How is litmus obtained from lichens? Find out and write a short research report.
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Answer:
determine the pH of an aqueous solution by treating filter paper with any of the common pH indicators. One of the first indicators used for this purpose was litmus.
Litmus paper is paper that has been treated with a specific indicator—a mixture of 10 to 15 natural dyes obtained from lichens (mainly Roccella tinctoria) that turns red in response to acidic conditions (pH 7). When the pH is neutral (pH = 7), then the dye is purple.
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Answer:
Here you go mate;
Litmus paper is a paper that has been treated with a specific indicator - a mixture of 10 to 15 natural dyes obtained from lichens (mainly Roccella Tinctoria) that turns red in response to acidic conditions (pH 7). When the pH is neutral (pH = 7) , the dye is purple.
HISTORY
The first known use of litmus was around 1300 CE by Spanish alchemist Arnaldus de Villa Nova. The blue dye has been extracted from lichens since the 16th century. The word "litmus" comes from the old Norse word for "dye" or "color".
While all litmus paper acts as pH paper , the opposite is not true. It's incorrect to refer to all pH paper as "litmus paper".
LITMUS TEST
To perform the test, place a drop of liquid sample on a small strip of paper or dip a piece of litmus paper in a small specimen of the sample. Ideally, don't dip litmus paper in an entire container of a chemical - the dye could contaminate a potentially valuable sample.
The litmus test is a quick method of determining whether a liquid or gaseous solution is acidic or basic ( alkaline ) . The test can be performed using litmus paper or an aqueous solution containing litmus dye.
Initially , the litmus paper is either red or blue. The blue paper changes to red, indicating acidity somewhere between the pH range of 4.5 to 8.3 .
(Note that 8.3 is alkaline). Red litmus paper can indicate alkalinity with a change to blue. In general litmus paper is red below the pH of 4.5 and blue a above a pH of 8.3.
If the paper turns purple , this indicates the pH is near neutral. Red paper that does not change color indicates the sample is an acid. Blue paper that does not change color indicates the sample is a base.
Remember, acids and bases refer only to aqueous ( water - based ) solutions, so pH paper won't change color in non - aqueous liquids such as vegetable oil.
Litmus paper may be dampened with distilled water to give a color change for a gaseous sample. Gases change the color of the entire litmus strip sice the whole surface is exposed. Neutral gases, such as oxygen and nitrogen, do not change the color of the pH paper.
LIMITATIONS
The litmus test is quick and simple, but it suffers from a few limitations. First, it's not an accurate indicator of pH;. it does not yield a numerical pH value. Instead , it roughly indicates. whether a sample is an acid or a base. Second, the paper can change colors for other reasons beside an acid base reaction.
For example, blue litmus paper turns white in chlorine gas. This color change is due to bleaching of the dye from hypochlorite ions, not acidity/basicity.
ALTERNATIVES TO LITMUS PAPER
Litmus paper is Handy as a general acid - base indicator, but you can get much more specific results if you use an indicator that has a more narrow test range or that offers a more wider color range.
Explanation:
Hope this helps.
All the best.
ps: I know this is big research report but I couldn't make a smaller one.....