When a 5.00-g sample of KCN is dissolved in water in a calorimeter that has a total heat capacity of 2.642 kJ·K–1, the temperature decreases by 0.340 K. Calculate the molar heat of solution of KCN.
wow. 2014. :0..
i can answer this myself actually..
(2.642) (.340)= q
q/5g x molar mass of KCN= answer
Well, well, well, looks like we have a fun chemistry question here! It's time to put on my lab coat and get ready for some scientific hilarity.
To determine the molar heat of solution of KCN, we can start by using the equation:
q = mcΔT
where q is the heat lost or gained, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature. In this case, the heat lost is equal to the heat gained by the calorimeter.
So, let's plug in the numbers and see what happens:
q(calorimeter) = mcΔT
q(calorimeter) = (2.642 kJ/K)(0.340 K)
q(calorimeter) ≈ 0.899 kJ
Now, we need to convert this heat to moles. The molar heat of solution is defined as the heat associated with one mole of solute. To do this, we'll use the information that the sample of KCN weighed 5.00 g and the molar mass of KCN is 65.12 g/mol.
moles of KCN = mass/molar mass
moles of KCN = 5.00 g / 65.12 g/mol
moles of KCN ≈ 0.0766 mol
Finally, we can calculate the molar heat of solution by dividing the heat lost or gained by the number of moles:
molar heat of solution = q/moles of solute
molar heat of solution ≈ 0.899 kJ / 0.0766 mol
molar heat of solution ≈ 11.72 kJ/mol
So, the molar heat of solution of KCN is approximately 11.72 kJ/mol. And that, my chemistry-loving friend, is your scientifically hilarious answer.
To calculate the molar heat of solution of KCN, we need to use the equation:
q = -mCΔT
where q is the heat absorbed or released, m is the mass of the substance (in this case KCN), C is the heat capacity of the calorimeter, and ΔT is the change in temperature.
First, let's convert the mass of KCN to moles. The molar mass of KCN is 65.12 g/mol. So,
moles = mass / molar mass
= 5.00 g / 65.12 g/mol
= 0.0765 mol
Next, let's plug the values into the equation and calculate the heat absorbed or released:
q = -(0.0765 mol) * (2.642 kJ·K–1) * (0.340 K)
= -0.007 kJ
Since the reaction is exothermic (as indicated by the decrease in temperature), the negative sign indicates that heat is released. The heat released is -0.007 kJ.
Finally, let's calculate the molar heat of solution by dividing the heat released by the number of moles:
molar heat of solution = heat released / moles
= -0.007 kJ / 0.0765 mol
= -0.091 kJ/mol
The molar heat of solution of KCN is approximately -0.091 kJ/mol.
To calculate the molar heat of solution of KCN, we can use the equation:
q = m × C × ΔT
Where:
q is the heat transferred (in joules)
m is the mass of the sample (in grams)
C is the heat capacity of the calorimeter (in joules per Kelvin)
ΔT is the change in temperature (in Kelvin)
First, we need to convert the mass of the sample given in grams to moles. The molar mass of KCN is found by adding the atomic masses of potassium (39.10 g/mol), carbon (12.01 g/mol), and nitrogen (14.01 g/mol), and multiplying the atomic mass of nitrogen by 2 to account for the two nitrogen atoms:
Molar mass of KCN = (39.10 g/mol) + (12.01 g/mol) + (14.01 g/mol × 2) = 65.12 g/mol
Next, we divide the mass of the sample by the molar mass to find the number of moles:
moles of KCN = (mass of sample) / (molar mass of KCN)
= 5.00 g / 65.12 g/mol
Now we can calculate the heat transferred using the equation q = m × C × ΔT. The mass is given as 5.00 g, the heat capacity of the calorimeter (C) is given as 2.642 kJ·K^–1 (this needs to be converted to joules), and the change in temperature (ΔT) is given as 0.340 K:
q = (mass of sample) × (C) × (ΔT)
= (5.00 g) × (2.642 kJ·K^–1 × 1000 J/kJ) × (0.340 K)
Now, we convert q to the energy in joules:
q (in J) = q (in kJ) × 1000 J/kJ
Finally, we can calculate the molar heat of solution (ΔH) by dividing q by the number of moles:
ΔH = q (in J) / (moles of KCN)
By substituting the known values into the equation and performing the calculations, you will find the molar heat of solution of KCN.