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KS3 SCIENCE QUIZZES (~US grades 6-9)

GCSE KS4 Science-CHEMISTRY (~US grades 8-10)

Advanced Level CHEMISTRY (~US grades 11-12)

docbchemicaltestsg updated April 20th 2008

useful alphabetical site index Doc Brown's Chemistry Clinic

CHEMICAL identification TESTS

Qualitative tests to identify inorganic gases & ions (cations/anions) and organic molecule functional groups

 Part 1 Introduction

 Part 2 Qualitative tests to identify organic molecule functional groups of homologous series

 Part 3 Metal cations (positive ions), metal carbonates, ammonium ion and hydrogen ions (acids)

 Part 4 Gases, water and non-metallic elements (this page)

 Part 5 Anions (negative ions) including hydroxide (alkalis)


 Part 4 Gases, water and non-metallic elements

Full list of KEYWORDS for inorganic/organic identification methods in alphabetical order e.g. test/reagent for: * acid ==> H+ * acid/acyl chloride RCOCl * alcohols - general ROH/prim RCH2OH/sec R2CHOH/tert R3COH) * aldehyde RCHO * prim aliphatic amine R-NH2 * aliphatic/aromatic carboxylic acids * alkali ==> OH- * alkane/alkene >C=C</alkyne -CC- (saturated versus unsaturated) * aluminium/aluminum ion Al3+ * amide RCONH2 * prim aliphatic amines R-NH2 * ammonia gas NH3 * ammonium ion NH4+ * prim aromatic amine C6H5-NH2 etc. * barium ion Ba2+ * Benedict's solution * Brady's reagent * bromide ion Br- * bromine Br2 * caesium ion Cs+ * calcium ion Ca2+ by flame or hydroxide ppt. * carbonate CO32-/hydrogencarbonate HCO3- with acid or effect of heating metal carbonate e.g. MCO3 * carbon dioxide gas CO2 * carboxylic acid RCOOH * carboxylic acid (aliphatic) salts e.g. RCOO-Na+ * chloride ion Cl- * chlorine gas Cl2 * Chomate(VI) ion CrO42- * copper(II) ion Cu2+ by flame or hydroxide ppt. * 24DNPH (for aldehydes/ketones test) * esters RCOOR * Fehlings test/solution * flame test for metal ions * haloalkanes/halogenoalkanes R-X * hydrogen gas H2 * hydrogen sulphide H2S * hydrogen ion, acids H+ * hydrogen bromide gas/hydrobromic acid HBr * hydrogen chloride gas/hydrochloric acid HCl * hydrogen iodide gas/hydriodic acid HI * hydroxide ion, alkali OH- * hydroxy/alcohol/phenol (organic) * iodide ion I- * iodine I2 * iodoform test - formation of CHI3 * iron(II) ion Fe2+ * iron(III) ion Fe3+ * ketone R2C=O * lead(II) ion Pb2+ * lithium ion Li+ * lime water Ca(OH)2(aq) * magnesium ion Mg2+ * metal carbonates-heating e.g. MCO3 * metal ions via hydroxide precipitate * nitrate or nitrate(V) NO3- * nitrite or nitrate(III) NO2- * nitrogen dioxide or nitrogen(IV) oxide NO2 * oxygen gas O2 * phenols C6H5OH etc. * potassium ion K+ * rubidium ion Rb+ * reducing sugars * saturated/unsaturated * silver nitrate AgNO3 (see chloride, bromide, iodide tests) * sugars (reducing) * sodium ion Na+ * strontium Sr+ * 'sulphate/sulfate' or sulphate(VI) SO42- * sulphide S2- * 'sulphite/sulfite' or sulphate(IV) SO32- * sulphur dioxide gas SO2 * Tollen's Reagent * unsaturated/saturated * water H2O * zinc ion Zn2+ *


Use the alphabetical test list above for identifying anions, cations, gases, molecules etc. to find what you require! for your KS3-KS4 Science-GCSE-IGCSE- Chemistry and AS-A2-IB-US grades 9-12 K12 advanced subsidiary chemistry course etc. and help you to identify unknown inorganic and organic compounds-molecules for qualitative analysis.

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 4. INORGANIC Qualitative TESTS for gases and non-metallic elements

TEST FOR TEST METHOD OBSERVATIONS TEST CHEMISTRY
hydrogen gas H2 Apply a lit splint or spill. A squeaky pop! (might see condensation on test tube) 2H2(g) + O2(g) ==> 2H2O(l) + energy!
carbon dioxide gas CO2 Bubble the gas into limewater (aqueous calcium hydroxide solution). It turns cloudy - fine milky white precipitate of calcium carbonate. BEWARE - the calcium carbonate precipitate dissolves in excess carbon dioxide! Ca(OH)2(aq) + CO2(g) ==> CaCO3(s) + H2O(l)

For diagram of a possible procedure see test for carbonate

If excess carbon dioxide bubbled through you form a clear colourless solution of calcium hydrogencarbonate.

