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M6: Exam - Requires Respondus LockDown
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- Due No due date
- Points 100
- Questions 10
- Time Limit 120 Minutes
- Requires Respondus LockDown Browser
Attempt History
Attempt Time Score LATEST Attempt 1 104 minutes 95 out of 100
Score for this quiz: 95 out of 100
Submitted Feb 11 at 2:31am This attempt took 104 minutes.
Question 1
10 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table
Identify each of the three compounds below as ACID, BASE or SALT on the basis of their formula and explain your answer. (1) MgCl 2 (2) HClO 4 (3) Cu(OH) 2 Your Answer: 1 - salt because metal and nonmetal 2 - acid because of H, and poly atomic group 3 - base because of OH and metal
**1. MgCl 2 Salt Contains Metal (Mg) + Nonmetal (Cl)
- HClO 4 Acid Contains H + Polyatomic group (ClO 4 )
- Cu(OH) 2 Base Contains Metal (Cu) + OH Polyatomic group**
Question 2
10 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table For the Brønsted-Lowry acid base reactions shown below, list the stronger acid, stronger base, weaker acid and weaker base in the answer blanks provided:
Your Answer: 1 - H 2 O - strongest acid 2 - because acids increase in size according to the periodic table as you go to the right and down. 3 - OH-
- H 2 O
- O has the higher electronegativity (of C, N or O) which makes the H-O bond most polar and most likely to form H+
- conjugate base of H 2 O is OH- O has the higher electronegativity
Question 4
10 / 10 pts
You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Show the calculation of the [OH-] and pH of a 0.00328 M solution of the strong base Ca(OH) 2. Your Answer: base 2 x .00328 =. antilog(-.00656) = 2.183096161 = [OH - ] pOH 14 - pOH = ph 14 - 2.18 = 11.82 = pH [OH-] = 2 x [Ca(OH) 2 ] = 0.00656 M pOH = - log (0.00656) = 2. pH = 14 - pOH = 14 - 2.183 = 11.
Question 5
7 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table In the titration of 0.304 grams of NaOH in the presence of bromothymol blue indicator, the blue solution turns yellow after 22.3 mL of H 2 SO 4 of unknown concentration is added. Show the calculation of the molarity of the H 2 SO 4 solution? Your Answer: looking for molarity of an acid, 1-OH / 2- H .304 grams NaOH base 22.3 ml H 2 SO 4 acid Ma × (mLa /1000) × (Sa/ Sb) = gb /MWb (Ma) (22.3 / 1000) (2/1) = .304 / 98. (ma) (.0223) (2) = (.003099321) (ma) (.0446) = (.003099321) or. (ma) H 2 SO 4 =. (ma) H 2 SO 4 ~ .069 or. ( H 2 SO 4 is the acid and Na OH is the base) Ma x mLa / 1000 x Sa / Sb = gb / MWb Ma x 22.3 / 1000 x 2 / 1 = 0.304 / 39. MH2SO4 = 0.170 M
Question 6
Question 7
10 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table Predict and explain whether a solution of AlBr 3 is acidic, basic or neutral. Your Answer: AlBr 3 is acidic, because Al+3^ hydrolyzes to form weak base, Br is a strong base. AlBr 3 : Acidic since Al+3^ hydrolyzes to form a weak base [Al(OH) 3 ] and H 3 O+
Question 8
10 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table Show calculation of the pH of a buffer prepared by mixing 0.060 M NH 4 Cl and 0.080 M NH 3. Your Answer: 0.060 M NH 4 Cl - pro 0.080 M NH 3 - re kb= 1.8 x 10-^5 = .060 /. = (1.8 x 10-^5 ) (.080) /.
= 1.44x10-^6 /. [OH-] = 2.4 x 10-^5 antilog (-OH) = 4.619788758 = pOH ~ 4. 14 - pOH = pH 14 - 4.62 = 9.38 = pH x = (1.8 x 10-^5 ) (0.0800) / (0.0600) x = 2.40 x 10-^5 = [OH-] pOH = - log [OH-] = - log (2.40 x 10-^5 ) = 4. pH = 14 - pOH = 14 - 4.62 = 9.
Question 9
10 / 10 pts
You may find the following resources helpful: Scientific Calculator (Links to an external site.) Periodic Table Equation Table Show the calculation of the pH of a solution obtained by adding 0.0100 mole of H+^ to a buffer of pH 9.26 which originally contains 0.100 M NH 4 Cl and 0.100 M NH 3. Your Answer: adding acid H+ .0100 to a base kb= 1.8 x 10-^5
Your Answer: weak acid, strong base titration end point is 9 Ph > 7 rapid rise from 7 to 11 indicator signal change color within that range indicating phenolphthalein being useful for this titration. The location of the equivalence point at pH > 7, indicates that this is a weak acid / strong base titration. The rapid rise occurs approximately between pH 7 and pH 11. The indicator chosen to signal this change should change color within that range indicating that we are limited in choice of indicator with only Phenolphthalein being useful for this titration Quiz Score: 95 out of 100
