When 3.2 g of ammonium chloride is dissolved in 75 g of water, the temperature of the solution decreases from 22.8°C to 20.1°C. What is the energy of dissolution of NH4Cl per mole? (The molecular mass of NH4Cl = 53.49 g/mol, and the specific heat of water = 4.18 J/g°C.)
A. 14.8 kJ/mol
B. 0.88 kJ/mol
C. 390 kJ/mol
D. 125 kJ/mol
Dissolving NH4Cl in H2O is an endothermic solution process. You measure how much it cools the solution by the temperature of the H2O.
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
The q you measure is for 3.2g/53.4g or q/0.0599 mol. You want to convert that to q/1 mol.
Did you get the Ni/water problem straightened out? I think about 21 (answerD) was the right one? unless I'm not remembering right.
u trippin
u butters fammin - im brod and this webiste pretty ded init hahahahahahahaha. i don't even get half th infor posted- simpligy then explain laterr
24.8
To calculate the energy of dissolution of NH4Cl per mole, we can use the formula:
Energy = mass of NH4Cl x specific heat of water x temperature change / number of moles of NH4Cl
First, let's calculate the number of moles of NH4Cl:
Number of moles = mass of NH4Cl / molar mass of NH4Cl
Number of moles = 3.2 g / 53.49 g/mol ≈ 0.0598 mol
Next, let's calculate the energy of dissolution:
Energy = 0.0598 mol x 4.18 J/g°C x (20.1°C - 22.8°C)
Energy = 0.0598 mol x 4.18 J/g°C x (-2.7°C)
Energy ≈ -0.697 kJ
Since we want the energy of dissolution per mole, we divide the energy by the number of moles:
Energy per mole = -0.697 kJ / 0.0598 mol
Energy per mole ≈ -11.63 kJ/mol
Since energy is typically given as a positive value, the answer is approximately 11.63 kJ/mol.
However, none of the options provided match exactly, so it is possible that there is a mistake in the question or the answer choices.