# Segment D: Stoichiometric Calculations

This segment explores stoichiometric calculations and mole ratios.

## Segment D: Stoichiometric Calculations

This segment explores stoichiometric calculations and mole ratios.

### Science

Obtain, evaluate, and communicate information about how the Law of Conservation of Matter is used to determine chemical composition in compounds and chemical reactions.

Use mathematics and computational thinking to balance chemical reactions (i.e., synthesis, decomposition, single replacement, double replacement, and combustion) and construct an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Plan and carry out an investigation to determine that a new chemical has been formed by identifying indicators of a chemical reaction (e.g., precipitate formation, gas evolution, color change, water production, and changes in energy to the system).

Use mathematics and computational thinking to apply concepts of the mole and Avogadro's number to conceptualize and calculate

- percent composition
- empirical/molecular formulas
- mass, moles, and molecules relationships
- molar volumes of gases

Use mathematics and computational thinking to identify and solve different types of reaction stoichiometry problems (i.e., mass to moles, mass to mass, moles to moles, and percent yield) using significant figures.

**atomic mass unit **- equals 1/12 the mass of a carbon atom.

**Avagadro's number** - the number of atoms in a mole, equal to 6.02x10^23 atoms.

**conversion factor **- a ratio expressed as a fraction that equals one.

**dimensional analysis** - the sequential application of conversion factors expressed as fractions and arranged so that any dimensional unit can be cancelled out until the desired set of dimensional units is obtained.

**empirical formula** - the simplest formula of a compound expressed as the smallest possible ratio of the elements.

**equivalence statement **- a statement that shows the quantities and units that are equal to each other.

**excess reactant** - the reactant in a chemical reaction that remains when a reaction stops once the limiting reactant is completely consumed.

**limiting reactant **- the reactant in a chemical reaction that limits the amount of product formed.

**molar mass **- the mass, in grams, of a mole of a substance.

**molar volume** - the volume of one mole of any gas at standard temperature and pressure.

**mole** - The SI unit that measures the amount of matter a substance has; one mole is equal to 6.022x10^23 representative particles, also known as Avagadro's number.

**mole ratio **- the ratio of moles of one substance to the moles of another substance in a balanced equation.

**molecular formula** - a formula which states the exact number and type of each atom present in a molecule of a substance.

**percent composition** - the percentage by mass of each element in a compound.

**percent yield **- the ratio of the actual yield to the theoretical yield of a material.

**stoichiometry **- the calculation of the quantities of reactants and products involved in a chemical reaction.

**theoretical yield** - the amount of product formed from the complete conversion of a limiting reactant in a chemical reaction.

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## Chemistry Matters Segments

### Unit 6: The Mole and Stoichiometry

In this unit, students learn the mathematical tool of dimensional analysis, alternately called the factor-label method. Students also explore how to predict and measure the outcome of a reaction.