Chemistry HELP!!!

[Kamdyn]

Hi everyone, I am in desperate need of some explaining!!! We have our first chem lab today and I have a pre-lab assignment I'm just NOT getting!!! (I swear he hasn't gone over any of this stuff in class yet)

So the first thing we had to do was calculate the volume of ice and water, which I did.

Ice: (mass) 1.000/(density) 0.9168= (volume)1.090750436

Water (mass) 1.000/(density) 0.9999= (volume)1.00010001

The next question is this: A sealed glass container with a capacity of exactly 100mL contains 96.0 mL of liquid water a 0 degrees C. If the water freezes, will the container rupture?

I'm really confused because doesn't water freeze at 0 degrees C? So how can water be at a liquid state at this temp? I'm not sure what the answer is or how to answer it!! Ughhh

I also do not know how to answer the following question:

A perfect cube of aluminum metal was found to weigh 20.00 g. The density of aluminum is 2.70 g mL -1. What are the dimensions of the cube?

I would ask my teacher but we're expected to hand this in when we get to lab today... Can someone please show me how to do these problems?!?!

Thanks SOO much for any and all help!!

[SaraFL]

What is the -1 after the density?

[SaraFL]

OK, I'm not positive about this, but since no one else has answered yet, I'll try...(trying to remember my chemistry LOL, and I'm not great at # of significant digits, so take that into account)

For the dimensions of the cube:

You need the volume of the cube.

Density = mass/volume, so volume = mass/density

V = (20.0 g) / (2.70 g/mL)

V = 7.407 mL

OK, so the volume of an object is length times width times height, and since it's a perfect cube, they should all be equal. So basically x3 (x cubed) should equal 7.407. So, cube root of 7.407 should equal x. I don't have my calculator with me, but that should be somewhere around 1.9-something.

Right?

[SaraFL]

As far as the ice, I'm not sure how to set up the formula, but to me it looks like for every 1.00 mL of water, that makes 1.09 mL of ice. Since you have 94 mL of water, that would make 102.46 mL of ice (I got that by multiplying 94 x 1.09), so I think that yes, the container would rupture.

I hope that someone who knows for sure will post, but I tried, LOL.

[QuarterLife88, MSN, RN, NP]

I wish I could help:crying2:, but my chem class has only gotten as far as dimensional analysis so far.

I have to say though, that I know what you mean about the pre-labs be given before you have learned the info. For some odd reason, chem labs are designed like this. Makes NO sense.

Luckily, a few semesters back, my teacher noticed this, and thought it wasn't fair to make us do them when we didn't have the info yet, so she wants us to only attempt them before lab, and then turn them in a week later AFTER we have learned the info. Maybe you can suggest that to your instructor, and get a few others to do it with you as well.

Good luck. Chem is a *****. I much prefer Bio classes myself.

[FazzDazzle]

I know your quiz was today so i'm sorry this will be too late for you but i recently took chemistry and you will need to know how to do this later on too. I'm not too sure of the cube thing i think SaraFl has it right. So here is the ice formula:

96.0mL x 0.9999= 95.99(mass)/0.9168= 105mL ice

[markuskristian]

I'm agreeing with the above stated.

1 unit of water is at 1 volume

1 unit of ice is at 1.09... volume

96mL of water becoming ice [96x1.09...] is ~105mL which will burst the sealed 100mL graduated cylinder.

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wait someone already posted about the second part. use the d=m/v formula and take the cube root of that [volume].