CaCO3(s) + H2O(l) + CO2(aq) ==> Ca(HCO3)2(aq)

oxygen gas O2 Apply a glowing splint or spill. It re-ignites to a flame. C(in wood) + O2(g)  ==> CO2(g)

The relighted splint is mainly combustible carbon.

HCl Hydrogen chloride gas, in water forms hydrochloric acid. (i) Damp blue litmus.

(ii) Apply a drop of silver nitrate on the end of a glass rod

(i) Litmus turns red

(ii) A white precipitate.

(i) Strongly acid gas.

(ii) In water forms chloride ions - hence precipitate with silver nitrate, see chloride test.

Hydrogen bromide HBr and Hydrogen iodide HI As above. In water they are hydrobromic acid and hydriodic acid. as above but cream precipitate with HBr or yellow precipitate with HI. As above - combination of acid and halide ion tests.

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Sulphur dioxide gas SO2 Freshly made potassium dichromate(VI) paper. paper changes from orange to green. The orange dichromate(VI) ion, Cr2O72-(aq)

is reduced to the green Cr3+(aq) ion.

Ammonia gas NH3

Strong pungent odour.*

(i) Damp red litmus.

(ii) Near fumes of conc. hydrochloric acid.

(i) Litmus turns blue.

(ii) Gives white clouds with HCl fumes.

(i) Ammonia is the only common alkaline gas.

(ii) It forms fine ammonium chloride crystals with HCl. (*volatile organic aliphatic amines give the same result, and smell more fishy)

Bromine Br2 (l or aq)

A dark red liquid - orange-brown fumes, yellow-orange aqueous solution. The other common orange-brown gas is nitrogen dioxide

(i) Shake with a liquid alkene.

(ii) Mix with silver nitrate solution.

(ii) Decolourised. See alkene test.

(ii) Cream ppt. of silver bromide. See bromide test.

(i) Forms a colourless organic dibromo-compound

>C=C< + Br2 ==> >CBr-CBr<

(ii) Ag+(aq) + Br-(aq) ==> AgBr(s) 

 Any soluble bromide gives a silver bromide precipitate.

Chlorine gas Cl2

A pungent green gas.

Test (ii) on its own is no good, could be HCl.

(i) Apply damp blue litmus. (Can use red litmus and just see bleaching effect.)

(ii) A drop silver nitrate on the end of a glass rod into the gas.

(i) litmus turns red and then is bleached white.

(ii) White precipitate.

(i) Non-metal, is acid in aqueous solution and a powerful oxidising agent

(ii) It forms a small amount of chloride ion in water, so gives a positive result for the chloride test.top

Iodine (i) solid or (ii) solution

A dark coloured solid.

(i) Gently heat the solid.

(ii) Test aqueous solution or solid with starch solution.

(i) Gives brilliant purple vapour.

(ii) A blue black colour.

(i) Iodine forms a distinctive coloured vapour.

(ii) Forms a blue-black complex with starch and in biology the test is used to detect starch with iodine solution.

Hydrogen sulphide H2S Test gas with damp lead(II) ethanoate paper (old name lead acetate). Rotten egg smell of hydrogen sulphide gas and the H2S gas turns lead(II) ethanoate paper black. Hydrogen sulphide gives sulphide ions in water, so

Pb2+(aq) + S2-(aq) => PbS(s) 

The gas is formed when acids react with sulphides.

Nitrogen(IV) oxide or nitrogen dioxide NO2 There is no simple relatively unambiguous test. The other common orange-brown gas is bromine. Its a nasty orange-brown gas Its a strong oxidising agent. Dissolved in water it gives a solution of nitrite and nitrate ions. The other common brown gas is bromine and the solution of nitrogen dioxide shouldn't give a cream ppt. with silver nitrate solution.
Water liquid H2O

Easy to get these colour changes muddled!

(i) Add a few drops to white anhydrous copper(II) sulphate.

(ii) Dip in dry blue cobalt chloride paper.

(i) Turns from white to blue.

(ii) Turns from blue to  pink.

