August 2010 Chemistry Regents #75 to 78

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Questions

 

Base your answers to questions 75 through 78 on the information below.

In one trial of an investigation, 50.0 milliliters of HCl(aq) of an unknown concentration is titrated with 0.10 M NaOH(aq). During the titration, the total volume of NaOH(aq) added and the corresponding pH value of the reaction mixture are measured and recorded in the table below.

75 On the grid in your answer booklet, plot the data from the table. Circle and connect the points. [1]

Answer to question 75

76 Determine the total volume of NaOH(aq) added when the reaction mixture has a pH value of 7.0. [1]

HIGHLIGHT TO SEE THE ANSWER

25.0 mL +/- 0.6 mL

77 Write a balanced equation that represents this neutralization reaction. [1]

HIGHLIGHT TO SEE THE ANSWER

Allowable answers

NaOH(aq) + HCl(aq) ==> NaCl(aq) + H2O(ℓ)

HCl + NaOH ==> NaCl + H2O

H+ + OH- ==> H2O

H3O+ + OH- ==> 2H2O

78 In another trial, 40.0 milliliters of HCl(aq) is completely neutralized by 20.0 milliliters of this 0.10 M NaOH(aq). Calculate the molarity of the titrated acid in this trial. Your response must include both a numerical setup and the calculated result. [2]

SETUP 1 point

(M)(40.0 mL) = (0.10 M)(20.0 mL)  

or   (0.1)(20)/40

Answer 0.050M 1 point

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51-53 Questions 54-56 Questions 57-58 Questions 59-60 Questions 61-63 Questions 64-66 Questions 67-69 Questions 70-72 Questions 73-74 Questions 75-78 Questions 79-81

 
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