A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of the .500 M HCl at 25 C is assed to 50 mL of .500 M NaOH at 25 C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2 C. What is the heat of reaction per mole of acid? Assume the mixture has a specific heat capacity of 4.18 J/gK and that the densities of the reactant solutions are both 1.00 g/mL
1339J
To find the heat of reaction per mole of acid, we need to calculate the heat released or absorbed during the neutralization reaction.
The heat released or absorbed during a reaction can be calculated using the equation:
q = m * c * ΔT
where:
- q is the heat released or absorbed (in joules),
- m is the mass of the solution (in grams),
- c is the specific heat capacity of the solution (in J/gK),
- ΔT is the change in temperature (in Celsius).
To calculate the mass of the solution, we need to know the density and volume of the solution.
First, let's calculate the mass of HCl solution:
Density = 1.00 g/mL
Volume = 50.0 mL = 50.0 g
So, the mass of HCl solution is 50.0 g.
Next, let's calculate the mass of NaOH solution:
Density = 1.00 g/mL
Volume = 50.0 mL = 50.0 g
So, the mass of NaOH solution is also 50.0 g.
Now, let's calculate the total mass of the solution:
Mass of solution = mass of HCl solution + mass of NaOH solution
= 50.0 g + 50.0 g
= 100.0 g
Next, the change in temperature (ΔT) can be calculated using the formula:
ΔT = final temperature - initial temperature
Given:
Initial temperature = 25 °C
Final temperature = 28.2 °C
So, ΔT = 28.2 °C - 25 °C = 3.2 °C
Now, we have all the required values to calculate the heat of reaction per mole of acid.
First, we need to calculate the number of moles of acid used. We can do this using the following formula:
moles of acid = concentration of acid * volume of acid (in liters)
Given:
Concentration of HCl = 0.500 M
Volume of HCl = 50.0 mL = 0.050 L
moles of HCl = 0.500 M * 0.050 L = 0.025 moles
Next, we can calculate the heat of reaction:
q = m * c * ΔT
= 100.0 g * 4.18 J/gK * 3.2 °C
= 1337.6 J
Finally, we can calculate the heat of reaction per mole of acid:
Heat of reaction per mole of acid = heat of reaction / moles of HCl
= 1337.6 J / 0.025 moles
= 53,504 J/mol
Therefore, the heat of reaction per mole of acid is 53,504 J/mol.
912
670J
q = heat released = [mass H2O x secific heat H2O x (Tfinal-Tinitial)]
mols of rxn = 0.5M x 0.050 L = 0.025 mols.
q/0.025 = delta H in J/mol. Usually this is quoted in kJ/mol so divide by 1000 for kJ/mol.