June 2014 Chemistry Regents #76-79

Highlight to reveal answers and explanations

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Question 51-54 Questions 55-56 Questions 57-58 Questions 59-61 Questions 62-65 Questions 66-69 Questions 70-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

 

Other Regents Exams

Question 76-79

 

 

Base your answers to questions 76 through 79 on the information below and on your knowledge of chemistry.

During a laboratory activity, a student places 25.0 mL of HCl(aq) of unknown concentration into a flask. The student adds four drops of phenolphthalein to the solution in the flask. The solution is titrated with 0.150 M KOH(aq) until the solution appears faint pink. The volume of KOH (aq) added is 18.5 mL.

76 What number of significant figures is used to express the concentration of the KOH (aq)? [I]

Answer--> 3 sig figs

77 Complete the equation in your answer booklet for the neutralization reaction that occurs during the titration. [I]

HCl + KOH--> ________________

Answer-->HCl + KOH-->  KCl + H2O ...(or HOH)

see #36 choice 4

78 Determine the concentration of the HCl(aq) solution, using the titration data. [I]

Answer-->0.111M or 0.11M or 0.1M 

the calc..  Ma x 25.0mL= 0.150M x 18.5mL

79 Describe one laboratory safety procedure that should be used if a drop of the KOH(aq) is spilled on the arm of the student. [I]

Answer--> rinse it off with water or tell the teacher

JUST STUPID WRONG--neutralize the base, that is on your skin, it with an acid

on to Questions 80-82

 

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Question 51-54 Questions 55-56 Questions 57-58 Questions 59-61 Questions 62-65 Questions 66-69 Questions 70-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

 

Back to Regents Exams