Unit+7+-+Balancing+Equations


 * Balancing Equations**

Steps to Balancing Equations 1. Write the correct formula for the reactants and the products. 2. Find the number of atoms for each element on the left side. Compare those against the number of the atoms of the same element on the right side. 3. Determine where to place coefficients in front of the formulas so that the left side has the same number of atoms as the right side for each element in order to balance the equation. 4. Check your answer to see if: -the numbers of atoms on both sides of the equation are now balanced -the coefficients are in the lowest possible whole number ratios. (reduced)

HINT: 1) save H and O for last 2) recognize ions 3) H20 = HOH 4) You can add coefficients but you can NOT change subscripts

Balancing Equations 1) Balance the following equation: B2O3(s) + HF(l) → BF3(g) + H2O(l) B. B2O3(s) + H6F6(l) → B2F6(g) + H6O3(l) C. B2O3(s) + 2HF(l) → 2BF3(g) + H2O(l) D. B2O3(s) + 3HF(l) → 2BF3(g) + 3H2O(l) E. B2O3(s) + 6HF(l) → 2BF3(g) + 6H2O(l) 2) Balance the following equation: UO2(s) + HF(l) → UF4(s) + H2O(l) A. UO2(s) + 2HF(l) → UF4(s) + H2O(l) C. UO2 (s) + H4F4(l) → UF4 (s) + H4O2(l) D. UO2(s) + 4HF(l) → UF4(s) + 4H2O(l) E. UO2(s) + 8HF(l) → 2UF4(s) + 4H2O(l) 3) Balance the following equation for the combustion of benzene: C6H6(l) + O2(g) → H2O(g) + CO2(g) A. C6H6(l) + 9O2(g) → 3H2O(g) + 6CO2(g) B. C6H6(l) + 9O2(g) → 6H2O(g) + 6CO2(g) D. C6H6(l) + 15O2(g) → 3H2O(g) + 6CO2(g) E. 2C6H6(l) + 9O2(g) → 6H2O(g) + 12CO2(g) 4) Balance the following equation: C8H18O3(l) + O2(g) → H2O(g) + CO2(g) A. C8H18O3(l) + 8O2(g) → 9H2O(g) + 8CO2(g) C. 2C8H18O3(l) + 22O2(g) → 9H2O(g) + 16CO2(g) D. C8H18O3(l) + 13O2(g) → 18H2O(g) + 8CO2(g) E. 2C8H18O3(l) + 17O2(g) → 18H2O(g) + 16CO2(g) 5) Balance the following equation: Ca3(PO4)2(s) + SiO2(s) + C(s) → CaSiO3(s) + CO(g) + P4(s) A. Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + P4(s) B. Ca3(PO4)2(s) + 3SiO2(s) + 14C(s) → 3CaSiO3(s) + 14CO(g) + P4(s) C. Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + 2P4(s) E. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + 4P4(s) 6) Select the precipitate that forms when the following reactants are mixed. Na2CO3(aq) + BaCl2(aq) → A. Ba2CO3 D. NaCl2 E. BaO 7) Select the precipitate that forms when the following reactants are mixed. Mg(C2H3O2)2(aq) + LiOH(aq) → B. Li(C2H3O2)2 C. MgOH E. CH3OH 8) Select the precipitate that forms when aqueous ammonium sulfide reacts with aqueous copper(II) nitrate. B. Cu2S D. NH4(NO3)2 E. CuSO4 9) Select the precipitate that forms when aqueous lead(II) nitrate reacts with aqueous sodium sulfate. B. Na2NO3 D. Pb2SO4 E. PbS 10) Select the correct name and chemical formula for the precipitate that forms when the following reactants are mixed. CuCl2(aq) + Na2CO3(aq) → A. copper(I) carbonate, Cu2CO3 B. copper(II) carbonate, Cu2CO3 C. copper(I) carbonate, CuCO3 11) Select the correct name and chemical formula for the precipitate that forms when the following reactants are mixed. CoSO4(aq) + (NH4)3PO4(aq) → B. cobalt(III) phosphate, Co3(PO4)2 C. cobalt(II) phosphate, CoPO4 D. cobalt(III) phosphate, CoPO4 12) The compound P4O10 is used in refining sugar. Select the classification for the reaction in which it is synthesized. P4(s) + 5O2(g) → P4O10(s) B. decomposition C. displacement D. acid-base E. precipitation 13) Select the classification for the following reaction. H2CO3(aq) → H2O(l) + CO2(g) A. combination C. displacement D. acid-base E. none of these choices is correct 14)Predict the product(s) for the following reaction. H2SO4(aq) + KOH(aq) → B. K2S(aq) + H2O(l) C. K(s) + H2(g) + SO3(g) D. KSO4(aq) + H2O(l) E. No reaction occurs. 15) Predict the product(s) for the following reaction. MgCO3(s) A. MgO2(s) + CO(g) C. Mg(s) + CO2(g) + O2(g) D. Mg2+(s) + CO2(g) + O2(g) E. No reaction occurs.
 * A**. B2O3(s) + 6HF(l) → 2BF3(g) + 3H2O(l)
 * B**. UO2(s) + 4HF(l) → UF4(s) + 2H2O(l)
 * C**. 2C6H6(l) + 15O2(g) → 6H2O(g) + 12CO2(g)
 * B**. C8H18O3(l) + 11O2(g) → 9H2O(g) + 8CO2(g)
 * D**. 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + P4(s)
 * B**. BaCO3
 * C**. 2NaCl
 * A**. 2LiC2H3O2
 * D**. Mg(OH)2
 * A**. CuS
 * C**. 2NH4NO3
 * A**. 2NaNO3
 * C**. PbSO4
 * D**. copper(II) carbonate, CuCO3
 * E**. sodium chloride, NaCl
 * A**. cobalt(II) phosphate, Co3(PO4)2
 * E**. ammonium sulfate, (NH4)2SO4
 * A**. combination
 * B**. decomposition
 * A**. K2SO4(aq) + H2O(l)
 * B**. MgO(s) + CO2