C2.1 – Purity and separating mixtures (10 hours – separate and combined) Links to KS3 Subject content the concept of a pure substance simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography mixtures, including dissolving the identification of pure substances Links to Practical Activity Groups (PAGs) Thin layer chromatography. (PAG C3) Using chromatography to identify mixtures of dyes in an unknown ink. (PAG C3) Distillation of mixtures. (PAG C4) Purification of compounds. (PAG C4, PAG C7) Separation of mixtures and purification of compounds. (PAG C4, PAG C7) Links to Mathematical Skills M1a M1c M1d M2a M3b M3c Links to Working Scientifically WS1.2b WS1.2c WS1.3c WS1.4a WS2a WS2b Suggested timings Statements Teaching activities Notes
C2 Topic 1 Part 3 2 hours (separate and combined) C2.1g – describe the techniques of paper and thin layer chromatography C2.1h – recall that chromatography involves a stationary and a mobile phase and that separation depends on the distribution between the phases [identification of the mobile and stationary phases] C2.1i – interpret chromatograms, including measuring Rf values [the recall and the use of the formula] C2.1k – suggest chromatographic methods for distinguishing pure from impure substances [paper, thin layer (TLC) and gas chromatography] CM2.1iii – change the subject of a mathematical equation CM2.1iv – arithmetic computation and ratio when determining empirical formulae, balancing equations The OCR Particles, Atoms and Elements provides ideas and resources for this part of the course. A useful website on paper chromatography and Rf values is . Chromatography can be carried out, covering PAG C3, for example with: Alternatively, learners could plan and carry out a into extracting and purifying the coloured compounds from, for example, red cabbage (anthocyanins) or grass (chlorophyll). Videos on the and their use in are available. CLEAPSS provide also provide a to carrying out simple, inexpensive and successful chromatography. This part moves directly on from the previous work on separation and purification. Chromatography is likely to be the first separation techniques learners will have met, possibly even at KS1/2 by separating out pen ink. If they are well versed in the basics, then this part provides opportunities to extend their knowledge – interesting contexts include forensic science, pharmaceutical development and environmental monitoring. Outline Scheme of Work: C2 – Elements, compounds and mixtures Total suggested teaching time – 28 / 24 hours (separate / combined)
Outline Scheme of Work: C2 – Elements, compounds and mixtures Total suggested teaching time – 28 / 24 hours (separate / combined) C2.3 – Properties of materials (10 / 6 hours – separate / combined) Links to KS3 Subject content representing chemical reactions using formulae and using equations properties of ceramics, polymers and composites (qualitative) Links to Practical Activity Groups (PAGs) Dissolving tablets. (PAG C8) Links to Mathematical Skills M1b M1c M1d M4a M5b M5c Links to Working Scientifically WS1.1c WS1.1d WS1.1e WS1.1f WS1.1h WS1.1i WS1.2a WS1.3c WS1.3f WS1.4a WS1.4c WS1.4d Suggested timings Statements Teaching activities Notes
C2 Topic 3 Part 2 4 hours (separate only) CM2.3ii – relate size and scale of atoms to objects in the physical world CM2.3iii – estimate size and scale of atoms and nanoparticles CM2.3iv – interpret, order and calculate with numbers written in standard form when dealing with nanoparticles CM2.3v – use ratios when considering relative sizes and surface area to volume comparisons CM2.3vi – calculate surface areas and volumes of cubes C2.3g – compare ‘nano’ dimensions to typical dimensions of atoms and molecules C2.3h – describe the surface area to volume relationship for different-sized particles and describe how this affects properties C2.3i – describe how the properties of nanoparticulate materials are related to their uses C2.3j – explain the possible risks associated with some nanoparticulate materials There are many good websites and resources available on nanotechnology, for example Steven Fry’s , this , this and this . Particle size affects properties – some interesting primary data here from , also summarised . Calculating surface-area to volume ratio can be helped by using Multilink Cubes/Snapcubes or similar. Hands on activity with these can help learners appreciate that chemical reactions can only occur at exposed faces – getting then to count total number of faces as they successively break down a 3x3x3 cube can be particularly instructive. Surface area to volume ratio allows linking forward to rates of reaction, and practicals around dissolving tablets (whole vs crushed), acid and different sized marble chips, or even . (PAG C8). Appreciation of the size of particles is returned to here, extending into more recent developments of nano-scale materials.