Chemical Literacy - Ionic equations

Transcription

1 Chemical Literacy - Ionic equations 2H + (aq) + Zn (s) --> Zn2+ (aq) (g) Ion age? We haven t reached the bronze age yet! This package will teach you how to write ionic equations. This is the tough stuff Boris! Watch your brains do not boil too much! Just let them simmer a little. Created by G.R. arsden Chemical Literacy 3.1

2 By Year 11 you should have learned this Page - It shows the common chemical valencies for metals, non metals and radicals. There are three columns for metals, non metals and radicals. Ion charges are also included and are the same as the valencies.. These you will use later. For the first assignments you will ignore the charges and use only the valence numbers as shown by the headings. If the charge is missing, no ion forms. VALENCE 1 Sodium Na + Fluorine F - Ammonium NH + 4 Potassium K + Chlorine Cl - Hydroxide H - Silver Ag + Bromine Br - Nitrate N - 3 Hydrogen H + Iodine I - Bicarbonate HC - 3 Bisulphate HS - 4 VALENCE 2 agnesium g 2+ xygen 2- Sulphate Calcium Ca 2+ Sulphur S 2- Carbonate S 2-4 C 2-3 Barium Ba 2+ Zinc Zn 2+ Lead Pb 2+ Copper II Cu 2+ Iron II Fe 2+ Tin II Sn 2+ ercury II Hg 2+ ne way to learn this is to make up a card system with the name on front and symbol and valence on the back. Shuffle the cards and practise. VALENCE 3 Aluminium Al 3+ Phosphate P 3-4 Iron III Fe 3+ VALENCE 4 Carbon Silicon C Si VALENCE 5 Nitrogen N Phosphorus P Chemical Literacy 3.2

3 RE ELEENTS... In case you were feeling lonely, we thought you might like a few more. Notice that some beasts have variable valence. It is all too common, particularly among non metals and transition metals in the centre of the periodic table. The most common valence is shown first. h and don't take them as Gospel. For instance chlorine can have a valence of 7. f such is the price of freedom in our universe... ELEENT SYB TYPE VALENCE APPEARANCE IN LD NAE (etal?) Aluminium Al 3 Silver solid Al 3+ Argon Ar N 0 Colourless gas Barium Ba 2 Silver solid Ba 2+ Bromine Br N 1 Brown liquid Br - Calcium Ca 2 Grey solid Ca 2+ Carbon C N 4 (2) Black solid Chlorine Cl N 1 Yellow-green gas Cl - Chromium Cr 3(2,6) Silver blue sol Cr 3+ Cobalt Co 2(3) Grey solid Co 2+ Copper Cu 2(1) Brown solid Cu 2+ Cuprum Fluorine F N 1 Green gas F - Gold Au 3(1) Yellow solid Au 3+ Aurum Helium He N 0 Colourless gas Hydrogen H N 1 Colourless gas H + Iodine I N 1 Purple grey solid I - Iron Fe 3(2) Grey solid Fe 3+ Ferrum Lead Pb 2(4) Grey solid Pb 2+ Plumbum Lithium Li 1 Grey solid Li + agnesium g 2 Grey solid g 2+ n 2+ Hg 2+ Hydrogyrum Ni K + Kalium Silicon Si 4 Grey solid Silver Ag 1 Silver solid Ag + Argentum Sodium Na 1 Silver solid Na + Natrium Sulphur S N 2(46) Yellow solid Tin Sn 4(2) Silver solid Stannum Wolfram Zn 2+ anganese ercury Neon Nickel Titanium Tungsten n Hg Ne Ni Ti W N 2(3467) 2(1) 0 2(3) 4(3) 6(5432) Grey solid Grey liquid Colourlessgas Grey solid Silver solid Grey solid Nitrogen Uranium N U N 3(542) 6(543) Colourless gas Grey solid xygen Zinc Zn N 2 2 Colourless gas Grey solid Phosphorus P Potassium K N 5(34) 1 Brown solid Grey solid Chemical Literacy 3.3

