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Check out what is available? Study the different examples then try the Quizzes! Doc Brown's Chemistry Clinic - Chemical Calculations

ANSWERS to Part 7 - the more advanced mole Q's

On-line chemistry CALCULATIONS for KS4 Science, GCSE Chemistry and AS Chemistry (basic calculations)

useful alphabetical site index * ORIGINAL mole Q

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Mole calculations introduction * Molar gas volume * Advanced Redox titration Q's * Non-redox titration Q's

Qa7.1 (a) f. mass Al2O3 = 102, 2 ÷ 102 x 3 x 6.02 x 1023 = 3.54 x 1022 oxide ions

(b) f. mass H2 = 2, 3 ÷ 2 x 6.02 x 1023 = 9.03 x 1023 molecules

(c) 1.2 ÷ 24000 x 6.02 x 1023 = 3.01 x 1019 molecules

(d) f. mass Cl2 = 71, 3 ÷ 71 x 6.02 x 1023 = 2.54 x 1022 molecules

(e) Neon exists as single atoms (Ar = 20), 10 ÷ 20 x 6.02 x 1023 = 3.01 x 1023 atoms

(f) 2Na + 2H2O ==> 2NaOH + H2,

1 mole sodium gives 0.5 moles hydrogen,

mole Na = 0.2 ÷ 23 = 0.008696, so mole H2 = 0.008696 ÷ 2 = 0.004348

so volume H2 = 0.004348 x 24000 = 104.3 cm3 or 0.104 dm3

(g) e.g. Mg + 2HCl ==> MgCl2 + H2

1 mole magnesium gives 1 mole hydrogen, mole Mg = 2 ÷ 24.3 = 0.0823

so mole H2 = 0.0823, so volume H2 = 0.0823 x 24 = 1.975 dm3

(h) both 1 mole of Na2CO3 or NaHCO3 will give 1 mole of CO2

(1) VCO2 = mol Na2CO3 x 24000 = 0.76 ÷ 106 x 24000 = 172cm3

(2) VCO2 = mol NaHCO3 x 24000 = 0.76÷ 84 x 24000 = 217cm3

(i) Zn + 2HCl ==> ZnCl2 + H2 , mole H2 = mole HCl ÷ 2

mol HCl = 50 ÷ 1000 x 0.2 = 0.01 mol

so mole H2 = 0.005, VH2 = 0.005 x 24000 = 120cm3

(j) CaCO3 + 2HCl ==> CaCl2 + H2O + CO2

mole CO2 = mole HCl ÷ 2, mol HCl = 75 ÷ 1000 x 0.05 = 0.00375 mol

so mole CO2 = 0.001875, VCO2 = 0.001875 x 24000 = 45cm3

 

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* Copyright © Dr W P Brown 2000-2008 All rights reserved including the revision notes pages, quizzes, worksheets etc. * Doc Brown's Chemistry Clinic * www.docbrown.info/ *

KS4 SCIENCE - Additional & Applied Chemistry help AQA GCSE Science - Chemistry CCEA GCSE Science - Chemistry Edexcel GCSE 360Science - Chemistry OCR GCSE 21st Century Science Suite - Chemistry  OCR GCSE Gateway Science Suite - Chemistry OCR GCSE Applied Science - Chemistry (double award) WJEC GCSE Science - Chemistry

ALL my KS3 SCIENCE Revision Quizzes (~US K12 grades 6,7,8)

GCSE-IGCSE-KS4 Science-CHEMISTRY notes & quizzes (~US K12 grades 9-10)

Advanced Level CHEMISTRY GCE AS A2 IB notes and quizzes (~US K12 grades 11-12)

All my GCSE-IGCSE Science-CHEMISTRY etc. syllabus help links

 All my GCE-AS-A2-IB AQA, Edexcel, OCR etc. Advanced Level Chemistry syllabus-specification help links

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