What will be the final temperature of 650 g of water initially at 5.5°C if it is heated by burning 7.5 g of carbon to carbon dioxide. The molar heat of reaction is -393.5 kJ/mol.
I do not understand how to do this question
heat to water = q = mass H2O x specific heat H2O x (Tfinal-Tinitial). You don't know q or Tfinal. But you can calculate q this way, then solve for Tfinal.
The problem tells you that burning 1 mol carbon to produce CO2 gas gives 393.5 kJ of heat. How many mols do you have? That's 7.5g/12 = ? mols carbon so you should produce for q 393.5 kJ/mol x (?mol) = ? kJ. Change that to J and substitute into the equation above and solve for Tfinal.
To solve this question, we need to use the equation q = m * C * ΔT, where q represents the heat gained or lost by an object, m is the mass of the object, C is the specific heat capacity of the object, and ΔT is the change in temperature.
In this case, we need to calculate the heat gained by the water and then use it to determine the final temperature.
Step 1: Calculate the heat gained by the water
The heat gained by the water can be calculated using the equation: q(water) = m(water) * C(water) * ΔT(water)
Given:
m(water) = 650 g (mass of water)
C(water) = 4.18 J/g°C (specific heat capacity of water)
ΔT(water) = final temperature - initial temperature
Step 2: Calculate the heat released by the combustion reaction
The heat released by the combustion reaction can be calculated using the equation: q(reaction) = n * ΔH
Given:
m(Carbon) = 7.5 g (mass of carbon)
molar mass(Carbon) = 12.01 g/mol (molar mass of Carbon)
ΔH = -393.5 kJ/mol (molar heat of reaction)
First, calculate the number of moles of carbon:
moles(Carbon) = m(Carbon) / molar mass(Carbon)
Then, convert moles to kilojoules:
q(reaction) = moles(Carbon) * ΔH
Step 3: Equate the heat gained by water to the heat released by the reaction
q(water) = q(reaction)
Step 4: Solve for the final temperature of the water
Substituting the known values, we get:
m(water) * C(water) * ΔT(water) = q(reaction)
Rearranging the equation, we have:
ΔT(water) = q(reaction) / (m(water) * C(water))
Substitute the known values and solve for ΔT(water).
Finally, calculate the final temperature:
final temperature = initial temperature + ΔT(water)
By following these steps, you should be able to calculate the final temperature of the water.