What is Heat capacity: Definition and 437 Discussions
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K).
Heat capacity is an extensive property. The corresponding intensive property is the specific heat capacity, found by dividing the heat capacity of an object by its mass. Dividing the heat capacity by the amount of substance in moles yields its molar heat capacity. The volumetric heat capacity measures the heat capacity per volume. In architecture and civil engineering, the heat capacity of a building is often referred to as its thermal mass .
Newton's Law of Cooling basically states (I believe):
TObj = (TInital-TEnv)ekt + TEnv
where k is a property of the material.
In the equation:
Q=mCΔT
Specific heat capacity, C, is also a material property.
So here's my question:
Is there a relation between Newton's Law's k and the...
Just a quick question of something I found in my textbook but can't get how they produced it.
C_p =(∂Q/∂T)_p
that is the definition of heat capacity at a constant pressure p. Q is heat and T is temperature. This equation is fine and I know how to derive it. Now it is the next line which...
Below 20K, The specific heat capacity c of silver varies with temperature according to the equationc/\text{J /kg /K} = 1.5x10^{-4}(T/K)^3 + 6.0x10^{-3} T/K.
If a small silver sphere of diameter 4am and at 20K is placed in 25g of liquid helium at 4K, what fraction of the liquid will evaporate...
I know how to do heat capacity problems but i am unsure of how to do them when two materials are combined together. Here is the question. Any help would be great, thanks.
A 5 kg pieces of low carbon steel at room temperature 25°C is placed into contact with a 300g piece of polyethylene at 180°C...
Homework Statement
0.2g of a radium salt was separated from a ton of uranium ore. The radioactive radium nuclide Ra-226 decays by alpha-particle emission with a half-life of 1600 years. 1 year = 3.16x107s.
The curie is defined as the number of disintegrations per second from 1.0g of Ra...
Homework Statement
The temperature of one mole of ideal gas is 360K. The gas is allowed to expand adiabatically to the double volume. Then it is compressed isothermally to original volume. The specified amount of heat is measured at 1304J. Determine C_p / C_v, and specify the type of ideal gas...
Throughout my time doing physics I have noticed that ice has a lower specific heat capacity than water.
I don't understand why.
To me it seems that the bonds between water molecules in a solid are stronger and hence require a greater deal of thermal energy to break. Hence, the PE of the...
When we deal with heat capacity or specific heat capacity Q=mc(delta temperature) why don't we take into consideration about the expansion of the thing? Since expansion (should) increase the potential energy of the item since potential energy is the bond strength which is related to the particle...
Homework Statement
Show that for a general (but simple) substance,
c_{p}-c_{v}=-T(\frac{∂v*}{∂T})_{p}(\frac{∂p}{∂v*})_{T}
where
v* is the specific volume
p is the pressure
c_{p} is the heat capacity when p is const
c_{v} is the heat capacity when v is const
Q is heat
T is temperature in...
I am doing my revision and noticed that metals all have a molar heat capacity ~25 J/mol/K = 3R. Ionic solids such as NaCl and CaF2 however have different molar heat capacities. (~51 and 72 respectively)
Why is this? there is no explination that my lecturer gave and I can't find it online but...
I completed high school 9 years ago... please bare with me :)
My problem is with how they calculate the actual answer - this is from an example problem in my textbook.
Homework Statement
A calorimeter cup is made from 0.15kg of Alu and contains 0.20 kg of water. Initially the water and...
Homework Statement
http://www.physics.ox.ac.uk/olympiad/Downloads/PastPapers/BPhO_PC_2006_QP.pdf
Q15b
Answers:
http://www.physics.ox.ac.uk/olympiad/Downloads/PastPapers/BPhO_PC_2006_MS.pdf
I am confused on how the answer is reached, specifically how the formula energy...
I am quite confused by this, because I have not yet found a compound that has a higher one. My understanding is that specific heat capacity of a molecule is based on a combination of the number of degrees of freedom the molecule has and the number of vibrational modes. As for the second factor...
At what phase is the heat capacity the greatest? Is it when the substance is a solid, liquid or gas? Please also explain why.
I believe that the heat capacity is the greatest when the subastance is a solid.
A bath contains 100kg of water at 60C. Hot and cold taps are then turned on to deliver 20kg per minute each at temperatures of 70C and 10C respectively. How long will it be before the temperature in the bath has dropped to 45C? Assume complete mixing of the water and ignore heat losses.
