Water is often called the universal solvent because it can dissolve more substances than any other liquid we use in daily life, which directly explains why is water known as universal solvent in basic science, according to the USGS. That single fact explains a lot: why blood can carry nutrients, why rivers move minerals, and why labs can make so many kinds of solution with plain water. But the nickname also leads to a fair question. If water is “universal,” why doesn’t it dissolve oil, wax, or plastic? The answer is simple: “universal” does not mean “dissolves everything.” It means water is the best all-around solvent for many common ionic and polar molecules, thanks to its special property as a polar water molecule with strong attractions.
Universal solvent meaning (fast, accurate answer)
A universal solvent is a liquid that can dissolve a very wide range of solutes. When people ask what is the universal solvent, they almost always mean water, because water is the universal solvent. In plain terms, water is the liquid that dissolves the most different kinds of everyday substances—especially salts and other charged or partly charged compounds.
Why Water Is Called the Universal Solvent
Water is called the universal solvent because it can dissolve more substances than any other liquid. It does this because each water molecule has a slightly negative charge near the oxygen atom and a slightly positive area near its two hydrogen atoms. That uneven charge helps water pull apart ions in salt, mix with many polar molecules, and keep them spread out in a stable mixture.
The 3 properties that explain “universal”
The key point is that water’s structure makes it unusually good at surrounding and separating solutes.
-
Water is polar: oxygen is slightly negative (δ⁻), and the hydrogen side is slightly positive (δ⁺).
-
Water forms hydrogen bonding, a network of weak attractions that can “hold” many dissolved particles in place.
-
Water has a high dielectric constant (about 80), which reduces the pull between opposite charges, making it easier for salts to split into ions.
What “universal” does not mean (myths vs reality)
It helps to clear up a common myth: water can’t dissolve everything. It is weak at dissolving nonpolar (hydrophobic) materials like oil, many waxes, and many plastics. If you have ever watched oil and water separate into two layers, you have already seen the limit of “universal.”
Visual: “1-minute” infographic (definition + do/don’t dissolve list)
Here is a quick, text-style infographic you can picture:
Universal solvent = water
Best at dissolving:
-
Salt (like sodium chloride), many minerals, many acids and bases
-
Sugar, many small alcohols, many amino acids
Sometimes dissolves (depends on conditions):
-
Some gases (oxygen, carbon dioxide)
-
Some weakly polar organics
Poor at dissolving:
-
Oil, grease, wax
-
Many plastics (like polyethylene)
If you remember one line, remember this: “Like dissolves like.” Water is polar, so it best dissolves ionic and polar solutes.
The science behind water’s dissolving power
You do not need advanced science to get the idea, but a few simple concepts explain almost everything you see.
Polarity + ion–dipole interactions (hydration shells)
A water molecule is shaped a bit like a bent “V.” The oxygen pulls electrons more strongly than hydrogen does, so oxygen becomes slightly negative and the hydrogens become slightly positive. This is water’s polar nature.
Now think about salt (sodium chloride). In solid salt, sodium and chloride stick together because opposite charges attract. When salt touches water, water molecules crowd around each ion and weaken that attraction.
This is called a hydration shell. Water lines up in a specific way:
-
Around sodium (Na⁺), the oxygen side (slight negative) points inward.
-
Around chloride (Cl⁻), the hydrogen side (slight positive electrical charge) points inward.
Once enough water molecules surround each ion, the ions can split apart and move freely. That is why salt water conducts electricity and why a salt water substance tastes salty in a uniform way throughout the glass.
Visual (hydration-shell diagram idea):
Imagine a single Na⁺ in the center. Around it is a ring of water molecules with their oxygen atoms facing inward. Next to it is a Cl⁻ with water molecules facing the other way, hydrogens pointing in. That “coating” is the hydration shell that keeps the ions from snapping back together.
Hydrogen bonding network (why many polar organics dissolve)
Water molecules also cling to each other through hydrogen bonding. These are not full chemical bonds like in salt; they are weaker attractions between a slightly positive hydrogen and a slightly negative oxygen on a nearby molecule. Even though each one is weak, there are many of them, so the network is powerful.