4 THE RADICALS... Radicals are complex particles which form when two or more atoms bond together to form a more stable species. During their initial formation, electrons are either gained from another chemical or lost, and so radicals are always charged..because they are charged ions, radicals are found only... Bonded ionically with other ions in crystals of ionic compounds. In solution or in the molten state where they are free. NTE. 1. The valence of a radical is the same as the charge 2. ost radicals form the second part of a chemical formula. The exceptions to this are acetate and its relatives, and the ammonium radical. Name Formula Name Formula Ammonium NH 4 + Acetate CH 3 C - Carbonate C 3 2- Bicarbonate HC 3 - (hydrogen carbonate) Chlorate Cl - 3 Chlorite Chromate Cr 2-4 Dichromate Cl - 2 Cr (bichromate) Hydroxide H - Hypochlorite Cl - ercurous Hg 2+ 2 Nitrate N - 3 Nitrite N - 2 xalate C Hydrogen oxalate HC 2-4 Perchlorate Cl - 4 Permanganate n - 4 Peroxide 2-2 Superoxide - 2 Phosphate P 3-4 Hydrogen phosphate HP 4 2- Dihydrogen phosphate H 2 P 4 - Sulfate S 2-4 Bisulfate HS - 4 (hydrogen sulfate) Bisulfide HS - Sulfite S 2-3 (hydrogen sulfide) Bisulfite HS - 3 Chemical Literacy 3.4

5 1. The Skill of breaking ionic compounds into ions Ionic compounds are mixtures of positive and negative ions which attract each other electrostatically to form ionic lattice solids. There are two types of ions - positive cations and negative anions. The cations are usually positive metal ions formed when metal atoms lose some electrons. The charge of the ion is equal to the valence. They are positive because the positive protons in the metal atom nuclei now outnumber the electrons. The ammonium radical NH 4 + is one of very few radical cations. Cations come first in formulae. +ve Cations are quite different chemically when compared to their parent atoms. You can eat sodium ions in salt with little effect. If you ate sodium, your head would probably shatter in a rather violent explosion. The same is true for anions and their parent non metal atoms. Anions are usually negative non metal ions formed when their atoms gained electrons. Again, the charge of the anion equals the valence. Anion radicals include hydroxide H -, sulfate S 4 2- and carbonate C Cations are +ve and come first The charge is the valence Examples These are some equations showing the effect of water in splitting some soluble ionic compounds into their ions. The ions are now totally independent of each other. Water is a terrible home wrecker because of the positive and negative ends of its covalent molecules. The numbers in front come from the hypothetical equations that the chemical comes from. 4g(HC 3 ) 2(S) --> 4g 2+ (AQ) + 8HC 3 - (AQ) 2AlCl 3(AQ) --> 2Al 3+ (AQ) + 6Cl- (AQ) 5(NH 4 ) 3 P 4(AQ) --> 15NH 4 + (AQ) + 5P 4 - Set 1 Breaking up ionics Express these chemicals, taken from equations, as mixtures of ions 1. 4Pb(N 3 ) 2 2. KH 3. 3NH 4 H 4. 2Al 2 (S 4 ) Fe(N 3 ) 3 -ve 6. 6NaHC Cu(HS 4 ) (NH 4 ) 3 P 4 9. Na 3 P NaN 3 Anions are -ve and come second The charge is the valence Chemical Literacy 3.5

