Outcome 51

Step 3a Balance the equation.

-Balance metals first. -Balance nonmetals. -Balance hydrogen and oxygen. -Check all other elements after each individual element is balanced to make sure other elements have not become unbalanced

Step 3a Balance the equation.

-Count and compare the number of atoms of each element on both sides of the equation. -Balance each element, one at a time, by placing coefficients in front of the chemical formulas. Consider: HgO → Hg + O2

p. 150 Practice 8.4 Consider the reaction that occurs when hydrogen gas reacts with chlorine gas to produce gaseous hydrogen chloride: (a) Write a word equation for this reaction. (b) Write an unbalanced formula equation including the state for each substance.

Answers: (a) Hydrogen Chloride gas, HCl (b) H2 (g) + Cl2 (g) ---> 2HCl (g)

p. 164 Write unbalanced equations for the following word equations: (a) Magnesium metal is placed into hydrobromic acid solution, forming hydrogen gas and aqueous magnesium bromide. (c) Lithium metal reacts with oxygen gas to form solid lithium oxide. (f) Solutions of silver nitrate and aluminum iodide are mixed together, forming solid silver iodide and aqueous aluminum nitrate.

Answers: (a) Mg(s) + HBr(aq) → H2(g) + MgBr2(aq) (c) Li(s) + O2(g) → Li2O(s) (f) AgNO3(aq) + AlI3(aq) → AgI(s) + Al(NO3)3(aq)

p. 164 Write unbalanced equations for the following word equations: (a) Upon heating, solid magnesium carbonate decomposes into solid magnesium oxide and carbon dioxide. (c) Solutions of iron(III) sulfate and sodium hydroxide are mixed together, forming solid iron(III) hydroxide and a solution of sodium sulfate. (e) Gaseous sulfur trioxide reacts with liquid water to form a solution of sulfuric acid. (f) Solutions of sodium carbonate and cobalt(II) chloride reacts to form solid cobalt(II) carbonate and a solution of sodium chloride.

Answers: (a) MgCO3(s) → MgO(s) + CO2(g) (c) Fe2(SO4)3(aq) + NaOH(aq) → Fe(OH)3(s) + Na2SO4(aq) (e) SO3(g) + H2O(l) → H2SO4(aq) (f) Na2CO3(aq) + CoCl2(aq) → CoCO3(s) + NaCl(aq)

p. 164 Write balanced equations for the following descriptions: (e) Gaseous sulfur trioxide reacts with liquid water to form a solution of sulfuric acid. (f)Solutions of sodium carbonate and cobalt(II) chloride react to form solid cobalt(II) carbonate and a solution of sodium chloride.

Answers: (e) SO3(g) + H2O(l) → H2SO4(aq) (f) Na2CO3(aq) + CoCl2(aq) → CoCO3(s) + 2 NaCl(aq)

Step 2 Write the unbalanced (skeleton) equation. [You must use your knowledge of chemical nomenclature.]

HgO-> Hg + O2 **The formulas of the reactants and products can never be changed.**

Step 1 Identify the reaction.

Mercury(II) oxide decomposes to form mercury and oxygen

Balance a chemical equation

Step 1 Identify the reaction. Write a description or word equation for the reaction. Mercury (II) oxide decomposes to form mercury and oxygen. mercury(II) oxide → mercury + oxygen