Complete and balance each gas-evolution equation. a. HBr(aq) + NiS(s) → d. HClO₄(aq) + Li₂CO₃(aq) →

Verified step by step guidance

1. Step 1: Identify the reactants and products for each reaction. For reaction (a), the reactants are HBr(aq) and NiS(s). For reaction (d), the reactants are HClO_4(aq) and Li_2CO_3(aq).
2. Step 2: Determine the type of reaction. Both reactions are gas-evolution reactions, which typically involve the formation of a gas as one of the products.
3. Step 3: Predict the products. For reaction (a), HBr reacts with NiS to form H_2S(g) and NiBr_2(aq). For reaction (d), HClO_4 reacts with Li_2CO_3 to form CO_2(g), H_2O(l), and LiClO_4(aq).
4. Step 4: Write the unbalanced chemical equations. For reaction (a), it is HBr(aq) + NiS(s) → H_2S(g) + NiBr_2(aq). For reaction (d), it is HClO_4(aq) + Li_2CO_3(aq) → CO_2(g) + H_2O(l) + LiClO_4(aq).
5. Step 5: Balance each equation by adjusting coefficients to ensure the same number of each type of atom on both sides of the equation. Start with the most complex molecule and balance elements one at a time, checking each element as you proceed.

Key Concepts

Gas-Evolution Reactions

Gas-evolution reactions are chemical reactions that produce a gas as one of the products. These reactions often involve the combination of an acid with a carbonate or sulfide, leading to the release of gases such as CO2 or H2S. Understanding the types of gases produced and the conditions under which they form is crucial for balancing these equations.

Balancing Chemical Equations

Balancing chemical equations involves ensuring that the number of atoms of each element is the same on both sides of the equation. This is achieved by adjusting the coefficients of the reactants and products. A balanced equation reflects the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between reactants. In the context of the given question, strong acids like HBr and HClO4 react with bases or salts, leading to the formation of new products, including gases. Recognizing the properties of acids and bases is essential for predicting the products of these reactions and balancing the equations correctly.