1 Grade 11 Chemistry Review The following questions highlight the main knowledge and skills from grade 11 chemistry. A good understanding of the concepts covered in grade 11 chemistry is essential for success in grade 12 chemistry and you may need to do some independent review of some material if you do not have a clear understanding of the concepts. 1. Use arrows to show the periodic trends for the following properties. Increasing Atomic Radius Increasing Metal Reactivity Increasing 1st Ionization Energy Increasing Electronegativity Increasing Non-Metal Reactivity Increasing Metallic Properties Increasing Electron Affinity 2. Rank the following elements in order of increasing 1st Ionization Energy. Explain your choice. N, Ba, Al, Mg Ba, Mg, Al, N - Ba is lowest and furthest to the left. The effective nuclear charge is the least and it has the most energy levels resulting in a weak force of attraction making the valence electrons easier to remove. - Mg is higher up than Ba therefore fewer energy levels meaning the valence electrons are closer and held more tightly making them harder to remove. It is further left than Al therefore it has a lower effective nuclear charge making the electrons easier to remove than Al. - Al is further right than Mg giving it a higher effective nuclear charge making its electrons harder to remove than Mg. It is lower and further left than N making its electrons easier to remove. - N is highest and furthest to the right. The effective nuclear charge is the greatest and it has the fewest energy levels resulting in a strong force of attraction making the valence electrons harder to remove. 3. Rank the following elements in order of decreasing 1st Atomic Radius. Explain your choice. O, F, S, Br Br, S, O, F - Br has the greatest number of energy levels and therefore will be the largest. - S has the next highest number of energy levels - O has the same number of energy levels as F but has a lower effective nuclear charge therefore its electrons are held in as tightly making it larger than F. - F is highest up so it has the fewest energy levels and is furthest to the right resulting in the highest effective nuclear charge which means the electrons are held most tightly making it the smallest atom. 4. Why is the ionic radius of a negative ion larger than the atomic radius of the corresponding neutral atom? Adding more electrons to the valence shell results in a greater repulsion causing everything to spread out more. 5. Why is the ionic radius of a positive ion smaller than the radius of the corresponding neutral atom? Removing an electron results in an overall positive charge which increases the attraction for the electrons pulling them in more closely resulting in a smaller radius. 6. Draw the full electron configuration for the following elements. A) F 1s22s22p5 2 B) Ti 1s22s22p63s23p64s23d2 C) Sn 1s22s22p63s23p64s23d104p65s24d105p2 7. Distinguish between an ionic bond, polar covalent bond, pure covalent bond and coordinate covalent bond. Ionic : electrostatic attraction between a positive and negative ion Polar Covalent: Unequal sharing of an electron pair between 2 atoms Pure Covalent: Equal sharing of an electron pair between 2 atoms Coordinate Covalent: Covalent bond where both electrons in the shared pair come from the same atom 8. Draw Lewis Dot diagrams for the following compounds. A) KI B) CH4 C) CO32- D) XeF6 **bonds should be dots also 9. Determine which of the following molecules contain polar covalent bonds and if the molecules are polar. A) Br2 non-polar bonds and molecule C) PCl3 polar bonds, non-polar molecule B) SrCl2 ionic D) HF polar bond and molecule 10. How is it possible for a non-polar molecule to have polar covalent bonds? If a molecule has polar bonds but is symmetrical the molecule will be non-polar because there is an equal distribution of charges. 11. Distinguish between intramolecular and intermolecular forces. Give examples of each. Intra: Within a molecule ex. Covalent bonds Inter: Between molecules ex. London dispersion, dipole-dipole and H bonds 12. Explain why polar molecules have higher boiling and melting points than non polar molecules. Polar molecules will have both London Dispersion forces and Dipole-Dipole forces where non polar molecules only have London Dipersion forces. This results in the polar molecules being held more tightly together taking more energy to disperse the molecules and therefore higher melting and boiling points. 