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Ch.22 - Chemistry of the Nonmetals
All textbooksBrown 15th EditionCh.22 - Chemistry of the NonmetalsProblem 65
Chapter 22, Problem 65

Complete the exercises below. Complete and balance the following equations: e. Ca(CN)₂ (s) + HBr (aq) → ?

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Identify the reactants and products: The reactants are calcium cyanide, Ca(CN)_2, and hydrobromic acid, HBr. The products will be calcium bromide, CaBr_2, and hydrogen cyanide, HCN.
Write the unbalanced chemical equation: Ca(CN)_2 (s) + HBr (aq) → CaBr_2 (aq) + HCN (g).
Balance the equation by adjusting coefficients: Start by balancing the calcium (Ca) atoms. There is 1 Ca atom on both sides, so they are balanced.
Balance the cyanide (CN) groups: There are 2 CN groups in Ca(CN)_2, so you need 2 HCN molecules on the product side. Adjust the equation to: Ca(CN)_2 (s) + HBr (aq) → CaBr_2 (aq) + 2 HCN (g).
Balance the bromine (Br) atoms: There are 2 Br atoms in CaBr_2, so you need 2 HBr molecules on the reactant side. The balanced equation is: Ca(CN)_2 (s) + 2 HBr (aq) → CaBr_2 (aq) + 2 HCN (g).

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Balancing Chemical Equations

Balancing chemical equations is essential to ensure that the law of conservation of mass is upheld, meaning the number of atoms of each element must be the same on both sides of the equation. This involves adjusting coefficients in front of compounds to achieve balance, reflecting the stoichiometry of the reaction.
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Types of Chemical Reactions

Understanding the types of chemical reactions, such as double displacement reactions, is crucial for predicting the products of a reaction. In this case, calcium cyanide (Ca(CN)₂) reacts with hydrobromic acid (HBr), leading to the formation of new compounds through the exchange of ions.
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Solubility Rules

Solubility rules help determine whether a compound will dissolve in water or precipitate out of solution. In this reaction, knowing that calcium bromide (CaBr₂) is soluble while calcium cyanide may form a precipitate can guide the prediction of the products and the overall reaction behavior.
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Related Practice