Precision Digital Conductivity Meter (1.00 kHz AC)
Measures electrolytic conductance and solution resistance using an audio-frequency AC Wheatstone bridge with ±0.001 mS/cm resolution.
Chemistry / Conductometric Saponification of Ethyl Acetate
FREE TO EXPLORELABORATORY 24 · NATURAL SCIENCES
Second-Order Chemical Kinetics: Conductometric Alkaline Saponification of Ethyl Acetate
To determine the second-order rate constant (k) and initial reaction half-life (t₁/₂) for the alkaline saponification of ethyl acetate at 25.00 ± 0.02 °C under equimolar initial conditions ([ester]₀ = [OH⁻]₀ = 0.0200 M) using continuous audio-frequency AC electrolytic conductometry, and verify Kohlrausch limiting ionic mobilities and second-order integrated rate kinetics. Explore interactive analytical gravimetry, Class A volumetric glassware and density determination.
MEASURE · CALIBRATE · ANALYSE
Your virtual chemistry laboratory.
SPECIFIC ELECTROLYTIC CONDUCTIVITY Κ_T—
MEASUREMENT STATUS
Ready to dispense 10.0 min of liquid.
Adjust elapsed time V, then weigh the dispensed aliquot.
Mass observations are determined by the high-precision thermodynamic equation of state for pure liquid water. Readings reflect thermal equilibrium and analytical balance force restoration.
Physical chemistry assumptions and metrological limits
Conductometric reaction tracking assumes that atmospheric carbon dioxide is strictly excluded. In open air, ambient CO₂ dissolves and reacts with hydroxide to form carbonate ions (CO₂ + 2 OH⁻ → CO₃²⁻ + H₂O), which lowers [OH⁻] and alters the effective solution conductance. The reaction vessel must be fitted with a tight Teflon lid or purged with inert nitrogen. Furthermore, because electrolytic conductivity has a high temperature coefficient (~2.0% per °C), thermal fluctuations exceeding ±0.05 °C can distort derived rate constants by over 1.5%. The simulation engine models the second-order saponification kinetics of ethyl acetate at 25.00 ± 0.02 °C. Baseline setup: 50.0 mL of 0.0400 M NaOH is combined with 50.0 mL of 0.0400 M ethyl acetate, establishing equimolar initial concentrations c₀ = 0.0200 M (20.0 mM) in a 100.0 mL jacketed cell. The true second-order rate constant is k = 6.600 L·mol⁻¹·min⁻¹ (0.1100 L·mol⁻¹·s⁻¹), yielding an initial half-life t₁/₂ = 1 / (k·c₀) = 1 / (6.60 × 0.0200) = 7.576 minutes. The specific electrolytic conductivity is governed by Kohlrausch's law: κ_t = 10⁻³·[c_t·λ(OH⁻) + (c₀ − c_t)·λ(CH₃COO⁻) + c₀·λ(Na⁺)], with limiting conductivities λ(OH⁻) = 198.6, λ(Na⁺) = 50.11, and λ(CH₃COO⁻) = 40.9 S·cm²·mol⁻¹. Baseline conductivity at t = 0 is κ₀ = 4.974 mS/cm; infinity conductivity at complete reaction (t = ∞) is κ_∞ = 1.820 mS/cm (Δκ_max = 3.154 mS/cm). At reaction times of 3.0, 6.0, 10.0, 15.0, 20.0, and 30.0 minutes, the simulated specific conductivities evaluate to 4.079, 3.580, 3.179, 2.878, 2.686, and 2.456 mS/cm, yielding reactant concentrations c_t of 14.33, 11.16, 8.62, 6.71, 5.49, and 4.03 mM. The derived reciprocal concentrations 1/c_t evaluate to 69.81, 89.60, 116.04, 149.05, 182.10, and 247.96 L/mol. Ordinary least-squares regression of 1/c_t against t yields an ideal slope m = k = 6.5995 L·mol⁻¹·min⁻¹ and intercept b = 50.03 L/mol with R² = 0.999999, isolating k within 0.008% of the accepted literature value.
