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Question 1:

What is the purpose of acid-base titration?

A) To determine the concentration of an acid
B) To determine the concentration of a base
C) To determine the pH of a solution
D) To neutralize an acidic solution

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Explanation: The correct answer is A) To determine the concentration of an acid. Acid-base titration is a laboratory technique used to determine the concentration of an acid or a base in a solution. It involves reacting a known volume and concentration of one solution (the titrant) with a solution of the other reactant (the analyte) until the reaction is complete, allowing the determination of the unknown concentration.

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Question 2:

Which indicator is commonly used in acid-base titrations?

A) Bromothymol blue
B) Phenolphthalein
C) Methyl orange
D) Litmus paper

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Explanation: The correct answer is B) Phenolphthalein. Phenolphthalein is a commonly used indicator in acid-base titrations. It is colorless in acidic solutions and turns pink or magenta in basic solutions, indicating the endpoint of the titration.

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Question 3:

What is the equivalence point in an acid-base titration?

A) The point at which the titrant is added in excess
B) The point at which the color change of the indicator is observed
C) The point at which the concentration of the analyte is determined
D) The point at which the reaction between the titrant and analyte is complete

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Explanation: The correct answer is D) The point at which the reaction between the titrant and analyte is complete. The equivalence point in an acid-base titration is the point at which the stoichiometrically equivalent amounts of the titrant and analyte have reacted completely. It is often indicated by a sharp change in pH and is used to determine the concentration of the analyte.

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Question 4:

In an acid-base titration, if the volume of the titrant is known and the concentration of the titrant is known, the concentration of the analyte can be calculated using the equation:

A) C1V1 = C2V2
B) pH = -log[H+]
C) Moles = Mass / Molar mass
D) PV = nRT

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Explanation: The correct answer is A) C1V1 = C2V2. In an acid-base titration, the concentration and volume of the titrant (C1 and V1) can be related to the concentration and volume of the analyte (C2 and V2) using the equation C1V1 = C2V2, which represents the principle of conservation of moles in a chemical reaction.

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Question 5:

In an acid-base titration, if the color change of the indicator is observed at a volume of 25 mL of titrant, and the concentration of the titrant is 0.1 M, the volume of the analyte is 20 mL, and the concentration of the analyte is unknown, what is the concentration of the analyte?

A) 0.08 M
B) 0.1 M
C) 0.125 M
D) 0.2 M

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Explanation: The correct answer is C) 0.125 M. Using the equation C1V1 = C2V2, we can calculate the concentration of the analyte. Given C1 = 0.1 M, V1 = 25 mL, V2 = 20 mL, and solving for C2, we have C2 = (C1 * V1) / V2 = (0.1 M * 25 mL) / 20 mL = 0.125 M.