Gr 10 Science Lab

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Acid and Bases 1

Determining Acids and Bases

SNC-2D1

April 02, 2013
Acid and Bases 2

Purpose
The purpose of this chemistry lab is to investigate and find patterns/tendencies between substances Introduction
An acid is a solution that has more free hydrogen ions (H + ) than hydroxyl ions (OH - ) and a pH less than 7. A base is a solution that has less free hydrogen ions (H + ) than hydroxyl ions (OH - ) and a pH of more than 7. In the late 1800s, the Swedish scientist Svante Arrhenius purposed that water can dissolve many compounds by separating them into their individual ions. Arrhenius suggested that acids are compounds that contain hydrogen and can dissolve in water to release hydrogen ions into solution. For example, hydrochloric acid (HCl) dissolves in water as follows: HCl| H2O

| H+(aq)|  + | Cl-(aq)|
Arrhenius defined bases as substances that dissolve in water to release hydroxide ions (OH-) into solution. For example, a typical base according to the Arrhenius definition is sodium hydroxide (NaOH): NaOH| H2O

  | Na+(aq)|  + | OH-(aq)|
The Arrhenius definition of acids and bases explains a number of things. Arrhenius's theory explains why all acids have similar properties to each other (and, conversely, why all bases are similar): because all acids release H+ into solution (and all bases release OH-). The Arrhenius definition also explains Boyle's observation that acids and bases counteract each other. This idea, that a base can make an acid weaker is called neutralization.

So an acid is a solution that has more free hydrogen ions (H + ) than hydroxyl ions (OH - ) and a pH less than 7. A base is a solution that has less free hydrogen ions (H + ) than hydroxyl ions (OH - ) and a pH of more than 7.

Acid and Bases 3

(A standard pH scale from 0-14, Acidic to base. 0-7 is acidic, 7 is neutral, 7-14 is basis ) I predict that that the substances that have a stronger smell to them will be acidic and...
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