A4.00 m solution of kcl was prepared using 1.00 kg of water at 25.0 ∘c. once the solid had all dissolved, the temperature of the solution was 12.3 ∘c. calculate the heat of solution, δhsoln, of kcl. assume that the specific heat of the solution is identical to that of water, 4.18 j/(g⋅∘c).

The heat of solution of KCl is 17.2 kJ

Explanation:

Step 1: given data

We have a 4m solution of KCl prepared in 1kg of water

⇒molality = number of moles / kg of solute

⇒ in this case it means 4 moles / 1kg of water = 4

Specific heat of water = 4.18J/g °C

KCl has a molar mass of 75.55g/mole

Step 2: calculate mass and change of temperature

Heat of solution = mass (g) * specific heat (j/g °C) * change of temperature

mass of KCl we can calculate through te formula mass = moles * Molar mass

⇒ m(KCl) = 4 moles * 74.55g/mole = 298.2g

⇒ total mass = 298.2g of KCl + 1000g of water = 1298.2g

Change of temperature = Final temperature T2 - initial temperature T1 = 12.3°C - 25°C = -12.7 °C   ⇔ this means the temperature reduces with 12.7 °C

Step3 : calculating heat of solution

heat of solution (q) = mass * specific heat * change in temperature

q = (1298g) * (4.18J/g °C ) * (-12.7) = -68910 J = -68.910 kJ

We will use the positve value of this

ΔH = q / moles = 68.91 kJ / 4 moles = 17.2 kJ

The heat of solution of KCl is 17.2 kJ

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.