Acids and Bases

Acids and Bases

Investigation OneAcids and Bases

Solution: homogeneous mixture of two substances:

Solute: the substance that changes state (Sugar) + Solvent: the substance that does not change (Water)

Solution (sugar water)

Concentration: the amount of anything dissolved in a solution; the amount of solute to the volume of solvent (mass/volume)

Solutions

Dissociation: chemical compound dissolves in water the solute separates into two or more ions

Ions: chemical compound that has a positive or negative charge◦ Cations (+) positive charge◦ Anions (-) negative charge

Solutions

group of chemical compounds that produce hydrogen ions (H⁺) when mixed with water

Every acid has at least one hydrogen (H) atom in the chemical formula that produces hydrogen ions (H⁺)

HCL H⁺ + Cl⁻◦ producing a H⁺ also produces a negative ion, Cl⁻

The chemical properties of acids result from the production of H⁺ which are very reactive

Acids

Greater amount of acid dissolved = greater amount of H⁺

The concentration of H⁺ depends on the acid

Molecules of strong acids full separate into H⁺ and a (-) ion

Molecules of weak acids do not completely separate resulting in a low conc. of H ⁺

Acids

A group of chemical compounds that produce hydroxide ions (OH⁻) when mixed with water

Every base has at least one Oxygen and one Hydrogen atom in their chemical formula that produces hydroxide ions (OH⁻)

NaOH Na⁺ + OH⁻

When a base is mixed with water it produces OH ⁻

Bases

pH Scale pH scale allows scientist to measure the

concentration of hydrogen ions (H⁺)

Scale starts at 0 with a high conc. of (H⁺) and continues to 14 with a low conc. of (H⁺)

pH Scale Strongest acids are found at 0 pH of 7 is neutral= neither acidic or basic (H₂O)

Substances with a pH higher than 7 are basic with 14 being a strong base

0(Strong Acid) 7(neutral) 14(strong Base) High conc. of H ⁺ Low conc. of H ⁺

pH Scale

When an acid is mixed with a base the OH ⁻ react with the H⁺ to form water.

OH ⁻ removes hydrogen from the solution(OH⁻ + H⁺ H₂O)

When an acid and a base react to form H₂O and reduce the H⁺ conc. is called neutralization

Mixing Acids and Bases

Water can be considered both an acid and a base since it can produce OH⁻ and H⁺ in low concentrations◦ H₂O OH⁻ + H⁺

Water is considered to be neutral and has a pH of 7

Water- Acid or a Base?

Acids release H⁺ ions when they are mixed with water and bases remove OH⁻ ions when they are mixed with water.

Properties that make Acids and Bases Chemically Reactive

Stronger acids are able to release more H⁺ ions when mixed with water resulting in a Higher conc. of H⁺

Weaker acids release fewer H⁺ ions resulting in a lower conc. of H⁺ ions

Relationship between Conc. of H⁺ ions in a solution and the Chemical Reactivity of strong and weak acids

Stronger bases are able to remove more H⁺ ions when mixed with water resulting in a lower conc. of H⁺

Weaker bases remove fewer H⁺ ions resulting in a higher conc. of H⁺ ions

Relationship between Conc. of H⁺ ions in a solution and the Chemical Reactivity of strong and weak Bases

Investigation Two

The concentration of a solute is described as the amount of a solute that is dissolved in a certain volume of solvent to make a solution.

Large amount of solute= higher conc. Smaller amount of solute= lower conc.

Concentration

A Less concentrated solution can be made by adding less solute or by diluting a more concentrated solution by adding more solvent

Dilution: the addition of more solvent to create a less concentrated dilution

Concentration

A serial dilution is the stepwise dilution of a substance in solution. 

Using serial dilution, a series of less and less concentrated solution can be made by a dilution factor of 10

Each time the pH of the solution increases by 1 pH unit, the conc. H⁺ was diluted 10 times, so the conc. is 10 times less

Serial Dilution

Serial DilutionEach time the pH of the solution increases

by one pH unit, the conc. H⁺ was diluted 10 times, so the conc. is 10 times less

As the pH of a solution increases, the conc. of H⁺ ions decreases.

As the conc. is decreased 10 times , the pH is increased by 1 pH unit.

As the conc. is increased 10 times, the pH is decreased by 1 pH unit.

Relationship between the pH of a solution and the conc. of H⁺

The conc. of H⁺ can be changed by diluting a solution by adding more solvent

Changing the Conc. of H⁺ ions

Investigation 3

Another way to decrease the conc. of H⁺ ions in a solution is to perform a chemical reaction by dissolving both and acid and a base in water

Acids dissolved in water will produce H⁺ ions Bases dissolved in water will produce OH⁻

Acids, Bases, and Water

When acids and bases are both dissolved in water a chemical reaction called neutralization occurs

Na⁺ + OH⁻ + H⁺ + Cl⁻ → H₂O + Na ⁺ + Cl⁻

As a result the conc. of H ⁺ ions decreases, the pH increases

Neutralization

Acid + Base = Neutralization

If a small amount of a base is added to a larger amount of an acid, only a small number of H ⁺ will react with the small number of OH⁻

Neutralization

When an acid and a base react, H ⁺ ion and OH⁻ ions react to produce water (H₂O) and decrease the conc. of H ⁺ ions

Conc. of H ⁺ ion when Acids and Bases React