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The Acidic Environment > 1. Indicators >
Perform a first-hand investigation to prepare and test a natural indicator[/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]
- To prepare a natural indictor:
- Select a suitable coloured plant material, such as purple cabbage.
- Extract the colour from the plant material by either:
- Boiling it in water.
- Crushing it with water or alcohol using a mortar and pestle.
- Decant the solution from the solid.
- To test a natural indicator:
- Dip the ends of two strips of filter paper into the indicator and allow to dry.
- Using an eyedropper, apply a drop of strong acid to one strip and a drop of strong base to the other strip.
- Record any changes in colour.
- Add additional drops of acid and base to the strips until no further changes in colour are observed.
- If an indicator is prepared from purple cabbage, the following colours should be observed:
- Initial/Neutral colour: Purple
- Colour when exposed to strong acid: Pink, then Red
- Colour when exposed to strong base: Blue-Green, then Yellow
Purple cabbage[/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;”][x_video_embed no_container=”false” type=”16:9″][/x_video_embed][/cs_column][/cs_row][/cs_section][/cs_content]