Chem help!!!

TRR8021 · Sep 10, 2009

Well, the answer to the 1st question is that yes, the container will rupture. Water has a unique property in that it expands as it freezes and the molecules spread out instead of packing together (due to hydrogen bonding.) That's why ice is less dense than water and floats in water.

As for the second part, a mL is the same as cc (or cubic centimeter) so the dimensions of the cube would be the mass divided by the density: (20.00 g)/(2.70 g/mL)= 7.41 mL or 7.41 cc, rounded to 3 sig figs.

I hope that helps. Good luck in chem!! :)

Kamdyn · Sep 10, 2009

Well, the answer to the 1st question is that yes, the container will rupture. Water has a unique property in that it expands as it freezes and the molecules spread out instead of packing together (due to hydrogen bonding.) That's why ice is less dense than water and floats in water.
As for the second part, a mL is the same as cc (or cubic centimeter) so the dimensions of the cube would be the mass divided by the density: (20.00 g)/(2.70 g/mL)= 7.41 mL or 7.41 cc, rounded to 3 sig figs.
I hope that helps. Good luck in chem!! :)

Thank you thank you thank you!!!! I have been looking through my book trying to find these formulas!!! And thanks for the good luck! I'm going to need it! Haha

Guest 360983 · Sep 10, 2009

I hope I'm not too late to help you!!

I imagine that your professor is looking for some calculations.

First, significant figures for your calcuations!! My old major required lots of chemistry, so I took lots of chemistry classes, and always had to pay attention to significant figures. I can link a site if you need an explanation.

Using significant figures, your ice density will be 1.091 g/mL. Your water density will be 1.000 g/mL. I'm assuming g & mL here, but substitute whatever measurement unit you used.

Your ice density is weird. I'm not trying to blame you (you did the math right), but ice ought to be less dense than water; this is what makes it float in water. The only reason I'm mentioning this is because it will mess with your answer for #1.

1. I think you're overthinking this problem. I do that a lot :)

Basically, you need to find the volume of the water when it turns to ice. You know the density of water and ice, and the volume of water. The mass of the water will be the same whether it's liquid or solid. Use the density formula to get the mass of water.

D=M/V

1.000=M/96.0

M=(1.000*96.0)

M=96.0 g

Now you know the mass of the ice and the density of it, so you can determine the volume it will occupy.

D=M/V

1.091=96.0/V

V=96.0/1.091

V=87.99 mL

This volume is less than the 100 mL container, so it will not shatter. See how the weird density changes the answer?

2. TRR was right in that the volume of the cube is 7.41 cc, but the question is asking for the dimensions of the cube. Volume is length x width x height; in a cube, they're all the same so (length cubed)=Volume; the cube root of 7.41, adjusted for sig figs, is 1.95 cc.

Good luck, hope I got to you in time, and I'll be happy to help with anything else (chemistry wise, anyways )

TRR8021 · Sep 10, 2009

Hmm, I don't know about the volume thing. The water loses volume when it freezes? Kamdyn, you'll have to let us know what your teacher says on that one lol. I think the trick of the question is that we'd logically think that 96.0

And yes, take the cube root to find the dimensions! Sorry!! So it would be 1.95 cc x 1.95 cc x 1.95 cc (length x width x height.)

Guest 360983 · Sep 10, 2009

I knew the answer wasn't right, but I just figured it out.

(It would probably help if I read everything more closely)

I got your density for ice wrong--you have .9168 g/mL.

So, editing in correct numbers, you have a mass of 95.90 g, leading to a volume of 104.6 mL. The glass will shatter.

So sorry to mess you up!!