Specific Heat (The Very Concept)

In summary, the specific heat of a substance is defined as the ratio of the quantity of heat required to raise the temperature of a unit of substance by one degree, to the quantity of heat required to raise the same unit of water by one degree. This means that for a 50-lbs ball of iron heated to 200 degrees, where iron has a specific heat of .11, the total quantity of heat needed would be 50(.11)(200), not 50(200) as one might expect. This is because the ratio of specific heat to mass plays a role in determining the total quantity of heat needed.
  • #1
aleph_0
7
0
So I don't get the concept of specific heat. I'm doing an ODE problem and I've never even looked at science, not even in high school. The book defines the specific heat of a substance as: The ratio of the quantity of heat required to raise the temperature of a unit of substance by one degree, to the quantity of heat required to raise the same unit of water by one degree.

Now take for instance a 50-lbs ball of iron heated to 200 degrees, where iron has a specific heat of .11. A priori I would have thought that the total quantity of heat would be 50(200) because, hey, temperature is like average quantity of heat in an object, right? And the object weighs 50-lbs, which can basically be treated like its mass. So the product should give the total heat, no? Huh? Right?

Well I would be wrong. It looks like the quantity of heat in such an object is 50(.11)(200) and I don't exactly get why. What in god's name does that ratio have to do with this sort of thing?

Thank you.
 
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  • #2
welcome to pf!

hi aleph_0! welcome to pf! :smile:

it means that if you need X amount of heat to raise 50-lbs of water by 200°, then you only need 0.11 times X to raise 50-lbs of iron by 200° :wink:
 
  • #3
OH MY GOD that was the perfect answer! So clear, so simple. THANK YOU!

(Part of this is general excitement about learning a concept; the other part is too much coffee.)
 

What is specific heat?

Specific heat is the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius. It is a physical property of a substance that describes how much energy it can hold and how quickly it can transfer that energy.

How is specific heat measured?

Specific heat is typically measured using a device called a calorimeter, which measures the change in temperature of a substance when a known amount of heat is added or removed. The specific heat can then be calculated using the equation q = m x c x ΔT, where q is the heat energy, m is the mass of the substance, c is the specific heat, and ΔT is the change in temperature.

Why is specific heat important?

Specific heat is an important concept in thermodynamics and heat transfer. It helps us understand how energy is transferred between different substances and how they respond to changes in temperature. It also plays a crucial role in many industrial and scientific processes, such as in designing heating and cooling systems.

What factors affect specific heat?

The specific heat of a substance is affected by several factors, including its molecular structure, temperature, and pressure. Generally, substances with stronger intermolecular forces and more complex molecular structures have higher specific heats. Temperature and pressure can also affect specific heat, as they can change the way molecules move and interact with each other.

How is specific heat related to other thermodynamic properties?

Specific heat is closely related to other thermodynamic properties, such as heat capacity, enthalpy, and entropy. Heat capacity is the amount of heat energy required to raise the temperature of a substance by a certain amount, while enthalpy is the total energy of a system. Entropy is a measure of the disorder or randomness of a system, and it is related to specific heat through the equation ΔS = q/T, where ΔS is the change in entropy, q is the heat energy, and T is the temperature.

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