This matters because many important solutes can join that network. Sugar, for example, has many oxygen‑hydrogen groups that can form hydrogen bonds with water. Many polar molecules—like small alcohols—have parts that can “plug into” water’s hydrogen-bond web. When that fit is good, water can dissolve the solute easily, turning it into a smooth, stable mix.
This is one reason your coffee can carry dissolved flavors, colors, and acids. The water is not just a passive liquid; it is actively grabbing and holding many compounds.
High dielectric constant (~80) and weakened ionic attraction
One of the most important technical reasons water is called the universal solvent is its dielectric constant, which is about 80 near room temperature, based on NIST. A simple way to say this is: water weakens the force between charges. If two ions strongly attract each other in air, they attract much less in water.
That is a big deal for dissolving salts. It helps explain why water can pull ions apart and keep them apart.
A quick comparison helps:
| Liquid (approx.) | Dielectric constant (room temp) | What that suggests |
| Water | ~80 | Very good at separating ions |
| Ethanol | ~25 | Less effective than water for many salts |
You do not need the math here. Just keep the idea: a higher dielectric constant makes it easier for charged particles to exist separately in a solution.
Water as an amphoteric solvent (broader reaction compatibility)
Water is also amphoteric, which means it can act like an acid or a base depending on what it is mixed with. Water can form both H₃O⁺ (hydronium) and OH⁻ (hydroxide):
(2H_2O rightleftharpoons H_3O^+ + OH^-)
This matters because it lets water support many kinds of chemical reactions. A lot of everyday chemistry—digestion, fermentation, rusting, acid-base reactions—takes place in water because water can take part in the process, not just sit there.
What water dissolves best and why
So what does water actually dissolve well, and what does it struggle with?
Solubility patterns: ionic vs polar vs slightly polar
Water is strongest with:
Ionic salts. If a solid is made of ions (like sodium and chloride), water often dissolves it because of hydration shells and that high dielectric constant. Salt is the classic example of water dissolving an ionic solid: the crystal breaks into separate ions and spreads out evenly.
Polar molecules. Many molecules that have uneven charge (even if they are not fully ionic) dissolve well because they can form hydrogen bonds or strong attractions with water. Sugar is a good example.
Some gases. Water can dissolve gases like oxygen and carbon dioxide, but the amount depends on conditions. Cold water often holds more dissolved gas than warm water. That is one reason fish can struggle in warm water: less dissolved oxygen is available.
Table: “Dissolves well / somewhat / poorly” with examples
This table is not about exact numbers; it is about patterns you can use to predict behavior.
| How well water dissolves it | Types of molecules | Examples |
| Dissolves well | Ionic, strongly polar | NaCl, KCl, baking soda, glucose |
| Dissolves somewhat | Mildly polar, condition-dependent | Carbon dioxide, oxygen, some small organics |
| Dissolves poorly | Nonpolar / hydrophobic | Oil, wax, many plastics (like polyethylene) |
Data angle: factors controlling solubility (where to find numbers)
Even when water can dissolve something, the amount can change a lot. If you have ever tried to dissolve sugar in iced tea versus hot tea, you have seen this.
The most common factors are:
Temperature. Many solids dissolve more at higher temperature, so hot water often dissolves faster and holds more. Gases often do the opposite: warmer water usually holds less gas.
Pressure (for gases). Higher pressure can push more gas into the liquid. This is a key idea behind carbonated drinks.
pH and ionization. Some substances dissolve better when they gain or lose a hydrogen ion. That is why some medicines dissolve differently in the stomach than in plain water.
If you want exact solubility numbers, good places to look are official chemical databases and public data sources like NIST or PubChem.
What substances cannot dissolve in water?
Many nonpolar substances cannot dissolve well in water. The most common examples are oil, grease, waxes, and many plastics. They do not have positive and negative areas that can interact strongly with water, so water molecules prefer to stick to each other instead of surrounding the solute. That is why oil and water separate into layers instead of forming one stable liquid.
Why water is called the universal solvent in biology
If water were not such a strong solvent, life would look very different. A lot of what your body does every day depends on the simple fact that water carries dissolved things.
