Acids and Bases
Key Terms
1. Solution: A mixture of two or more substance that is homogenous or the same throughout.
2. Solute: The substance that changes state when a solution is prepared or is present in the smallest amount.
3. Solvent: The substance that does not change state when a solution prepared or is present in the largest amount.
4. Dissociate: When a chemical compound is dissolved in a solvent, e.g. water, and separates into 2 or more ions.
5. Ion: A chemical compound that has a negative or a positive charge e.g. cation is positive, anion is negative
6. Acid: A chemical compound that dissociates into a hydrogen ion(s) and a negatively charged ion when in H2O.
7. Base: A chemical compound that dissociates into hydroxide ion(s) and a positively charged ion when in H2O.
8. Hydrogen ion: acid mixed with water, it dissociates into a negatively charged ion and hydrogen ion H+. A
hydrogen ion is a hydrogen atom that has lost 1 electron, only the nucleus and single proton remain.
9. Hydroxide ion: base is mixed with water, it dissociates into a positively charged ion and hydroxide ion, OH-. A
hydroxide ion is H2O molecule that has lost a hydrogen ion, H+, leaving its electron.
10. pH scale: A linear scale from 0-14 that measures the hydrogen ion concentration.
11. Concentration: The ratio of the amount of solute to the volume of solvent, certain mass or volume of solute that
is dissolved in 1 ml, 100 ml or 1 liter.
12. Dilution: When a less concentrated solution is prepared by adding additional solvent.
13. Neutralization: An acid and base reacts to form a H2O molecule and reduce the hydrogen ion concentration.
Investigation One
A) Acids are a group of chemical compounds that produce hydrogen ions (H+) when mixed with water
1) acids- least 1 hydrogen(H) atom in their chemical formula produce (H+) when acid is mixed with H20 the acid
chemically reactive; H+ is very reactive
2) Concentration of (H+) depends on amount of acid dissolved; large amount of dissolved acid results large number
of (H+) in water
3) molecule of strong acid hydrochloric acid (HCl) separates into one hydrogen ion (H+) and negative chloride (Cl-)
4) molecule of weak acid vinegar, does not completely separate into hydrogen ion (H+) and a negative ion, lower
concentration of hydrogen ions
5) pH scale allows a scientist to measure the concentration of hydrogen ions (H+)
a) 0 represents high concentration of hydrogen ions (H+)
b) 14 represents low concentration of hydrogen ions (H+)
c) solution with a pH value of 8 or higher are called basic
B) Bases group of chemical compounds that produce ions when mixed with water
1) base- least 1 oxygen (O) and one hydrogen (H) atom in chemical formulas when (H2O) produces hydroxide ions
(OH-) plus positively charged ion
2) concentration of base increases, concentration of hydrogen ions (H+) decreases because of reaction with
hydroxide ions (OH-)
C) Water considered both an acid and a base produce hydrogen ions (H+) and hydroxide ions (OH-) low
concentrations
1) pure water pH of 7 considered neutral; 0 to 7 acidic range of pH scale, 7 to 14 basic range of pH Scale
D) Acids release H+ ions when they are mixed with water and bases remove H+ ions when mixed with water
E) Stronger acids able to release more H+ ions when mixed with water resulting in higher concentration of H+ ions;
weaker acids release fewer H+ ions resulting in a lower concentration of H+ ions
F) Stronger bases able to remove more H+ ions when mixed with water resulting in lower concentration of H+ ions;
weaker bases remove fewer H+ ions resulting in a higher concentration of H+ ions
Investigation Two
A) ratio of the amount of solute to solvent is a concentration; concentration of solute is amount of solute that is
dissolved in certain volume of solvent to make a solution
1) dissolving large amount of solute in a certain volume would result in a high concentration
2) dissolving small amount of solute in same volume results in a low concentration
B) pH solution increases, concentration of H+ ions decreases; concentration decreases 10 times is increased by 1pH;
as the concentration increases 10 times the pH decreases by 1 pH unit
C) concentration of hydrogen ions (H+) can be changed by diluting a solution by adding more solvent
Investigation Three
A) acidic region has higher concentration, basic region has lower concentration; neutral region has intermediate
concentration of H+ ions
B) when an acid and base react with one another the concentration of (H+) ions decreases, H+ ions and OH- ions react
to produce water and decrease the concentration of H+ ions
C) serial solution- dilution method where each solution is diluted by a dilution factor of 10