States of Matter Flashcards

All 9 cards in this deck

How are the particles arranged, and how do they move, in a solid, a liquid and a gas?

Solid: regular arrangement, touching, vibrate about fixed positions (least energy).
Liquid: close together but random, slide past one another (more energy).
Gas: far apart, random, move quickly in all directions (most energy).

What is the name of each change of state?
e.g. solid $\rightarrow$ liquid, liquid $\rightarrow$ gas, gas $\rightarrow$ liquid, liquid $\rightarrow$ solid, solid $\rightarrow$ gas

Solid $\rightarrow$ liquid: melting
Liquid $\rightarrow$ gas: boiling (or evaporation)
Gas $\rightarrow$ liquid: condensing
Liquid $\rightarrow$ solid: freezing
Solid $\rightarrow$ gas: sublimation

True or false? Boiling water to make steam is a chemical change.

False. It is a physical change — no new substance is made and it can be reversed by condensing.

What are the steps to explain, in particle terms, what happens when a solid melts?
e.g. ice melting at $0\ ^{\circ}\mathrm{C}$

1. Particles gain energy and vibrate faster (ice particles vibrate more).
2. Forces between the particles are overcome, so they leave their fixed positions.
3. Particles stay close but become randomly arranged and can move past each other — liquid water.

What are the steps to predict the state of a substance at a given temperature from melting point and boiling point data?
e.g. melting point $30\ ^{\circ}\mathrm{C}$, boiling point $2403\ ^{\circ}\mathrm{C}$, at $20\ ^{\circ}\mathrm{C}$

1. Below the melting point $\rightarrow$ solid ($20 < 30$, so solid).
2. Between melting and boiling point $\rightarrow$ liquid.
3. Above the boiling point $\rightarrow$ gas.
   Answer: solid.

True or false? On a heating curve, the temperature keeps rising while a pure substance is melting.

False. The temperature stays constant (a plateau); the energy transferred is used to overcome the forces between particles, not to raise the temperature.

What do the state symbols $(s)$, $(l)$, $(g)$ and $(aq)$ mean in a balanced equation?

$(s)$ solid, $(l)$ liquid, $(g)$ gas, $(aq)$ aqueous — dissolved in water.
e.g. $2\mathrm{Na}(s) + 2\mathrm{H_2O}(l) \rightarrow 2\mathrm{NaOH}(aq) + \mathrm{H_2}(g)$

What happens to steam when it touches a cold surface, and what is seen?

It condenses to liquid water, so droplets form on the surface.
e.g. droplets on a cold glass held above a kettle

True or false? The white cloud you can see above a boiling kettle is water vapour in the gas state.

False.
Water vapour is an invisible gas; the visible cloud is tiny drops of liquid water formed when the vapour condenses in the cooler air.