Nutrient and waste transport in organisms (blood/fluids)
Your blood is mostly water. That watery base carries dissolved substances that your cells need and also carries waste away.
A few clear examples make this real:
Glucose dissolves in water, so it can travel through blood to reach cells for energy. Electrolytes (like sodium and potassium ions) dissolve, which helps maintain fluid balance. Waste chemicals like urea dissolve, so your body can move them to the kidneys and remove them.
In other words, the same “hydration shell” idea you saw with salt matters inside you too. Dissolved ions can move through watery fluids, which supports many basic body functions.
Protein folding, enzyme action, and digestion in aqueous environments
Proteins live in water. That sounds simple, but it has big effects. Many proteins fold into shapes where water-friendly (polar) parts face outward, and water-shy (nonpolar) parts hide inward. This folding is not just a detail; it helps proteins work correctly.
Enzymes—proteins that speed up reactions—also work in watery surroundings. Digestion happens in water-based fluids. When you eat food, water helps break it down, dissolve small pieces, and move them where they need to go.
Case study concept: osmosis and electrolyte solutions (everyday physiology)
Have you ever felt better after drinking water with electrolytes during heavy sweating? The idea is not magic. Dissolved ions change how water moves across cell membranes through osmosis. Hydration shells help ions stay mobile, and that supports things like nerve signaling and muscle function.
This is not medical advice, but it shows the same basic chemistry shows up in everyday life.
Visual: “From molecule to cell” diagram (concept)
If you were sketching this, you might draw: a water molecule → surrounding ions → dissolved nutrients in blood → a cell membrane with water moving through → a cell using those dissolved nutrients. It is one story from tiny charge differences to whole-body transport.
Environmental and Earth-system impacts—an explanation
Water’s power to dissolve shapes the surface of Earth. The same process that dissolves salt in a glass also dissolves minerals from rock, slowly but steadily.
Weathering + mineral transport (rivers as solvent systems)
Rainwater picks up carbon dioxide from the air and soil. That slightly changes the water’s chemistry and can help break down rock. Over time, water dissolves small amounts of minerals and carries them away. Rivers are not just flowing water; they are moving solutions.
If you have seen a mineral stain in a sink or a white crust on rocks near a spring, you have seen dissolved minerals leaving a mark after water evaporates.
Pollutant mobility and water quality implications
Water dissolves many helpful things, but it can also dissolve and move harmful things. Nitrates and phosphates from fertilizers can dissolve and travel through soil into waterways. That can contribute to algae growth and poor water quality.
On the other hand, many hydrophobic pollutants do not dissolve well. Oil spills often form slicks because oil and water separate. Even so, oil can still spread across the surface and cause damage, which shows that “not dissolving” does not mean “not a problem.”
Public health agencies focus on dissolved contaminants because if something is dissolved, it can travel widely and be hard to remove without treatment.
Case study: salinity and marine chemistry (why oceans are salty)
Why are oceans salty? One simple explanation is time. Rivers dissolve tiny amounts of minerals from land and carry ions to the sea. Water evaporates, but most dissolved salts stay behind. Over long periods, that can build up salts in ocean water.
So when you taste seawater, you are tasting a long story of rock weathering, transport, and evaporation—powered by water’s solvent ability.
Chart suggestion: watershed dissolved load pathways (concept)
A useful mental picture is a hillside with rainwater moving through soil, dissolving ions, entering streams, and then entering the ocean. Along the way, the dissolved load changes based on geology, land use, and human activity.
Industrial and laboratory applications (where “universal” matters)
Water is not only important in nature. It is also the main working liquid in many industries and most science labs.
Pharma/biotech: dissolution, buffers, and formulation basics
Many products and processes rely on water as the base solvent because it dissolves salts and many polar compounds, and it is generally safe to handle compared with many organic solvents. In labs, water is used to make buffers (solutions that resist pH change), to dissolve reagents, and to rinse equipment.
In these settings, purity matters a lot. Small differences in dissolved ions can change pH, reaction speed, or measurement accuracy.
Cleaning and separation: when water works vs when co-solvents are needed
Ever tried to clean a sugary spill versus greasy cookware? Sugar dissolves in water quickly. Grease does not. That difference comes straight from polarity.
When water struggles with oils, we often use surfactants (like soaps) that have one end that likes water and one end that likes oil. They help oil break into tiny droplets so it can be carried away. In some cases, people use a different solvent or a co-solvent (a mix of liquids) to dissolve a stubborn substance. The “like dissolves like” rule still runs the show.
Lab practice: preparing solutions and controlling variables
In basic lab work, small choices can change results. Temperature affects dissolving speed. Stirring changes how fast a solid spreads out. pH can change whether a solute stays neutral or becomes charged. Even the type of water matters, which is why labs choose between tap, distilled, deionized, or ro water (reverse osmosis water) depending on the goal.
If you have ever had a “mystery” result in an experiment, it might have been contamination from dissolved minerals in the water.
Table: water grades (tap vs distilled vs deionized) + best uses
Different water types mainly differ in how many dissolved ions and other impurities they contain.
| Water type | What it usually contains | Best practical uses |
| Tap water | Dissolved minerals, disinfectant residuals, varying ions | Drinking (when safe), general washing |
| Distilled water | Very low minerals (boiled and condensed) | Mixing solutions when minerals would interfere, steam irons |
| Deionized water | Ions removed (often still has some organics) | Lab rinsing, many lab solutions |
| RO water | Many dissolved solids reduced by membrane filtration | Drinking systems, aquariums, pre-lab rinsing |
In short, cleaner water gives you more control. That matters in science, in manufacturing, and even at home.
Limitations, edge cases, and alternatives
If water is called the universal solvent, it is fair to ask where it fails and what other liquids do better.
Why water fails on hydrophobic molecules (nonpolar interactions)
Nonpolar substances do not have strong positive/negative areas to attract water. Water molecules prefer to hydrogen-bond with each other instead of surrounding a nonpolar molecule. That is why droplets of oil pull together and float as a separate layer.
This is also why many plastics do not dissolve in water. Their molecules are often long chains with few charged or polar parts, so water has little to grab onto.
Is acetone a universal solvent? (and why not)
Acetone is a common solvent that can dissolve many organic compounds, including some paints and resins. So people sometimes wonder, is acetone a universal solvent? No. It is powerful for certain materials, but it is not “universal.” It does not dissolve salts well the way water does, and it is not the best choice for many ionic or strongly polar solutes.
A better way to think about it is this: water is the most versatile solvent for ionic and polar chemistry, while some organic solvents are more versatile for nonpolar or oily materials.
Comparison table: water vs common solvents (use cases + tradeoffs)
This is a simplified comparison to help you choose the right mental model.
| Solvent | What it’s great at dissolving | Common limits | Safety notes (general) |
| Water | Salts, many polar solutes, many biomolecules | Oils, waxes, many plastics | Generally safest, but purity matters |
| Ethanol | Many polar organics, mixes with water | Many salts dissolve poorly | Flammable |
| Acetone | Many organics, oils, some polymers | Poor for many salts | Flammable, can irritate skin |
| DMSO | Very wide range of organics and some salts | Not ideal for all materials; strong skin absorption | Handle carefully; carries substances through skin |
This is not a shopping guide. It is a “why” guide: different solvents work because their molecules interact differently with solutes.
Hard water vs soft water (dissolved minerals as a practical limitation)
Here is an everyday limitation many people feel: hard water. Hard water contains more dissolved calcium and magnesium ions. Because water dissolves minerals so well, those ions travel easily through plumbing. When hard water evaporates or is heated, it can leave mineral scale behind.
That scale can reduce the efficiency of kettles, water heaters, and some appliances. It can also make cleaning harder because soap reacts with calcium and magnesium, leaving a film instead of rinsing clean.
Soft water has fewer of those ions, so it tends to lather better and leave fewer deposits. This is not water “being bad.” It is water doing its job as a strong solvent—sometimes a little too well.
Is water truly a universal solvent?
No, water is not truly universal. Water is considered the universal solvent because it dissolves more substances than any other common liquid, especially ionic and polar ones. But it does not dissolve many nonpolar materials like oils and many plastics. So “universal” is a nickname, not a scientific promise.
