Phase change resulting in pressure

In summary, to find the pressure generated by expanding ice as it freezes in a biological cell, we can use the equation P = F/A and calculate the force (F) by finding the difference in mass between water and ice, and the area (A) by using the formula for the surface area of a sphere. Q=mL can also be used to find the heat of transformation required for the phase change.
  • #1
chris_0101
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Homework Statement


The density of water at 0 C is 999.8 kg/m^3 while that of ice at 0 C is 917.0 kg/m^3. What is the pressure generated by expanding ice as it freezes in a biological cell whose major component is water? Assume the cell to be a sphere of radius 5 micrometres.

I have started this question but I do not know how to complete it. I can't picture the right expression that will yield pressure with respect to a phase change.

Homework Equations


P = F/A
Density = mass/volume
Q=mc[tex]\Delta[/tex]T
Q=mL
where L is the heat of transformation


The Attempt at a Solution


question 5.JPG
 
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  • #2
Let F be the force generated by expansion of ice, and A be the surface area of the sphere. The volume of the sphere can be found using V = 4/3(pi)r^3. The mass of the sphere can be found using the density values given in the problem statement. The heat of transformation (Q) required to convert the sphere from water to ice can be found using Q=mL. F/A can then be calculated to find the pressure generated in the cell.
 

1. What is a phase change?

A phase change is the transformation of a substance from one state of matter to another, such as from a solid to a liquid or from a liquid to a gas.

2. How does a phase change affect pressure?

A phase change can result in a change in pressure due to the change in volume of the substance. For example, when a substance transitions from a liquid to a gas, it expands and exerts more pressure on its surroundings.

3. What is the relationship between pressure and temperature during a phase change?

The relationship between pressure and temperature during a phase change is described by the phase diagram of the substance. Generally, as temperature increases, pressure also increases during a phase change.

4. Can phase changes be reversed?

Yes, phase changes can be reversed by altering the conditions of temperature and pressure. For example, a gas can be turned back into a liquid by decreasing its temperature and increasing its pressure.

5. How do phase changes play a role in everyday life?

Phase changes are an important part of our everyday lives. For example, the phase change of water from a liquid to a gas is what causes evaporation, which is essential for the water cycle and weather patterns. Phase changes also play a role in cooking and food preservation, as well as in industrial processes such as freezing and distillation.

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