Dilute and dissolve are two different steps of the same chemistry. To dissolve is for a solid to break apart and spread through a liquid, making a solution — the sugar cube vanishing into the glass. To dilute is to weaken an existing solution by adding more liquid — the same sugar-water made less sweet. A solute dissolves; a solution gets diluted.
The confusion is one of order rather than meaning. Dissolving creates the mixture: from Latin dissolvere, 'to loosen apart', a solid loses its structure into a solvent and is carried away molecule by molecule. Diluting acts on a mixture that already exists — from diluere, 'to wash away' — by adding more solvent so the same amount of substance is spread through a greater volume and everything gets weaker. Dissolve is about a solid disappearing into liquid; dilute is about strength going down. You dissolve the salt; then you dilute the brine.
dilute
To dilute is to weaken by spreading thin — classically by adding water, so a strong solution becomes mild. From the Latin diluere, 'to wash away', it keeps that sense of strength draining out: dilute the acid, dilute the juice. Figuratively, anything concentrated can be diluted — a message, a brand, a share of power — when it is stretched across too much. It is the opposite of saturate: where one packs more in, the other thins it out until little force remains.
dissolve
To dissolve is for a solid to break apart into a liquid until it disappears into it — sugar dissolves in water — or, by extension, for something to fade out or be formally ended (a marriage, a company, a parliament is dissolved). From the Latin dissolvere, 'to loosen apart', from solvere 'to loosen', the root of solve and solvent. A substance dissolves when its particles separate and spread evenly through the liquid — the reverse of what happens when droplets coalesce. Governments dissolve; tension dissolves; a crowd can dissolve into laughter.
| dilute | dissolve | |
|---|---|---|
| Meaning | weaken a solution by adding solvent | break a solid apart into a liquid |
| Acts on | a solution that already exists | a solid (the solute) |
| Order | second — after something dissolved | first — it makes the solution |
| What changes | concentration falls | the solid loses its form |
| Typical sentence | dilute the syrup with water | dissolve the tablet in water |
| Nouns | dilution | dissolution |
The blooming drop and the vanishing cube. Dissolve is the cube: a solid gives up its edges and disperses into the water until no solid is left — the solution is born. Dilute is the drop of colour spread thinner and thinner: nothing new dissolves, the same substance is simply asked to fill more room, and everything grows fainter. Ask what you added. Added a solid to a liquid: it dissolves. Added liquid to a mixture: you diluted it.
dilute
- iDilute the concentrate with four parts water.
- iiRain diluted the pond until the salinity readings halved.
- iiiAdding new shares dilutes the value of the existing ones.
dissolve
- iStir until the salt dissolves completely.
- iiThe tablet dissolves in water in under a minute.
- iiiLimestone slowly dissolves in acidic rain.
The vocabulary around them is worth holding together: the substance that dissolves is the solute, the liquid it dissolves into is the solvent, and the result is a solution — which you then dilute by adding still more solvent. The two verbs also lead separate figurative lives that never overlap: influence, brands and voting power are diluted (weakened by spreading), while parliaments, marriages and partnerships are dissolved (formally ended). Dilute's other confusable, the look-alike dilate, is handled on its own page in the 'Related' list below.
Science tasks reward the chain in the right order: the solute dissolves in the solvent to form a solution, which can then be diluted. TOEFL chemistry and biology passages assume it — osmosis, saline concentrations, buffer preparation — and the marked error is treating them as synonyms ('dilute the sugar in water' when you mean dissolve it). One quantitative fact makes the difference stick and is worth a clause in a process answer: diluting does not remove any of the dissolved substance; it only spreads the same amount through more liquid, so concentration falls while the quantity stays put.