Writing+and+Balancing+Chemical+Equations


 * __Balancing Equations with compounds__ **


 * Valency tables **


 * || = CATIONS = || || || ** ANIONS **  || ||
 * ** 1+ ** ||  ** 2+ **  ||  ** 3+ **  ||  ** 1- **  ||  ** 2- **  ||  ** 3- **  ||
 * Ammonium NH4+ || Barium Ba2+ || Aluminium Al3+ || Bicarbonate HCO3- || Carbonate CO32- || Nitride N3- ||
 * Cuprous (I) Cu+ || Beryllium Be2+ || Chromium Cr3+ || Bromide Br- || Chromate CrO42- || Phosphate PO43- ||
 * Hydrogen H+ || Calcium Ca2+ || Ferric (III) Fe3+ || Chloride Cl- || Dichromate Cr2O72- || Phosphide P3- ||
 * Lithium Li+ || Copper (II) Cu2+ ||  || Chlorate ClO3- || Zincate Zn(OH)42- ||   ||
 * Potassium K+ || Iron (II) Fe2+ ||  || Permanganate MnO4- || Silicate SiO32- ||   ||
 * Silver Ag+ || Lead (II) Pb2+ ||  || Acetate CH3COO- || Oxide O2- ||   ||
 * Sodium Na+ || Magnesium Mg2+ ||  || Fluoride F- || Peroxide O22- ||   ||
 * || Strontium Sr2+ ||  || Hydride H- || Sulfate SO42- ||   ||
 * || Tin Sn2+ ||  || Hydroxide OH- || Sulfide S2- ||   ||
 * || Zinc Zn2+ ||  || Iodide I- || Sulfite SO32- || ||
 * || Mercury Hg2+ ||  || Nitrate NO3- || Thiosulfate S2O32- ||   ||
 * **.** ||  ||   || Nitrite NO2- ||   ||   ||

View an animation of balancing to further understand this process

= Here is a worked example = eg. A solution of Lead Nitrate reacts with a solution of Aluminium Chloride. // Solution means in water = (aq) //


 * Step 1. Determine the symbol and charge of each ion (the numerals in represent the ion’s charge) but write the cation (+ ions) before the non-metal anion(s) (- ions) except for substances with acetate.**

eg. Al3+Cl-, Charge number of Al is a 3 and the charge number of Cl is a 1 so Al1Cl3 but write it as AlCl3 eg. Pb2+NO3-. Charge number on Pb is a 2, and NO3 is only a 1 so Pb1(NO3)2 but write it as Pb(NO3)2.
 * Step 2. To write a chemical formula, write __ONE__ of each ion & balance the ion charges so the total is 0 by writing the required coefficient to the __bottom right of the ion__ ** . **For multiples of an atom group, use .**

eg. Charge number of Pb(NO3)2 is 2 and the charge number of AlCl3 is 3. Both 2 and 3 go into 6 so use 3 Pb(NO3)2 and 2 AlCl3. eg. 3 Pb(NO3)2 + 2 AlCl3 --->
 * Step 3. To balance one side (products or reactants), the total charge number must be same for both sides of the --> so find a common multiple and write the required coefficient __in front of each chemical__. **

eg. 3 Pb2+(NO3-)2 + 2 Al3+(Cl-)3 ---> Pb2+Cl- + Al3+(NO3-) If H2CO3 is produced, change it to H2O(l) + CO2(g).
 * Step 4. When reacting the cations and anions swap partners so write each ion in the products.**


 * Step 5. Repeat STEPS’ 2 and 3 to balance the charges of the products and write the final equation including states. ** eg. 3 Pb(NO3)2(aq) + 2 AlCl3(aq) ---> 3 PbCl2(s) + 2 Al(NO3)3(aq)
 * Regard H2O as H+ and OH- if hydroxide ions are present or as 2 H+ and O2- if oxide ions are present. **

QUESTIONS:
1. Determine the charges of each ion in each of the following compounds:- a). LiCl. b). Na2CO3. c). AlCl3. d). Na3PO4. e). K2SO4. . Li = ___, Cl = ___ Na = ___, CO3 = ___ Al = ___, Cl = ___ Na = ___, PO4 = ___ K = ___, SO4 = ___

2. Balance the following equations (the states have been omitted deliberately): a). __ LiOH + __ K2CO3 ---> __ Li2CO3 + __ KOH b). __ H2SO4 + __ NaCl ---> __ Na2SO4 + __ HCl c). __ LiOH + ___ H2SO4 ---> __ Li2SO4 + __ H2O d). __ AgNO3 + __ FeCl2 ---> __ Fe(NO3)2 + __ AgCl e). __ Cu(NO3)2 + __ KOH ---> __ Cu(OH)2 + __ KNO3

3. Write balanced chemical equations for the following reactions showing the possible products: a). A solution of silver nitrate reacts with a solution of potassium chloride. b). A solution of iron(II) chloride reacts with a solution of lithium hydroxide. c). A solution of potassium hydroxide reacts with a solution of nitric acid (HNO3). d). A solution of aluminium nitrate reacts with a solution of copper sulfate. e). A solution of strontium chloride reacts with a solution of lead(II) bicarbonate (hydrogen carbonate). f). A solution of lead nitrate reacts with a solution of copper chloride.

ANSWERS: 1. a). Li+(aq), Cl-(aq). b). 2 Na+(aq), CO32-(aq). c). Al3+(aq), 3 Cl-(aq). d). 3 Na+(aq), PO43-(aq). e). 2 K+(aq), SO42-(aq).

2. a). 2 LiOH + K2CO3 --> Li2CO3 + 2 KOH. b). H2SO4 + 2 NaCl --> Na2SO4 + 2 HCll. c). 2 LiOH + H2SO4 --> Li2SO4 + 2 H2O, d). 2 AgNO3 + FeCl2 ---> Fe(NO3)2 + 2 AgCl. e). Cu(NO3)2 + 2 KOH --> Cu(OH)2 + 2 KNO3..

3. a). AgNO3(aq) + KCl(aq) --> AgCl(s) + KNO3(aq). b). FeCl2(aq) + 2 LiOH(aq) --> Fe(OH)2(s) + 2 LiCl(aq). c). KOH(aq) + HNO3(aq) --> KNO3(aq) + H2O(l). d). 2 Al(NO3)3(aq) + 3 CuSO4(aq) --> 3 Cu(NO3)2(aq) + Al2(SO4)3(aq). e). SrCl2(aq) + Pb(HCO3)2(aq) --> Sr(HCO3)2(aq) + PbCl2(s). f). Pb(NO3)2(aq) + CuCl2(aq) --> PbCl2(s) + Cu(NO3)2(aq).