need to select the indicator that would best show that the pH of a solution has [2], The presence of one moderate electron-withdrawing group (bromine atom) and two moderate donating groups (alkyl substituents) are responsible for bromothymol blue's active indication range from a pH of 6.0 to 7.6. Bromophenol Blue, ACS - Thermo Fisher Scientific What would happen if we used phenolphthalein? Since the equivalence point for the titration (pH=7) occurs within the pH range for the visible colour change of the indicator (the end point between pH 6.8 and 8.4), this indicator can be used for this titration. 3,3-bis(3,5-dibromo-4-hydroxyphenyl)-3H-2,1-benzoxathiole-1,1-dione, OC1=C(Br)C=C(C=C1Br)C1(OS(=O)(=O)C2=CC=CC=C12)C1=CC(Br)=C(O)C(Br)=C1, Visual transition interval pH 3.0 (yellow) to pH 4.6 (blue). The equivalence point for the reaction is represented by the blue line at pH=8.7. that undergo a color change over a specific pH range. arrow_forward. The bottle became warm throughout this process creating . Uses of bromophenol blue indicator include testing for soap in unwashed biodiesel and glycerol. Bromothymol blue - Wikipedia The indicator that would be best to show that the pH of a solution has changed from 8 to 11 will be an indicator that undergoes a color change in this pH range. (c) You may be expected to calculate the pH of the solution. BROMOPHENOL BLUE: In the pH scale, the pH value of the solution could be less than 4.0. As a biological stain, it plays an important role to stain proteins and nucleic acids. Bromophenol Blue Cayman Chemical Commonly used as a pH indicator, a color marker in agarose or polyacrylamide gel electrophoresis, and a dye to detect proteins and nucleic acids (absorbance at 610 nm), particularly when staining living tissues. What is the pH range of Bromothymol blue? - KnowledgeBurrow.com Copyright 2006-2023 Thermo Fisher Scientific Inc. All rights reserved, Spectroscopy, Elemental and Isotope Analysis. As CO2 is absorbed from the breath into the solution, forming carbonic acid, the solution changes color from green to yellow. Preparation of 6X DNA Loading Dye (Bromophenol blue, Xylene Cyanol FF, Ficoll 400) - Laboratory Notes. It is typically sold in solid form as the sodium salt of the acid indicator. Beyond the ranges shown, the color of the indicator will remain the same. Initially there is a large excess of acid, the solution is acidic, and the methyl orange indicator is red. Chris has the following acid-base indicators currently available in the lab: Which indicator should Chris use for the titration? (ii) Decide on the pH range of the indicator and hence name the most suitable acid-base indicator to use: Ideally, indicator's colour change at the end point should occur at the same pH as the equivalence point of the neutralisation reaction. Acid-Base Indicators - Wired Chemist When the pH increases to about 3.1, the colour of the indicator starts to look more orange than red so the end point of the titration as indicated by the indicator has been reached. Bromophenol blue changes color at pH less than 7 Antacid titration is an acid-base titration in which antacid that acts as bases and is mainly composed of metal hydroxides like NaOH reacts with excess amount of acid such as HCl. Learn more about our Privacy Policy. over different pH ranges. Reagents; Culture Medium; Insect Cell Culture Bromothymol blue has been used in conjunction with phenol red to monitor the fungal asparaginase enzyme activity with phenol red turning pink and bromothymol blue turning blue indicating an increase in pH and therefore enzyme activity. The table below shows the color During this experiment, the yeast acted as a catalyst to remove oxygen from the hydrogen peroxide. Thermo Fisher Scientific. Bromophenol blue - OpenWetWare Categories: PH indicators | Triarylmethane dyes. An aqueous solution of sodium hydroxide, NaOH(aq), is a strong base. San Diego, CA USA. You probably won't be using "equivalents" as a measure of quantity in your high school chemistry course, but it is useful to understand where the term "equivalence point" comes from. Other . Consider bromothymol blue (pH range 6.2 - 7.6) and phenol red (pH range 6.8 - 8.4) as possible indicators for this neutralisation reaction: A suitable indicator for this strong acid - strong base titration would be bromothymol blue (pH range 6.2 - 7.6) or phenol red (pH range 6.8 - 8.4). Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE. cresolphthalein. A small amount of phenol red added to this growth medium will have a pink-red color under normal conditions. 0.02 Normal) NaOH and dilute with water to 250cm3. [8] This means it has the largest change in colour hue, when the thickness or concentration of observed sample increases or decreases. strong acid + weak base, resultant solution pH < 7 (acidic), weak acid + strong base, resultant solution pH > 7 (basic), strength of acid = strength of base, resultant solution pH = 7 (neutral). Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). No ads = no money for us = no free stuff for you! Bromophenol Blue. It is bright aquamarine by itself, and greenish-blue in a neutral solution. APExBIO - Bromophenol Blue Alizarine yellow will be . Phenolphthalein is an indicator of acids (colorless) and bases (pink). The protonated form of bromothymol blue has its peak absorption at 427nm thus transmitting yellow light in acidic solutions, and the deprotonated form has its peak absorption at 602nm thus transmitting blue light in more basic solutions. Use our request page at this link. The nature of this aqueous salt solution determines the pH of the resultant solution. An intermediate of the deprotonation mechanism is responsible for the greenish color in neutral solution.[2]. The background colour represents the colour of the solution containing the indicator over the same range of pH values. However, the color change doesnt As a biological stain, it plays an important role to stain proteins and nucleic acids. Catalog No. On these ranges, phenolphthalein goes from colorless to pink, methyl red goes from red to yellow, and bromothymol blue goes from yellow to blue. Magic Pitcher Demonstration. At low pH, the dye absorbs ultraviolet and blue light most strongly and appears yellow in solution. Senior Scientist at Sorrento Therapeutics, Inc. since July 2018, specializing in antibody discovery and engineering using high-throughput . Question: Chris the Chemist has been asked to determine the concentration of acetic acid (ethanoic acid) in Gran's homemade apple cider vinegar. Compare this item Bromophenol Blue sodium salt BeanTown Chemical Bromophenol blue is an intermediate and is used as an acid-based indicator in the pH range of 3-4.6 where the color changes from yellow to blue. At this point, the bromothymol is already blue, and a few drops of BTB are used on a water slide. Which indicator would be best to and Bromophenol Blue using a digital camera . Chris should use the phenolphthalein indicator. It is a good indicator of dissolved carbon dioxide (CO2) and other weakly acidic solutions. The table below shows the color range for several different indicators. The background colour represents the colour of the solution containing the methyl red indicator over the same range of pH values. It acts an intermediate and an acid-base indicator in the pH range 3.0 to 4.6. Animal Cell Culture. They are used to visually signal the acidity or alkalinity of an aqueous (water-based) solution. Customers are responsible for shipping costs. The resulting solution is an acidic solution having pH less than 7. The PH range of Xylenol Orange indicator is between 3.2 and 4.4. That is, the end point (end-point) of the titration as indicated by the indicator must be the same as the equivalence point of the acid-base reaction. Consider bromothymol blue (pH range 6.2 - 7.6) and phenol red (pH range 6.8 - 8.4) as possible indicators for this neutralisation reaction: The equivalence point for the reaction is represented by the blue line at pH=7. Phenol red - Wikipedia Advantec MFS 7010030 pH Test Paper, Narrow Range, Booklet, Bromophenol Blue, pH 2.8-4.4, 7mm Width, 70mm Length (Pack of 200) OC Indoor Range Rates Chemicals with hazard fees are limited to the 48 contiguous U.S. states. pH range > 7 therefore the base must be stronger than the acid. On this Wikipedia the language links are at the top of the page across from the article title. As a pH indicator, bromothymol blue, for example, would be