Melting ice using latent heat and heat of fusion

Since the heat of fusion is given in kJ/mol, you will also need to convert it to J/g by dividing by the molecular weight. This will allow you to solve for the mass of ice that can be melted by 100 J of heat at 2 deg Celsius. In summary, to determine the quantity of ice that can be melted by 100 J of heat at 2 deg Celsius, you can use the equations q = m c (delta) t and q = m l, and convert between grams and moles using the molecular weight of water.
  • #1
Navygal
4
0

Homework Statement



What quantity of ice at 2 deg Celsius can be melted by 100 J of heat?


Homework Equations



q = m c (delta) t (mass x specific heat x change in temp)
q = m l (mass x heat of fusion)

specific heat of ice = 2.09 j/g-K
heat of fusion = 6.01 kJ/mol

The Attempt at a Solution



I've tried to solve this problem by combining both equations for the same q such that
q = mc(delta)t + ml which rearranges to:
q = m (c delta t + l)

solving for m: m = q/ (c delta t + l)

The part I got stuck is when I tried to solve for m since m is in grams, and the heat of fusion is in moles. Is there another way to solve this or am I missing something?
Any help would be greatly appreciated
 
Physics news on Phys.org
  • #2
You can use the molecular weight of water (~18g/mol) to convert between grams and moles.
 
  • #3
.

I would first clarify that the heat of fusion is the amount of heat required to melt a substance at its melting point without changing its temperature. In this case, we are dealing with ice at 2 degrees Celsius, which is already below its melting point. Therefore, we can use the specific heat equation to calculate the amount of heat needed to raise the temperature of the ice to its melting point (0 degrees Celsius). This would be equal to q = m c (delta) t, where q = 100 J, c = 2.09 J/g-K, (delta) t = (0-2) = -2 K.

Next, we can use the heat of fusion equation to calculate the amount of heat needed to melt the ice at its melting point. This would be equal to q = m l, where q = 100 J, l = 6.01 kJ/mol. However, we need to convert the units of l from kJ/mol to J/g by dividing by the molar mass of ice (18.02 g/mol). This gives us l = 333.5 J/g.

Now, we can combine the two equations to solve for the mass of ice (m) that can be melted by 100 J of heat. This would be equal to m = q/ (c delta t + l), which gives us m = 100 J / (2.09 J/g-K x -2 K + 333.5 J/g) = 0.301 g.

Therefore, 100 J of heat can melt 0.301 g of ice at 2 degrees Celsius.
 

1. What is latent heat and how does it play a role in melting ice?

Latent heat is the amount of energy required to change the phase of a substance without changing its temperature. In the case of melting ice, the latent heat is absorbed by the ice to break the bonds between its molecules and change it from a solid to a liquid state.

2. How does the heat of fusion contribute to melting ice?

The heat of fusion is the amount of energy required to change a substance from a solid to a liquid state. In the case of melting ice, this is the same as the latent heat. The heat of fusion is necessary to break the bonds between the molecules of ice and allow it to transition into a liquid form.

3. What factors affect the rate of melting ice using latent heat and heat of fusion?

The rate of melting ice using latent heat and heat of fusion is affected by the temperature of the surroundings, the amount of energy being applied, and the initial temperature of the ice. Higher temperatures and more energy will result in a faster rate of melting, while lower temperatures and less energy will result in a slower rate of melting.

4. Can latent heat and heat of fusion be used to freeze liquid water?

Yes, just as these two factors contribute to melting ice, they can also be used to freeze liquid water. By removing energy from liquid water, the molecules slow down and form bonds, transitioning the water into a solid state. This process is known as freezing or solidification.

5. Are there any other applications for melting ice using latent heat and heat of fusion?

Yes, these principles are used in refrigeration and air conditioning systems to remove heat from a space. The refrigerant in these systems undergoes a phase change from a liquid to a gas, absorbing heat and cooling the surrounding area. This gas is then compressed and converted back into a liquid, releasing the heat and repeating the cycle.

Similar threads

  • Biology and Chemistry Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
965
  • Biology and Chemistry Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
989
  • Introductory Physics Homework Help
Replies
17
Views
3K
  • Biology and Chemistry Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
1K
  • Biology and Chemistry Homework Help
Replies
7
Views
2K
  • Introductory Physics Homework Help
Replies
7
Views
1K
  • Biology and Chemistry Homework Help
Replies
1
Views
4K
Back
Top