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The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?
- a)2/3
- b)3/4
- c)1/2
- d)9/11
Correct answer is option 'A'. Can you explain this answer?
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The indicator constant of phenolphthalein is approximately 10-10. A so...
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To solve this question, we need to understand the concept of acid-base reactions and the role of indicators in determining the endpoint of a reaction.
1. Acid-base reactions: In an acid-base reaction, an acid donates a proton (H+) to a base, forming a salt and water. The strength of an acid or a base is determined by its concentration.
2. Indicator: An indicator is a substance that changes color when the pH of a solution changes. It is commonly used to determine the endpoint of an acid-base titration, where the acid and base are mixed in known concentrations until they neutralize each other.
3. Phenolphthalein: Phenolphthalein is a commonly used indicator in acid-base titrations. It is colorless in acidic solutions and turns pink in basic solutions.
Now, let's solve the question step by step:
Step 1: Calculate the number of moles of sodium hydroxide (NaOH) and hydrochloric acid (HCl) in the given volumes.
Number of moles of NaOH = 0.01 N * 100.01 c.c. = 0.0101 moles
Number of moles of HCl = 0.01 N * 100.00 c.c. = 0.01 moles
Step 2: Determine the limiting reagent.
Since the number of moles of NaOH is higher than HCl, HCl is the limiting reagent. This means that all the HCl will react, and some NaOH will be left over.
Step 3: Determine the number of moles of phenolphthalein.
The number of moles of phenolphthalein can be calculated using the concept of the indicator constant. The indicator constant is defined as the ratio of the concentration of the colored form to the concentration of the colorless form.
Indicator constant (K) = [Colored form]/[Colorless form] = 10^-10
Let's assume the initial concentration of phenolphthalein is C. After the reaction, the concentration of the colored form will be C - x (where x is the fraction converted to the colored form) and the concentration of the colorless form will be x.
Using the indicator constant, we can write the equation:
K = (C - x)/x
Substituting the value of K:
10^-10 = (C - x)/x
10^-10 * x = C - x
x + x = C / 10^10
2x = C / 10^10
x = C / 2 * 10^10
From this equation, we can see that the fraction of the indicator converted to its colored form (x) is C / 2 * 10^10.
Step 4: Determine the fraction of the indicator converted to its colored form.
Since the concentration of phenolphthalein is not given, we can assume it to be 1.
x = 1 / 2 * 10^10
x = 0.5 * 10^-10 = 5 * 10^-11
Therefore, the fraction of the indicator converted to its colored form is 5 * 10^-11.
Since the options given in the question are not in scientific notation, we need to convert the answer to a fraction.
5 * 10^-11 = 5 / (10^
1. Acid-base reactions: In an acid-base reaction, an acid donates a proton (H+) to a base, forming a salt and water. The strength of an acid or a base is determined by its concentration.
2. Indicator: An indicator is a substance that changes color when the pH of a solution changes. It is commonly used to determine the endpoint of an acid-base titration, where the acid and base are mixed in known concentrations until they neutralize each other.
3. Phenolphthalein: Phenolphthalein is a commonly used indicator in acid-base titrations. It is colorless in acidic solutions and turns pink in basic solutions.
Now, let's solve the question step by step:
Step 1: Calculate the number of moles of sodium hydroxide (NaOH) and hydrochloric acid (HCl) in the given volumes.
Number of moles of NaOH = 0.01 N * 100.01 c.c. = 0.0101 moles
Number of moles of HCl = 0.01 N * 100.00 c.c. = 0.01 moles
Step 2: Determine the limiting reagent.
Since the number of moles of NaOH is higher than HCl, HCl is the limiting reagent. This means that all the HCl will react, and some NaOH will be left over.
Step 3: Determine the number of moles of phenolphthalein.
The number of moles of phenolphthalein can be calculated using the concept of the indicator constant. The indicator constant is defined as the ratio of the concentration of the colored form to the concentration of the colorless form.
Indicator constant (K) = [Colored form]/[Colorless form] = 10^-10
Let's assume the initial concentration of phenolphthalein is C. After the reaction, the concentration of the colored form will be C - x (where x is the fraction converted to the colored form) and the concentration of the colorless form will be x.
Using the indicator constant, we can write the equation:
K = (C - x)/x
Substituting the value of K:
10^-10 = (C - x)/x
10^-10 * x = C - x
x + x = C / 10^10
2x = C / 10^10
x = C / 2 * 10^10
From this equation, we can see that the fraction of the indicator converted to its colored form (x) is C / 2 * 10^10.
Step 4: Determine the fraction of the indicator converted to its colored form.
Since the concentration of phenolphthalein is not given, we can assume it to be 1.
x = 1 / 2 * 10^10
x = 0.5 * 10^-10 = 5 * 10^-11
Therefore, the fraction of the indicator converted to its colored form is 5 * 10^-11.
Since the options given in the question are not in scientific notation, we need to convert the answer to a fraction.
5 * 10^-11 = 5 / (10^
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The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer?
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The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer? for Class 11 2024 is part of Class 11 preparation. The Question and answers have been prepared according to the Class 11 exam syllabus. Information about The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 11 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer?.
The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer? for Class 11 2024 is part of Class 11 preparation. The Question and answers have been prepared according to the Class 11 exam syllabus. Information about The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Class 11 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The indicator constant of phenolphthalein is approximately 10-10. A solution is prepared by adding 100.01 c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?a)2/3b)3/4c)1/2d)9/11Correct answer is option 'A'. Can you explain this answer?.
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