Question

Write balanced equations for the preparation of sodium nitrite by (a) heating sodium nitrate and (b) heating sodium nitrate with carbon.

Short answer

(a) \(2NaNO_3 \rightarrow 2NaNO_2 + O_2\); (b) \(4NaNO_3 + C \rightarrow 2NaNO_2 + 4CO_2 + N_2\).

Step-by-step solution

Understanding the Reaction Process (a)

For the preparation of sodium nitrite by heating sodium nitrate, recognize that sodium nitrate (\( NaNO_3 \)) decomposes upon heating to form sodium nitrite (\( NaNO_2 \)) and oxygen (\( O_2 \)).

Write the Unbalanced Equation (a)

The decomposition of sodium nitrate can be initially written as:\[NaNO_3 ightarrow NaNO_2 + O_2\]

Balance the Equation (a)

Balance the chemical equation by ensuring the same number of each type of atom on both sides. The balanced equation is:\[2NaNO_3 ightarrow 2NaNO_2 + O_2\]

Understanding the Reaction Process (b)

For the preparation of sodium nitrite by heating sodium nitrate with carbon, recognize that sodium nitrate reacts with carbon to form sodium nitrite, carbon dioxide (\( CO_2 \)), and nitrogen gas (\( N_2 \)).

Write the Unbalanced Equation (b)

The reaction can be initially represented as:\[NaNO_3 + C ightarrow NaNO_2 + CO_2 + N_2\]

Balance the Equation (b)

Balance the chemical equation by ensuring the same number of each type of atom on both sides. The balanced equation can be written as:\[4NaNO_3 + C ightarrow 2NaNO_2 + 4CO_2 + N_2\]

Key concepts

Sodium Nitrite Preparation

To prepare sodium nitrite, different methods can be used depending on the materials available. One conventional method is through the decomposition of sodium nitrate by heating. When heated, sodium nitrate (\(NaNO_3\)) breaks down into sodium nitrite (\(NaNO_2\)) and oxygen gas (\(O_2\)). This reaction requires careful control of temperature to ensure it proceeds properly.
Another method involves using carbon to assist in the conversion. Here, sodium nitrate reacts with carbon when heated, producing sodium nitrite, carbon dioxide (\(CO_2\)), and nitrogen gas (\(N_2\)). Both these methods are important in industrial settings for producing sodium nitrite efficiently. Understanding both reactions provides insights into alternative production strategies.

Balanced Chemical Equations

A balanced chemical equation is crucial because it reflects the conservation of mass. According to the law of conservation of mass, matter is neither created nor destroyed in a chemical reaction. Thus, a balanced equation has the same number of each type of atom on both sides of the equation.

• Identify the reactants and products.
• Count the number of atoms for each element.
• Adjust coefficients to balance the atoms.

When preparing sodium nitrite from sodium nitrate, the initial unbalanced equation is \(NaNO_3 \rightarrow NaNO_2 + O_2\). By balancing, the equation becomes \(2NaNO_3 \rightarrow 2NaNO_2 + O_2\), ensuring all atoms are accounted for on each side.

Decomposition Reactions

Decomposition reactions involve a single compound breaking down into two or more simpler substances. In the preparation of sodium nitrite from sodium nitrate, a decomposition reaction occurs when sodium nitrate decomposes to form sodium nitrite and oxygen gas.
Such reactions typically require energy input, often as heat, to proceed. This is why heating is used in the process. Decomposition reactions are characterized by a single reactant transforming into multiple products, demonstrating the compound's internal breakdown.

Reaction Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It allows chemists to predict the quantities of substances consumed and produced. For balanced equations, stoichiometry involves using the coefficients to determine the ratio of reactants to products.
In the sodium nitrite preparation from sodium nitrate, the balanced equation \(2NaNO_3 \rightarrow 2NaNO_2 + O_2\) conveys that two moles of sodium nitrate yield two moles of sodium nitrite and one mole of oxygen. This proportion helps in scaling reactions in industrial processes, ensuring the efficient use of resources and predicting yields accurately.