When 3.00 g potassium carbonate (K2CO3 ) was mixed with 20.0 mL of hydrochloric acid (HCl, 4.0M) in a calorimeter, the temperature raised 3.0 degrees Celsius.
B. Calculate the enthalpy change (H) of the reaction for per mole patassium carbonate. Assume the specific heat of all solutions are 4.18 J/g.oC and all solutions have a density =1.0 g/mL. (A:-13.3 kJ)
I do not how to get the answer.
q = mass fluid x specific heat fluid x (Tfinal-Tinitial)
Most of these problems are worked WITHOUT including the mass of the dissolved solid; however, if we use as the mass of the fluid 20 + 3 g = 23 I obtain the 13.3 kJ/mol.
To calculate the enthalpy change (ΔH) of the reaction per mole of potassium carbonate, you can use the formula:
ΔH = (q / n)
where ΔH is the enthalpy change in Joules per mole (J/mol), q is the amount of heat transferred in Joules (J), and n is the number of moles of the substance involved in the reaction.
To find the amount of heat transferred in the reaction, you can use the equation:
q = m * c * ΔT
where q is the amount of heat transferred in Joules (J), m is the mass of the solution in grams (g), c is the specific heat capacity of the solution in J/(g·°C), and ΔT is the temperature change in degrees Celsius (°C).
First, you need to determine the mass of the solution. To do this, you can add together the mass of potassium carbonate (3.00 g) and the mass of hydrochloric acid.
Next, you need to calculate the amount of heat transferred (q) using the given values in the question. The mass of the solution can be determined by adding the mass of potassium carbonate (3.00 g) and the mass of hydrochloric acid (which can be obtained by multiplying the volume (20.0 mL) by the density (1.0 g/mL)).
After calculating the amount of heat transferred (q), you can then calculate the number of moles of potassium carbonate (n) using the molar mass of potassium carbonate (K2CO3), which is 138.21 g/mol.
Finally, you can substitute the values of q and n into the formula ΔH = (q / n) and calculate the enthalpy change in Joules per mole (J/mol). To convert this value to kilojoules per mole (kJ/mol), divide the result by 1000.
Given the specific heat capacity of all solutions as 4.18 J/g·°C, the density of the solution as 1.0 g/mL, and assuming the reaction occurs under constant pressure and in an aqueous solution, following these steps should yield the answer, which is -13.3 kJ/mol.