If the heat from burning 5.800 g of C6H6 is added to 5691 g of water at 21 °C, what is the final temperature of the water?
2C6H6(l) +15O2 (g)----> 12CO2(g)+6H2O(l) +6542
I got an answer of 24.23 degrees celsius and it marked me wrong? Can someone please explain and tell me what they get.
I posted this for David, I think. Here is a link. I think the answer is closer to 33 C.
http://www.jiskha.com/display.cgi?id=1328853263
To calculate the final temperature of the water, we need to use the formula for heat transfer:
Q = mcΔT
Where:
Q = heat transferred
m = mass of the substance
c = specific heat capacity
ΔT = change in temperature
First, let's find the heat transferred when burning 5.800 g of C6H6. The balanced chemical equation tells us that 2 moles of C6H6 produce 6 moles of H2O. So, we need to calculate the moles of C6H6 using its molar mass and then use the ratio to find the moles of H2O formed.
1. Calculate moles of C6H6:
Molar mass of C6H6 = 78.114 g/mol
moles of C6H6 = mass / molar mass = 5.800 g / 78.114 g/mol
2. Use the mole ratio from the balanced equation to find moles of H2O:
moles of H2O = moles of C6H6 * (6 moles H2O / 2 moles C6H6)
Now, let's calculate the heat transferred from the burning C6H6 to the water. The heat transferred to the water can be found using the equation Q = mcΔT:
3. Calculate the heat transferred:
Q = mcΔT
Q = (mass of water) * (specific heat capacity of water) * (change in temperature)
Since the mass of water is given as 5691 g and the initial temperature is 21 °C, we plug these values into the equation. The specific heat capacity of water is approximately 4.184 J/g°C.
4. Substitute the values:
Q = (5691 g) * (4.184 J/g°C) * (final temperature - 21 °C)
Now, equate the heat transferred from burning C6H6 to the heat transferred to the water and solve for the final temperature:
5. Set the equations equal to each other:
(moles of H2O) * (-6542 kJ/mol) = (mass of water) * (4.184 J/g°C) * (final temperature - 21 °C)
Finally, solve for the final temperature by rearranging the equation and plugging in the known values:
6. Substitute the known values:
(final temperature - 21 °C) = ((moles of H2O) * (-6542 kJ/mol)) / ((mass of water) * (4.184 J/g°C))
7. Calculate the final temperature by plugging in the numbers and converting units if necessary.
Note: Make sure to convert the units to kJ and divide by 1000 to match the units of kJ/mol:
final temperature = ((moles of H2O) * (-6542 kJ/mol)) / ((mass of water) * (4.184 J/g°C)) + 21 °C
By following these steps, you should be able to calculate the final temperature of the water when the heat from burning C6H6 is added to it.