Chemistry Lecture Notes: Stoichiometry, Organic Compounds, and Energetics

These flashcards cover fundamental chemistry concepts including stoichiometry, percentage composition, naming organic compounds, acid-base properties, and chemical energetics.

Empirical formula

The simplest ratio in which atoms combine.

Molecular formula

The actual numbers of atoms that combine to form a molecule.

Calculation for $n$ in Molecular Formula

$$n = \frac{\text{Molar Mass of Compound}}{\text{Empirical Formula Mass}}$$

Alkanes

A family of hydrocarbons characterized by carbon-carbon single bonds and the general formula $C_nH_{2n+2}$. Names end in -ane.

Alkenes

A family of hydrocarbons characterized by carbon-carbon double bonds and the general formula $C_nH_{2n}$. Names end in -ene.

Alkynes

A family of hydrocarbons characterized by carbon-carbon triple bonds and the general formula $C_nH_{2n-2}$.

Alcohols

Organic compounds whose names end in -ol.

Carboxylic acids

Organic compounds whose names end in -oic acid.

meth-

A prefix in organic chemistry names meaning $1$ carbon atom.

eth-

A prefix in organic chemistry names meaning $2$ carbon atoms.

prop-

A prefix in organic chemistry names meaning $3$ carbon atoms.

but-

A prefix in organic chemistry names meaning $4$ carbon atoms.

pent-

A prefix in organic chemistry names meaning $5$ carbon atoms.

hex-

A prefix in organic chemistry names meaning $6$ carbon atoms.

Relative formula mass ($M_r$)

The relative atomic mass multiplied by how many atoms there are in a formula.

Percentage composition

The percent by mass of each element in a compound, calculated as $\text{\% by mass} = \frac{\text{mass of element}}{\text{mass of compound}} \times 100\%$ or $\frac{A_r \times 100\%}{M_r}$.

Mole

A number equal to the number of carbon atoms in exactly $12$ grams of pure carbon-12, equivalent to Avogadro's number ($6.02 \times 10^{23}$).

Avogadro's number

$6.02 \times 10^{23}$ particles per mole.

Mole ratios

A comparison of the moles of substances in a balanced chemical equation using coefficients.

Molar volume

The volume occupied by one mole of a gas at a specified temperature and pressure, typically $22.4\,dm^3$ at STP or $24\,dm^3$ at room condition.

Chemical formula

The composition of a substance represented using chemical symbols and numbers.

Acids

A group of soluble chemicals that produces hydrogen ions ($H^+$) when dissolved in water, tastes sour, turns blue litmus paper red, and reacts with alkalis to form salt and water only.

Alkalis

A base that is soluble in water, produces hydroxide ions ($OH^-$), has a bitter taste and soapy feel, turns red litmus paper blue, and reacts with acids to form salt and water only.

Neutral substance

A substance that is neither acid nor alkali.

Indicator

A chemical that turns a different color depending on if it is added to acid or alkali, such as litmus paper.

pH scale

A scale from $1$ to $14$ used to measure the strength of an acid or alkali, where $1$ is a strong acid, $7$ is neutral, and $14$ is a strong alkali.

Relative atomic mass ($A_r$)

The weighted average of the masses of the isotopes on a scale where a carbon-12 atom has a mass of exactly $12$ units, measured in $g/mol$.

Exothermic reactions

Reactions where heat is released ($\Delta H$ is negative), bonds are made, and the surroundings become warmer.

Endothermic reactions

Reactions where energy is taken in ($\Delta H$ is positive), bonds are broken, and the surroundings become colder.

Dynamic equilibrium

A state in a chemical reaction where the forward and backward reactions occur at the same rate, resulting in no overall change in the system.