13. Why does chloromethane have a higher solubility in water than methane? Draw a diagram to aid in your explanation. Methane is a symmetrical molecule therefore the only intermolecular forces present are London dispersion. Chloromethane is asymmetrical due to the Cl which means it has London Dispersion and dipole-dipole forces. Since chloromethane has greater intermolecular forces, it will then have a higher melting and boiling point. 14. What is the charge on the stable ion formed by the following elements? A) Na = Na+ C) Ba = Ba2+ B) S = S2- D) I = I- 3 15. Complete the following word equations, identify the type of reaction and write balanced chemical equations. (BEWARE NOT ALL WILL RESULT IN A REACTION) A) iron + copper (II) sulphate copper + iron (II) sulphate Fe + CuSO4 Cu + FeSO4 Single displacement B) potassium bromide + iodine NO REACTION (Br is more reactive than I so I will not displace Br) C) sodium chlorate sodium chloride + oxygen 2 NaClO3 2 NaCl + 3 O2 Decomposition D) ethane (dicarbon hexahydride) + oxygen carbon dioxide + water 2 C2H6 + 7 O2 4 CO2 + 6 H2O Complete combustion E) magnesium oxide + carbon dioxide magnesium carbonate MgO + CO2 MgCO3 synthesis F) calcium hydroxide calcium oxide + water Ca(OH)2 CaO + H2O decomposition G) sulphur trioxide + water sulfuric acid SO3 + H2O H2SO4 synthesis H) lithium hydroxide + phosphoric acid lithium phosphate + water 3 LiOH + H3PO4 Li3PO4 + 3 H2O neutralization 16. Determine the molar mass for the following compounds. A) Mg(SCN)2 B) SrCl2∙ 4H2O 140.49 g/mol 230.52 g/mol C) CsHS2O2 230.06 g/mol 17. Determine the number of molecules in 45.2 g of calcium carbonate. MM = 100 g/mol # of molecules = nNA m = 45.2 g = (0.452 mol)(6.02 x 1023) n = m/MM = 2.72 x 1023 = (45.2 g)/100 g/mol Therefore there are 2.72 x 1023 molecules. = 0.452 mol 18. Determine the number of moles of HCl in 36 mL of a 0.15 M solution. C= 0.15 M V= 0.036 L n = cV n = (0.15M)(0.036 L) n = 0.0054 mol 19. Determine the percent composition of the following compounds. A) SO3 B) CuSO3 MM = 80.07 g/mol MM = 139.00 g/mol % S= 32.07 g/mol/80.07 g/mol x 100% % Cu= 63.55 g/mol/139.00 g/mol x 100% = 40.05 % = 45.72 % % O= 48.00 g/mol/80.07 g/mol x 100% % S= 32.07 g/mol/139.00 g/mol x 100% = 59.95 % = 23.07 % % O= 48.00 g/mol/139.00 g/mol x 100% = 34.53 % 4 20. A sample of copper (II) sulphate pentahydrate weighs 6.8 g. What mass of the sample is due to the water? CuSO4∙5 H2O MM= 249.62 g/mol mwater = % water X mass of hydrate = 90 g/mol /249.62 g/mol x 6.8 g = 2.5 g 21. A compound contains 85.6 % C and 14.4 % H. A) Determine the empirical formula of the compound. Species %/MM of element ÷ by smallest Whole # Ratio C 85.6/12.01 = 7.127 7.127/7.127 = 1 1 H 14.4/1.01 = 14.257 14.257/7.127 = 2 2 Therefore the empirical formula is CH2 B) If the molar mass of the compound is 42.1 g/mol, what is the molecular formula of the compound. MMEF = 14.03 g/mol MMMF = 42.1 g/mol # of EF = MMMF/ MMSF = 42.1 g/mol/14.03 g/mol =3 Therefore the molecular formula is C3H6 22. What is the concentration in % w/v and mol/L of the solution prepared by dissolving 13.6 g of sodium hydroxide in 450 mL of water? MM = 40 g/mol c = n/V n = 13.6 g/40 g/mol = 0.34/0.45 L = 0.34 mol = 0.76 mol/L % w/v = 13.6 g/450g x 100% = 3.0 % w/v 23. Write an ionic equation for the dissociation of calcium chloride in water. CaCl2(s) Ca2+(aq) + 2 Cl-(aq) 24. Complete the following table by indicating the products of the double displacement reaction and by circling any insoluble products. Reactants NaCl MgSO4 Na2CO3 CaCl2 PbNO3 Li3PO4 KC2H2O2 BaS NaNO3 PbCl2 LiCl Na3PO4 KCl NaC2H2O2 BaCl2 Na2S PbSO4 Mg(NO3)2 Li2SO4 Mg3(PO4)2 K2SO4 Mg(C2H2O2)2 BaSO4 MgS 25. Sketch a typical solubility curve for a solid and a gas. Solid NaNO3 PbCO3 Li2CO3 Na3PO4 K2CO3 NaC2H2O2 BaCO3 Na2S Gas Solubility Solubility Temperature Temperature PbCl2 Ca(NO3)2 LiCl Ca3(PO4)2 KNO3 Ca(C2H2O2)2 BaCl2 CaS 5 26. Using an example to help you, distinguish between dissociation and ionization. Dissociation is the