Aqueous Reactions: Precipitation, Acids, and Bases

Vocabulary flashcards covering aqueous precipitation reactions, solubility guidelines, acid-base definitions (Arrhenius and Brønsted-Lowry), strong and weak electrolytes, neutralization, and gas-forming reactions.

Precipitate

An insoluble solid compound formed during a chemical reaction in solution.

Precipitation Reaction

A chemical reaction occurring in aqueous solution that, when written as a molecular reaction, has the form of an exchange reaction.

Exchange Reaction

A reaction that, when written as a molecular equation, appears to involve the exchange of parts between the two reactants, also known as a double displacement or metathesis reaction ($AB + CD \rightarrow AD + CB$).

Single Displacement Reaction

A chemical reaction that follows the general form $AB + C \rightarrow A + CB$.

Solubility Rule: Group 1/1A and Ammonium

Any substance containing a Group 1/1A cation or an ammonium ($NH_4^+$) cation is soluble, with no exceptions.

Solubility Rule: Nitrates and Acetates

Any substance containing a nitrate ($NO_3^-$) or acetate ($CH_3COO^-$) anion is soluble, with no exceptions.

Solubility Rule: Halogens

Most substances with a halogen ($Cl^-$, $Br^-$, $I^-$) anion are soluble, with the exceptions of the cations $Pb^{2+}$, $Hg_2^{2+}$, and $Ag^+$.

Solubility Rule: Sulfates

Most sulfates ($SO_4^{2-}$) are soluble, with the exceptions of the cations $Pb^{2+}$, $Hg_2^{2+}$, $Ag^+$, $Ca^{2+}$, $Ba^{2+}$, and $Sr^{2+}$.

Solubility Rule: Carbonates and Phosphates

Most carbonates ($CO_3^{2-}$) and phosphates ($PO_4^{3-}$) are insoluble, except when paired with Group 1/1A cations or ammonium ($NH_4^+$).

Solubility Rule: Hydroxides

Most hydroxides are insoluble, except when the counterion is from Group 1/1A, is $NH_4^+$, or is $Ca^{2+}$, $Ba^{2+}$, or $Sr^{2+}$.

Acid (Physical Properties)

A solution that has a sour taste and causes specific color changes in an indicator dye.

Base (Physical Properties)

A solution that has a bitter taste, is soapy to the touch, and causes specific color changes in an indicator dye.

Arrhenius Acid

A substance that produces hydrogen ions ($H^+$) when dissolved in water.

Arrhenius Base

A substance that produces hydroxide ions ($OH^-$) when dissolved in water.

Brønsted-Lowry Acid

A species (molecule or ion) that donates a proton ($H^+$) to another species in a proton-transfer reaction.

Brønsted-Lowry Base

A species (molecule or ion) that accepts a proton from another species in a proton-transfer reaction.

Strong Acid

An acid that ionizes completely ($100\%$) into ionic form in water, acts as a strong electrolyte, and is limited to six specific compounds: $HCl$, $HBr$, $HI$, $HNO_3$, $H_2SO_4$, and $HClO_4$.

Weak Acid

An acid that partly ionizes in water, tends to be a weak electrolyte, and exists in solution mostly as non-ionized molecules (examples include $HCN$ and $HF$).

Strong Base

A base present in aqueous solution entirely as ions (one of which is $OH^-$) that acts as a strong electrolyte, composed of Group 1A and 2A elements excluding beryllium hydroxide: $LiOH$, $NaOH$, $KOH$, $Ca(OH)_2$, $Sr(OH)_2$, and $Ba(OH)_2$.

Weak Base

A base that undergoes partial ionization in solution and acts as a weak electrolyte, such as ammonia ($NH_3$).

Neutralization Reaction

A reaction between an acid and a base that results in an ionic compound, and possibly water.

Salt

An ionic compound that is produced as a product of a neutralization reaction.

Polyprotic Acid

An acid that yields two or more acidic hydrogens per molecule, signified in its formula by the acidic hydrogens being listed first (e.g., $H_2SO_4$).

Gas-Forming Acid-Base Reaction

A reaction in which an acid reacts with a sulfide, carbonate, or sulfite to generate a gas such as $CO_2(g)$ or $H_2S(g)$.