(i) Blue hydrated copper(II) crystals or solution formed

(ii) Pink hydrated cobalt ion formed [Co(H2O)6]2+

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KS3 SCIENCE * KS4 SCIENCE GCSE IGCSE GCE AS A2 IB CHEMISTRY * SITE PURPOSE EDUCATION - online learning or 'self-private-tuition' using revision notes, quizzes, practice tests involving SCIENCE in the areas of REVISING only the CHEMISTRY-Earth Science-Radioactivity at Doc Brown's Chemistry Clinic via HOMEPAGE in secondary school/schools, 6th form college/colleges, academy/academies or home self-study and may help with 1st year undergraduate university chemistry courses. Hopefully it will encourage interest and understanding of Chemistry, Earth Science and Radioactivity in any country of the world, though the site is written entirely in English. The website is designed to help and unofficially support students/teachers revise-learn/teach the chemistry for modular or co-ordinated examination science courses from UK QCA based AQA, OCR (Oxford and Cambridge) Twenty First (21st) Century and Gateway Science, Edexcel 360Science , Nuffield, Salters, Cambridge International (CIE), London International, WJEC, CCEA exams etc. Also, national award assessments-examinations for GCSE-IGCSE-KS4-O level-BTEC-NVQ applied, additional and chemistry science courses and examinations, Advanced Subsidiary Level GCE-AS-A2-IB-KS5-BTEC-NVQ National Chemistry assessment levels, KS3 SATs Science-biology/chemistry/physics (SAT revision levels 3-5 or 5-7) and covers much of the revising, learning and teaching chemistry of the International Baccalaureate, K12 US grade 6,7,8,9,10,11,12,AP basic level examinations courses for the national curriculum for secondary schools and colleges. The site does not support the content of England, Wales or Northern Ireland primary science KS1 or KS2. The notes should also provide some background theory for a coursework assignment or a project. BUT please note that my on-line revision notes and quizzes are no substitute for good classroom teaching-lecturing and thorough studying of your own notes and textbooks, practicing past papers and a copy of the syllabus which are readily downloaded from the examination board sites, but I hope here and there they will lend a tutoring hand on some topic, unit, module etc. For final revision you have to be intellectually honest about what you don't know or follow, YOU have to take the stuff to pieces, analyse what you do/do not understand and reconstruct it so it all makes sense in the end. There is no other way, there are no magic secrets on how to revise and learn, its mainly down to hard work and just good old fashioned study and employing teach-yourself strategies without the need for extra tutors and tutoring lessons. I also think there is too much hit and miss revision using past papers (which I do NOT supply) and not enough systematic revision. I also hope it will help teachers in planning lessons and developing schemes of work for science-chemistry. There are no lesson plans on the site but there are plenty of quizzes to incorporate into classroom activities whether photocopied or on electronic whiteboard projector for use as self-tuition-assessment purposes and a variety of teaching and learning styles and the images may be used in Microsoft Word documents and powerpoint projections. The site seems to be used by a large number of home study tutors, particularly the revision notes. An individual tutor may printout out the notes for science-chemistry learning teaching-tuition purposes and for background material for assignments and projects. I have no interest or time in producing WORD.doc or xxxx.pdf revision notes files of the notes at the moment. Neither have I time to write up many practical laboratory experiments ('lab'-'labs') at the moment, but the notes contain lots of background information of chemical reactions in terms of observations-balanced equations-reactants-products-theory etc. I also find it difficult to recommend specific exam websites or syllabus textbooks, it depends exactly on what you need, what you have time for, and there are so many of them to choose from and I do not supply past examination papers for classes. The sites resources include revision notes, quizzes and worksheets which provide support for home study or tuition for homework and coursework help e.g. science investigations for any of the key stage courses indicated, but I do not supply lesson plans. Dr W P Brown I 29-11-2007 * KS3 SCIENCE * KS4 SCIENCE GCSE IGCSE GCE AS A2 IB CHEMISTRY

useful alphabetical site index

Online free help resources for Key Stages 3 SATs (S.A.T.s), 4 & 5AQA, Edexcel, OCR, CIE GCSE IGCSE BTEC Science, GCE, AS, A2 Advanced subsidiary Chemistry A levels, IB Diploma and US K12 (K-12 grades) courses and examinations and revising for the various syllabuses and specifications. Exploring the site for lessons, plans, ideas for projects and coursework, professional development. Through hard work the site has been built up over the course of many years with no need of special pc software except FrontPage and Hot Potatoes (uvic) for quizzes and worksheets. It is used in the classroom, home learning-tutoring-schooling and guidance, private tuition, school retakes revision. Whether you are a teacher/tutor teaching, a student studying, using the pages as self-study guides for your science-chemistry studies etc. etc. I hope the site supports your endeavour. scientific investigations, educational development, scientific exhibitions, scientific adventures, science projects, fantasy science, science fiction, interesting science demonstrations, fascinating science experiments, science education conferences, scientific expeditions, scientific information and databases, revision tutoring resources for syllabuses specifications examinations, chemical physical biological forensic science, scientific applications, science-chemistry tuition courses

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KS3 SCIENCE QUIZZES (~US grades 6-9)

GCSE KS4 Science-CHEMISTRY (~US grades 8-10)

Advanced Level CHEMISTRY (~US grades 11-12)

docbchemicaltestsg updated April 20th 2008

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