Problem 66 - Chemistry: The Central Science

Question

Write balanced equations for the following reactions: (a) potassium oxide with water, (b) diphosphorus trioxide with water, (c) chromium(III) oxide with dilute hydrochloric acid, (d) selenium dioxide with aqueous potassium hydroxide.

Step-by-Step Solution

Answer

The balanced equations for the given reactions are: a) \( K_2O + H_2O \rightarrow 2KOH \) b) \( P_2O_3 + 3H_2O \rightarrow 2H_3PO_3 \) c) \( Cr_2O_3 + 6HCl \rightarrow 2CrCl_3 + 3H_2O \) d) \( SeO_2 + 2KOH \rightarrow K_2SeO_3 + H_2O \)

Step 1: Reaction A - Potassium Oxide with Water

1. Write the formulas for the reactants and products: Potassium oxide (K2O) reacts with water (H2O) to form potassium hydroxide (KOH). 2. Balance the equation: For this equation, we need equal numbers of each element on both sides. \( K_2O + H_2O \rightarrow 2KOH \) Now the equation is balanced: there are two potassium atoms, two oxygen atoms, and two hydrogen atoms on both the reactant and product sides.

Step 2: Reaction B - Diphosphorus Trioxide with Water

1. Write the formulas for the reactants and products: Diphosphorus trioxide (P2O3) reacts with water (H2O) to form phosphoric acid (H3PO3). 2. Balance the equation: For this equation, we need equal numbers of each element on both sides. \( P_2O_3 + 3H_2O \rightarrow 2H_3PO_3 \) Now the equation is balanced: there are two phosphorus atoms, six oxygen atoms, and six hydrogen atoms on both the reactant and product sides.

Step 3: Reaction C - Chromium (III) Oxide with Dilute Hydrochloric Acid

1. Write the formulas for the reactants and products: Chromium (III) oxide (Cr2O3) reacts with hydrochloric acid (HCl) to form chromium (III) chloride (CrCl3) and water (H2O). 2. Balance the equation: For this equation, we need equal numbers of each element on both sides. \( Cr_2O_3 + 6HCl \rightarrow 2CrCl_3 + 3H_2O \) Now the equation is balanced: there are two chromium atoms, three oxygen atoms, and six hydrogen atoms, and six chlorine atoms on both the reactant and product sides.

Step 4: Reaction D - Selenium Dioxide with Aqueous Potassium Hydroxide

1. Write the formulas for the reactants and products: Selenium dioxide (SeO2) reacts with aqueous potassium hydroxide (KOH) to form potassium selenite (K2SeO3) and water (H2O). 2. Balance the equation: For this equation, we need equal numbers of each element on both sides. \( SeO_2 + 2KOH \rightarrow K_2SeO_3 + H_2O \) Now the equation is balanced: there is one selenium atom, three oxygen atoms, two potassium atoms, and two hydrogen atoms on both the reactant and product sides.