Evaporation vs Sublimation — Difference (with Table & FAQs)
Evaporation vs Sublimation compared side by side — a 5-row comparison table, 4 key points and 7 exam FAQs. Class 9 Chemistry, free and no sign-up.
TL;DR: Evaporation vs Sublimation compared side by side — a 5-row comparison table, 4 key points and 7 exam FAQs. Class 9 Chemistry, free and no sign-up.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
The main difference between Evaporation and Sublimation: Evaporation converts liquid to gas while sublimation converts solid directly to gas. Both are phase changes studied in CBSE chemistry.
Evaporation vs Sublimation — Comparison Table
| Basis | Evaporation | Sublimation |
|---|---|---|
| Initial state | Liquid | Solid |
| Final state | Gas | Gas |
| Intermediate state | No intermediate | No intermediate |
| Temperature | Below boiling point | Below melting point |
| Examples | Water drying from clothes | Dry ice, naphthalene |
Key Points
- Evaporation occurs at surfaces of liquids
- Sublimation requires very low pressure
- Both are endothermic processes
- Sublimation is used in freeze-drying
Evaporation: liquid to gas, from the surface only
Evaporation is a liquid changing into vapour at temperatures below its boiling point. The key idea is that it happens only at the surface. Particles in a liquid move at a range of speeds; a few at the surface happen to be moving fast enough to escape the attraction of their neighbours and leave as vapour. This is why a puddle dries at 30 °C even though water boils at 100 °C.
Because the fastest particles are the ones that escape, the average energy of the particles left behind falls — and lower average energy means lower temperature. That is why evaporation causes cooling. It is why you feel cold stepping out of a swimming pool, why sweating cools you down, and why water stays cool in an earthen pot: water seeps through the pores, evaporates from the outside, and takes heat from the pot with it.
Sublimation: solid straight to gas
Sublimation is a solid changing directly into vapour without ever becoming a liquid. The liquid state is skipped entirely, and that single fact is the whole difference. Camphor left in a cupboard shrinks and disappears without ever leaving a puddle; naphthalene balls behave the same way.
The standard laboratory demonstration uses ammonium chloride heated in an inverted funnel over a china dish: the solid turns straight to vapour, rises, and re-forms as a solid on the cool glass above. Iodine and solid carbon dioxide (dry ice) also sublime — dry ice is named for exactly this reason, since it leaves no liquid behind.
The four factors that speed up evaporation
This list is examined directly almost every year. Learn all four with a reason for each.
- Surface area — more exposed surface means more particles positioned to escape. Clothes spread out dry faster than clothes bundled up.
- Temperature — heat gives particles more kinetic energy, so more of them can break free. Clothes dry faster in the sun.
- Humidity — humidity is how much water vapour the air already holds. When the air is nearly saturated, evaporation slows. This is why clothes take so long to dry during the monsoon.
- Wind speed — moving air carries away the vapour that has just formed, keeping the air above the liquid unsaturated so more can evaporate. Clothes dry faster on a breezy day.
All six changes of state, and their names
Naming the reverse processes correctly separates a full-mark answer from a partial one.
- Melting (fusion) — solid to liquid, at the melting point.
- Freezing (solidification) — liquid to solid, the reverse of melting.
- Vaporisation — liquid to gas. This covers both evaporation (at the surface, any temperature) and boiling (throughout the liquid, at the boiling point only).
- Condensation — gas to liquid, the reverse of vaporisation. Dew on grass, water droplets on a cold glass.
- Sublimation — solid straight to gas.
- Deposition (also called desublimation) — gas straight to solid, the reverse of sublimation. Frost forming on a cold window is water vapour depositing as ice.
Why latent heat matters here
During a change of state, heat is absorbed or released but the temperature does not change. That hidden heat is called latent heat, and it goes into overcoming the forces holding the particles together rather than into raising temperature.
The latent heat of fusion of ice is 3.34 × 10⁵ J/kg and the latent heat of vaporisation of water is 22.5 × 10⁵ J/kg. The vaporisation figure is far larger because the particles must be separated completely, not merely loosened. This is why steam at 100 °C causes a much worse burn than water at 100 °C: the steam releases all that extra latent heat as it condenses on your skin.
Evaporation vs Sublimation — Worked Examples
- Wet clothes drying on a line — Evaporation. Liquid water at the fabric's surface becomes vapour well below 100 °C.
- A camphor tablet vanishing over a week — Sublimation. The solid became vapour directly — the shelf underneath stayed dry.
- Feeling cold after a swim — Evaporation causes cooling. The fastest water particles leave your skin, taking energy with them.
- Dry ice producing white fog — Sublimation. Solid carbon dioxide becomes gas directly; the visible fog is water vapour from the air condensing in the cold.
- Frost on a windowpane — Deposition — the reverse of sublimation. Water vapour becomes solid ice without becoming liquid first.
Common Mistakes Students Make
- Saying sublimation is 'fast evaporation'. They start from different states entirely — sublimation starts from a solid, evaporation from a liquid.
- Claiming evaporation only happens at the boiling point. It happens at all temperatures, because it only needs surface particles with enough energy.
- Confusing evaporation with boiling. Evaporation is a surface phenomenon at any temperature; boiling happens throughout the liquid at a fixed temperature.
- Forgetting that evaporation causes cooling, and forgetting to explain why (the higher-energy particles leave).
- Naming the reverse of sublimation as 'condensation'. Gas to solid is deposition; condensation is gas to liquid.
Diagrams
Where This Shows Up in Real Life
Why an earthen pot keeps water cool
The classic Indian example, and it is pure evaporation. Clay is porous, so water seeps slowly to the outer surface and evaporates there. Because only the fastest-moving particles escape, the average kinetic energy of the water left behind drops, and the temperature with it. The pot works best in dry, breezy weather and barely works during the monsoon, when high humidity slows evaporation. The same physics explains why desert coolers work well in Delhi in May but fail in coastal Chennai.
Sweating, and why a fan helps
Your body cools itself by evaporating sweat. The energy needed to turn liquid sweat into vapour is drawn from your skin, which is why you feel cold as it dries. A fan does not lower the air temperature at all — it increases the wind speed over your skin, carrying away saturated air and letting more sweat evaporate. On a very humid day a fan feels far less effective, because the air already holds close to as much water vapour as it can.
Sublimation in the kitchen and the laboratory
Naphthalene balls placed in a cupboard shrink and vanish over weeks without ever leaving a puddle, because they sublime directly to vapour. Dry ice — solid carbon dioxide — is used to keep ice cream and vaccines cold precisely because it sublimes: it leaves no liquid mess behind. In the school laboratory, ammonium chloride heated under an inverted funnel sublimes and re-forms as a white solid on the cool glass above, which is the standard demonstration of the process.
Separating a subliming solid from a mixture
Sublimation is a separation technique, not just a change of state. Given a mixture of common salt and ammonium chloride, gentle heating sublimes the ammonium chloride away as vapour, leaving pure salt behind; the vapour then deposits as a solid on a cool surface and can be collected. The same method separates camphor or iodine from sand. This is a favourite practical question because it tests whether you know which substances actually sublime.
Solved Numericals — Step by Step
Problem 1. How much heat is required to convert 200 g of ice at 0 °C completely into water at 0 °C? (Latent heat of fusion of ice = 3.34 × 10⁵ J/kg)
- Convert the mass to kilograms: 200 g = 0.2 kg.
- Use Q = mL, where L is the latent heat of fusion.
- Q = 0.2 × 3.34 × 10⁵
- Q = 0.668 × 10⁵ J = 6.68 × 10⁴ J.
Answer: 6.68 × 10⁴ J (66,800 J). Note the temperature does not change during the melting — all the heat goes into breaking the bonds holding the solid together.
Problem 2. Calculate the heat needed to convert 50 g of water at 100 °C into steam at 100 °C. (Latent heat of vaporisation of water = 22.5 × 10⁵ J/kg)
- Mass in kilograms: 50 g = 0.05 kg.
- Q = mL with L = 22.5 × 10⁵ J/kg.
- Q = 0.05 × 22.5 × 10⁵
- Q = 1.125 × 10⁵ J.
Answer: 1.125 × 10⁵ J (112,500 J). This large hidden energy is exactly why steam at 100 °C scalds far worse than water at 100 °C — it releases all of it on condensing.
Problem 3. Convert 30 °C into kelvin, and 300 K into degrees Celsius.
- To go from Celsius to kelvin, add 273: K = °C + 273.
- 30 + 273 = 303 K.
- To go from kelvin to Celsius, subtract 273: °C = K − 273.
- 300 − 273 = 27 °C.
Answer: 30 °C = 303 K, and 300 K = 27 °C.
Board-Style Questions with Model Answers
Define evaporation. List four factors that affect the rate of evaporation. (5 marks)
Evaporation is the process by which a liquid changes into vapour at temperatures below its boiling point, occurring only at the surface of the liquid. Four factors affect its rate. Surface area: a larger exposed surface means more particles are positioned to escape, so clothes spread out dry faster than clothes bundled up. Temperature: heating gives particles more kinetic energy, so a greater fraction can overcome the attraction of their neighbours. Humidity: humidity is the amount of water vapour already present in the air, and when the air is close to saturated the rate falls sharply, which is why washing takes so long to dry during the monsoon. Wind speed: moving air carries away the vapour that has just formed, keeping the air above the liquid unsaturated so evaporation can continue.
Why does evaporation cause cooling? Explain with an everyday example. (3 marks)
In any liquid the particles move at a range of speeds. Only the fastest-moving particles at the surface have enough energy to overcome the forces of attraction and escape as vapour. When they leave, the average kinetic energy of the particles remaining is lower, and since temperature is a measure of average kinetic energy, the liquid cools. The energy required for the escape is also drawn from the surroundings. An everyday example is stepping out of a swimming pool: water evaporating from your skin takes heat from your body, so you feel cold even on a warm day.
Distinguish between evaporation and boiling. (3 marks)
Evaporation occurs only at the surface of the liquid, whereas boiling occurs throughout the entire bulk of the liquid, with bubbles forming inside it. Evaporation happens at all temperatures below the boiling point, whereas boiling happens only at one fixed temperature, the boiling point, which is 100 °C for water at normal atmospheric pressure. Evaporation is a slow, gradual and quiet process; boiling is rapid and vigorous. Evaporation causes cooling of the remaining liquid, whereas during boiling the temperature stays constant while heat continues to be supplied.
What is sublimation? Name three substances that sublime and describe how sublimation can be used to separate a mixture. (5 marks)
Sublimation is the change of a solid directly into vapour without passing through the liquid state. Three substances that sublime are camphor, naphthalene and ammonium chloride; iodine and solid carbon dioxide (dry ice) also do. To separate a mixture of common salt and ammonium chloride, the mixture is placed in a china dish and covered with an inverted funnel whose stem is plugged with cotton. On gentle heating, the ammonium chloride sublimes and rises as vapour, then cools on the inner surface of the funnel and deposits there as a white solid, which can be scraped off. The common salt, which does not sublime, remains in the dish. The technique works whenever one component of a mixture sublimes and the other does not.
Why does steam at 100 °C cause a more severe burn than water at 100 °C? (2 marks)
Both are at the same temperature, but steam carries an additional 22.5 × 10⁵ J per kilogram of latent heat of vaporisation — the hidden energy absorbed when the water became vapour. When steam touches skin it first condenses into water, releasing all of that latent heat onto the skin, and only then does it cool from 100 °C. Water at 100 °C delivers only the second part. The extra latent heat is what makes the steam burn far worse.
Assertion–Reason Questions (CBSE Format)
For each question choose: (a) both A and R are true and R is the correct explanation of A; (b) both are true but R is not the correct explanation; (c) A is true but R is false; (d) A is false but R is true.
1. Assertion (A): Evaporation causes cooling.
Reason (R): The particles with the highest kinetic energy escape from the surface of the liquid.
Answer: (a) — Both are true and the reason explains the assertion. When the highest-energy particles leave, the average kinetic energy of those remaining falls, and lower average kinetic energy means a lower temperature.
2. Assertion (A): Water in an earthen pot becomes cooler in summer.
Reason (R): Clay is a good conductor of heat.
Answer: (c) — The assertion is true but the reason is false. The cooling has nothing to do with conduction — clay is porous, so water seeps through and evaporates from the outer surface, carrying heat away with it.
3. Assertion (A): Sublimation involves the liquid state.
Reason (R): A solid must melt before it can turn into vapour.
Answer: (d) — The assertion is false — sublimation goes directly from solid to gas and skips the liquid state entirely. The reason is also a false statement about sublimation, though it is the mistake students most often make.
4. Assertion (A): The temperature of a substance does not change during a change of state.
Reason (R): The heat supplied is used to overcome the forces of attraction between particles.
Answer: (a) — Both are true and correctly linked. This hidden energy is called latent heat; it does work against interparticle forces rather than raising the temperature.
Quick Self-Check
Q1. Camphor left in the open disappears without leaving any liquid. This is:
- A. Evaporation
- B. Condensation
- C. Sublimation
- D. Deposition
Answer: C. Sublimation — The solid turned straight into vapour with no liquid stage — the definition of sublimation.
Q2. Which of these does NOT increase the rate of evaporation?