useful between from about pH 6.0 to pH 7.6. Looking at pH five, we see that Bromophenol Blue sodium salt (3,3,5,5-Tetrabromophenolsulfophthalein); Undefined, for electrophoresis; Suitable for use with agarose or polyacrylamide gel electrophoresis (PAGE); Bromophenol blue sodium salt is used as tracking dye in electrophoresis; Bromophenol Blue is a pH indicator, and a It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). Bromophenol blue, Tetrabromophenolsulfonephthalein, is an acid-base indicator whose useful range as an indicator lies between pH 3.0 and 4.6. They work only in colorless solutions in which a color change can be observed and can only give an approximate pH value. 3,3-Bis(3,5-dibromo-4-hydroxyphenyl)-2,1, InChI=1S/C19H10Br4O5S/c20-12-5-9(6-13(21)17(12)24)19(10-7-14(22)18(25)15(23)8-10)11-3-1-2-4-16(11)29(26,27)28-19/h1-8,24-25H, InChI=1/C19H10Br4O5S/c20-12-5-9(6-13(21)17(12)24)19(10-7-14(22)18(25)15(23)8-10)11-3-1-2-4-16(11)29(26,27)28-19/h1-8,24-25H, Brc1cc(cc(Br)c1O)C3(OS(=O)(=O)c2ccccc23)c4cc(Br)c(O)c(Br)c4, Except where otherwise noted, data are given for materials in their. Since the relative strength of the acid and base determined by working backwards agrees with the information given in the question we are reasonably confident that our answer is plausible. (2) What is the relationship between what you know and what you need to find out? 3,3-Bis[3-bromo-4-hydroxy-2-methyl-5-(propan-2-yl)phenyl]-2,1, InChI=1S/C27H28Br2O5S/c1-13(2)17-11-20(15(5)23(28)25(17)30)27(19-9-7-8-10-22(19)35(32,33)34-27)21-12-18(14(3)4)26(31)24(29)16(21)6/h7-14,30-31H,1-6H3, InChI=1/C27H28Br2O5S/c1-13(2)17-11-20(15(5)23(28)25(17)30)27(19-9-7-8-10-22(19)35(32,33)34-27)21-12-18(14(3)4)26(31)24(29)16(21)6/h7-14,30-31H,1-6H3, Brc1c(O)c(cc(c1C)C3(OS(=O)(=O)c2ccccc23)c4cc(c(O)c(Br)c4C)C(C)C)C(C)C, Except where otherwise noted, data are given for materials in their, http://www.sciencelab.com/msds.php?msdsId=9927468, "Substituent effects on absorption spectra of pH indicators: An experimental and computational study of sulfonphthaleine dyes", "Thin film optical BTB pH sensors using solgel method in presence of surfactants", "The Equilibrium Constant for Bromothymol Blue: A General Chemistry Laboratory Experiment Using Spectroscopy", "Isolation and screening of L-asparaginase free of glutaminase and urease from fungal sp", "The determination of rupture of the membranes", Bromothymol Blue (Sodium Salt) -Sigma Aldrich, https://en.wikipedia.org/w/index.php?title=Bromothymol_blue&oldid=1138089652, Short description is different from Wikidata, Pages using collapsible list with both background and text-align in titlestyle, Articles containing unverified chemical infoboxes, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 7 February 2023, at 23:58. Imagine we are adding NaOH(aq) to HCl(aq) in a conical flask. Any kD Mini-PROTEAN TGX Precast Protein Gels 7 cm IPG/prep well 250 So bromophenol blue will be yellow The solution's pH will range from 2.8 to 4.5. Work backwards: Assume we use phenolpthalein, what sort of acid and base would be used in the titration? In PH. Streuli, in "Handbook of Analytical Chemistry," L. Meites, Ed., McGraw-Hill . To use all the functions on Chemie.DE please activate JavaScript. 3,3,5,5-tetrabromophenolsulfonephthalein, BPB, Albutest, Tetrabromphenol Blue, Oc1c(Br)cc(cc1Br)C2(OS(=O)(=O)c3ccccc23)c4cc(Br)c(O)c(Br)c4, 1S/C19H10Br4O5S/c20-12-5-9(6-13(21)17(12)24)19(10-7-14(22)18(25)15(23)8-10)11-3-1-2-4-16(11)29(26,27)28-19/h1-8,24-25H. Therefore: pH(end point) > 7, Phenolphthalein would be the best choice because its whole pH range is greater than 7, that is, its pH range is 8.3 - 10.0. On this Wikipedia the language links are at the top of the page across from the article title. In an acid-base titration, the following chemical reaction (Arrhenius neutralisation) takes place: When all the acid has reacted with all of the base the resultant solution is an aqueous salt solution, MA(aq). It changes from yellow at pH3.0 to blue at pH4.6; this reaction is reversible. The bromophenol blue is also used as a dye. wikipedia.en/SDS-PAGE.md at main chinapedia/wikipedia.en Bromophenol Blue | Inhibitor | TargetMol changes in pH that occur as HCl(aq) is added to NaOH(aq). Please enable