Question

Write a balanced equation for each of the following processes: (a) On heating, ammonium nitrate produces nitrous oxide. (b) On heating, potassium nitrate produces potassium nitrite and oxygen gas. (c) On heating, lead nitrate produces lead(II) oxide, nitrogen dioxide \(\left(\mathrm{NO}_{2}\right),\) and oxygen gas.

Short answer

(a) NH4NO3 -> N2O + 2H2O. (b) 2KNO3 -> 2KNO2 + O2. (c) 2Pb(NO3)2 -> 2PbO + 4NO2 + O2.

Step-by-step solution

Identify the given compounds and products

For each given process, identify the compounds involved as both reactants and products.

Write the skeleton equation

Write the chemical reaction using the chemical formulas of the reactants and products without worrying about balancing yet. For (a), it's NH4NO3 -> N2O. For (b), it's KNO3 -> KNO2 + O2. For (c), it's Pb(NO3)2 -> PbO + NO2 + O2.

Balance the equations

Adjust the coefficients in front of each compound to ensure that the number of atoms of each element is the same on both sides of the equation. - For (a), NH4NO3 -> N2O + 2H2O is balanced. - For (b), 2KNO3 -> 2KNO2 + O2 is balanced. - For (c), 2Pb(NO3)2 -> 2PbO + 4NO2 + O2 is balanced.

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry. It ensures that the conservation of mass is respected in a chemical reaction. This means that the number of atoms for each element is identical on both sides of the equation. Imagine you have a scale, and you want it to be perfectly balanced. Similarly, your chemical equation should have an equal number of atoms of each element on both sides.

When balancing equations, start by writing down the unbalanced equation. Look at each element separately and adjust the coefficients, which are the numbers before the chemical formulas, to balance the different atoms.

Here's a tip: Always begin with the most complex molecule. Leave the elements that appear in their natural state (like oxygen or hydrogen) for last, as they are easier to balance later.

• Start with complex molecules.
• Balance by adjusting coefficients, not subscripts.
• Use whole numbers.
• Double-check your work.

Chemical Reactions

Chemical reactions involve the breaking and forming of bonds between atoms, leading to a transformation of substances. During a reaction, reactants are transformed into products. For example, when ammonium nitrate \(NH_4NO_3\) is heated, it decomposes into nitrous oxide \(N_2O\) and water.

There are different types of chemical reactions. In decomposition reactions, a single compound breaks down into simpler products, usually from the influence of heat, light, or electricity. Other common types of reactions include:

• Combustion
• Synthesis
• Single Replacement
• Double Replacement

Chemical reactions are all around us, from the air we breathe to the food we digest. Understanding these reactions helps us manipulate them for desired results, like producing oxygen in the decomposition of potassium nitrate \(KNO_3\).

Chemical Formulas

Chemical formulas show the elements present in a compound and the number of each type of atom. For example, the formula for water is \(H_2O\), indicating each molecule contains two hydrogen atoms and one oxygen atom. Knowing chemical formulas is crucial for writing and balancing chemical equations.

In formulas, the subscript numbers indicate the number of atoms of that element in the molecule. If there is no subscript, it is understood to be one. Formulas must accurately represent the compounds in a reaction. For instance, potassium nitrate is represented as \(KNO_3\), and its decomposition gives rise to potassium nitrite \(KNO_2\) and oxygen \(O_2\).

Remember, while you adjust coefficients when balancing equations, you should never change subscripts in chemical formulas, as this would change the actual compound. Subscripts are inherent to the compound's nature, while coefficients can be adjusted to conserve mass.

Stoichiometry

Stoichiometry is the quantitative study of reactants and products in a chemical reaction. It is like looking at a recipe for making a cake -- you need the right amount of each ingredient to get the desired result.

It uses balanced chemical equations to determine the proportions of materials involved in chemical reactions. This way, you can predict the amounts of products formed based on the amounts of reactants used. Using stoichiometry, chemists can answer questions like:

• "How much product will this reaction yield?"
• "What quantity of reactants is needed?"
• "What ratio should my reactants be in?"

Understanding stoichiometry helps in planning reactions in the lab to ensure that there is neither too much reactant wasted nor too little product formed.