WJEC Chemistry for AS: Student Bk

MATHS As assessment of your mathematical skills is very important, this feature demonstrates some common uses of mathematics in chemistry. There is nothing difficult here. You are preparing for a chemistry examination, not a maths exam, but it is still important to apply numerical analysis, and these features will help you to do so. Mathematical requirements are given in Appendix B (AS) or Appendix C (A Level), at the end of the specification course content. The level of understanding is equivalent to Level 2, or GCSE. HOW SCIENCE WORKS In some cases it helps you to see how chemistry itself has evolved, the interactions between theory and experiments as well as their limitations. Science works by using theories and ideas, knowledge and understanding, IT and ICT and experimental investigations to obtain, analyse, interpret and evaluate data. Also by considering the applications of science, benefits, risks and ethical issues it evaluates how society may use science to inform decision making. AS Chemistry – a summary of assessment Assessment in the AS Specification consists of two written papers of 1 hour 30 minutes each, and there is one paper for each of two units that are themselves each 50% of the qualification. There are 80 marks available on each paper. Unit 1 deals with the Language of Chemistry, the Structure of matter and Simple reactions. Unit 2 covers Energy, Rate and the Chemistry of Carbon compounds. Each paper consists of Section A short answer questions (for 10 marks), and Section B structured and extended answer questions. Section B questions are worth 70 marks. There are no multiple choice questions in these papers. Assessment objectives (AOs) and weightings Assessment objectives Examination questions are written to reflect the assessment objectives described in the specification. You must meet the following assessment objectives in the context of the subject content, which is given in detail in the specification. AO1 Covers showing knowledge and understanding of all aspects of the subject. AO2 Covers applying this knowledge and understanding theoretically, practically and qualitatively and quantitatively. AO3 Covers analysis, interpretation and evaluation of scientific information and evidence, making judgements, reaching conclusions and developing practical design and procedures. The weightings of these objectives – which are the same for both units 1 and 2 – are as follows: AO1 – 17.5% AO2 – 22.5% AO3 – 10% Thus the overall weighting across both papers is as follows: AO1 – 35% AO2 – 45% AO3 – 20% Mathematical skills These will be assessed throughout the two papers and have a total weighting of at least 20%. The skills tested include: ▪ Algebraic manipulation ▪ Use of calculators ▪ Means ▪ Significant figures ▪ Graph plotting and analysis ▪ Analysis of spectra ▪ Understanding 2d and 3d structures in molecular shapes Practical work This is an important and intrinsic part of the specification and is covered in two ways: first as a part of the written papers in which its weighting is at least 15% and, secondly, through direct practical work in the laboratory that will prepare candidates to deal with the written work. Although there is no mark as such for the laboratory work, the exercises selected by the teacher must be performed satisfactorily, recorded and inspected. The type of direct practical work to be undertaken is listed in the specifications of both units and includes the use and application of scientific method and practices, graph plotting, data analysis, errors and precision and the use of instruments and equipment. Experiments will include preparations, titrations, finding enthalpy changes and measuring rates of reaction. 5 About this book