Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 16: Problem 39

Addition of the indicator methyl orange to an unknown solution leads to a yellow color. The addition of bromthymol blue to the same solution also leads to a yellow color. (a) Is the solution acidic, neutral, or basic? (b) What is the range (in whole numbers) of possible pH values for the solution? (c) Is there another indicator you could use to narrow the range of possible pH values for the solution?

Short Answer

Expert verified
(a) The solution is acidic, as its pH range lies between 3.1 and 6.0. (b) The possible pH value range for the solution is 4 to 5. (c) To narrow the pH range further, we can use the indicator "methyl red," which has a transition range between pH 4.4 and 6.2, allowing us to observe color change and further refine the pH range.

Step by step solution

01

Research color changes of methyl orange and bromthymol blue

Both methyl orange and bromthymol blue are pH indicators that change color depending on the pH of a solution. Specifically: Methyl orange: - Red in acidic conditions (pH < 3.1) - Yellow in basic conditions (pH > 4.4) - Orange in the transition range (3.1 < pH < 4.4) Bromthymol blue: - Yellow in acidic conditions (pH < 6.0) - Blue in basic conditions (pH > 7.6) - Green in the transition range (6.0 < pH < 7.6)
02

Deduce the pH range of the unknown solution

Given that methyl orange turns yellow in the unknown solution, we can deduce that the solution is either basic or within the transition range of methyl orange (pH > 3.1). Also, bromthymol blue turns yellow in the unknown solution, which means the pH of the solution is less than 6.0 (acidic range of bromthymol blue). Consequently, the possible pH range of the solution lies between 3.1 < pH < 6.0.
03

Determine if the solution is acidic, neutral, or basic

Since the pH range we found in step 2 is greater than 3.1 and less than 6.0: (a) The solution is considered acidic (although it's a weak acid, as the pH is not far below 7).
04

State the range of possible pH values

(b) The range (in whole numbers) of possible pH values for the solution is 4 to 5.
05

Suggest another indicator to narrow the pH range

(c) To narrow the pH range further, we need an indicator with a transition range within our current pH range (3.1 < pH < 6.0). A suitable indicator is "methyl red", which has a transition range between pH 4.4 and 6.2. This indicator will allow us to determine if the solution is closer to pH 4.4 or 6.0 by observing the color change (red) in the acidic pH range and yellow in the transition range (4.4 < pH < 6.2).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Determine the \(\mathrm{pH}\) of each of the following solutions \(\left(K_{a}\right.\) and \(K_{b}\) values are given in Appendix D): (a) \(0.095 \mathrm{M}\) hypochlorous acid, \((\mathbf{b}) 0.0085 \mathrm{M}\) hydrazine, (c) \(0.165 \mathrm{M}\) hydroxylamine.

Identify the Brønsted-Lowry acid and the Brønsted-Lowry base on the left side of each of the following equations, and also identify the conjugate acid and conjugate base of each on the right side: (a) $\mathrm{NH}_{4}^{+}(a q)+\mathrm{CN}^{-}(a q) \rightleftharpoons \mathrm{HCN}(a q)+\mathrm{NH}_{3}(a q)$ (b) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons$ $$ \left(\mathrm{CH}_{3}\right)_{3} \mathrm{NH}^{+}(a q)+\mathrm{OH}^{-}(a q) $$ (c) \(\mathrm{HCOOH}(a q)+\mathrm{PO}_{4}^{3-}(a q) \rightleftharpoons\) $$ \mathrm{HCOO}^{-}(a q)+\mathrm{HPO}_{4}^{2-}(a q) $$

Succinic acid $\left(\mathrm{H}_{2} \mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{4}\right),\( which we will denote \)\mathrm{H}_{2} \mathrm{Suc}$ is a biologically relevant diprotic acid with the structure shown below. At \(25^{\circ} \mathrm{C}\), the acid-dissociation constants for succinic acid are \(K_{a 1}=6.9 \times 10^{-5}\) and \(K_{a 2}=2.5 \times 10^{-6} .\) (a) Determine the pH of a \(0.32 \mathrm{M}\) solution of $\mathrm{H}_{2} \mathrm{Suc}\( at \)25^{\circ} \mathrm{C}$, assuming that only the first dissociation is relevant. (b) Determine the molar concentration of \(\mathrm{Suc}^{2-}\) in the solution in part (a). (c) Is the assumption you made in part (a) justified by the result from part (b)? (d) Will a solution of the salt NaHSuc be acidic, neutral, or basic?

Determine whether each of the following is true or false: (a) All strong bases are salts of the hydroxide ion. (b) The addition of a strong base to water produces a solution of \(\mathrm{pH}>7.0\) (c) Because \(\mathrm{Mg}(\mathrm{OH})_{2}\) is not very soluble, it cannot be a strong base.

Predict the stronger acid in each pair: (a) \(\mathrm{HCl}\) or HF; (b) \(\mathrm{H}_{3} \mathrm{PO}_{4}\) or \(\mathrm{H}_{3} \mathrm{AsO}_{4} ;\) (c) \(\mathrm{HBrO}_{3}\) or \(\mathrm{HBrO}_{2}\) (d) \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\) or \(\mathrm{HC}_{2} \mathrm{O}_{4} \overline{;} ;(\mathbf{e})\) benzoic acid \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right)\) or phenol \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}\right) .\)
See all solutions

Recommended explanations on Chemistry Textbooks

Chemistry Branches

Read Explanation

Kinetics

Read Explanation

Inorganic Chemistry

Read Explanation

Chemical Reactions

Read Explanation

Chemical Analysis

Read Explanation

The Earths Atmosphere

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free