Re: Why do some liquids melt faster that others?

Hi Emily! Let's first clarify that liquids are already melted from their solid state... so your question title is a bit confusing. But good on you for noticing that ice cubes don't melt as fast as ice cream! Here is generally why:

Ice cubes take a longer time to melt because of a few different factors:
1) the liquid (your drink) surrounding the ice helps insulate the ice cubes and keep them colder longer;
2) ice is generally a very efficient solid (few bubbles or gaps in the middle of the cube), which means heat has to work its way in from the outside surface (which takes a long time); and
3) drink containers, glasses, cups, etc are designed to be narrow and tall cylinders, which provides a compact surface area across which this heat transfer will occur from the surrounding air.

Ice cream is a very complex product, in which a balance of gas, liquid and solid all exist at the same time. It's one of my favorite things to eat but also to study because it is impossible to quantitatively describe in this three-phase state. :) But more simply, ice cream melts faster because:
1)the rate at which heat travels through "something" is different depending on whether the "something" is in a solid, liquid or gaseous state. Generally speaking, heat travels fastest through liquids, slower through gas and much slower through solids. Since ice cream is a mixture of all three states, heat will be absorbed faster by the ice cream than by a pure solid like an ice cube;
2)Ice cream is usually eaten out of a bowl. The surface area of a bowl (half-sphere) is much greater than a glass (cylinder) so the ice cream is being exposed to more warm air than the ice cubes. More heat means it will melt faster; and
3) your ice cream isn't insulated from the warm air like the ice cubes in your drink.

So, I know this answer is a long one for such a short question but I hope it has helped you understand a little more about the complexity of heat transfer and different states of matter. Enjoy!

Kieran