In the following experiment, a coffee-cup calorimeter containing 100ml of H2O is used. The initial temperature of the calorimeter is 23 degrees celcius. If 7.20g of CaCl2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of solution of CaCl2 is -82.8kj/mol .
Please note the correct spelling of Celsius.
How much heat does the CaCl2 add to the water? That is 7.2 g (1 mol/molar mass CaCl2) x (82,800 Joules/mol).
Then q = mass water x specific heat water x (Tf-Ti) where Tf is the final T and Ti is the initial T. Most dilute solutions will have a density for the solution of 1.0 g/mL; therefore, 100 mL has a mass of 100 grams. The specific heat of water is 4.184 J/g*C. Post your work if you get stuck.
5.69
Johns answer is incorrect. who can answer this correctly?
32363.376 kJ/mol
34.9 degrees Celsius.
1) convert CaCl2 to moles then multiply it by 82.8kj/mol to find the heat of CaCl2.
2) Use the q=mct equation. Make sure the mass is the TOTAL MASS (of water + CaCl2)
3) Solve.
hope this helps! :)
To calculate the final temperature of the solution in the calorimeter after adding CaCl2, we can use the principle of heat transfer, specifically the equation:
q = m * c * ΔT
where:
- q is the heat transferred to or from the system,
- m is the mass of the substance,
- c is the specific heat capacity of the substance, and
- ΔT is the change in temperature.
In this case, we are calculating the final temperature, so we need to rearrange the equation:
ΔT = q / (m * c)
First, we need to find the heat transferred (q). We can calculate it using the equation:
q = n * ΔH
where:
- q is the heat transferred to or from the system,
- n is the number of moles of the substance, and
- ΔH is the enthalpy change of the substance (heat of solution in this case).
To find the number of moles (n) of CaCl2, we can use the equation:
n = m / M
where:
- n is the number of moles of the substance,
- m is the mass of the substance, and
- M is the molar mass of the substance.
In this case, the mass of CaCl2 is given as 7.20g. The molar mass of CaCl2 can be calculated by adding the atomic masses of calcium (Ca) and chlorine (Cl), which are 40.08 g/mol and 35.45 g/mol, respectively. Therefore:
M = (40.08 g/mol) + 2 * (35.45 g/mol)
M = 110.98 g/mol
Using the given heat of solution of CaCl2 as -82.8 kJ/mol, we can now calculate the heat transferred (q):
q = (7.20 g / 110.98 g/mol) * (-82.8 kJ/mol)
q = -5.31 kJ
Now, we can plug in the values for mass (m), specific heat capacity (c), and heat transferred (q) into the rearranged equation to calculate the change in temperature (ΔT):
ΔT = (-5.31 kJ) / (100 g * 4.18 J/g°C)
ΔT ≈ -1.28 °C
Finally, to find the final temperature, we add the change in temperature (ΔT) to the initial temperature of the calorimeter (23 °C):
Final temperature = Initial temperature + ΔT
Final temperature = 23 °C + (-1.28 °C)
Final temperature ≈ 21.72 °C
Therefore, the final temperature of the solution in the calorimeter after adding CaCl2 will be approximately 21.72 degrees Celsius.