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Formulas, Equations, and Moles
Objectives
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Chapter Learning Goals- Write and balance chemical equations for simple chemical reactions.
- Calculate molar mass.
- Interconvert grams, moles, and numbers of formula units.
- Determine the number of moles and grams of one reactant needed to react with a given number of moles and grams of another reactant, and the number of moles and grams of product(s) that result from the reaction.
- Calculate percent yield.
- Calculate the mass of products produced from a given mass of reactants when the theoretical yield is less than 100%.
- Identify the limiting and excess reactants in a reaction mixture.
- Determine the mass of excess reactant remaining at the end of a reaction and the mass of product(s) produced.
- Describe how to prepare a solution of known molarity by dissolving a solid in a solvent, and by diluting a more concentrated solution.
- Interconvert solution molarity, solution volume, solute moles, and solute grams.
- Determine the volume of one reactant solution needed to react with a given volume of a second reactant solution.
- Determine the percent composition and empirical formula of a compound.
- Use combustion analysis data to obtain the empirical formula of a compound containing carbon, hydrogen, and one other element.
- Determine the molecular formula of a compound from empirical formula and molar mass.
It's sometimes possible when beginning the study of chemistry to lose sight of the fact that reactions are at the heart of the science. New words, ideas, and principles are sometimes introduced so quickly that the central concern of chemistry—the change of one substance into another—gets lost in the rush.
In this chapter, we'll begin learning how to describe chemical reactions, starting with a look at the conventions for writing chemical equations and at the necessary mass relationships between reactants and products. Since most chemical reactions are carried out using solutions rather than pure materials, we'll also discuss units for describing the concentration of a solution. Finally, we'll see how chemical formulas are determined and how molecular masses are measured.
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