[cs_content][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]The Acidic Environment > 3. Acids >
Describe the use of the pH scale in comparing acids and bases[/cs_text][/cs_column][/cs_row][/cs_section][cs_section parallax=”false” separator_top_type=”none” separator_top_height=”50px” separator_top_angle_point=”50″ separator_bottom_type=”none” separator_bottom_height=”50px” separator_bottom_angle_point=”50″ style=”margin: 0px;padding: 45px 0px;”][cs_row inner_container=”true” marginless_columns=”false” style=”margin: 0px auto;padding: 0px;”][cs_column fade=”false” fade_animation=”in” fade_animation_offset=”45px” fade_duration=”750″ type=”1/1″ style=”padding: 0px;”][cs_text]
- Pure water contains very small amounts of hydrogen and hydroxide ions due to self-ionisation:
- At 25°C, the concentration of hydrogen ions is 1.0 x 10-7 mol L-1.
- When an acid is added to water, the above equilibrium shifts in the reverse direction, causing a decrease in the hydroxide concentration.
- When a base is added to water, the above equilibrium shifts in the reverse direction, causing a decrease in hydrogen ion concentration.
- Thus, acidic solutions have a higher concentration of hydrogen ions than 1.0 x 10-7 mol L-1, while basic solutions have a lower concentration of hydrogen ions than 1.0 x 10-7 mol L-1.
- The pH scale is used to compare the concentration of hydrogen ions in solutions of acids and bases.
- It is a logarithmic scale, as the concentration of hydrogen ions would require a very large linear scale.

THE PH SCALE
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