Chemistry project

Ph indicators

Natural ph indicators are indicators found in nature that will change colour corresponding to a certain ph. The following is a list of natural ph indicators:

Beets Blueberries Carrots Cherries Curry Powder Delphinium Petals Geranium Petals Grapes Horse Chestnut Leaves Morning Glories Onion Pansy Petals

Petunia Petals Poison Primrose Poppy Petals Purple Peonies Red cabbageRed Radish Rhubarb Rose Petals Strawberries Tea Thyme Turmeric Tulip Petals Violet Petals

Natural Indicators

Various types of ph indicators

alizarin red S

Approximate pH range for color change: 4.6-6.0Color of acid form: yellowColor of base form: red

alizarin yellow GG

Type: In + H2O InH+ + OH-

pK: 11.0Approximate pH range for color change: 10.0-12.0Color of acid form: clearColor of base form: yellow

brilliant yellow

Approximate pH range for color change: 6.6-7.8Color of acid form: yellowColor of base form: orange

bromocresol green

Also known as: 3',3'',5',5''-tetrabromo-m-cresol-sulfonephthaleinType: HIn + H2O In- + H3O+

pK: 4.90Approximate pH range for color change: 3.8-5.4Color of acid form: yellowColor of base form: blue

bromophenol blue

Also known as: 3',3'',5',5''-tetrabromophenolsulfonephthaleinType: HIn + H2O In- + H3O+

pK: 4.10Approximate pH range for color change: 3.0-4.6Color of acid form: yellowColor of base form: purple

bromothymol blue

Also known as: 3',3''-dibromothymolsulfonephtaleinType: HIn + H2O In- + H3O+

pK: 7.30Approximate pH range for color change: 6.0-7.6Color of acid form: yellowColor of base form: blue

chlorophenol red

Also known as: 3',3''-dichlorophenolsulfonephthaleinType: HIn + H2O In- + H3O+

pK: 6.25Approximate pH range for color change: 4.8-6.4Color of acid form: yellow

clayton yellow

Approximate pH range for color change: 12.2-13.2Color of acid form: yellowColor of base form: amber

congo red

Approximate pH range for color change: 3.0-5.0Color of acid form: blueColor of base form: red

cresol red (in acid solution)

Also known as: o-cresolsulfonephthaleinApproximate pH range for color change: 0.0-1.0Color of acid form: redColor of base form: yellow

crystal violet

crystal violet

Type: HIn + H2O In- + H3O+

pK: -Approximate pH range for color change: 0.0-1.8Color of acid form: yellowColor of base form: blue

erythrosine (sodium salt)

Approximate pH range for color change: 2.2-3.6Color of acid form: orangeColor of base form: red

malachite green

pK: 1.0Approximate pH range for color change: 0.2-1.8Color of acid form: yellowColor of base form: blue-green

metacresol purple (in acid solution)

Also known as: m-cresol purple, cresol purple, m-cresolsulfonephthaleinpK: ~2.0Approximate pH range for color change: 1.2-2.8Color of acid form: red

methyl green

Approximate pH range for color change: 0.2-1.8Color of acid form: yellowColor of base form: blue

methyl orange

Type: InH+ + H2O In + H3O+

pK: 3.46Approximate pH range for color change: 3.1-4.4Color of acid form: redColor of base form: orange-yellow

phenolphthalein

Type: HIn + H2O In- + H3O+

pK: 9.5Approximate pH range for color change: 8.0-9.8Color of acid form: clearColor of base form: red-violet

quinaldine red

Approximate pH range for color change: 1.0-2.2Color of acid form: clearColor of base form: red

resazurin

Approximate pH range for color change: 3.8-6.4Color of acid form: orangeColor of base form: violet

thymolphthalein

Type: HIn + H2O In- + H3O+

pK: 9.7Approximate pH range for color change: 9.3-10.5Color of acid form: colorlessColor of base form: blue

PRESENTED BY VARSHITH OF IX