A chemist dissolves a 1.497-g sample of a type of metal (an alloy of Sn, Pb, Sb, and Cu) in nitric acid, and metastannic acid, \(\mathrm{H}_{2} \mathrm{SnO}_{3}\), is precipitated. She heats the precipitate to drive off the water, which leaves \(0.4909 \mathrm{g}\) of tin(IV) oxide. What was the percentage of tin in the original sample?

Stoichiometry is the study of the quantitative relationships or ratios of reactants and products in chemical reactions. It involves using the coefficients from balanced chemical equations to calculate the amounts of substances involved. In the context of the problem provided, stoichiometry allows you to determine the amount of tin (Sn) present in the tin(IV) oxide (SnO₂) compound. Here's a clearer view of what stoichiometry looks like:

• We know that the reaction between tin and oxygen yields tin(IV) oxide.
• The balanced equation would show that one mole of tin reacts with two moles of oxygen to form one mole of tin(IV) oxide.
• Therefore, the stoichiometric ratio of tin to tin(IV) oxide is 1:1.

Using this stoichiometric relationship, you can then calculate the mass of tin in a given mass of tin(IV) oxide, which is essential for working out the percentage composition of an alloy.

The molar mass is the weight of one mole of a substance, usually expressed in grams per mole (g/mol). It is a crucial element in chemical calculations and stoichiometry, as it allows chemists to convert between the mass of a substance and the number of moles. In our problem:

• We calculate the molar mass of tin(IV) oxide (SnO₂) by adding the molar mass of one mole of tin to the molar mass of two moles of oxygen.
• For tin (Sn), the molar mass is 118.71 g/mol, and for oxygen (O), it is 16.00 g/mol. So, the total molar mass of SnO₂ is 118.71 + (2 × 16.00) = 150.71 g/mol.
• Knowing the molar mass of tin(IV) oxide allows you to find out how much tin is in a sample of SnO₂.

For instances like the textbook exercise, understanding molar masses leads to accurate determination of the composition of the alloy in question.

Chemical reactions involve the transformation of one or more substances into new substances. These transformations occur during the breaking and forming of chemical bonds. When dealing with chemical reactions, conservation of mass is an important principle to keep in mind – matter is not created or destroyed during a chemical reaction. For example, when our metal alloy reacts with nitric acid, different products are formed, including tin(IV) oxide. The precipitation and subsequent heating process are part of a series of chemical reactions that ultimately allow the chemist to isolate tin in its oxide form. Each chemical reaction can be represented by a balanced chemical equation, which serves as a recipe that describes the reactants, products, and their respective quantities.

Tin(IV) oxide, denoted as SnO₂, is an inorganic compound where a single tin (Sn) atom is bonded to two oxygen (O) atoms. In this textbook’s exercise:

• The chemist obtained tin(IV) oxide by heating the precipitate to drive off water.
• The mass of this oxide provides direct information about the amount of tin present in the original alloy.
• The compound itself is important since the way the elements are combined provides insights into the ratios used to calculate the percentage of each element in a compound.
• In our specific scenario, tin(IV) oxide becomes a means to understand the amount of tin in the original alloy, which links back to the concept of percentage composition.

Knowing the role of tin(IV) oxide in this chemical context is invaluable for interpreting experimental results and understanding the underlying stoichiometry in the exercise.