javascript and pop-ups to view all page content. (d) You may be given a titration curve to use to determine which indicator you would use (examples of this are shown in the next section). Bromophenol blue and bromothymol blue will both remain blue as the pH changes from 8 to 11. The molecular weight of bromophenol blue is around 670 Daltons or grams per mole. Reaxys. Alizarine yellow does undergo a Solutions of the dye, therefore, are blue. Yes, we have named one of the indicators given. Bromophenol blue (BPB) is most commonly used as an agarose gel electrophoresis size marker. Bromothymol Blue is an indicator in the pH range from 6.0 to 7.6. Bromophenol blue (3,3,5,5-tetrabromophenolsulfonphthalein, BPB),[2] albutest[3] is used as a pH indicator, an electrophoretic color marker, and a dye. Litmus is not used in titrations because the pH range over which it changes colour is too great (pH range is 5.0 - 8.0) . Clinical trial: N/A. Because acetic acid is a weak acid, Chris has decided to titrate it with an aqueous solution of sodium hydroxide because this is a strong base. Demonstration experiments using universal indicators. The deprotonation of the neutral form results in a highly conjugated structure, accounting for the difference in color. The gel must firstly be immersed in a fixation solution containing acid (phosphoric acid or acetic acid) and alcohol (ethanol or methanol) as a . The original Alfa Aesar product / item code or SKU reference has not changed as a part of the brand transition to Thermo Scientific Chemicals. hospital patients (CDC, 2016). The pH of blood ranges from 7.35 to 7.45, for instance. Cresolphthalein, however, undergoes The balanced chemical equation below represents the neutralisation reaction between HCl(aq) and NaOH(aq): At the equivalence point of the neutralisation reaction the only species present will be NaCl(aq) and H2O(l) Consider thymol blue (pH range 8.0 - 9.6) or phenolphthalein (8.3 - 10.0) as suitable indicators. HCl, then make up to 500 ml. Search Notes This mixture displays the colors red, orange-yellow, green, blue, and indigo-violet: How pH Indicators Work Most pH indicators are weak acids or weak bases. Since the equivalence point for the titration (pH=8.7) occurs within the pH range for the visible colour change of the indicator (the end point between pH 8.3 and 10.0), this indicator can be used for this titration. Store at 4C. It changes from yellow at pH 3.0 to purple at pH 4.6; this reaction is reversible. Determining the Color of an Indicator at One pH Value and Which Better weighing performance in 6 easy steps Daily Visual Balance Check How to quickly check pipettes? What is the pH range of bromophenol red? Please do not block ads on this website. Some examples are given below: Methyl red : published 3.1 to 4.4 (total interval 1.3 pH units) bromophenol blue: published 3.0 to 4.6 (total interval 1.6 pH units) Part 2. In solution at pH 3.6 (in the middle of the transition range of this pH indicator) obtained by dissolution in water without any pH adjustment, bromophenol blue has a characteristic green red color. An aqueous solution of hydrochloric acid, HCl(aq), is a strong acid. (Its peak absorbance is 600nm at a basic pH of 12.) Neutral Litmus Paper - (Acid & Base test), Methylene Chloride, 500mL, Reagent ACS, 99.5%. While the conjugation is responsible for the length and nature of the color change range, these substituent groups are ultimately responsible for the indicator's active range. The general carbon skeleton of bromothymol blue is common to many indicators including chlorophenol red, thymol blue, and bromocresol green. The specimen is mixed with blue BTB solution and fixed to a slide by a cover slip. All rights reserved. bromophenol blue, that is often used as an acid-base indicator. So bromophenol blue will be yellow below a pH of three and blue above a pH of approximately 4.6. It acts an intermediate and an acid-base indicator in the pH range 3.0 to 4.6. Expert Solution. Some content on this page could not be displayed. The background colour represents the colour of the solution containing the bromothymol blue indicator over the same range of pH values. Answered: You are titrating a 1L solution of 1M | bartleby The solution