States of Matter Flashcards

All 6 cards in this deck

Which two changes of state take place at the melting point?

Melting (solid to liquid) and freezing (liquid to solid).

Which two changes of state take place at the boiling point?

Boiling (liquid to gas) and condensing (gas to liquid).

What are the steps to predict the state of a substance at a given temperature?

e.g. bromine, melting point $-7^\circ$C, boiling point $59^\circ$C, at $100^\circ$C

1. Below the melting point it is a solid: $100 > -7$, so not solid.

2. Between melting and boiling point it is a liquid: $100 > 59$, so not liquid.

3. Above the boiling point it is a gas: bromine is a gas at $100^\circ$C.

What decides how much energy is needed to change a substance from solid to liquid or liquid to gas?

The strength of the forces between the particles, which depends on the type of bonding and the structure of the substance.

True or false? The stronger the forces between the particles of a substance, the lower its melting and boiling points.

False. The stronger the forces, the higher the melting and boiling points, because more energy is needed to overcome them.

True or false? At a temperature above its boiling point, a substance is a liquid.

False. Above the boiling point the substance is a gas.