Last modified: Sun 01/17/2016 06:54:36 pm
BCE

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Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.

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1. Look at Figure 9.2 on page 330 in your textbook and answer the following questions:

a. What is the standard definition of an ionic bond?

b. What is the standard definition of a covalent bond?

c. Indicate whether the bond(s) in each of the following compounds is/are ionic or covalent. (Check out Figure 9.1 and the information on pages 330 and 331 in your textbook.)

i. NaCl

ii H2O

iii. NH3

iv. CH4

v. Al2O3

2a. What is the formula for water at 25 °C when it is in its liquid phase?

b. What is the formula for water at 100 °C when it is in its liquid phase?

c. What is the formula for water at 100 °C when it is in its gas phase?

3. The enthalpy of vaporization (H2O(l) ----> H2O(g)) for water is 44 kJ mol-1 and the O-H bond energy in water is 328 kJ mol-1.

a. Answer the two questions:

i) How much energy is required to convert one mole of water from the liquid phase into the gaseous phase?

kJ mol-1

ii) How much energy is required to break the two O-H bonds in a mol of water molecules?

kJ mol-1

b. Given the information in Q3 which of the following statement(s) do you agree with and which statement(s) do you not agree with?

i) When water boils at 100 °C, water molecules are separated from each other as the phase changes from liquid to vapor.

agree/disagree

ii) When water boils at 100 °C, the O-H bonds are broken in water molecules to form H2 gas and O2 gas.

agree/disagree

iii) When it rains, water in the gas phase is condensing to form liquid water.

agree/disagree

iv) When it rains, H2 gas and O2 gas in the atmosphere combine to form water liquid.

agree/disagree

4. Below is a graphic showing the boiling points for three noble gases.

What would you predict is the approximate boiling point for the noble gas He? °C

Briefly, explain how you arrived at your answer.

5. Below is a graphic showing the boiling points for three Group IV compounds.

What would you predict is the approximate boiling point for CH4? °C

Briefly, explain how you arrived at your answer.

 

6. Below is a graphic showing the boiling points for three Group VI compounds.

What would you predict is the approximate boiling point for H2O? °C

Briefly, explain how you arrived at your answer.

7. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

8. If there is one question you would like to have answered in lecture, what would that question be?