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Chemistry Homework Help => AP Chemistry => Topic started by: ann on February 08, 2023, 11:29:42 PM

Title: Thermodynamics- Bomb Calorimeter and heat of combustion
Post by: ann on February 08, 2023, 11:29:42 PM
 I need some help with these questions
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Title: Re: Thermodynamics- Bomb Calorimeter and heat of combustion
Post by: uma on February 09, 2023, 06:52:55 AM
In bomb calorimeter
q(water ) = C Delta t  = Heat of combustion of 1.535 g CH3OH
q(water) in  kJ .

∆H = - q (water)/ n
n = moles of methanol.
Title: Re: Thermodynamics-heat of combustion and Hess's law
Post by: uma on February 09, 2023, 06:53:55 AM
Quote from: ann on February 08, 2023, 11:29:42 PM
I need some help with these questions
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Enthalpy of formation reaction is
C(s) +2S (s) ---> CS2---∆Hreaction
Use Hess's law
CS2 + 3O2------> CO2   + 2SO2--- ∆H1
S(s)    + O2 ---> SO2---∆H2
C(s)    + O2 ---> CO2---∆H3
∆Hreaction = -∆H1 +2∆H2 +∆H3



Title: Re: Thermodynamics- Bomb Calorimeter and heat of combustion
Post by: uma on February 09, 2023, 07:15:59 AM
Quote from: ann on February 08, 2023, 11:29:42 PM
I need some help with these questions
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This is based on law of conservation of energy.
Heat lost by one system of water at high temperature = heat gained by another system of water(low temperature)
Final temperature of both the systems will be same as they get the thermal equilibrium.Let us assume final temperature is x.
q(lost) =- mc ∆ t = - 100 * 4.18*(x-80)
q(gained) = m ∆H fusion of ice  + mc∆t = 10*335 + 10 4.18(x-0)
Equate these equations to get the value of x .