Thermostatic Circulating Water Bath (±0.02 °C)
Maintains the 100 mL reaction vessel and reagent stocks strictly at 25.00 ± 0.02 °C via PID heating and chilled counter-cooling.
Chemistry / Acid Hydrolysis Kinetics of Methyl Acetate
FREE TO EXPLORELABORATORY 23 · NATURAL SCIENCES
Pseudo-First-Order Chemical Kinetics: Acid-Catalyzed Hydrolysis of Methyl Acetate
To determine the pseudo-first-order rate constant (k') and reaction half-life (t₁/₂) for the acid-catalyzed hydrolysis of methyl acetate in 1.000 M hydrochloric acid at 25.00 ± 0.02 °C, verify first-order integrated rate kinetics via ice-water quenched titrimetry against standardized 0.200 M sodium hydroxide, and compare conventional infinity metrology with the Guggenheim infinity-free formulation. Explore interactive analytical gravimetry, Class A volumetric glassware and density determination.
MEASURE · CALIBRATE · ANALYSE
Your virtual chemistry laboratory.
TITER VOLUME OF 0.200 M NAOH (V_T)—
MEASUREMENT STATUS
Ready to dispense 30.0 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
The pseudo-first-order approximation requires that water remain in massive stoichiometric excess and that the hydronium ion activity remain constant. At ester concentrations exceeding 1.0 M, the depletion of water and the formation of significant concentrations of weak acetic acid introduce minor deviations. Furthermore, heating the reaction mixture to 60 °C to determine V_∞ can induce minor volatile ester evaporation or secondary esterification equilibrium shifts if the digestion vessel is not hermetically sealed. Titrations must be executed rapidly (< 90 seconds) post-quench to avoid post-sampling hydrolysis warming errors. The physical simulation engine numerically integrates the multi-component kinetic and chemical equilibrium differential equations governing the acid-catalyzed hydrolysis of methyl acetate at 25.00 ± 0.02 °C in 1.000 M HCl. Baseline formulation: 5.00 mL of chilled methyl acetate (density d = 0.932 g/mL, molar mass M = 74.08 g/mol) is rapidly introduced into 100.0 mL of 1.000 M HCl, establishing an initial ester concentration [ester]₀ = (5.00 × 0.932 / 74.08) / 0.100 = 0.6291 M. Quenched aliquots of 5.00 mL are transferred into 25 mL of crushed ice-water (< 2 °C) and titrated with standardized 0.2000 M NaOH using phenolphthalein indicator. The stoichiometric titration endpoints evaluate to: V₀ = (0.00500 L × 1.000 M) / 0.200 M = 12.50 mL (neutralization of 0.00250 mol HCl catalyst); maximum acetic acid generated at 100% conversion = 0.00500 L × 0.6291 M = 0.003145 mol, consuming an additional 15.73 mL of titrant, yielding the infinity titer V_∞ = 12.50 + 15.73 = 28.23 mL. The true pseudo-first-order rate constant is k' = 0.006850 min⁻¹ (4.110 × 10⁻⁴ s⁻¹), corresponding to a reaction half-life t₁/₂ = ln(2)/k' = 101.19 minutes. For scheduled sampling intervals across 15.0, 30.0, 45.0, 60.0, 90.0, and 120.0 minutes, the simulated burette readings evaluate to 14.04, 15.42, 16.67, 17.80, 19.74, and 21.32 mL, generating logarithmic values y = ln[(V_∞ − V₀)/(V_∞ − V_t)] of 0.1030, 0.2053, 0.3080, 0.4109, 0.6167, and 0.8226. Linear regression of y against elapsed time t yields slope m = k' = 0.006855 min⁻¹ and intercept b = −0.00023 with an ideal correlation coefficient R² = 0.999999, isolating the rate constant within 0.08% of the accepted benchmark.
Analytical chemistry apparatus & tools.
Class A Volumetric Transfer Pipettes (5.00 mL)
Delivers precision aliquots of reaction mixture and ester stock with an uncertainty of ±0.01 mL.
50.00 mL Schellbach Precision Glass Burette
Dispenses standardized 0.200 M NaOH titrant with 0.02 mL readability and blue contrast stripe.
Ground-Glass Stoppered Reaction Flask (150 mL)
Holds the hydrolyzing reaction mixture hermetically sealed to prevent volatile ester evaporation.
Crushed Ice Quenching Vessel and Cold Water Dispenser
Rapidly cools withdrawn aliquots to < 2 °C to arrest chemical reaction velocity during titrimetric handling.
Analytical Digital Stopwatch and Dual Timer
Monitors reaction elapsed time from initial ester injection through 120 minutes with 0.01 s precision.
FOLLOW THE METHOD
A reason behind every step.
To determine the pseudo-first-order rate constant (k') and reaction half-life (t₁/₂) for the acid-catalyzed hydrolysis of methyl acetate in 1.000 M hydrochloric acid at 25.00 ± 0.02 °C, verify first-order integrated rate kinetics via ice-water quenched titrimetry against standardized 0.200 M sodium hydroxide, and compare conventional infinity metrology with the Guggenheim infinity-free formulation. Suggested independent volumetric settings: 15.0, 30.0, 45.0, 60.0, 90.0, 120.0 min.
01
Reagent Preparation and Titrant Standardization
Prepare and standardize reagents: standard 0.200 M sodium hydroxide (standardized against potassium hydrogen phthalate), 1.000 M hydrochloric acid, and pure analytical-grade methyl acetate.
02
Thermal Conditioning of Reaction Mixture
Thermostat 100.0 mL of 1.000 M HCl solution in a ground-glass reaction flask inside the 25.00 ± 0.02 °C circulating water bath for 20 minutes.
03
Reaction Initiation and Time Zero (t = 0)
Rapidly pipet 5.00 mL of chilled methyl acetate into the acid solution, simultaneously starting the digital stopwatch timer (t = 0), and swirl vigorously to achieve complete homogeneity.
04
Zero-Time Blank Aliquot Titration (V₀)
Immediately withdraw a 5.00 mL aliquot at t ≈ 0, discharge into 25 mL of ice-cold deionized water to arrest hydrolysis, add 2 drops of phenolphthalein, and titrate to faint pink with 0.200 M NaOH to record V₀ (12.50 mL).
05
Periodic Aliquot Sampling and Quenched Titration
At scheduled time intervals (15.0, 30.0, 45.0, 60.0, 90.0, and 120.0 minutes), withdraw 5.00 mL aliquots, quench in ice water, and titrate rapidly with 0.200 M NaOH to record V_t.
06
Infinity Titer Evaluation (V_∞)
To obtain the infinity titer V_∞, transfer 20 mL of reaction mixture to a sealed flask, heat in a 60 °C water bath for 30 minutes to achieve quantitative hydrolysis, cool to 25.0 °C, titrate 5.00 mL, and record V_∞ (28.23 mL).
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
\ln\left(\frac{V_\infty - V_0}{V_\infty - V_t}\right) = k' \cdot t \implies y = 0.00685 \cdot t
| # | Reaction elapsed time t (min) (min) | Titer volume of 0.200 M NaOH (V_t) (mL) | Reaction elapsed time t (min) | Logarithmic progression ln[(V_∞ − V₀)/(V_∞ − V_t)] | Remove |
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