Universal indicator: Difference between revisions
New page: {{SI}} {{EH}} '''Universal indicator''' is a pH indicator that transitions through numbers 3-12 (on the pH chart) to indicate the acidity or alkalinity of solutions. Although there ar... |
m Robot: Automated text replacement (-{{reflist}} +{{reflist|2}}, -<references /> +{{reflist|2}}, -{{WikiDoc Cardiology Network Infobox}} +) |
||
| (One intermediate revision by the same user not shown) | |||
| Line 1: | Line 1: | ||
{{SI}} | {{SI}} | ||
'''Universal indicator''' is a [[pH indicator]] that transitions through numbers 3-12 (on the pH chart) to indicate the acidity or alkalinity 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.<ref>''Jap. Pat.'' 99,664, Feb 21, 1933</ref> Details of this patent can be found in ''Chemical Abstracts''.<ref>''Chem Abstr'', '''28''', 2258 (1934)</ref> | '''Universal indicator''' is a [[pH indicator]] that transitions through numbers 3-12 (on the pH chart) to indicate the acidity or alkalinity 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.<ref>''Jap. Pat.'' 99,664, Feb 21, 1933</ref> Details of this patent can be found in ''Chemical Abstracts''.<ref>''Chem Abstr'', '''28''', 2258 (1934)</ref> | ||
| Line 29: | Line 29: | ||
==References== | ==References== | ||
{{reflist}} | {{reflist|2}} | ||
[[Category:pH indicators]] | [[Category:pH indicators]] | ||
| Line 39: | Line 39: | ||
[[zh:廣範試劑]] | [[zh:廣範試劑]] | ||
{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} | ||
Latest revision as of 15:45, 6 September 2012
Universal indicator is a pH indicator that transitions through numbers 3-12 (on the pH chart) to indicate the acidity or alkalinity 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]
Details
A universal indicator is typically composed of water, methanol, propan-1-ol, phenolphthalein sodium salt, methyl red bromothymol blue monosodium salt, and thymol blue monosodium salt [4]
The colours that indicate the pH of a solution, after adding universal indicator are:
0-3. Strong acid - Red
3-6. Acid - Orange/Yellow
7. Neutral - Green
8-11. Alkali - Blue
11-14. Strong Alkali - Purple
There are now also available wide range pH test papers with distinct colours for each pH from 1 to 14. Colour matching charts are supplied with the specific test strips purchased.
See also
References
- ↑ Jap. Pat. 99,664, Feb 21, 1933
- ↑ Chem Abstr, 28, 2258 (1934)
- ↑ For a discussion of these experiments, as well as recipes for Yamada and other universal indicators, see Foster, S.F. and Gruntfest, J.Chem.Educ., 14, 274(1937)
- ↑ "Universal Indicator". ISCID Encyclopedia of Science and Philosophy.