UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
Home
How it Works
Ask a Question
Search Topics
Webcasts
Our Scientists
Science Links
Contact Information
Hello I am looking for someone who could you help me I am trying to find out what is the lowest temperature silver will melt ice? And also if any other metal or plastic has a lower melting point than silver to melt ice; thank you.
Question Date: 2017-05-14
Answer 1:

Any object that has a higher temperature than the ice will begin to melt it. How fast this happens will depend on what that object is made of, like metal or plastic.

To better understand this, let's define heat and temperature. Materials can store energy in the movement of their atoms, and we call this thermal kind of energy heat. Atoms move faster in hotter materials than in colder materials. This energy can be transferred from hotter atoms to colder atoms when they bump into each other. Materials that are at the same temperature will not transfer heat between them. But, this does not mean that they contain the same amount of thermal energy. Consider two pieces of silver that weight 1g and 5g each. They can both be at room temperature but 5g piece has five times the thermal energy because it has five times the number of atoms.

The amount of heat a material can store (the heat capacity) depends on its structure. Generally, materials that are organized and made of the same type of atoms (like metals) don't need much thermal energy to raise their temperature. Aluminum is a good example - it heats up in your oven and cools very quickly once you take it out. Water, on the other hand, doesn't change temperature easily so you need a lot more heat to bring water to the same temperature as aluminum. Materials also take different amounts of time to transfer their heat (called thermal conductivity). Generally, things that store a lot of heat (high heat capacity) transfer it slowly (low thermal conductivity) and vice versa.

Imagine that you have an ice cube at 0°C, right at its melting temperature. Any material at 0°C won't transfer heat to the ice so it won't melt. But, any object at any higher temperature (no matter what it's made of) will transfer some energy to the ice until they are both at the same temperature. This will happen no matter how small the temperature difference.

Let's do some math.How much ice could one gram of silver at room temperature (25°C ) melt? (I'm going to assume that there's a lot more ice than silver such that the temperature of the ice, water and silver all end up at 0°C at equilibrium.) The amount of heat energy transferred to the ice is equal to the amount of silver, the heat capacity of silver and the temperature difference. Thus, the silver transfers

( 1g x 0.240 J/g x 25°C ) = 6 joules of heat to the ice.

Since it takes 333.5 J to melt a gram of ice, only 0.018 g of ice is melted.

That's not much but it is enough to make the area where the silver touches the ice slick with water. Now let's do the same math with plastic. While there are many types of plastic, most have high heat capacities (~1.67 J/g). Thus,

1 g of plastic at room temperature will melt 0.125 g of ice - nearly seven times as much!

But, if that's the case,why doesn't ice slide on plastic in the same way that it does on silver? The key is in thermal conductivity, not heat capacity. Heat transfers much more quickly from the silver than from the plastic so the ice melts much faster. (Less of it melts overall.) Silver has the highest thermal conductivity of any pure metal (at 406 W/mK). Check out this table of thermal conductivities:

thermal conductivities

If you want to melt ice faster than on silver, you need a material that is even more organized such as diamond, conducts heat more than twice as fast (1000 W/mK)!



Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2017 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use