Stir sugar into water and it vanishes, becoming sugar water.
This is dissolving: a solute (sugar) spreads through a solvent (water) to form a solution.
Add too much and it stops, but stirring, crushing, or heating speeds it up.
Move the sliders for sugar amount and concentration and the dissolving and the strength come into view.
What does dissolving mean?
When sugar you put in water drops out of sight, it gets hard to say in words whether that water is still the old water or a different one. Naming the side that dissolves, the side that does the dissolving, and the two together is there because it is so easy to say it vanished while the taste is still in the cup. Put in too much and leftover grains sit on the bottom; the same water tastes stronger when more went in. Fix those names first and you stop using one word for invisible and gone.
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Sugar dissolving in water — solute spreads through solvent
The first picture is a beaker. Moving the sugar-amount slider from 0g to 100g in 5g steps changes how deep the water tint looks and how many yellow dots are drawn. At a low amount the dots sit only in the water; at a high amount extra dots sit on the beaker floor and the title at the top switches to the words for no more dissolving. Tags for solute and solvent sit beside the beaker. The second picture lines up three cups labeled dilute, medium, and concentrated; moving the concentration slider from 0% to 100% changes which cup has the strong outline, and the dots inside look denser in the stronger cup. The dots do not drift through the water, and there is no control on this screen for temperature.
40g
🧊 What is dissolving?
①Dissolving: a solute mixes evenly into a solvent
②Solution: liquid formed when solute dissolves in solvent
③Sugar water = sugar (solute) + water (solvent)
④Too much solute and it stops dissolving (saturated)
Concentration of a Solution
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Comparing concentrations — more solute = stronger
50%
🔬 Concentrated vs. Dilute
①Lots of sugar in same water → concentrated
②Little sugar → dilute
③Concentrated sugar water tastes sweeter
④A denser solution can float an egg. This page's picture is sugar-water concentration
Speeding Up Dissolving
If you cannot see the sugar, it is easy to say it left the water. Dissolving is the state where the grains sit scattered between the water, so the water stays sweet and a solid is left after you evaporate it. Flip the names solute and solvent and the story of what dissolves and what does the dissolving runs backward. Dots left on the floor mean the water is near the side that will not take more sugar, which is a different case from never dissolving at all.
In sugar water, which is the substance that dissolves (solute) and which is the liquid that dissolves it (solvent)?
1
Dissolving is one substance mixing evenly into a liquid.
2
In sugar water, the sugar that dissolves is the solute and the water is the solvent.
▸ Solute: sugar / solvent: water
Solution = solute + solvent. Sugar water is sugar (solute) dissolved in water (solvent).
Example 2
What are three ways to dissolve a sugar cube in water faster?
1
Stirring makes the solute and solvent meet more often, so it dissolves faster.
2
Crushing it increases the surface area, and warming the water makes molecules more active; both speed up dissolving.
▸ Stir, crush into smaller pieces, raise the water temperature
All three help the solute mix with the solvent, speeding up dissolving.
Unit-test style
Which statement about dissolving and solutions is correct?
①The solute is the liquid that dissolves other substances
②Warming the water makes sugar dissolve faster
③Crushing the solute makes it dissolve more slowly
④A concentrated solution has less solute than a dilute one
⑤A saturated solution can dissolve even more solute
▸ ② Warming the water makes sugar dissolve faster
1
The higher the temperature, the more active the molecules, so dissolving is faster.
2
The solute is the substance that dissolves (①), crushing makes it faster (③), a concentrated solution has more solute (④), and a saturated solution dissolves no more (⑤).