What is the specific heat capacity of the petroleum?

AI Thread Summary
The discussion focuses on calculating the specific heat capacity of petroleum using a calorimetry experiment involving a copper calorimeter and a copper weight. The initial temperatures and masses of the substances involved are provided, along with the heat capacity of the calorimeter. The user attempts to isolate the specific heat capacity of petroleum but arrives at an incorrect value of 20.4 J/(kg*K), which contradicts known values around 1900 J/(kg*K). The user seeks hints to resolve the discrepancy and correctly apply the heat transfer equation. Accurate calculations are essential for determining the specific heat capacity of petroleum in this context.
Hoejer
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Homework Statement


A copper calorimeter with the heatcapacity of 75 J/K has 300 g of petrolium in it. The starttemp. is 17.8 C. A kobberweight of 100 g. is 100Celcius. It is being put in the petroleum, where the temperature ends up being 22 C. The specifik heatcapacity of coppe ris 387J(kg/K)
What is petroleums specifik heat capacity?


Homework Equations



C_pet*m_pet(t2-ts)+C_cop*m_cop(t2-t1)+C_cal*m_cal(t2-t1)=0

The Attempt at a Solution


I think I have overlooked something - so I just need hints on the way.

I don't have the mass of the calorimeter, but I now that it's heatcapacity is 75 J/K and I know that it's made of coper and the specifik heat capacity of that is 387 J(kg*K)

If that is the way to go, then I have all the variables except the specifik heat capacity of petroleum, and then I just isolate C-Pet and it's piece of cake!
 
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the the mass of the calorimeter must be 75/387 = 0.193 kg = 193 g

Which then means C_pet*300(22-100)+387*100(22-17.8)+387*193(22-17.8)=0

C_pet = 20.4 J(kg/K)
 
Which isn't true as looking in table it is around 1900 J/(kg*K)
 
No help?
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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