was poured (20 mL) into Petri dishes and 1 mM ampicillin was added to . NaCl(aq) will have a pH=7 pH indicators generally change color over a range of two pH units. This 0.1% aqueous bromothymol blue solution (also known as Bromthymol Blue) is a commonly used pH indicator. Bromophenol Blue - Thermo Fisher Scientific Biomolecules | Free Full-Text | Peptidomics as a Tool to Assess the Indicator Thymol Blue Bromophenol Blue pKa 1.65 4.10 5.00 Methyl Red Bromothymol Blue Phenophthalein The K values for citric acid are: 7.30 9.50 4 Ka1 = 8.4 x 10-4 Ka2 = 1.8 x 10-5 Ka3 = 4.0 x 10-6. pH indicators generally change color over a range of two pH units. Since the equivalence point for the titration (pH=8.7) occurs within the pH range for the visible colour change of the indicator (the end point between pH 8.0 and 9.6), this indicator can be used for this titration. Bromophenol blue is an intermediate and is used as an acid-based indicator in the pH range of 3-4.6 where the color changes from yellow to blue. yellow, and bromophenol blue is blue. In practice, pH(equivalence) occurs within the pH range of the indicator: pH(lower limit colour change) < pH(equivalence point) < pH(upper limit colour change)(. 25% glycerol, 0.01% bromophenol blue : Recommended running buffer (Tris/glycine/SDS) 25 mM Tris, 192 mM glycine, 0.1% SDS, pH 8.3 : Gel dimensions (W x L x thickness), cm : 8.6 x 6.7 x 0.1 : Cassette dimensions (W x L x thickness), cm : 10 x 8 x 0.46 : pH range (phenolphthalein) is 8.3 - 10.0 Solutions of the dye therefore are blue. Since acetic acid is a weak acid and sodium hydroxide is a strong base, that is, base is stronger than acid: pH(end point) = pH(equivalence) David S. - Senior Scientist - Sorrento Therapeutics, Inc. | LinkedIn Preparation of 6X DNA Loading Dye (Bromophenol blue, Xylene Cyanol FF, Ficoll 400) - Laboratory Notes, Ammonium Acetate [CH3COONH4] Molecular Weight Calculation, Aluminum Sulfide [Al2S3] Molecular Weight Calculation, Aluminum Oxide [Al2O3] Molecular Weight Calculation, Aluminum Fluoride [AlF3] Molecular Weight Calculation, Aluminum Bromide [AlBr3] Molecular Weight Calculation, Aluminum Sulfate [Al2(SO4)3] Molecular Weight Calculation, Aluminum Hydroxide [Al(OH)3] Molecular Weight Calculation. The table shows us the range of pH The aqueous solution of a salt of a strong acid and a strong base will have a pH=7 at 25C. Your email address will not be published. So the indicator that is blue at a An appropriate indicator for an acid-base titration will change colour over a narrow pH range, and have distinctive colour at lower pH and a different, distinctive colour at higher pH. Different indicators change color Bromophenol blue is also used as a dye. The balanced chemical reaction below represents the reaction between HCl(aq) and NH3(aq): NH4Cl is the salt of a strong acid and a weak base, so a solution of NH4Cl will have a pH < 7 (NH4+ is a weak acid) pH's yielding the characteristic sigmoid shaped titration curve. The table below gives a list of common laboratory pH indicators. The litmus test is quick and simple, but it suffers from a few limitations. At low pH, the dye absorbs ultraviolet and blue light most strongly and appears yellow in solution. . 1997-2023 LUMITOS AG, All rights reserved, https://www.chemeurope.com/en/encyclopedia/Bromophenol_blue.html, Your browser is not current. Our ammo is only required to be shot with our rental guns. Other indicators work in different pH ranges. Bromothymol Blue pH Indicator, 1 oz. - Science Company A common use is for measuring the presence of carbonic acid in a liquid. [5], Bromothymol blue is synthesized by addition of elemental bromine to thymol blue in a solution in glacial acetic acid. Bromothymol blue may be used for observing photosynthetic activities, or as a respiratory indicator (turns yellow as CO2 is added). Bromophenol blue is also used as a pH indicator with a transition range of pH 3 to 4.6. Bromophenol Blue - an overview | ScienceDirect Topics All rights reserved. Choosing Acid-Base Titration Indicators Chemistry Tutorial - AUS-e-TUTE Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). changed from eight to 11. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). Why Is Bromothymol Blue A Good Indicator For Titration? pH of five is bromophenol blue. Sodium hydroxide is a base, and it was in the pitcher at the beginning, so when added to the phenolphthalein in beakers 2 and 4, it turned pink . At neutral pH, the dye absorbs red light most strongly and transmits blue light. The background colour represents the colour of the solution containing the phenolphthalein indicator over the same range of pH values. Nagwa uses cookies to ensure you get the best experience on our website. [5] Bromophenol blue is structurally related to phenolphthalein (a popular indicator). Unopened chemicals in original packaging may be returned within 30 days of shipment with prior approval. T21481 CAS 115-39-9. Chart of pH Indicator Ranges - Science Company Copyright 2006-2023 Thermo Fisher Scientific Inc. All rights reserved, Colonnes et cartouches de chromatographie, Consommables en plastique et fournitures de laboratoire, Afficher toutes les catgories de produits, Spectroscopie, analyse lmentaire et isotopique, Voir toutes les applications et techniques, Services aux organisations de dveloppement et de fabrication sous contrat (CDMO) et pour les essais cliniques, Consultez toutes les rubriques d'aide et d'assistance. Bromophenol blue - Wikipedia Acid-base pH indicators are solutions that have a characteristic color at certain pH levels. What would happen if we used methyl orange? below a pH of three and blue above a pH of approximately 4.6. For example, common indicators such as phenolphthalein, methyl red, and bromothymol blue are used to indicate pH ranges of about 8 to 10, 4.5 to 6, and 6 to 7.5 accordingly. For a given solute, there is often one wavelength (or a small range of wavelengths) at which the absorbance is greatest (and therefore the transmittance the least). (Its peak absorbance is 600 nm at a basic pH of 12.) (adsbygoogle = window.adsbygoogle || []).push({}); Want chemistry games, drills, tests and more? Range Time (Non-Members) $20.00 per visit. Ground-only (No-Fly) chemicals are limited to the 48 contiguous U.S. states and Canada. What would happen if we used a different indicator instead? cells in the range of 190-1100 nm were made on a Shimadzu (Kyoto, Japan) 1601 UV/VIS Spectrophotometer controlled by an UVProbe-2.5 so ware. In gel electrophoresis it can be used as a color marker and as a biological stain it can be used to stain proteins and nucleic acids. Weak acid + strong base salt + water (see Calculating pH of Aqueous Salt Solutions). Bromophenol is also used as a colour marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. . titration has been reached. Approximate pH range for color change: 3.0-4.6: Color of acid form: yellow: Color of base form: purple: CAS Number: 115-39-9: ChEBI: CHEBI:59424: ChEMBL: ChEMBL2103765: . A sample universal indicator (covering a pH range of 1 through 13) can be prepared by dissolving .04 g of methyl red, .02 g of methyl orange, .02 g of phenolphthalein, .10 g of thymol blue, and .08 g of bromothymol blue in 100 mL of 95% ethanol. [2], Bromothymol blue is sparingly soluble in oil, but soluble in water, ether, and aqueous solutions of alkalis. [9] However, a recent study suggests that methyl red is more useful in determining activity due to the bright yellow ring formed in the zone of enzyme activity.[10]. Ideally: pH at the end point = pH at the equivalence point. As the pH of the solution increases, the indicator changes color from red 3,3-bis(3,5-dibromo-4-hydroxyphenyl)-3H-2,1-benzoxathiole-1,1-dione, OC1=C(Br)C=C(C=C1Br)C1(OS(=O)(=O)C2=CC=CC=C12)C1=CC(Br)=C(O)C(Br)=C1. Bromophenol blue, Tetrabromophenolsulfonephthalein, is an acid-base indicator whose useful range as an indicator lies between pH 3.0 and 4.6. However, the apparent color shifts mostly depend on the concentration and/or path length through which the solution is observed. A suitable indicator for the titration of the weak acid CH3COOH(aq) and the strong base NaOH(aq) would be either thymol blue (pH range 8.0 - 9.6) or phenolphthalein (pH range 8.3 - 10.0). They would both appear yellow. Your email address will not be published. The indicator that is blue at a pH of 5 is bromophenol blue. Used as a pH indicator, it changes color over a pH range from 3.0 (yellow) to 4.6 (blue).