I've...
Homework Statement
A cube of gold is heated to a temperature of 94.2 degrees celsius, and then submerged in 31.3 mL of water at an initial temperature of 28.7 degrees celsius. If the final temperature of the water is 45.6 degrees celsius, calculate the volume of the cube of gold (s=0.130...
Homework Statement
Using the viral theorem, the heat capacity of a star is given as C=-3*k/2.
Using this, I need to calculate the entropy of a star in terms of the average temperature T, then in terms of U (total energy).
Homework Equations
dS=C*dT/T
The Attempt at a Solution
To...
Homework Statement
Let C_{X}=T(\partial S/\partial T)_{X} with X=p~or~V. Show that C_{p}-C_{V}=T(\partial S/\partial V)_{T}(\partial V/\partial T)_{p}.
Homework Equations
C_{p}-C_{V}=T[(\partial S/\partial T)_{p}-(\partial S/\partial T)_{V}]
The Attempt at a Solution
I honestly don't know...
Homework Statement
there is a bath of 160L of water at 41oc (shc 4000). A rock of 15kg is dropped into the bath at 250oc with shc of 2000
What temperature does the water end up at?
Homework Equations
Q=cmT
The Attempt at a Solution
Very sorry but I don't have a clue. Not...
Hi there,
I am not an engineer but i do have scientific background. It is just a long time since i did any calculations!
I am trying to design myself a new way of melting barrels of honey. I have 200L, 300kg barrels of crystalized honey that I need to melt. One method I envisage is to make an...
Homework Statement
215 cm3 of hot tea at 95°C are poured into a very thin paper cup with 40 g of crushed ice at 0°C. Calculate the final temperature of the "ice tea". (Hint: think about two processes: melting the ice into liquid and, maybe, warming the liquid.)
Homework Equations
0 =...
What is the the relationship between the specific heat capacity and power (e/t) required to raise the objects temperature? Of course the energy required increases, but does the time it takes change also?
I have a problem with heat capacity of different materials. i know that heat capacity is the mount of energy needed in order to rise the temperature of a material by 1 degree, but i also know that different amount of energy is needed to rise the temperature from 0 to 1 degree and different...
You warm 1.00 kg of water at a constant volume of 1.00 L from 20.0 degrees C to 30.0 degrees C in a kettle. For the same amount of heat, how many kilo grams of 20.0 degree C air would you be able to warm to 30.0 degree C? What volume would this air occupy at 20.0 degrees C and a pressure of 1.00...
What are the Debye model`s assumptions for heat capacity or density of states? According to the einstein model we assume that N oscillators of the same frequency [ω][/o] and in one dimention. In three dimention N is replaced by 3N, there being three modes per oscillator.
Can the specific heat capacity be negative? Is there any substance for which i have to add heat to decrease its temperature?
By the way,why specific heat capacity has the word "capacity" in it? Is there any physical significance to it or it is simply traditional(historical)?
How can i determine Specific heat capacity of Water cpv if i know all variables
If i use this equation:
[(mi1 + mi2 +mv)cpv + mg*cpg]dT/dt = H
mi1 = mass 1
dT/dt = 0.05
cpg = 890 J/(kg*K)
mi2 = mass 2
mv = mass 3
H = 300 W
masses are arbitrary numbers
Its cpv that...
Homework Statement
cp=cv+TV?^2/?
Homework Equations
cp=T/N(\partialS/\partialT)p
The Attempt at a Solution
I have the equation, just not sure how to apply it? Any help would be appreciated
Homework Statement
a 0.20kg lead shot is heated to 90 degrees celsius and dropped into an ideal calorimeter containing 0.50kg of water initially at 20 degrees celsius. What is the final equilibrium temperature of the lead shot? The specific heat capacity of lead is 128 Joules/(kg degrees...
Homework Statement
The question is presented as picture.
Homework Equations
What is the expression of this 'heat capacity C'?
The x-process is isothermal then C=nCΔT=0?
Please give me some ideas.
The Attempt at a Solution
set V1=V2, V3=V4, T1=T4, T2=T3, p1+p0=p2, p3-p0=p4...
Homework Statement
An unknown metal with C=3.6 Mass=150g Temp=160c is added to copper container(85g) filled with water(105g) both with an initial temp of 20c
I have to find the final temp of water,container and metal
Homework Equations
none given but I assume it will be E=Cm(t1-t2)...
