Question

Freon-11, CCl3F, has a boiling point of 23.8 degrees celsius. The specific heat of the liquid is 0.87 J/g degrees celsius and the specific heat of the gas is 0.59 J/g degrees celsius. The heat of vaporization is 24.75 kJ/mol. Calculate the heat required to convert 10.0 g of Freon-111 from a liquid at -50.0 degrees celsius to a gas at 50.0 degrees celsius

Answer 1

2.60 kJ

Step-by-step explanation:

I have drawn a generalized heating curve for you below.

We are heating the liquid Freon to its boiling point, evaporating it completely, and then heating the vapour.

1. Heating the liquid

(a) Calculate ΔT

ΔT = [23.8 -(-50.0)] °C = (23.8 + 50.0) °C = 73.8 °C

(b) Calculate q₁

q₁ = mC₁ΔT = 10.0 × 0.87 × 73.8 = 642 J

2. Boiling the liquid

(a) Calculate the moles of Freon

`n = \text{10.0 g} * \frac{\text{1 mol}}{\text{137.37 g }} = \text{0.072 80 mol}`

(b) Calculate q₂

q₂ = nΔHvap = 0.07280 mol × 24 750 J/mol = 1802 J

3. Heating the vapour

(a) Calculate ΔT

ΔT = (50.0 - 23.8) °C = 26.2 °C

(b) Calculate q₃

q₃ = mC₃ΔT = 10.0 × 0.59 × 26.2 = 154 J

4. Calculate the total heat

q₁ = 642 J

q₂ = 1802 J

q₃ = 155 J

TOTAL = 2600 J = 2.60 kJ

It takes 2.60 kJ to heat the Freon from -50.0 °C to 50.0 °C .

Answer 2

The heat required to convert CCl3F from liquid at -50°C to gas at 50°C is 248, 296.64 J OR 248.30kJ

Step-by-step explanation:

To calculate the heat required to convert CCl3F from a liquid at -50 °C to a gas at 50 °C, we calculate the heat required to increase the temperature of the liquid from -50°C to liquid at 0°C, then the heat needed to convert the liquid at 0°C to gas at 0°C, and then the heat needed to convert the gas at 0°C to gas at 50°C, adding these three values we obtain the total heat required.

Step 1: heat needed to increase the temperature from -50°C to 0°C

H = mcΔT ( m = 10g , C = 0.87 J/g, ΔT = ( B.p of CCl3F - (-50°C) = (23.8 +50) = 73.8°C

H = 10 * 0.87 * 73.8

H = 642.06 J

Step 2: heat required to convert liquid at 0°C to gas at °C

H = m Hv ( m = 10g, Hv = heat of vaporization = 24.75kJ/mol)

H = 10 * 24.75 *10^3

H = 247.5 *10^3 J

Step 3: heat needed to convert gas at 0°C oto gas at 50°C

H = mc T ( m =10g , c = 0.59J/g , T = (50°C- 23.8°C) = 26.2°C

H = 10 * 0.59 * 26.2

H = 154.58J

Step 4: adding the three values together

H = H1 + H2 + H3

H = 642.06 + 247500 + 154.58

H = 248, 296.64 J

h = 248.30kJ