KCl(s) → K+(aq) + Cl‾ (aq)

Solid KCl dissolves as shown in the above equation. A 6.60 g sample of KCl was dissolved in 42.3 g of water. The initial temperature of the water was 21.90°C. After the compound dissolved, the temperature of the water was 10.20°C. Assume the heat was completely absorbed from the water and no heat was absorbed by the reaction container or the surroundings. Calculate the heat of solution of KCl in kJ/mol. The specific heat of water is 4.184 J/g·°C. (Do not take the added mass of the KCl into account when calculating q for the solution.)

q = mass H2O x specific heat H2O x (Tfinal-Tinitial)

That gives you q/6.60g KCl = q/gram.
To convert to q/mol it will be
q/6.60 x (molar mass KCl/1 mol) = ? J/mol
Convert to kJ/mol.

q= 4.184(42.3)(10.2-21.9)

= -2070.70 J
-2070.70J/6.60g KCl = -313.74 J/g
-313.74 J/g(74.55g/ 1 mol KCl)= -23389.32J/mol
-23.4 kJ/mol
Is this correct?

To calculate the heat of solution of KCl, we need to calculate the amount of heat absorbed by the water. We can use the equation:

q = m * c * ΔT

where:
- q is the heat absorbed or released
- m is the mass of the water
- c is the specific heat of water
- ΔT is the change in temperature of the water

First, let's calculate the mass of the water. We know the mass of the water is 42.3 g.

Next, let's calculate the change in temperature of the water, ΔT. The initial temperature was 21.90°C, and the final temperature was 10.20°C.

ΔT = final temperature - initial temperature
ΔT = 10.20°C - 21.90°C
ΔT = -11.70°C

Now we can calculate the heat absorbed by the water using the equation mentioned earlier.

q = m * c * ΔT
q = 42.3 g * 4.184 J/g·°C * -11.70°C

Next, we'll convert the units from J to kJ.

q = (42.3 g * 4.184 J/g·°C * -11.70°C) / 1000
q = -2.311 kJ

The negative sign indicates that heat was absorbed by the water.

Now, we need to calculate the heat of solution per mole of KCl. To do this, we need to determine the number of moles of KCl in the 6.60 g sample.

To calculate the number of moles, we can use the molar mass of KCl, which is approximately 74.55 g/mol.

moles of KCl = mass of KCl / molar mass of KCl
moles of KCl = 6.60 g / 74.55 g/mol

Now we can calculate the heat of solution per mole of KCl.

heat of solution per mole of KCl = heat absorbed / moles of KCl
heat of solution per mole of KCl = -2.311 kJ / (6.60 g / 74.55 g/mol)

Finally, we can simplify the calculation.

heat of solution per mole of KCl = -2.311 kJ * (74.55 g/mol / 6.60 g)
heat of solution per mole of KCl ≈ -26.07 kJ/mol

Therefore, the heat of solution of KCl is approximately -26.07 kJ/mol.

To calculate the heat of solution of KCl, we need to determine the amount of heat absorbed by the water.

First, let's calculate the mass of water using the given information:
Mass of water = 42.3 g

Next, let's calculate the change in temperature of the water:
Change in temperature = Final temperature - Initial temperature
= 10.20°C - 21.90°C
= -11.7°C

Now, let's calculate the amount of heat absorbed by the water using the equation:
q = mcΔT

where:
q = heat absorbed (in joules)
m = mass of water (in grams)
c = specific heat of water (in J/g·°C)
ΔT = change in temperature (in °C)

Let's plug in the values:
q = (42.3 g)(4.184 J/g·°C)(-11.7°C)
q = -2199.24 J

The negative sign indicates that heat is being released by the water.

Next, let's convert the heat absorbed to kilojoules:
q = -2199.24 J * (1 kJ/1000 J)
q = -2.19924 kJ

Now, we need to determine the heat of solution per gram of KCl. We can use the following equation:

Heat of Solution (per gram of KCl) = q / mass of KCl

To find the mass of KCl, we subtract the mass of water from the total mass of the solution:
Mass of KCl = Total mass of solution - Mass of water
= (6.60 g + 42.3 g) - 42.3 g
= 6.60 g

Finally, let's calculate the heat of solution per gram of KCl:
Heat of Solution (per gram of KCl) = -2.19924 kJ / 6.60 g
= -0.3333 kJ/g

The negative sign indicates that the process of dissolving KCl releases heat.

To determine the heat of solution of KCl in kJ/mol, we need to calculate the molar mass of KCl. The molar mass of KCl is 74.5513 g/mol.

Using the molar mass, we can find the heat of solution per mole of KCl:

Heat of Solution (per mole of KCl) = Heat of Solution (per gram of KCl) * Molar Mass of KCl
= -0.3333 kJ/g * 74.5513 g/mol
= -24.857 kJ/mol

Therefore, the heat of solution of KCl is approximately -24.857 kJ/mol.