Beforethe grading scheme varied between examination boards, but typically there were "pass" grades of 1 to 6 and "fail" grades of 7 to 9. However the grades were not displayed on certificates.
Its also a good idea to read the brief notes after the alphabetical list. Most of the tests describe use simple apparatus like test tubes, teat pipette, wire for flame test nichrome, platinum best but costly and standard chemical reagents accessible in most school or college laboratories.
Where possible balanced symbol equations are given for the reactions occurring in doing the test. Sometimes a precipitate ppt initially forms with a limited amount of a reagent, it may then dissolve in excess of reagent to give a clear solution.
Both observations will be crucial for a positive id. There are no tests specific to identify a compound e. Not all the reactions are good definitive tests, but they may well be important reactions of cations or anions you need to know about. In the organic section, only the alkene test is in GCSE double award science, but some others might be found in a full single or coordinated triple award GCSE syllabus.
Quite correctly, though updating A level chemistry is intellectually challenging at times, it isn't always as much fun! The methods described give no recipe details or risk assessment, just basically what is needed, what you see and what you can or cannot deduce.
Consult teacher, 'practical' text books and Hazcards before attempting any analysis. Most tests involve 'standard' chemical reactions and few tests are totally specific so observations should be viewed in context, i.
Please remember each syllabus has its own 'list' of required tests — so do not 'over learn' — check out what is needed! There is a web page covering the methods some safety aspects of " Preparing and collecting gases ".
Use the alphabetical list to find the test you need. This section just illustrates the use of hazard warning signs with common examples, and may NOT provide sufficient detail for specific experiments, concentrations, coursework write up etc.
Most acidic and alkaline solutions unless very dilute, VERY small quantities of acidic gases like chlorine, sulfur dioxide, nitrogen dioxide, very dilute bleaches. These may not be that corrosive BUT they are irritating e. Harmful - poisonous but not toxic: Any substance like concentrated acidic or alkaline solutions which will attack many materials and destroy living tissue too!
Also includes substances like bromine. Most organic solvents like hexane, propanone acetonepetrol and other hydrocarbon fuels are easily ignited, easily catch fire. Chlorine, sulfur dioxide, hydrogen cyanide can cause death if breathed in with sufficient quantity, absorbed through the skin or ingested by swallowing.
Salts of hydrogen cyanide e. Chemicals that can act as oxidising agents e. Many oxidising agents donate oxygen to materials that burn and can be dangerously reactive. Many can cause combustion if mixed with an oxidisable combustible material.
They may cause materials to burn more fiercely. Radioisotopes giving off dangerous ionising radiation Explosive: These are due to electronic changes in the atoms, the electrons are excited and then lose energy by emitting energy as photons of light.
The high temperature promotes electrons to higher energy levels and the electrons re-emit the energy as photons of light as they go back to their normal stable level.
These emitted frequencies can be recorded on a photographic plate, or these days, more likely onto a sensitive photocell like in a digital camera and displayed on a high resolution computer screen.
Each emission line spectra is unique for each element and so offers a different pattern of lines i. Note the double yellow line for sodium, hence the dominance of yellow in its flame colour. In fact the simple flame test colour observations for certain metal ions relies entirely on the observed amalgamation of these spectral lines.
This is an example of an instrumental chemical analysis called spectroscopy and is performed using an instrument called an optical spectrometer simple ones are called spectroscopes.
It is a fast and reliable method of chemical analysis and this type of optical spectroscopy has enabled scientists to discover new elements in the past and today identify elements in distant stars and galaxies. The alkali metals caesium cesium and rubidium were discovered by observation of their line spectrum and helium identified from spectral observation of our Sun.GCE Biology has two levels: AS and A2.
There are three units in each level.
Students can take the AS qualification or complete both levels to achieve the full A level qualification. Practical assesment about biology: To determine the water potential of potato tuber cells Essay determine the water potential of potato tuber cells.
Background knowledge Osmosis is defined as the movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane. Internal Assessment. Units AS 3 and A2 3 are partly assessed by internal assessment.
For each unit, students carry out practical tasks during the course of their studies. Students provide some form of evidence for each practical task.
The teacher assesses the quality of this evidence and determines how well the student carried out the practical task. A Level Biology Coursework And Others Coursework Types We Can Offer You Whatever you want to be done, we can do it.
Whether it be the above-mentioned coursework or if it would be A2 biology coursework ideas, biology coursework brewing or biology coursework examples. E-Moderation has been introduced to modernise the process of providing controlled assessment/coursework marks and General What is E-Moderation?
E-Moderation is a suite of applications developed by CCEA to modernise the collection of controlled assessment/coursework marks and in some subjects online submission of samples for moderation. Coursework Tasks Description Assessment Weighting (%) Students plan and carry out an investigative practical task that tests a simple scientific hypothesis.
Students must design their own investigation and are assessed in the following skill areas: A Planning; B Implementing and Recording; and.