Density experiment question

[chapin]

For a density experiment we have to say one reason why the density of water might have been lower at the end of an experiment, one reason why it could be higher and what happened to the density of a substance at end of experiment if the percentage change was a negative number.

Do you have any suggestions?

I said  lower because some of the water may have spilled out during the experiment

It could be higher if other materials are inside it

Not sure what would have happened to get a percentage of change as a negative number?

Any advice would be helpful.  Thanks so much !!!

 

[Asthfx]

On 20/9/2017 at 1:36 AM, chapin said:

i said  lower because some of the water may have spilled out during the experiment

It could be higher if other materials are inside it

I think you're confusing density with volume, if some of the water had spilled the volume would have also diminished, so the density, which is mass / volume, would remain the same. If other material were inside the water the total volume would increase but the volumen occupied by the water would be the same and so would the density.

You'd have a lower density if the water was frozen; the mass of it would remain the same but the volume would have diminished, so the density would be lower (that's the reason ice floats on liquid water).

Maybe you can think about the other questions?

[chapin]

thank you, that's a big help

[studiot]

2 hours ago, Asthfx said:

You'd have a lower density if the water was frozen; the mass of it would remain the same but the volume would have diminished, so the density would be lower (that's the reason ice floats on liquid water).

You are correct the answer to the OP probably has to do with the temperature of the water.

 

Asthfx perhaps you live in a part of spain where they don't have ice?
If the  same mass is squashed into a smaller volume will the density go up or down?
I have underlined you proposed answer.

 

Chapin if you define % change you will see that a positive tells you the density has increased, but a negative change tells you that it has .................?

Do you know that water is an anomalous substance?
For most substances density increases as temperature falls and this is true of water between 100^oC and 4^oC but water has its maximum density at 4^oC and the density then decreases between 4^oC and0^oC. When water freezes it expands so ice floats on water, unlike most solids on their respective liquids.
 

Edited September 21, 2017 by studiot

[Asthfx]

On 21/9/2017 at 9:37 PM, studiot said:

Asthfx perhaps you live in a part of spain where they don't have ice?

If the  same mass is squashed into a smaller volume will the density go up or down?
I have underlined you proposed answer.

My bad I meant the volume would increase (don't know what was I thinking about).