Name: Date: Spring 2018 Pre-Laboratory Assignment #4 Directions: Each student mu

Question

Name: Date: Spring 2018 Pre-Laboratory Assignment #4 Directions: Each student must print their own copy of this assignment from Blackboard, Instructor:M CHEM 1011.150 complete it, and turn it in to the instructor at the class meeting on February 17,2018 to receive credit for on-time submittal. You must neatly show all workf for consideration of partial credit. You may write on this page (including the back) and/or attach additional sheets, as needed #1: A sample of human blood was measured to have a hydroxide ion concentration of Hi- H,o']-3.8 x10 M. Calculate the pH and pOH of this blood sample. #2: Table sugar (ie, sucrose) is readily soluble in water. Why? Explain your answer. #3: Regular household vinegar is a 5% solution of acetic acid. Is acetic acid a strong acid or a weak acid? Explain your answer. [Consult a reliable reference (e.g. CHEM101 textbook, MSDS, Handbook of Chemistry and Physics), and attach a copy of the reference to this assignment. #4: A strip of blue litmus paper was immersed in a quantity of household oven cleaner. The litmus paper did not change color. Why? Explain your answer. Zumdahl, S S (1989) Chemistry, second ed Toronto, Canada: D. C. Heath and Company Catalyst, General Chemistry, Chemistry 101, Morgan State University, Custom Edition, Copyright O2011 by Pearson Learning Solutions

Explanation / Answer

(1)

pH = -log([H+]) = 8-log(3.8) = 7.42

pOH = 14 - pH = 14-7.42 = 6.58

(2)

Sucrose is a polar molecule and water is also a polar solvent. This is the reason that sucrose is readily soluble. The polar bond between O and H is the cause of polarity in the sucrose molecule.

(3)

Acetic acid is a weak acid, because it does not dissociate completely in aqueous solution. This is visible from the fact that it has a pKa value of 4.74 which is too high.

(4)

Household cleansers are basic, and basic solutions turn red litmus blue. So blue litmus will remain blue in a basic solution.

Hope this helps !

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