Experiments, tools, and actionable takeaways
If you want to make this real, you can test it at home with safe kitchen items. Doing it once makes the idea stick.
DIY experiment: test solubility across household substances (safe protocol)
You only need clear cups, room-temperature water, a spoon, and a few common solids and liquids. Try salt, sugar, baking soda, and vegetable oil.
Step-by-step
-
Fill four clear cups with the same amount of water.
-
Add one teaspoon of salt to cup 1. Stir for 20 seconds.
-
Add one teaspoon of sugar to cup 2. Stir for 20 seconds.
-
Add one teaspoon of baking soda to cup 3. Stir for 20 seconds.
-
Add one teaspoon of vegetable oil to cup 4. Stir for 20 seconds.
-
Watch each cup for one minute, then again after five minutes.
What do you expect to see? Salt and sugar should disappear into the water and form a clear solution (or close to it). Baking soda dissolves, but sometimes more slowly or with slight cloudiness. Oil forms droplets and then separates into a layer because it does not mix well in water.
Control variables (so your test is fair): keep the same water volume, same spoon, same stirring time, and similar particle size (fine salt dissolves faster than rock salt), using a filter ensures your water is clean and free of minerals that could affect solubility.
Interactive tool idea: “Predict solubility” chooser (simple rules)
If you want a quick way to guess solubility without memorizing tables, ask three questions:
-
Is the solute ionic (like many salts) or does it form ions in water? If yes, water often dissolves it well.
-
Does the solute have polar groups that can hydrogen-bond (like many sugars and alcohols)? If yes, water often dissolves it.
-
Is the solute mostly nonpolar (like oils, waxes, many plastics)? If yes, water usually dissolves it poorly unless you add a surfactant or change the chemistry.
How does temperature affect solubility in water?
Temperature often increases the solubility of many solid solutes in water and speeds up dissolving. That is why sugar dissolves faster in hot tea than iced tea. For gases, warmer water usually holds less dissolved gas, which is why cold water can contain more oxygen than warm water.
Key takeaways
Water has the ability to dissolve more substances because it is a polar molecule with hydrogen bonding and a high dielectric constant. That makes it excellent at dissolving ionic and polar solutes, from table salt to many nutrients in your body. At the same time, water is weak at dissolving nonpolar materials like oil and many plastics, so it is not “universal” in the literal sense. When results matter—cleaning, lab work, or even taste—conditions like temperature, pH, and water purity (tap vs distilled vs deionized vs ro water) can change what happens. Using a filter can provide consistently pure water for experiments, cooking, and daily drinking.
FAQs
1. What is a universal solvent?
In everyday terms, a universal solvent is a liquid that can dissolve many substances rather than just a few specific ones. In science, this idea usually points to water, which is often referred to as the universal solvent because it interacts easily with a wide range of materials. From salts and sugars to gases and nutrients, water can handle an impressive combination of solutes. Scientists rely on this property when mixing elements in labs, cleaning glassware, or studying reactions involving bacteria. The science behind this lies in how water molecules interact with other particles, making it unusually versatile compared with most liquids.
2. Is acetone a universal solvent?
Acetone is sometimes casually called a strong or “all-purpose” solvent, but it is not a universal solvent in the scientific sense. It works very well on many organic materials, especially oily or resin-like substances, and that makes it useful in certain situations. However, acetone struggles with many salts and ionic compounds that dissolve easily in water. Unlike water, it cannot support the same range of chemical and biological processes. A scientist would choose acetone for a specific task, not as a one-liquid solution for many substances the way water is used.
3. Why is water called the universal solvent?
Water is called the universal solvent because its molecular structure gives it a special dissolving power, which is the main reason why water is called a universal solvent in science. Each water molecule has a slight negative charge on one side and a slight positive charge on the other, allowing it to pull apart ions and surround them effectively. This makes it possible for water to dissolve spices in cooking, nutrients in the body, and minerals in nature. Unlike mercury or other elements that tend to stay separate, water forms stable mixtures with many substances. This unique combination of polarity and flexibility explains why water plays such a central role in chemistry, biology, and everyday life.
References