6 2. The Skill of writing ionic equations The next worksheet will be dedicated to some acid/metal reactions: Note the subscripts: Acid + metal --> salt + hydrogen (AQ) stands for aqueous. It means the chemical is dissolved in water. You always use it for ions dissolved in water, or chemicals dissolved in water. (S) stands for solid. etals are solid. (G) stands for gas. Common gases include C 2(G), H 2(G) (L) stands for liquid. The most common is H 2 (L) Worked Example Write the word, symbol and ionic equation for sulfuric acid + magnesium Step 1 Word equation Sulfuric acid + magnesium --> magnesium sulfate + hydrogen gas We use valence rules to write formulae H S 4 + g --> g S H 2 S 4 + g --> gs 4 This equation is already balanced. We have ARKED the solutions that need breaking into ions. These include soluble acids, alkalis and salts. It is time for the ionic equation 2H + (AQ) + S 4 2- (AQ) + g (S) --> g 2+ (AQ) + S 4 2- (AQ) (G) Finally, we cross out the spectator ions common to both sides. They are not reacting and are just cluttering up our equation 2H + (AQ) + S 4 2- (AQ) + g (S) --> g 2+ (AQ) + S 4 2- (AQ) (G) 2H + (AQ) + g (S) --> g 2+ (AQ) (G) Chemical Literacy 3.6

7 Set 2 Ionic equations - acid + metal We pay tribute to an effervescent popping little beauty: Acid + metal --> salt + hydrogen eg Hydrochloric acid + zinc --> zinc chloride + hydrogen Sulfuric acid + calcium --> calcium sulfate + hydrogen. Nitric acid does not react in this way. Assume that the salts are soluble in water unless otherwise indicated. Write word, symbol and ionic equations for: 1. Hydrochloric acid + zinc 2. Hydrochloric acid + aluminium 3. Sulfuric acid + calcium (Calcium sulfate is insoluble). 4. Sulfuric acid + iron (Fe has valence 2 in this reaction) 5. Hydrochloric acid + magnesium 6. Phosphoric acid + aluminium 7. Phosphoric acid + magnesium Set 3 These are some acid-base reactions: Ionic equations - neutralisations Acid + metal hydroxide --> salt + water Acid + metal carbonate --> salt + carbon dioxide + water Acid + metal bicarbonate --> salt + carbon dioxide + water eg Hydrochloric acid + zinc carbonate --> zinc chloride + carbon dioxide + water Assume salts and bases are soluble in water unless otherwise stated Write word, symbol and ionic equations for: 1. Hydrochloric acid + sodium hydroxide solution 2. Hydrochloric acid + ammonium hydroxide solution 3. Sulfuric acid + calcium hydroxide (Calcium sulfate and calcium hydroxide are insoluble). 4. Sulfuric acid + sodium bicarbonate solution 5. Hydrochloric acid + sodium carbonate solution 6. Phosphoric acid + potassium hydroxide solution 7. Phosphoric acid + sodium bicarbonate solution 8. Nitric acid + ammonium hydroxide solution 9. Nitric acid + potassium carbonate solution 10. Hydrochloric acid + solid calcium carbonate Chemical Literacy 3.7

8 3. Precipitation Reactions Precipitation reactions occur when two ions in solution get together to form a solid. eg ixing silver nitrate solution with sodium chloride solution. When we do this, a white precipitate forms. Unfortunately, there are two possibilities - silver chloride or sodium nitrate. To find which it is, chemists consult chemical data books which list the solubilities in water of various chemicals. This table may be of use: All hydrogen, ammonium, nitrate and bicarbonate compounds are soluble. All chlorides are soluble except silver, lead and mercurous All sulfates are soluble except silver, calcium, strontium, lead, mercurous and barium All carbonates are insoluble except lithium, sodium, potassium, hydrogen and ammonium. All hydroxides are insoluble except lithium, sodium, potassium, barium, calcium and strontium So with our problem above, we check the two possible chemicals: sodium nitrate is soluble silver chloride is insoluble. Writing the precipitation reaction is simple. We write the precipitate formula on the right using our valence rules, then write the ions whch form it on the left: Ag + (AQ) + Cl- (AQ) --> AgCl (S) Set 4 Ionic equations - precipitation reactions Write ionic equations in one step for those of the following which work : 1. Hydrochloric acid + lead nitrate solution 2. Sodium hydroxide solution + calcium nitrate solution 3. Lead nitrate solution + sodium sulfate solution 4. agnesium sulfate solution + sodium hydroxide solution 5. Sodium chloride solution + potassium carbonate solution 6. Copper sulfate solution + sodium hydroxide solution 7. Lead nitrate solution + sodium carbonate solution 8. Copper sulfate solution + potassium carbonate solution 9. Lead nitrate solution + sulfuric acid 10. Ammonium carbonate solution + magnesium chloride solution Precipitate Chemical Literacy 3.8

