this is when a solid becomes a liquid and a liquid becomes a gas.

when a solid melts some intermolecular bons are broken so the molecules a re more dissordered and more free to move.

when a liquid becomes a gas the particles become more dissordered, further apart and faster moving as all of the intermolecular bonds have been broken

how does the energy change a s a block of ice is melted?

the ice starts below 0⁰C, the molecules gain energy and vibrate more.

at 0⁰C the ice is melting and the potentional energy (PE) is increasing

as the temp increases the ice becomes water, the molecules mover more quickly and their kinetic energy (KE) is increasing.

at 100^oC the water is boling and the molecules become more separate increasing the PE

further heating leads to their KE increasing as the molecules are moving even faster.

the specific heat capacity of a substance is numerically equal to the amount of energy required to raise the temperature of 1kg of the substance by 1 K

ΔQ = mcΔθ

the specific latent heat of a substance is numerically equal to the energy that must be supplied to change the state of 1 kg of the substance without any change in temperature.

ΔQ = mL