Analytical chemistry apparatus & tools.
Platinized Dip-Type Conductivity Cell (θ = 1.000 cm⁻¹)
Features two matched platinum plates coated with platinum-black to eliminate capacitive double-layer electrode polarization.
Thermostatic Circulating Water Bath (25.00 ± 0.02 °C)
Regulates the double-walled jacketed glass reaction vessel at constant temperature via closed-loop PID control.
Jacketed Borosilicate Reaction Vessel with Teflon Lid
Encloses the 100 mL reaction mixture hermetically to exclude atmospheric carbon dioxide and eliminate evaporative loss.
Class A Volumetric Transfer Pipettes (50.00 mL)
Delivers equimolar 50.00 mL volumes of 0.0400 M NaOH and 0.0400 M ethyl acetate with ±0.03 mL accuracy.
Digital Stopwatch and Integrated Magnetic Micro-Stirrer
Times reaction intervals from mixing and maintains gentle 250 rpm vortex-free stirring to avoid optical or bubble artifacts.
FOLLOW THE METHOD
A reason behind every step.
To determine the second-order rate constant (k) and initial reaction half-life (t₁/₂) for the alkaline saponification of ethyl acetate at 25.00 ± 0.02 °C under equimolar initial conditions ([ester]₀ = [OH⁻]₀ = 0.0200 M) using continuous audio-frequency AC electrolytic conductometry, and verify Kohlrausch limiting ionic mobilities and second-order integrated rate kinetics. Suggested independent volumetric settings: 3.0, 6.0, 10.0, 15.0, 20.0, 30.0 min.
01
Reagent Standardization and CO₂ Scavenging
Standardize stock solutions: 0.0400 M sodium hydroxide (standardized against potassium hydrogen phthalate) and 0.0400 M ethyl acetate in carbon-dioxide-free deionized water.
02
Conductivity Cell Calibration and Cell Constant Verification
Calibrate the dip-type conductivity cell against standard 0.0100 M potassium chloride (KCl) solution to verify cell constant θ = 1.000 cm⁻¹ at 25.00 °C.
03
Thermal Conditioning of Reactant Stocks
Thermostat 50.00 mL of 0.0400 M NaOH and 50.00 mL of 0.0400 M ethyl acetate in separate stoppered flasks inside the 25.00 ± 0.02 °C water bath for 20 minutes.
04
Reaction Initiation and Cell Immersion (t = 0)
Rapidly mix the two pre-equilibrated solutions in the jacketed reaction vessel, simultaneously starting the digital stopwatch (t = 0), and insert the conductivity cell.
05
Periodic Conductometric Telemetry Acquisition
Maintain gentle magnetic stirring (250 rpm) and record the specific electrolytic conductivity κ_t at scheduled elapsed intervals (3.0, 6.0, 10.0, 15.0, 20.0, and 30.0 minutes).
06
Infinity Reading Evaluation (κ_∞)
To evaluate κ_∞, heat a portion of the reaction mixture in a sealed tube at 60 °C for 20 minutes to achieve complete saponification, re-equilibrate to 25.00 °C, and measure κ_∞ (1.820 mS/cm).
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into quantitative chemical insight.
Points are your recorded gravimetric observations. The regression line validates the linear mass-volume proportionality and extracts density.
ORDINARY LEAST-SQUARES FIT · m = ρ·V + m₀
\frac{1}{c_t} = k \cdot t + \frac{1}{c_0} \implies \frac{1}{c_t} = 6.60 \cdot t + 50.00
| # | Reaction elapsed time t (min) (min) | Specific electrolytic conductivity κ_t (mS·cm⁻¹) | Reaction elapsed time t (min) | Reciprocal reactant concentration 1/c_t (L·mol⁻¹) | Remove |
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