Chemistry homework -7 questions due at 10 pm today

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Homework 10

Due: 11:00 am on Wednesday, November 16th in class (100 points) Question 1: Predicting the Polarity of Molecules (20 points) Identify the molecular shape and predict the molecular polarity. Draw 3D structure of molecule, calculate ∆EN value and draw dipole of each bond to support your answer. Molecules molecular shape ∆EN and bond

polarity Dipole of bonds Molecular

polarity (a) CO2

(b) N2

(c) CH3Cl

(d) BCl3

Name: Lab Section:

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Question 2: Hydrogen Bonding (20 points) Draw the hydrogen bonds between the two molecules in the following pairs. (a) H2O and NH3 (b) HF and HF (c) HF and H2O (d) HF and CH3OH

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Question 3: Predicting Ions in Solution(20 points) (a)Write down the chemical equations for the following compounds when dissolved in water: Solution 1: aluminum nitrate Solution 2: Potassium hydroxide Solution 3: Barium chloride

(b)Which combinations of solutions when mixed will result in the formation of a precipitate? Write the balanced equations.

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Question 4: Calculating Molarities of Ions in Aqueous Solutions (20 points) a. To form Solution A, 2.6 g of sodium sulfate is dissolved in 0.7 L of water. Write the

balanced chemical equation for the dissolution of sodium sulfate in water:

b. Calculate the molarities of each of the ions in Solution A: (10 points)

c. Write down the chemical formula for a compound that is soluble in water, but when mixed

with solution A would form a precipitate: (3 points)

d. What is the chemical formula of the precipitate that would form? (3 points)

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Question 5: Unique Properties of Water (20 points) (1) Briefly explain why ice floats on water. Use diagrams if helpful.

(2) Briefly explain why sugar dissolves in water. Why the resulting solution does not conduct electricity.

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PERIODIC TABLE

CONSTANTS AND EQUATIONS Avogadro’s number: NA = 6.02 x 1023

ELECTRONEGATIVITY VALUES

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IONS AND SOLUBILITIES