Question

A sample of C_3 H_4Br_2 has a normal boiling temperature of 131.5^∘C. The enthalpy of vaporization for this compound is 35.4 kJ/mol. a) What would be the boiling temperature in ∘C of C_3 H_4Br_2 at a pressure of 540.0 mmHg ? Report your answer using three significant figures. b) How much energy would be required to heat a 16.9 gram sample of liquid C_3H_4Br_2 from 97.5 ^∘C to a gas at 187.2^∘C ? The specific heat for the liquid is 0.865 J/g⋅^∘C and the specific heat for the gas is 0.364 J/g⋅^∘C.

Answer 1

In order to find the boiling temperature of C3H4Br2 at a new pressure, we can use the Clausius-Clapeyron equation. To calculate the energy required to heat the sample of C3H4Br2, we can use the specific heat equation.

Step-by-step explanation:

In order to ascertain the boiling temperature of C3H4Br2 at a pressure of 540.0 mmHg, the Clausius-Clapeyron equation becomes instrumental.

The equation, ln(P2/P1) = -(ΔHvap/R)((1/T2) - (1/T1)), involves known values of pressure (P1) and temperature (T1), along with unknowns P2 and T2.

By rearranging the equation and solving for T2, the boiling temperature at the new pressure can be determined.

For the calculation of the energy required to elevate a 16.9-gram sample of C3H4Br2 from 97.5 °C to a gaseous state at 187.2 °C, the specific heat equation, q = mcΔT, proves valuable.

This involves computing the energy needed to raise the liquid to its boiling point, the energy needed for vaporization, and the energy required to heat the resulting gas to the final temperature.

Employing this approach facilitates a comprehensive understanding of the energy transformations involved in the heating process for the given substance

Answer 2

To estimate the new boiling temperature of C3H4Br2 at 540.0 mmHg, the Clausius-Clapeyron equation is used with the known enthalpy of vaporization and normal boiling point. The total energy required to heat and vaporize a 16.9 gram sample from 97.5 °C to a gas at 187.2 °C is calculated in three steps: heating the liquid, vaporizing it, and then heating the gas.

Step-by-step explanation:

To calculate the boiling temperature of C3H4Br2 at a pressure of 540.0 mmHg, we need to use the Clausius-Clapeyron equation.

Part A: Estimating the Boiling Temperature at 540.0 mmHg

1. Convert 540.0 mmHg to kPa by multiplying with the conversion factor (101.3 kPa / 760 mmHg).
2. Use the Clausius-Clapeyron equation to solve for the new boiling point at a pressure of 540.0 mmHg, using the known enthalpy of vaporization and boiling point at atmospheric pressure.

Part B: Energy Required to Heat and Vaporize the Sample

1. Calculate the energy needed to heat the liquid from 97.5 °C to its boiling point using the formula q = mcΔT, where m is the mass, c is the specific heat, and ΔT is the change in temperature.
2. Compute the energy required for the phase transition using the given enthalpy of vaporization and the mass of C3H4Br2.
3. Calculate the energy needed to heat the vapor from the boiling point to 187.2 °C using the same formula as in step 1, but with the specific heat for the gas phase.
4. Add all three amounts of energy to determine the total energy required.