Calculate the percentage of copper in the bronze alloy note

Question

SECTION A

1. A sample of bronze alloy weighing 0.2500 g is dissolved in nitric acid (HNO₃). This resulting solution is then treated with potassium iodide (KI) in order to liberate iodine, I2. This liberated iodine is then titrated with 0.100-­ M sodium thiosulfate (Na₂S₂O₃) solution, requiring a titer of 32.00 cm³ for this analysis.

Calculate the percentage of copper in the bronze alloy. Note, the atomic mass of copper is 63.5 g/mol. The appropriate equations are provided below.

2 Cu²⁺ + 2 I^- → 2 Cu⁺ + I₂

I₂ + 2 S₂O₃^2-­ → 2 I^-­ + S₄O₆^2-­

2 Cu²⁺ + 2I^-­- → 2 Cu⁺ + I₂

2. It is observed that atomic radius and ionization energy have opposite periodic trends. Explain this observation.

3. An alcohol solution contains 35.0 g of 1-­propanol (C₃H₇OH) and 150.0 g of ethanol (C₂H₅OH).

a. Calculate the mass percent of each alcohol.

SECTION B

4. Give the group number and general electron configuration of an element with each electron-­-dot symbol.

5. Indicate the bonds in each of the following as ionic, non-­-polar covalent or polar covalent.

(a) S₈ (b) RbCl (c) PF₃ (d) SCl₂ (e) F₂ (f) SF₂

For polar covalent substances, arrange them in order of increasing bond polarity.

6. Draw the molecular shapes and predict the bond angles (relative to the ideal angles) of:

(a) CBr₄ (b) SF₂

7. Chlorate ion has the formula ClO₃^-­. With the help of a Lewis dot diagram,

(a) Show what the hybridization of chlorine is in this ion

(b) State the shape of this ion.

8. Two p orbitals from one atom and two p orbitals from another atom are combined to form molecular orbitals for the joined atoms. How many molecular orbitals will result from this combination? Explain.

9. Draw the molecular orbital (MO) diagram for Be₂⁺ and answer the following questions.

(a) Is it stable? (Hint: bond order)

(b) Is it diamagnetic?

(c) What is its outer (valence) electron configuration.