Identity?

[Banks]

Ok,

 

So I've completed the question #8 from textbook. What I'm confused about is question #9.

 

Here is the question 8.

 

#8. For each substance below, identify it as ionic or molecular. Explain how you came to your conclusion.

 

a) Compound 1: melting point: 48C, low solubility in water, flammable, mild odour, colourless solid easily crushed

 

My answer: molecular - because of low melting point

 

b) Compound 2: melting point: 800C, highly soluble, solution is highly conductive, hard, white crystals

 

My answer: ionic - because of high melting point + tight crystal structure

 

c) Compound 3: melting point: 185C, decomposes at 190C, highly soluble, solution is not conductive, hard, white crystals

 

My answer: molecular - because it's not conductive + hard

 

d) Compound 4: sublimates (goes from solid to gas) at -56C, moderately soluble in water, colourless, odourless

 

My answer: molecular - because it's able to change from solid to gas + low melting point

 

e) Compound 5: highly flammable liquid at room temperature, does not mix with water, less dense than water

 

My answer: molecular - because it's liquid

 

f) Compound 6: colourless, odourless liquid, tends to dissolve ionic substances, boils at 100C

 

My answer: molecular - because it's liquid

 

#9. All of the compounds in question 8 are common materials. Suggest the identity of each material from the descriptions of the physical properties.

 

So, I have to suggest the identity? What kind of identities? Is it names such as coffee, water, cooking oil, table salt, or...? Confusing question, if you ask me. How would I go about determining the identities?

 

Thanks.

Edited February 26, 2012 by Banks

[imatfaal]

I wouldn't be too harsh. I am no chemist but I reckon you have at least one right in your list already. try wkiipedia on both the white crystalline substances you might find on a dinner table which should give you two of them.

 

Trying to find out what stuff is from limited info is good practice (melting points and decomposition temps are good data to use). I will have a think what the others might be.

 

Edit iPhone probs

 

Ok. I reckon I can guess all of them except number 4 - and i have a shrewd guess there might be a typo in the question.

 

A few hints

1. 48 deg C. Not that hot - when used, if I hve guessed correctly, it melt and burns soon after - all part of a simple process

 

2. See above

 

3. See above

 

4. If it sublimates at -56 deg C then it is a gas at room trmperature. What examples of materials that sublimate can you find - the most common are iodine Which is gray/purple snd another which fits this description nicely apart from temp

 

5. Not sure about your guess. I wouldn't call cooking oil highly flammable - ok a chip pan fire is pretty terrible, but there are other coomon clear liquids that fit the bill

 

6. Boils st 100 deg c ....

Edited February 27, 2012 by imatfaal