What is universal indicator?
Answer:
You can make it at home, I do it in my class all the time.
Buy some red cabbage, then extract the juice from it by:
Peeling off some leaves, put them in boiling water for 10-15 minutes, then pour the liquid through a strainer and you'll have purple cabbage juice.
You can change the colors of it by adding acidic and basic items in your house like: Pop, lemon juice, baking soda, bleach, drain cleaner, vinegar.
It refers to a chemically sensitive material (typically paper) that changes color when exposed to an acid or a base (it's called universal when it works with either of them). Typically, it will turn blue if exposed to acid, and will turn red if exposed to a base.
Universal indicator is is a pH indicator that transitions through several colors to indicate the acidity of solutions. Some examples are Thymol blue, Methyl Red, Bromothymol blue, Phenolphthalein etc. Thats it!
Methyl Orange
Bromocresol Green
Methyl Red
Bromothymol Blue
Phenol Red
Thymol Blue
Phenolphthalein
basically its the pH paper...but sometimes certain cpds are used also like phenolthalein, methyl orange, etc...
Universal Indicator is a pH indicator that transitions through several colors to indicate the acidity of solutions. Although there are a number of commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1923.[1] Details of this patent can be found in Chemical Abstracts.[2]
Experiments with Yamada’s Universal Indicator are also described in the Journal of Chemical Education.[3]
The indicator components of Yamada’s Universal Indicator are:
Thymol blue 5.0 mg
Methyl Red 12.5 mg
Bromothymol blue 60 mg
Phenolphthalein 100 mg
The above components are dissolved in 100 mL of ethanol. The resulting solution is neutralized to the green color of the indicator with dilute sodium hydroxide (0.05 M). Finally, this green solution is diluted to a total volume of 200 mL with distilled water.
The pH color ranges for Yamada’s Universal Indicator follow the standard seven color spectrum mnemonic – ROYGBIV. The approximate pH transitions for these color changes are 4,5,6,7,8,9,10.
Yamada's Universal Indicator is a flammable liquid. The indicator dyes should be considered toxic by ingestion and skin contact should also be avoided. Until 1997, Phenolphthalein was the active ingredient in the laxative EX-LAX. In 1997, the FDA banned phenolphthalein as a drug additive because large doses were found to produce tumors in laboratory rats.
Physical state: Liquid
Appearance: light green in water solvent; dark green alone
Odour: alcohol-like
pH value: Approximately 7
Vapour pressure: 25 mmHg (3.3 kPa)
Vapour Density: 1.3 kg/m³
Boiling point: 80 °C
Solubility: Soluble in water.
Specific gravity/Density: 0.93 g/cm³
Molecular formula: Mixture
Universal Indicator is a pH indicator that:
-Indicates transitions through several colors to indicate the acidity of solutions.
-Although there are a number of commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1923.
Universal indicator changes colour in acids and alkalis. Its colour shows the strength of an acid or alkali.
strong acid = red
weak acid = orange / yellow
neutral = green
weak alkali = turquoise / blue
strong alkali = deep blue / purple
The strength of an acid or alkali is shown on the pH scale of numbers.
Experiments with Yamada’s Universal Indicator are also described in the Journal of Chemical Education.
The indicator components of Yamada’s Universal Indicator are:
Thymol blue 5.0 mg
Methyl Red 12.5 mg
Bromothymol blue 60 mg
Phenolphthalein 100 mg
The above components are dissolved in 100 mL of ethanol. The resulting solution is neutralized to the green color of the indicator with dilute sodium hydroxide (0.05 M). Finally, this green solution is diluted to a total volume of 200 mL with distilled water.
The pH color ranges for Yamada’s Universal Indicator follow the standard seven color spectrum mnemonic – ROYGBIV. The approximate pH transitions for these color changes are 4,5,6,7,8,9,10.
A universal indicator is a mixture of dyes which is used to in a lab to find out the pH of an unknown solution
The answers post by the user, for information only, FunQA.com does not guarantee the right.
More Questions and Answers: