Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.
What to Focus On
Core idea:State of Matter asks what the sample is, what property is being used, and whether a new substance is formed.
Common stuck point:Students often know a formula related to state of matter but skip the recognition step: Am I classifying matter or using properties, state, particle behavior, or mixture evidence to describe a sample? That leads to a correct-looking substitution attached to the wrong chemical model.
Sense of Study hint:Ask: Am I classifying matter or using properties, state, particle behavior, or mixture evidence to describe a sample?
Worked Examples
Example 1
easy
Compare the three common states of matter (solid, liquid, gas) in terms of particle arrangement, shape, and volume.Particle arrangement in the three common states of matter
Solid: particles tightly packed in fixed positions. Definite shape and definite volume.
Full solution
2
Liquid: particles close together but can slide past each other. Indefinite shape but definite volume.
3
Gas: particles far apart with rapid random motion. Indefinite shape and indefinite volume.
The state of matter depends on the balance between kinetic energy (motion) and intermolecular forces (attraction). Increasing temperature provides more kinetic energy, favoring less ordered states.
Example 2
medium
Why can gases be compressed easily while liquids and solids cannot?
Example 3
medium
A 50g ice cube at 0°C melts to water at 0°C. Heat absorbed if ΔHfus=334J/g?
Example 4
hard
Heating curve: 20g ice at −10°C is heated to 110°C vapor at 1 atm. Identify all segments and their energy types.
Example 5
hard
Compute total energy to heat 100g water from 25°C to 100°C then fully boil it. (c=4.18J/(g\cdotp°C), ΔHvap=2260J/g)
Example 6
challenge
A pressure cooker raises water's boiling point. If pressure inside reaches 1.5atm, why does food cook faster, and what state of matter is the water inside?
Practice Problems
Try these problems on your own first, then open the solution to compare your method.
Example 1
easy
At room temperature, classify each as solid, liquid, or gas: (a) mercury, (b) oxygen, (c) table salt.
Example 2
hard
Glass appears solid but some claim it is actually a very slow-moving liquid because old windows are thicker at the bottom. Evaluate this claim using the particle model of solids and liquids.
Example 3
easy
In which state are particles packed tightly in fixed positions, only vibrating?Which state of matter has particles packed tightly in fixed positions, only vibrating?
Example 4
easy
Which state has particles that are close together but can slide past one another?Which state has particles close together but able to slide past one another?
Example 5
easy
Which state has particles far apart, moving freely and filling any container?Which state has particles far apart, moving freely and filling any container?
Example 6
easy
Which state of matter has a fixed shape AND a fixed volume?
Example 7
easy
Which state has a fixed volume but takes the shape of its container?Which state has a fixed volume but takes the shape of its container?
Example 8
easy
Name the fourth state of matter, an ionized gas found in stars and lightning.
Example 9
easy
Does a gas have mass? Use a balloon example.
Example 10
easy
Which state is most easily compressed: solid, liquid, or gas?Which state is most easily compressed?
Example 11
medium
A substance keeps its volume but flows to fit any container shape. Name the state and describe its particle arrangement.
Example 12
medium
Why can gases be compressed but solids and liquids essentially cannot?
Example 13
medium
Classify melting ice into water as a physical or chemical change, and explain using states of matter.
Example 14
medium
Rank solid water (ice), liquid water, and water vapor by particle spacing, from closest to farthest.Rank ice, liquid water, and vapor from closest to farthest particle spacing
Example 15
medium
A sealed rigid jar of gas is heated. Does the gas's state change? What happens to particle motion?
Example 16
medium
Which state of matter is most abundant in the universe, and why is it often overlooked on Earth?
Example 17
medium
Why does a solid keep its shape while a liquid does not, in terms of forces between particles?
Example 18
medium
Identify the state for each: (a) keeps shape and volume, (b) no fixed shape or volume, (c) ionized and conductive.
Example 19
medium
A material has a definite volume but takes the shape of whatever container holds it, and cannot be easily compressed. Identify its state and justify.Identify the state: definite volume, takes container shape, not easily compressed
Example 20
challenge
Explain why steam (water vapor) and liquid water have the same chemical identity but very different volumes for the same mass, in terms of particle spacing.
Example 21
challenge
Two identical sealed flasks each hold the same gas at the same temperature, but flask A has twice the volume of flask B. Compare their gas densities and explain using particles per volume.
Example 22
challenge
A demonstration shows a balloon shrinking when dipped in liquid nitrogen, then re-expanding when warmed. No gas escapes. Explain the state and volume changes in terms of particle motion and spacing.
In which state are particles arranged in a regular repeating pattern?
Example 25
easy
Water boils at 100°C at sea level. Which state change occurs and what direction is energy moving?Water boils at 100°C — which state change occurs and which direction does energy move?
Example 26
easy
A balloon of air weighs more than the same empty balloon. What does this prove about gases?
Example 27
medium
Dry ice (solid CO2) is left on a table. It shrinks and 'smokes' but never makes a puddle. Name the phase change and explain.Dry ice shrinks and 'smokes' without making a puddle — name the phase change
Example 28
medium
Why does water expand when it freezes, unlike most substances?
Example 29
medium
A sealed bottle of cold soda is opened on a hot day. Drops form on the outside of the bottle. Identify the phase change in the air.Cold soda bottle on a hot day: identify the phase change in the surrounding air
Example 30
medium
Boiling point of water at sea level vs. on a high mountain — which is lower, and why?
Example 31
medium
Compare diamond (solid) and helium (gas) at room T in terms of compressibility.
Example 32
medium
Mercury is a liquid at room temperature, but most metals are solids. Why is mercury different?
Example 33
hard
How much heat to fully melt 200g of ice at 0°C? (ΔHfus=334J/g)
Example 34
hard
Compare 1mol of water as ice, liquid, and vapor (at 100°C, 1 atm) in approximate volume. Use density: ice 0.917g/cm3, water 1.00g/cm3, vapor ∼30.6L/mol.
Example 35
hard
A material has shape that yields under shear (like a fluid) but holds its volume. Identify the state and provide one example.
Example 36
hard
Why is condensing steam so dangerous compared to hot water at the same temperature?
Example 37
hard
A neon sign glows because a noble gas, at low pressure, is ionized by electricity. What state of matter is in the tube while glowing?
Example 38
challenge
At extremely low T, certain materials enter Bose-Einstein condensate (BEC) state. Briefly state what makes BEC a distinct state of matter from ordinary solid.