S105.ANALYTICAL CHEMISTRY
ACTIVITY 4
Please provide an answer with complete solutions to each of the following. Discuss how you
were able to solve for your answers for each of the given problems through a recorded video
discussion. Kindly copy and paste the link of your recorded video discussion on your answer
sheet/s. Thank you
1. How many Na⁺ ions are contained in 4.62 g NaPO? (5 pts)
4.62 g × 1 mol = 0.0282 mol
3 (22.99) + 30.97 + 4(16) = 163.94g
0.0282 mol × 3mol Na+ = 0.0845 mol Na+
1 mol
+
0.0845 mol Na × 6.02 × 1023 Na+ ions = 5.09 × 1023 Na+ ions
1 mol Na
2. What is the mass in grams of (10 pts)
a.) 6.21 mol of KBr (potassium bromide)
= 119.0023 g/m × 6.21 m
= 739.004283 g
= 739 g
b.) 4.92 mol of MgSO₄ (magnesium sulfate)
= 120.37 g/m × 4.92 m
= 592.2204 g
= 592 g
3. Convert the following p-functions to molar concentrations: (12 pts)
a.) pH = 8.67
b.) pBr = 0.034
c.) pLi = -0.321
d.) pMn = 0.0025
4. A 15.0% (w/w) NiCl₂ (129.61 g/mol) solution has a density of 1.149 g/mol. Calculate (15
pts)
a.) the molar concentration of NiCl₂ in this solution. = 1.33 M
15.0 g NiCl2
× 1.149 g solution × 1 mol NiCl2 × 1000 Ml = 1.33 M
100 g solution
mL solution
129.60 NiCl2
L
b.) the molar Cl⁻ concentration of the solution. = 0.274 M solution of Cl35.45 m /129.61 L = 0.274 M solution of Clc.) the grams of NiCl₂ contained in each liter of this solution. = 0.9999 g/l
129.5994/129.61 L = 0.9999
5. Describe the preparation of (15 pts)
a.) 5.00L of 0.0500M KMnO₄ from the solid reagent.
Molarity of KmnO4 from the solid reagent = 0.0500 M
Solution 5.00 L
Volume = 5.00 × 10-3 mL
Molar mass of KmnO4 = 158.0339 g/mol
Mass of KmnO4 in
KmnO4 = 0.0500 mol KMnO4 × 5.00 ×10-3 L KMnO4 × 158.0339 KMnO4
L KMnO4
mol KMnO4
Mass = 39.51 KMnO4
Therefore, 0.0500 M KMnO4 solution can be prepared by dissolving 39.51 g of KMnO4
in water and diluting to 5.00 L.
b.) 400 mL of a solution that is 0.0250M in I⁻ , starting with MgI₂
c.) 1.50 L of 0.215M NaOH from the concentrated commercial reagent [50% NaOH
(w/w), sp. Gr. 1.525]
6. Identify the acid on the left and its conjugate base on the right in the following equations:
(25 pts)
a.) HOCl + H₂O ↔ H₃O⁺ + OCl⁻
Acid
acid
base
base
b.) HONH₂ + H₂O ↔ HONH₃⁺ + OH⁻
Acid
acid
base
base
c.) NH₄⁺ + H₂O ↔ NH₃ + H₃O⁺
Base
acid
acid
base
d.) 2HCO₃⁻ ↔ H₂CO₃ + CO₃²⁻
Base
acid
base
e.) PO₄³⁻ + H₂PO₄⁻ ↔ 2HPO₄²⁻
Base
acid
acid
7. Calculate the solubility-product constant for each of the following substances, given that
the molar concentrations of their saturated solutions are as indicated: (15 pts)
a.) AgVO₃ (71.x10⁻ ⁴ mol/L)
b.) Pb(IO₃ )₂ (4.3x10⁻ ⁵ mol/L)
c.) Th(OH)₄ (3.3x10⁻ ⁴ mol/L)
Link for the recorded video discussion of answers (50 pts):
https://youtu.be/nLVuRhhcajc