14
$\begingroup$

When I dissolve sugar in my cup of tea/coffee, does the sugar go from being a solid to being a liquid?

Figure 1

Related: https://physics.stackexchange.com/questions/5562/what-keeps-the-sugar-suspended-in-the-tea

$\endgroup$

migrated from physics.stackexchange.com Sep 22 '14 at 0:20

This question came from our site for active researchers, academics and students of physics.

  • $\begingroup$ Does NaCl dissolve apart into individual molecules? If so, how then can it be considered a solid anymore? If it doesn't, why? $\endgroup$ – User 17670 Sep 20 '14 at 18:11
  • 2
    $\begingroup$ @User17670 NaCl is not molecular, it is a crystal. You'd expect it to come apart into its constituent ions (atoms). $\endgroup$ – Kyle Sep 21 '14 at 3:26
  • $\begingroup$ @Kyle +1 for interesting statement! So, the Na would break apart from the Cl? Would this only happen above the melting point? $\endgroup$ – User 17670 Sep 21 '14 at 12:10
  • $\begingroup$ @User17670 You could melt it, but you can also dissolve it in e.g. water well below the melting point (melting point of NaCl is quite high, hundreds of degrees, but it dissolves easily at room temperature). $\endgroup$ – Kyle Sep 21 '14 at 18:46
  • $\begingroup$ @dani table salt dissolved in water is most definitely not a solid: it is a solution of table salt in water. Under what definition of solid can it possibly be still considered a solid? $\endgroup$ – matt_black May 28 '18 at 16:09
10
$\begingroup$

When the sugar dissolves, it is broken up into individual particles; each molecule is surrounded by water molecules. Essentially, you are trying to decide if a single molecule is a solid or liquid when dissolve.

The best fit is a liquid since the molecules are free to move independently and will take on the shape of the container.

$\endgroup$
  • $\begingroup$ I've thought about it a bit more and I think that the 'best' answer is that 'it doesn't make sense to consider only the sugar' - e.g. to decide if the sugar is a liquid or a gas, you have to say that it is compressible or not. On the one hand, you have sugar particles that are well spaced like a gas, but on the other hand, you can't really ask whether the sugar is compressible. So, I'm happy to go with 'it becomes part of the liquid'. $\endgroup$ – User 17670 Sep 21 '14 at 12:09
  • 1
    $\begingroup$ Indeed, usually in chemistry, a dissolved compound is indicated with the (aq) subscript, like $\ce{NaCl(aq)}$ rather than (s), (l), or (g). In essence, we're indicating it's not solid, liquid, or gas really, but something a bit different - a mixture. $\endgroup$ – Geoff Hutchison Sep 22 '14 at 15:23
  • 1
    $\begingroup$ (aq) specifically means dissolved in water (aqua). There are plenty of other solvents. $\endgroup$ – MSalters Sep 23 '14 at 15:14
  • $\begingroup$ @MSalters yes, it specifically means water, but the OP asked about dissolving sugar in tea (i.e., water solution). Thus my answer. $\endgroup$ – Geoff Hutchison Sep 23 '14 at 15:45
  • $\begingroup$ WTF? How is the best fit a liquid? Sugar in water isn't a liquid, it is a solution: a completely different thing. $\endgroup$ – matt_black May 28 '18 at 16:05
4
$\begingroup$

When I dissolve sugar in my cup of tea/coffee, does it become a liquid?

The premise of your question is wrong. There is no more "it" for the sugar when dissolved in water. You can't just consider the sugar alone. Rather the sugar becomes a constituent of the liquid phase.

$\endgroup$
2
$\begingroup$

When we dissolve sugar in tea or coffee,the sugar particle get dissociated into smaller particle. As you might be knowing there is inter molecular distance in case of solid,liquid and gas as well. In case of liquid the particles are loosely held compared to solid and also inter molecular distance is more as to solid. So finally particles get packed in those interstitial spaces.so the sugar particles do not get transformed to liquid or gas rather it get surrounded by water molecules.

.

$\endgroup$
0
$\begingroup$

Sugar added to tea becomes a solution not a liquid

Sugar is very soluble in water. When you add the solid to the tea the key process is that the solid sugar dissolves in the warm liquid: the solid crystals are broken up into molecules which are every dispersed throughout the existing liquid. When well mixed (because sugar doesn't dissolve instantly) the liquid is homogeneous with the sugar molecules evenly distributed in the single phase bulk liquid. There is no point where the sugar crystals become liquid sugar. And no chemist would describe the result as a sugar liquid. The correct description is a solution of sugar in water.

$\endgroup$
-3
$\begingroup$

When sugar dissolves into tea or coffee, the liquid transforms the sugar into a liquid so it can fit in with the liquid and slide in with the molecules. If you try to evaporate the water for long enough, you will turn the sugar back into a solid.

$\endgroup$
  • $\begingroup$ Sugar is not transformed into a liquid: it is dissolved. $\endgroup$ – matt_black May 28 '18 at 16:07
-3
$\begingroup$

when you dissolve sugar crystals into tea or coffee the tea turns the sugar (solid) into a liquid.It separates the participles in the sugar crystals into smaller particles.

$\endgroup$
  • 3
    $\begingroup$ No. Things dissolved in other liquids are not themselves described as liquids. $\endgroup$ – matt_black May 28 '18 at 16:06

Not the answer you're looking for? Browse other questions tagged or ask your own question.