splitting of ions when a substance is put into water such as when sodium chloride is dissolved in water, the sodium and chloride ions are separated so they are free in solution. Ionization is the formation of ions. For example when hydrogen chloride gas is dissolved in water, it ionizes to form hydronium and chloride ions. 27. Lead (II) nitrate reacts with potassium iodide to produce a bright yellow solid. Write a balanced chemical equation, an ionic equation and a net ionic equation for the reaction. MAKE SURE TO INCLUDE STATES. Balanced Chemical Equation: Pb(NO3)2(aq) + 2 KI(aq) PbI2(s) + 2 KNO3(aq) Full Ionic Equqtion: Pb2+(aq) + 2 NO3-(aq) + 2 K+(aq) + 2 I-(aq) PbI2(s) + 2 K+(aq) + 2 NO3-(aq) Spectator Ions Crossed Out: Pb2+(aq) + 2 NO3-(aq) + 2 K+(aq) + 2 I-(aq) PbI2(s) + 2 K+(aq) + 2 NO3-(aq) Net Ionic Equation: Pb2+(aq) + 2 I-(aq) PbI2(s) 28. Distinguish between an Arrhenius acid and a Bronsted-Lowry acid? An Arrhenius acid is a solution with acidic properties such as a pH below 7 and a Bronsted-Lowry acid is a species that donates a proton in a given reaction. 29. Give an example of a conjugate acid-base pair. H2O and OH-, H2CO3 and HCO330. Which of the following could be an amphiprotic substance. A) H2O B) SO42C) HCO3- D) OH- 31. Determine the pH of solutions with the following hydronium concentrations. A) [H3O+ (aq)] = 2.5 x 10-3 B) [H3O+ (aq)] = 6.76 x 10-5 + pH = -log [H3O ] pH = -log [H3O+] = -log (2.5 x 10-3 mol/L) = -log (6.76 x 10-5 mol/L) = 2.60 = 4.170 32. Determine the hydronium concentrations for solutions with the following pHs. A) pH= 5.60 B) pH= 2.31 + -pH [H3O ] = 10 [H3O+] = 10-pH -6 = 2.5 x 10 = 4.9 x 10-3 C) pH= 12.80 [H3O+] = 10-pH = 1.6 x 10-13 33. Magnesium metal reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas. How many hydrogen molecules are produced when 60.0 g of hydrochloric acid are reacted with excess magnesium. Mg(s) + HCl(aq) MgCl2(aq) + H2(g) nhydrogen = 1.74 mol Molar Ratio 1 1 1 1 NA = 6.02 x 1023 entities/mol m (g) 60.0 molecules of H2= 1.74 mol x 6.02 entities/mol MM (mol/g) 24.3 36.46 = 1.05 x 1024 molecules n (mol) 1.74 1.74 Therefore 1.05 x 1024 molecules of hydrogen gas are produced. 6 34. Determine the mass of silver chloride (AgCl) produced when 75.0 mL of a 4.50 M solution of silver nitrate (AgNO3) reacts with 15.0 g of sodium chloride (NaCl). NaCl is the limiting factor AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3 (aq) NAgCl = 0.257 mol Molar Ratio 1 1 1 1 MMFe = 143.32 g/mol C (mol/L) 4.50 mFe = 0.257 mol x 143.32 g/mol V (L) 0.0750 = 36.8 kg m (g) 15.0 36.8 MM (g/mol) 58.44 143.32 n (mol) 0.338 0.257 0.257 Therefore 36.8 g of silver chloride can be produced. 35. When solid iron (II) oxide is heated in the presence of carbon monoxide gas, iron metal and carbon dioxide gas are produced. A) Write a balanced chemical equation for the reaction. FeO(s) + CO(g) Fe(s) + CO2(g) B) If 74.20 kg of iron (II) oxide and 40.30 kg of carbon monoxide are reacted, what is the mass of iron that can be produced. FeO is the limiting factor FeO(s) + CO(g) Fe(s) + CO2(g) nFe = 1033 mol Molar Ratio 1 1 1 1 MMFe = 71.85 g/mol m (g) 74 200 40 300 57 690 mFe = 1033 mol x 55.85 g/mol MM (mol/g) 71.85 28.01 55.85 = 57.69 kg n (mol) 1033 1439 1033 Therefore 57.69 kg of iron can be produced. C) If 48.90 kg of iron metal is actually produced what is the % yield of the reaction? % yield = Actual/Theoretical x 100 % = 48.90 kg/57.69 kg x 100% = 84.95 % Therefore the percentage yield of the reaction is 84.95 %. 36. 20.0 mL of 0.20 M NaOH reacts with 25.0 mL of 0.25 M HCl (aq). What mass of sodium chloride would be produced and what would the pH of the solution be after the reaction was complete? NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) NaOH is the limiting factor nNaCl = 0.0040 mol Molar Ratio 1 1 1 1 MMNaCl = 58.44 g/mol C (mol/L) 0.20 0.25 mNaCl = 0.0040 mol x 58.44 g/mol V (L) 0.0200 0.0250 = 0.23 g n (mol) 0.0040 0.0063 0.0040 Reacted HCl = 0.0040 mol Excess HCl = 0.0063 mol- 0.0040 mol = 0.0023 mol Therefore the mass of sodium chloride produced is 0.23 g moles of hydronium = 0.0023 mol and the pH of the final solution is 1.29. [H3O+] = 0.0023 mol/0.045 L = 0.051 mol/L pH = -log [H3O+] = -log (0.051 mol/L) = 1.29