9 Solutions Set Pb(N 3 ) 2(S) --> 4Pb 2+ (AQ) + 8N 3 - (AQ) 2. KH (S) --> K + (AQ) + H- (AQ) 3. 3NH 4 H (S) --> 4. 2Al 2 (S 4 ) 3(S) --> 4Al 3+ (AQ) + 6S Fe(N 3 ) 3(S) --> 3Fe 3+ (AQ) + 9N 3 - (AQ) 6. 6NaHC 3(S) --> 6Na + (AQ) + 6HC 3 - (AQ) 7. 5Cu(HS 4 ) 2(S) --> 5Cu 2+ (AQ) + 10HS 4 - (AQ) 8. 2(NH 4 ) 3 P 4(S) --> 6NH 4 + (AQ) + 2P 4 3- (AQ) 9. Na 3 P 4(S) --> 3Na + (AQ) + P 4 3- (AQ) 10. 4NaN 3(S) --> 4Na + (AQ) + 4N 3 - (AQ) Solutions Set 2 1. Hydrochloric acid + zinc --> zinc chloride + hydrogen gas 2HCl + Zn --> ZnCl 2 2H + (AQ) + Zn (S) --> Zn 2+ (AQ) (G) 2. Hydrochloric acid + aluminium --> aluminium chloride + hydrogen gas 6HCl + 2Al --> 2AlCl 3 + 3H 2 6H + (AQ) + 2Al (S) --> 2Al 3+ (AQ) + 3H 2(G) 3. Sulfuric acid + calcium --> calcium sulfate + hydrogen gas H 2 S 4 + Ca --> CaS 4 2H + (AQ) + S 4 2- (AQ) + Ca (S) --> CaS 4(S) (G) 4. Sulfuric acid + iron --> iron (2) sulfate + hydrogen gas H 2 S 4 + Fe --> FeS 4 2H + (AQ) + Fe (S) --> Fe 2+ (AQ) (G) 5. Hydrochloric acid + magnesium --> magnesium chloride + hydrogen gas 2HCl + g --> gcl 2 2H + (AQ) + g (S) --> g 2+ (AQ) (G) 6. Phosphoric acid + aluminium --> aluminium phosphate + hydrogen gas 2H 3 P 4 + 2Al --> 2AlP 4 + 3H 2 6H + (AQ) + 2Al (S) --> 2Al 3+ (AQ) + 3H 2(G) 7. Phosphoric acid + magnesium --> magnesium phosphate + hydrogen gas 2H 3 P g --> g 3 (P 4 ) 2 + 3H 2 6H + (AQ) + 3g (S) --> 3g 2+ (AQ) + 3H 2(G) Chemical Literacy 3.9

