Which Cup Will Sugar Dissolve Faster In? Why?

[BakyX]

I have two same glasses. In both glasses I have water with the same temperature. I put sugar cube to the first cup and in the second cup I fix sugar cube so that the cube doesn’t touch bottom of glass. In which cup will sugar dissolve before ? Why ?

Hello..Next problelm..At first, sorry for bad english. At second..I try it and sugar dissolve before in the second cup..But there is still question WHY

Thanks everyone for help

 

[Ranger Mike]

i assume the sugar cube in first cup fell to the bottom and came to rest with bottom surface flush with bottom of the glass..correct
the cube wit hall 6 sides exposed to the water will dissolve simply because more area is exposed ..the sugar cube resting on the bottom has only five sides exposed to the water

 

[Naty1]

No SURE way to tell...maybe the motion abrasion of falling all the way to the bottom of the glass results is a quicker dissolve...if the volumes of water are different and the shapes [depths] of the glasses that could also affect the results...

but keeping things simple I agree with the logic above...

How much of a difference did you observe?? How often did you repeat the measurements??

One sugar cube exposed to humid moist air before immersion might dissolve more quickly than a dry one in an air tight container...I would guess...

Different brands may differ in dissolution characteristics...how artificial creamer particles dissolve was apparently a big issue with those products...and reportedly took lots of experimentation...

 

[Redbelly98]

Besides the more surface area in the second case, I wonder if, as sugar molecules are heavier than water, they will tend to sink to the bottom of the glass. This would mean the sugar cube on the bottom of the glass will be surrounded by a solution with a higher sugar concentration as it dissolves, perhaps near saturation. So the rate of dissolving (per surface area) would be lower for the sugar cube at the bottom of the glass.

But I could be wrong, and the dissolved sugar might distribute pretty uniformly thoughout the glass.

To test this, you could do the experiment with both sugar cubes suspended; one near the bottom of the glass and one near the middle or top.