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Transcript of 3.06 :))
3.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).
a.Why do you think ionic compounds are not able to conduct electricity as solids, even though they can as liquids and in solution?
The reason is because in molten or aqueous state, they contain free ions that are able to conduct electricity. In solid state, they are packed in 3d structure in their lattice.
b.Based on your research and observations, why do you think pure (distilled) water does not conduct electricity but tap water usually does? Pure water only contains water molecules, no ions, no electrons, no charges and tap water contains or minerals that form into ions and move freely in the solution, these free moving ions help to conduct electricity.
2.Explain, in your own words, the differences between ionic and covalent bonding that account for the differences in their melting points.
Covalent bonds are between 2 non metals, which causes their electrons to be shared. Since they are shared, there are no bonds to be broken between them which causes them to be easier to separate. Thus, they have a lowing melting point.
Ionic compounds are between a metal and a nonmetal. In this type of bond, electrons are transferred from metal to nonmetal. Ionic compounds have very high melting points because they do have bonds that are extremely tight and close together, making them a lot harder to pull apart. So the higher the temperature, the easier it is to pull the tights bonds in an ionic compound apart.
Part | Conclusion
1.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.
A and C are Ionic Bonds because their melting points were over 300C, and their liquid states had conductive properties. Substances B and D are Covalent Bonds because they are under 300C and are not conductive in any form.
Lab part | continued
Substance A – did not conduct as a solid, but did conduct (lights up the light bulb when the alligator clips are connected to the metal electrodes in the liquid) as a liquid and in aqueous solution.
Substance B – did not conduct as solid, liquid, or in aqueous solution.
Substance C – did not conduct as a solid, but did conduct as a liquid and when in aqueous solution.
Substance D – did not conduct as solid, liquid, or in aqueous solution.
Lab Part |
Substance| Melting Point|
A.White Powder, Did not melt oven went to 600c
B.White powder -180c
C.Blue powder, turned into white but did not melt oven went up to 600c
1.Which type of compound usually has higher melting points: ionic compounds or covalent compounds? What is the reason for this difference in melting points?
Ionic Compounds have higher melting and boiling points than covalent compounds.The electrostatic attraction in an ionic bond is very strong, so a lot of heat energy is required to break it down; ionic bonds have high melting and boiling points. In covalent bonds, the intermolecular forces are very weak and are easily broken, so lesser heat is required and thus covalent bonds have melting and boiling points.
3.Do covalent compounds conduct electricity as:
Aqueous solutions (when the covalent compounds are dissolved in water)? No
2. Do ionic compounds conduct electricity as:
Solids? No they are insulators
Aqueous solutions (when the ionic compounds are dissolved in water)? Yes