When 2.53 g of NaOH(s)(40.0g/mol) dissolves in 100.0 g of water, the temperature of the solution changes from 20 degrees C to 26.3 degrees C. Calculate qrx in KJ/mol specific heat of the solution is 4.18 J/(g*K)
q = mass water x specific heat water x (Tfinal-Tinitial) = ?? Joules and change to kJ.
Then kJ/# moles = kJ/mol.
You can find moles by 2.53/molar mass NaOH.
Thank you for all of your help DrBob!!!!
To calculate the heat absorbed or released during the dissolution of NaOH, we can use the equation:
qrx = m × Cs × ΔT
where:
qrx is the heat absorbed or released during the reaction (in Joules),
m is the mass of the solution (in grams),
Cs is the specific heat of the solution (in J/(g*K)),
and ΔT is the change in temperature (in Kelvin).
First, let's convert the change in temperature from Celsius to Kelvin:
ΔT = 26.3°C - 20°C = 6.3 K
Next, we need to calculate the mass of the solution by summing the mass of NaOH and the mass of water:
Mass of solution = Mass of NaOH + Mass of water = 2.53 g + 100.0 g = 102.53 g
Now, we can plug the values into the formula to calculate qrx:
qrx = (102.53 g) × (4.18 J/(g*K)) × (6.3 K)
Calculating this gives us:
qrx = 2707.4418 J
To convert this value to kilojoules per mole, we need to divide by the molar mass of NaOH:
Molar mass of NaOH = 23.0 g/mol + 16.0 g/mol + 1.0 g/mol = 40.0 g/mol
qrx (in KJ/mol) = qrx (in J) / molar mass of NaOH (in g/mol)
qrx (in KJ/mol) = 2707.4418 J / 40.0 g/mol
qrx (in KJ/mol) ≈ 67.686 KJ/mol
Therefore, the heat of the reaction (qrx) is approximately 67.686 KJ/mol.
To calculate the qrx (heat released or absorbed in a reaction) in kJ/mol, you need to use the equation:
qrx = m × C × ΔT
where:
qrx is the heat released or absorbed (in J)
m is the mass of the solute (in grams)
C is the specific heat of the solution (in J/(g*K))
ΔT is the change in temperature (in Kelvin)
First, convert the given mass of sodium hydroxide (NaOH) from grams to moles:
moles of NaOH = mass of NaOH / molar mass of NaOH
moles of NaOH = 2.53 g / 40.0 g/mol
moles of NaOH = 0.06325 mol
Now, calculate the heat released or absorbed (qrx) using the equation:
qrx = m × C × ΔT
we have:
m = mass of water = 100.0 g
C = specific heat of the solution = 4.18 J/(g*K)
ΔT = change in temperature = (final temperature - initial temperature)
ΔT = 26.3°C - 20.0°C = 6.3°C
However, to use this value in the equation, we need to convert the temperature to Kelvin:
ΔT = 6.3°C + 273.15
Now, substitute the values into the equation and solve:
qrx = m × C × ΔT
qrx = 100.0 g × 4.18 J/(g*K) × (6.3°C + 273.15)
Calculate the answer to get qrx in J:
qrx = 11108.7 J
Finally, convert the answer to kJ/mol by dividing by the moles of NaOH:
qrx (kJ/mol) = qrx (J) / moles of NaOH
qrx (kJ/mol) = 11108.7 J / 0.06325 mol
qrx (kJ/mol) ≈ 175.63 kJ/mol
Therefore, the value of qrx is approximately 175.63 kJ/mol.