesis is the process by which raw materials are made into useful products such as: Food additives Fertilisers Dyestuffs Pigments Pharmaceuticals Cosmetics Paints...
C5.4 How can we extract useful materials from minerals? The lithosphere contains many naturally occurring elements and compounds called minerals. Ores are rocks that contain varying amounts of minerals, from which metals can be extracted. Sometimes very large amounts...
C5.3 What types of chemicals make up the Earth’s lithosphere? The Earth’s lithosphere is the rigid outer layer that is made up of the crust and the part of the mantle just below it – the lithosphere is made up of a mixture of minerals The chart shows the relative...
C5.2 What reactions happen in the hydrosphere? HYDROSPHERE – all the water on the Earth including oceans, seas, lakes and rivers) – the water contains dissolved compounds called salts. Ions in crystals of a solid ionic compound are arranged in a regular way forming a...
C5.1 What types of chemicals make up the atmosphere? The Earth is surrounded by an atmosphere that is a mixture of gases – some of these gasses are molecular elements and some are molecular compounds. Most non-metal elements are molecular and most of these consist of...
C4.2 How do chemists explain the patterns in the properties of elements? At the centre of every atom is a nucleus containing protons and neutrons and electrons arranged in shells around the nucleus. All atoms of the same elements have the same number of protons An...
C4.1 What are the patterns in the properties of elements Elements are the ‘building blocks’ of all materials – the atoms of each element have a different proton number. The elements are arranged in order of ascending atomic (or proton) number, this is the number of...