- A. Increasing surface area
- B. Increasing temperature
- C. Increasing humidity
- D. Increasing wind speed
Answer: C. Increasing humidity — Higher humidity means the air already holds a lot of water vapour, which slows evaporation down.
Q3. Water in an earthen pot stays cool because:
- A. Clay is a good conductor
- B. Water evaporates through the pores and takes heat with it
- C. Clay reflects sunlight
- D. The water sublimes
Answer: B. Water evaporates through the pores and takes heat with it — Water seeps through the porous clay and evaporates from the surface; the escaping high-energy particles carry heat away, cooling what remains.
Q4. The change of a gas directly into a solid is called:
- A. Sublimation
- B. Condensation
- C. Deposition
- D. Fusion
Answer: C. Deposition — Gas to solid is deposition (desublimation). Sublimation is the opposite direction, solid to gas.
Key Terms Glossary
- Evaporation
- The change of a liquid into vapour at the surface only, at any temperature below the boiling point.
- Sublimation
- The change of a solid directly into vapour without passing through the liquid state.
- Deposition
- The reverse of sublimation — a gas changing directly into a solid, as when frost forms on a cold window.
- Boiling
- Vaporisation throughout the whole bulk of a liquid, occurring only at the fixed boiling point.
- Condensation
- The change of a gas into a liquid, the reverse of vaporisation.
- Melting (fusion)
- The change of a solid into a liquid at the melting point.
- Latent heat
- The heat absorbed or released during a change of state without any change in temperature.
- Latent heat of fusion
- The heat needed to change 1 kg of a solid into liquid at its melting point. For ice it is 3.34 × 10⁵ J/kg.
- Latent heat of vaporisation
- The heat needed to change 1 kg of a liquid into vapour at its boiling point. For water it is 22.5 × 10⁵ J/kg.
- Humidity
- The amount of water vapour already present in the air. High humidity slows evaporation.
- Volatile
- Describes a liquid that evaporates readily at ordinary temperatures, such as petrol or spirit.
- Kelvin scale
- The SI temperature scale. K = °C + 273; 0 K is absolute zero.
One-Minute Revision
- Evaporation: LIQUID → gas, SURFACE only, at ANY temperature below boiling.
- Sublimation: SOLID → gas directly. The liquid state is skipped entirely — that is the whole difference.
- Four factors speeding evaporation: surface area ↑, temperature ↑, wind speed ↑, humidity ↓.
- Evaporation causes COOLING because the fastest particles are the ones that escape.
- Boiling ≠ evaporation. Boiling is throughout the liquid at ONE fixed temperature.
- Reverse of sublimation is DEPOSITION (gas → solid), not condensation (gas → liquid).
- Substances that sublime: camphor, naphthalene, ammonium chloride, iodine, dry ice.
- Temperature stays CONSTANT during any change of state — the energy goes to latent heat.
Syllabus reference: NCERT Class 9 Science, Chapter 1 — Matter in Our Surroundings.
Frequently Asked Questions
Is sublimation different from evaporation?
Yes. In evaporation a liquid turns into vapour (liquid → gas) at its surface, below the boiling point. In sublimation a solid turns directly into vapour (solid → gas) without first becoming a liquid.
Give examples of evaporation and sublimation.
Evaporation: wet clothes drying, water drying up from a puddle. Sublimation: camphor, naphthalene balls and dry ice (solid carbon dioxide) turning directly into vapour.
Does sublimation skip the liquid state?
Yes — that is the key point. Sublimation goes straight from solid to gas without passing through the liquid state, while evaporation starts from a liquid.
Why does evaporation cause cooling?
Only the fastest-moving particles at the surface have enough energy to escape as vapour. When they leave, the average energy of the particles remaining is lower — and lower average kinetic energy means a lower temperature. The energy needed to escape is drawn from the liquid and its surroundings.
What is the difference between evaporation and boiling?
Evaporation happens only at the surface of a liquid and at any temperature below boiling point. Boiling happens throughout the whole liquid, forming bubbles, and only at one fixed temperature — the boiling point (100 °C for water at normal pressure).
Give three substances that sublime.
Camphor, naphthalene (mothballs), ammonium chloride, iodine and solid carbon dioxide (dry ice) all sublime. Ammonium chloride is the one usually used in the school laboratory demonstration.
Why does steam at 100 °C burn more badly than water at 100 °C?
Steam carries an extra 22.5 × 10⁵ J/kg of latent heat of vaporisation. When it touches skin it condenses and releases all of that energy on top of the heat from its temperature, so the burn is far more severe.