Determine the specific latent heat of vaporization of water (L_v) by condensing dry steam into a known mass of cold water inside a calibrated copper calorimeter, measuring the resulting temperature elevation, and analyzing the thermal energy balance with radiation exchange corrections. Explore a virtual apparatus, collect readings and analyse a graph.
Ready for a virtual observation.
Adjust the apparatus, then take a reading.
Readings are generated by an ideal model. The diagram is schematic and is not to scale.
The teaching simulation models condensation calorimetry under ideal dry steam conditions with constant steam temperature T_s = 100.00 °C, initial water temperature T_0 = 15.00 °C, and an invariant system heat capacity C_sys = 866.08 J K⁻¹. In physical laboratory execution, entrained liquid water droplets escaping through the steam trap can introduce wet steam errors, evaporative cooling from the warm water surface can reduce the apparent equilibrium temperature, thermometer stem emergent exposure can slightly depress readings, and barometric pressure departures alter the true boiling point from 100 °C. The simulation evaluates equilibrium temperatures using the exact thermodynamic conservation relation T_f = (m_v L_v + m_v c_w T_s + C_sys T_0) / (C_sys + m_v c_w), where m_v is the condensed steam mass in kilograms, L_v = 2,260,000 J kg⁻¹ (2,260.00 kJ kg⁻¹) is the reference latent heat of vaporization, c_w = 4,186 J kg⁻¹ K⁻¹ is the specific heat capacity of water, T_s = 100.00 °C is the steam temperature, T_0 = 15.00 °C is the initial chilled water temperature, and C_sys = 866.08 J K⁻¹ is the aggregate thermal capacity. Equilibrium temperatures are rounded to 0.01 °C to simulate precision calorimetric thermometry, and ordinary least-squares regression of Q_net against m_v yields the reported latent heat of vaporization.
A robust cylindrical copper boiler equipped with a water-level sight glass, a vertical safety pressure-release manometer tube, and an adjustable Bunsen burner to produce a steady, vigorous stream of saturated steam at 100.0 °C.
An inline bulbous glass trap inserted between the boiler and delivery tube to catch, collect, and drain entrained liquid water droplets, guaranteeing that only dry saturated vapor reaches the calorimeter vessel.
A thin-walled cylindrical copper container (mass 75.0 g) supported on insulating cork pegs inside a concentric air jacket, sealed with a vulcanite lid with apertures for the steam delivery tube, thermometer, and stirrer.
A high-resolution mercury-in-glass thermometer graduated from 10 °C to 50 °C in 0.05 °C divisions to measure T_0 and T_f, paired with a dual-pan analytical balance resolving mass to ±0.01 g to determine the condensed steam mass m_v.
Determine the specific latent heat of vaporization of water (L_v) by condensing dry steam into a known mass of cold water inside a calibrated copper calorimeter, measuring the resulting temperature elevation, and analyzing the thermal energy balance with radiation exchange corrections. Suggested independent settings: 3.0, 4.5, 6.0, 7.5, 9.0 g.
Weigh the clean, dry copper calorimeter vessel together with its brass wire loop stirrer to ±0.01 g. Add exactly 200.00 g of distilled water pre-cooled to approximately 14 °C to 15 °C (approximately 5 °C below room temperature, T_room = 20.0 °C). Place the calorimeter vessel inside the double-walled outer jacket and seat the insulated lid firmly.
Pre-cooling the initial water below room temperature implements Rumford's radiation compensation principle: heat gained from the room during the cool half of the experiment balances heat radiated to the room during the warm half.
Fill the copper boiler two-thirds full with distilled water, add anti-bumping boiling chips, and heat vigorously with the Bunsen burner. Connect the delivery tube through the glass water trap. Allow steam to blast freely through the trap into a waste beaker for at least three minutes until the trap and delivery nozzle are thoroughly pre-heated and discharging clean, dry steam without sputtering.
Pre-heating the glass walls prevents steam from condensing prematurely in cold tubing before reaching the calorimeter, which would otherwise introduce liquid water droplets and severely distort the latent heat calculation.
Agitate the calorimeter water bath gently with the wire stirrer and record the steady initial temperature T_0 = 15.00 °C. Position the calorimeter beneath the pre-heated steam delivery nozzle, lower the nozzle tip approximately 2 cm below the water surface, and allow steam to bubble into the liquid while maintaining continuous, gentle stirring.
Submerging the nozzle tip ensures complete thermal capture and instantaneous condensation of the steam bubbles before vapor can escape into the atmosphere.
Monitor the rising temperature closely. When the water temperature approaches approximately 25 °C to 35 °C (so the final temperature excess above room temperature roughly mirrors the initial depression below room temperature), pinch the rubber delivery hose, remove the delivery nozzle promptly from the water, and shake any adhering droplets back into the calorimeter.
Withdrawing the nozzle promptly prevents back-siphoning of calorimeter water into the cooling delivery tube as internal steam pressure collapses.
Continue stirring the water bath thoroughly until the thermometer reaches its maximum steady reading, recording this value as the final equilibrium temperature T_f. Remove the calorimeter vessel from its jacket and reweigh it to ±0.01 g. Subtract the initial tare mass to determine the exact mass of condensed steam m_v = m_final − m_initial.
The condensed mass m_v is the central independent variable; gravimetric determination on a precision analytical balance provides high experimental accuracy.
Repeat the condensation procedure across five distinct steam charges (m_v = 3.0 g, 4.5 g, 6.0 g, 7.5 g, and 9.0 g). For each run, compute the sensible heat absorbed by the system Q_gain = C_sys (T_f − T_0) and subtract the sensible heat lost by the condensed water cooling from 100 °C to T_f: Q_sens = m_v c_w (T_s − T_f). Plot Q_net = Q_gain − Q_sens against m_v (kg) and extract the latent heat of vaporization L_v from the slope.
Linear regression over multiple condensation runs isolates the latent heat of transformation from random weighing and reading fluctuations, validating the first-order thermodynamic energy balance.
Points are your observations. The fit uses SI x and y values before display scaling.
| # | Mass of condensed steam m_v (g) | Equilibrium temperature T_f (°C) | Mass of condensed steam m_v (kg) | Net latent heat liberated Q_net (J) | Remove |
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