HW5-Chapter5-Chem106 - Balancing Different Types of Chemical Equations

When aluminum, Al, metal is dipped in an aqueous solution of hydrochloric acid, HCl, hydrogen gas, H2, is produced with the formation of an aluminum chloride, AlCl3, solution. Write the balanced chemical equation showing the phases of reactants and products. HINT: Write the unbalanced chemical equation using the correct formulas for each reactant and product. HINT: The unbalanced chemical equation is Al(s)+HCl(aq)→AlCl3(aq)+H2(g). How many atoms in reactants and products?

2Al(s) + 6HCl(aq) = 3H2(g) + 2AlCl3(aq) Since all of the elements have an equal number of atoms on the reactant and product sides, the equation is balanced. A chemical equation must be balanced with respect to mass because matter can be neither created nor destroyed. The equation must also be balanced with respect to charge because the total number of electrons does not change; this is called charge balance. HINT: Al(s) + HCl(aq) = H2(g) + AlCl3(aq) If you didn't add phases to your answer, you will need to do that before writing the final balanced equation. Read the main question to determine the phases of each species. Phases are solid (s), liquid (l), gas (g), and aqueous (aq). Aqueous means a solution in water. A strong acid, such as hydrochloric acid, would form an aqueous solution with water. Now, add appropriate coefficients to balance the number of atoms of each element. Check the equation to make sure the numbers and kinds of atoms on both sides of the equation are the same. Your final answer should include coefficients as well as the phase for each species in the chemical reaction. HINT: Element Al=1 atom in reactants, 1 atom in products Element H= 1 atom in reactants, 2 atoms in products Element Cl = 1 atom in reactants, 3 atoms in products The elements hydrogen and chlorine are not balanced in the chemical equation. Add appropriate coefficients until the numbers and kinds of atoms on both sides of the equation are the same. Make sure the coefficients are reduced to their lowest whole-number values.

Balance the chemical equation by indicating the number of each species in the appropriate blanks. For this exercise, indicate coefficients of 1 explicitly. HINT: How many atoms of each element are in the reactants and products of the unbalanced equation? _____ Fe(s) + _____ H2O(l) → _____Fe3O4(s) + _____ H2(g)

3Fe(s) + 4H2O(l) = 1Fe3O4(s) + 4H2(g) In any balanced chemical equation, if the coefficient of any reactant or product is one, then it is not required to write the numeral 1, and the coefficient can be omitted. Hence, the equation 3Fe+4H2O→1Fe3O4+4H2 is written as 3Fe+4H2O→Fe3O4+4H2 HINT: Element Fe = 1 atom in reactants, 3 atoms in products Element H = 2 atoms in reactants, 2 atoms in products Element O = 1 atom in reactants, 4 atoms in products The elements iron and oxygen in the chemical equation are not balanced. Add appropriate coefficients until the numbers and kinds of atoms on both sides of the equation are the same. Make sure the coefficients are reduced to their lowest whole-number values.

Listed are examples of several types of chemical equations. Note that a combination reaction and a synthesis reaction are the same type of reaction. Each reaction is only partially balanced. Complete the task of balancing each chemical equation. Chemical Reaction: Combustion... C2H5OH(l) + ___O2(g) = 2CO2(g) + ___H2O(l) + energy Chemical Reaction: Decomposition... __AgCl(s) = ___ Ag(s) + Cl2(g) Chemical Reaction: Single replacement... ___ AgNO3(aq) + Zn(s) = ___ Ag(s) + Zn(NO3)2(aq) Chemical Reaction: Double replacement... ____ BaCl2(aq) +Al2(SO4)3(aq) = 3BaSO4(s) + ___AlCl3(aq) Chemical Reaction: Combination... H2(g) + I2(g) = ___HI(g) HINT: How many atoms of each element are indicated by the partially balanced chemical equation for the following combustion reaction? C2H5OH(l)+O2(g)→2CO2(g)+H2O(l)+energy

Chemical Reaction: Combustion... C2H5OH(l) + 3O2(g) = 2CO2(g) + 3H2O(l) + energy Chemical Reaction: Decomposition... 2AgCl(s) = 2Ag(s) + Cl2(g) Chemical Reaction: Single replacement... 2AgNO3(aq) + Zn(s) = 2Ag(s) + Zn(NO3)2(aq) Chemical Reaction: Double replacement... 3BaCl2(aq) +Al2(SO4)3(aq) = 3BaSO4(s) + 2AlCl3(aq) Chemical Reaction: Combination... H2(g) + I2(g) = 2HI(g) HINT: Element C=2 atoms in reactants, 2 atoms in products Element H=6 atoms in reactants, 2 atoms in products Element O=3 atoms in reactants, 5 atoms in products The elements hydrogen and oxygen are not balanced in the chemical equation. Add appropriate coefficients until the numbers and kinds of atoms on both sides of the equation are the same. Make sure the coefficients are reduced to their lowest whole-number values. You can use this same process to balance the other four equations. Setting up a table is a good way to check your answer after the equation is balanced as well.