the diagram shows the heating curve of paraffin wax, which is a solid at room temperature. the solid paraffin was pack of mass 1.5kg is first heated up until it partially melts. it is then inserted at the bottom of the sleeping bag with the baby lying on top of it and wrapped around by the sleeping bag. the pack is able to keep the baby warm at about the body temperature of 37°C for a few hours. The specific heat capacity of paraffin wax is 2500J/(kgK) while the specific latent heat of fusion of paraffin wax is 2.2x 10^5 J/kg. explain why it is dangerous to use the paraffin wax pack if it has fully melted

When the paraffin wax pack is partially melted, it is able to keep the baby warm at a temperature of about 37°C for a few hours. This is because the paraffin wax undergoes a phase change from solid to liquid, releasing a large amount of latent heat of fusion. The specific latent heat of fusion of paraffin wax is 2.2x10^5 J/kg, which means that for every kilogram of paraffin wax that melts, 2.2x10^5 J of heat is released.

However, it is dangerous to use the paraffin wax pack if it has fully melted. This is because once the paraffin wax is fully melted, it no longer has the ability to release latent heat of fusion. The specific heat capacity of paraffin wax is 2500 J/(kgK), which means that it requires 2500 J of heat to raise the temperature of 1 kilogram of paraffin wax by 1 degree Celsius.

If the paraffin wax pack has fully melted, it will no longer be able to maintain the baby's body temperature at 37°C. Instead, it will continue to absorb heat from the baby's body and the surroundings, causing the temperature to drop. This can lead to hypothermia and other health risks for the baby.

Therefore, it is important to ensure that the paraffin wax pack is only partially melted and still in a semi-solid state when used to keep the baby warm.