Question

2.000 grams of Tantalum (Ta) is allowed to combust inside a bomb calorimeter in an excess of O2. The temperature inside changes from 32.00 °C to 39.15 °C. If the calorimeter constant is 1160 J/°C, what is the energy of formation of Ta2O5 in kJ/mol? (remember, it could be positive or negative). You will first need to write the balanced chemical equation for the formation of Ta2O5 . Tantalum is stable in the solid state at 25 °C and 1.00 atm of pressure.

Answer 1

To calculate the energy of formation of Ta2O5, we need to use the equation:

2 Ta + 5/2 O2 -> Ta2O5

Given the temperature change inside the bomb calorimeter (∆T = 39.15 °C - 32.00 °C = 7.15 °C) and the calorimeter constant (C = 1160 J/°C), we can use the formula:

q = C * ∆T

where q is the heat absorbed or released in the reaction.

Since the combustion of 2 grams of Tantalum (Ta) occurred in excess O2, we can assume that the reaction went to completion.

Now, we need to convert the mass of Ta to moles. The molar mass of Ta is approximately 180.95 g/mol, so:

moles of Ta = (mass of Ta) / (molar mass of Ta)
= 2.000 g / 180.95 g/mol

Next, we use the stoichiometric coefficients from the balanced equation to find the moles of Ta2O5 produced:

moles of Ta2O5 = 0.5 * (moles of Ta)

Finally, we can calculate the energy of formation (∆Hf) of Ta2O5 in kJ/mol:

∆Hf = q / (moles of Ta2O5)

Remember to convert the result to kJ/mol.

Please note that the values used in this calculation are approximate and may vary based on the actual molar mass and other factors.