Chem 3.06

Research the answers to the following questions on the internet and write your answers in your own words. For each answer, include the address of the web site (or title and author of a book or article) that you used to help you answer the question.
Which type of compound usually has higher melting points: ionic compounds or covalent compounds? What is the reason for this difference in melting points? (3 points)
Link: http://misterguch.brinkster.net/covalentcompounds.html
Answer: Ionic compounds have a higher melting point the heat needed to break down the bonds between the compounds is much higher than not needing to break down any bonds at all.

Do ionic compounds conduct electricity as: (3 points)
Link: http://antoine.frostburg.edu/chem/senese/101/compounds/faq/print-properties-ionic-vs-covalent.shtml

Solids?
No
Liquids?
Yes
Aqueous solutions (when the ionic compounds are dissolved in water)?
Yes

Do covalent compounds conduct electricity as: (3 points)
Solids?
no
Liquids?
No
Aqueous solutions (when the covalent compounds are dissolved in water)?
No

Substance
Melting Point
1
Substance “A”
Over 300 degree c
2
Substance “B”
280 degree c
3
Substance “C”
Over 300 degree c
4
Substance “D”
110 degree c

Substance “A”
Conductivity
SOLID
No
Liquid
Yes
AQUEOUS yes Substance “B”
Conductivity
SOLID
No
LIQUID
No
AQUEOUS no Substance “C”
Conductivity
SOLID
No
LIQUID
Yes
AQUEOUS yes Substance “D”
Conductivity
SOLID
No
LIQUID
No
AQUEOUS
No

Based on your observations in the lab, categorize each unidentified compound as ionic or covalent. Explain in one or two sentences why you categorized the compounds the way that you did. (5 points) 



Answer: Substance A and C are both Ionic bonds. This is because they are only conductive after they are melted to a liquid and dissolved in an aqueous solution. Substance B and D are covalent because, they are not able to conduct electricity at all. Also they have a much lower melting point because the bond holding them together requires less energy to break them apart.

Explain, in your own words, the differences between ionic and covalent bonding that account for the differences in their melting points. (4 points)



Answer: the difference between ionic and covalent bonding is that during a covalent bond the electrons are shared which causes it to be a weaker bond and makes the amount of energy required or temperature less than that of an ionic bond which transfers electrons and makes the melting point higher.

In order to conduct an electrical current, a substance must have charged particle s (ions or electrons) that are free-moving (able to move about throughout the sample). 

Why do you think ionic compounds are not able to conduct electricity as solids, even though they can as liquids and in solution? (2 points)


Answer: since the ionic compounds are forced to share the ions when solid but when they are melted and put in a solution the ions become free.

Based on your research and observations, why do you think pure (distilled) water does not conduct electricity but tap water usually does? (2 points)

Answer: The pure water will not have any free moving ions where as the tap water will