Homework Statement
Heating a .8 kg disk of iron from 20 C to 400 C, but the specific heat capacity changes from 456 at 20 C, to 615 at 400 C. It hints that I'm supposed to find the average to solve the equation.
Homework Equations
E = mC(dT)
The Attempt at a Solution
I have a...
Homework Statement
When a car brakes, an amount of thermal energy equal to 112500J is generated in the brake drums. If the mass of the brake drums is 28 kg and their specific heat capacity is 460.5 Jkg^-1K^-1?
A piece of iron of mass 200g and temperature 300°C is dropped into 1.00kg of water...
Homework Statement
A material has 104 atoms in its primitive cell with a speed of sound of 1500 m/s. It is well above the debye temperature. From Cv=3kb per atom, we calculate the volumetric heat capacity of 1.4*10^6 J m^-3 K^-1.
What fraction of he heat capacity is in the acoustic branches...
Homework Statement
An ice cube of mass 40g is transferred directly from the freezer where it is at -8 CELSIUS to a cup containing 120g of water at 95 degrees CELSIUS. Calculate the final temperature of water. Ignore any heat transfer to the cup or its surroundings
Homework Equations
tf = ti +...
Homework Statement
A mixture is made by adding 75g of an unknown liquid at a temperature of 25 degrees Celsius to 60g of water at a temperature of 90 degrees Celsius. The final temperature f the mixture is 65 degrees Celsius. Calculate the specific heat capacity of the liquid. What is the...
Homework Statement
what is the different in term of definition between Heat capacity and Specific heat capacity ?
Homework Equations
Q=mΔTC →C=Q/mΔT
The Attempt at a Solution
Specific heat capacity is the amount needed per unit mass of material so is a number independent of the...
Homework Statement
Atoms of the inert gas Krypton are adsorbed onto a smooth solid
surface at 90K. They can move freely over the surface but they cannot leave it. For a
sample with total surface area 2.5 m^2, and a surface density 3 nm-2, what is the heat
capacity of the krypton?
Homework...
Homework Statement
"Derive a more accurate approximation for the heat capacity at high temperatures, by keeping terms through x^{3} in the expansions of the exponentials and then carefully expanding the denominator and multiplying everything out. Throw away terms that will be smaller than...
I am trying to understand the nature of the dependence of heat capacity/specific heat on pressure.
I understand that one may give the the following relations:
\frac{C_p}{C_v}=1+\alpha\gamma T
where C_p,C_v,\alpha,\gamma, and T are isoberic specific heat, isochoric specific heat, thermal...
hello,
I'd like to know if there is any heat capacity database of some common substances. I've searched the internet for a while and I haven't found anything so it would be really kind if someone could provide me this data or link/refernce to it, because now I really need it for a project...
Calculate Specific Heat Capacity HELP!
Hi guys,
I having big troubles with how to calculate the specific heat (cp) for refrigerant r134a i gas phase.
I think that assuming ideal gas behavior is a bad idea since this is going to be used in a actual system...
I have values of entropy...
Homework Statement
Hello everyone!
I'm using the text:
"Elements of Solid State Physics - JP Srivastava (2006)"
I have followed the argument leading up to the derivation of the Debye formula for specific heat capacity, so we now have;
C_V = \frac{9N}{\omega_D^3} \frac{\partial}{\partial T}...
Homework Statement
A 100.0 g copper sample (specific heat 0.385 J/g K) at 100 C is added to 50.0 g of water at 26.5 C. What is the final temperature of the copper-water mixture?
Homework Equations
q = q(copper) + q(water)
q = (heat capacity)(change in Temp.)
q = (specific...
Homework Statement
A student performs an experiment on an ideal gas by adding 42.0 J of heat to it. As a result the student finds that the volume of the gas changes from 50 cm3 to 150 cm3 while the pressure remains constant at 101.3 kPa.
i) If the quantity of the gas present is 0.007...
Homework Statement
I am given the amount of moles of gas, how many joules of heat I put into the system, and a positive change in temperature. Then it says "calculate the molar heat capacities at constant volume and constant pressure of the gas."
Homework Equations
q=CT, C(constant...
dQ = nCvdT if volume is constant.
However, n = pV/RT.
What I don't understand is, why are we thinking n as constant when doing the integral?
I had two problems that involved this on a test I had today. At first I kept it constant and then changed n. But then I thought, wait... isn't there a T...