10 Solutions Set 3 1. Hydrochloric acid + sodium hydroxide solution --> sodium chloride solution + water HCl + NaH --> NaCl H + (AQ) + H- (AQ) --> H 2 (L) 2. Hydrochloric acid + ammonium hydroxide solution --> ammonium chloride solution + water HCl + NH 4 H --> NH 4 Cl H + (AQ) + H- (AQ) --> H 2 (L) 3. Sulfuric acid + calcium hydroxide --> calcium sulfate + water H 2 S 4 + Ca(H) 2 --> CaS 4 + 2H 2 2H + (AQ) + S 4 2- (AQ) + Ca(H) 2(S) --> CaS 4(S) + 2H 2 (L) 4. Sulfuric acid + sodium bicarbonate solution --> sodium sulfate solution + carbon dioxide + water H 2 S 4 + 2NaHC 3 --> Na 2 S 4 + 2C 2 + 2H 2 2H + (AQ) + 2HC 3 - (AQ) --> 2C 2(G) + 2H 2 (L) 5. Hydrochloric acid + sodium carbonate solution --> sodium chloride solution + carbon dioxide + water HCl + NaHC 3 --> NaCl + C 2 H + (AQ) + HC 3 - (AQ) --> C 2(G) (L) 6. Phosphoric acid + potassium hydroxide solution --> potassium phosphate solution + water H 3 P 4 + 3KH --> K 3 P 4 + 3H 2 3H + (AQ) + 3H- (AQ) --> 3H 2 (L) 7. Phosphoric acid + sodium bicarbonate solution --> sodium phosphate solution + carbon dioxide + water H 3 P 4 + 3NaHC 3 --> Na 3 P 4 + 3C 2 + 3H 2 3H + (AQ) + 3HC 3 - (AQ) --> 3C 2(G) + 3H 2 (L) 8. Nitric acid + ammonium hydroxide solution --> ammonium nitrate solution + water HN 3 + NH 4 H --> NH 4 N 3 H + (AQ) + H- (AQ) --> H 2 (L) 9. Nitric acid + potassium carbonate solution --> potassium nitrate solution + carbon dioxide + water 2HN 3 + K 2 C 3 --> 2KN 3 + C 2 2H + (AQ) + C 3 2- (AQ) --> C 2(G) (L) 10. Hydrochloric acid + solid calcium carbonate --> calcium chloride solution + carbon dioxide + water 2HN 3 + CaC 3 --> Ca(N 3 ) 2 + C 2 2H + (AQ) + CaC 3(S) --> Ca2+ (AQ) + C 2(G) (L) Chemical Literacy 3.10

11 Solutions Set 4 1. Pb 2+ (AQ) + 2Cl- (AQ) --> PbCl 2(S) 2. Ca 2+ (AQ) + 2H- (AQ) --> Ca(H) 2(S) 3. Pb 2+ (AQ) + S 4 2- (AQ) --> PbS 4(S) 4. g 2+ (AQ) + 2H- (AQ) --> g(h) 2(S) 5. No reaction 6. Cu 2+ (AQ) + 2H- (AQ) --> Cu(H) 2(S) 7. Pb 2+ (AQ) + C 3 2- (AQ) --> PbC 3(S) 8. Cu 2+ (AQ) + C 3 2- (AQ) --> CuC 3(S) 9. Pb 2+ (AQ) + S 4 2- (AQ) --> PbS 4(S) 10. g 2+ (AQ) + C 3 2- (AQ) --> gc 3(S) Chemical Literacy 3.11

12 Writing ionic equations Skill Test Name Data Equations Acid + metal --> salt + hydrogen Acid + metal hydroxide --> salt + water Acid + metal carbonate --> salt + carbon dioxide + water Acid + metal bicarbonate --> salt + carbon dioxide + water Write word equations, symbol equations and ionic equations for these reactions. Assume all salts are soluble in water. 1. Hydrochloric + zinc --> acid 2. Hydrochloric + sodium --> acid 3. Hydrochloric + sodium carbonate --> acid solution 4. Hydrochloric + sodium bicarbonate --> acid solution 5. Hydrochloric + calcium carbonate --> acid solid Chemical Literacy 3.12

13 6. Sulfuric acid + magnesium --> 7. Nitric acid + calcium carbonate --> solid 8. Nitric acid + potassium hydroxide --> solution 9. Precipitation of calcium carbonate from calcium chloride and sodium carbonate solutions. (Ionic equation only) 10. Precipitation of silver chloride from its ions Chemical Literacy 3.13

14 has mastered the skill of writing ionic equations Grade has mastered the skill of writing ionic equations Grade Chemical Literacy 3.14