Determine the density of pure deionized water with high analytical precision across systematic volumetric increments from 5.0 mL to 35.0 mL using an electronic analytical balance (±0.0001 g) and Class A volumetric glassware, evaluate buoyant air displacement corrections, and extract density via ordinary least-squares linear regression. Explore interactive analytical gravimetry, Class A volumetric glassware and density determination.
Ready to dispense 20.0 mL of liquid.
Adjust dispensed volume 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.
The gravimetric and volumetric determinations in this laboratory assume ideal liquid behavior and constant ambient conditions. In real physical laboratories, micro-environmental perturbations can modulate observations: (1) Evaporative vapor mass loss during prolonged series of measurements, which decreases apparent net mass unless covered vessels are utilized; (2) Ambient atmospheric barometric pressure and relative humidity fluctuations, which alter moist air density ρ_air and modulate Archimedean buoyancy corrections by up to ±0.01%; (3) Dissolved atmospheric gases (nitrogen, oxygen, and carbon dioxide), which slightly alter the refractive index and density of water relative to de-aerated water standards; and (4) Thermal expansion of the borosilicate glassware itself (linear thermal expansion coefficient α ≈ 3.3 × 10⁻⁶ K⁻¹), causing internal glass volume to expand slightly at non-calibration temperatures. The theoretical density of air-saturated pure liquid water at 20.00 °C under standard atmospheric pressure (101.325 kPa) is exactly ρ_ref = 0.99820 g/mL (or 0.99820 g/cm³) according to the Tanaka, Girard, Cavarroc, Peuto, and Bignell standard water density formulation endorsed by the International Committee for Weights and Measures (CIPM). Under ordinary least-squares linear regression of net mass m (g) against dispensed volume V (mL), the theoretical slope is exactly m_slope = 0.99820 g/mL with an intercept of b = 0.0000 g representing perfect tare balance zeroing. When applying Archimedes' buoyancy correction to convert apparent balance mass m_app into true vacuum mass m_vac, the relation is m_vac = m_app · [1 + ρ_air · (1/ρ_liquid - 1/ρ_weights)], where ρ_air ≈ 0.00120 g/mL and ρ_weights ≈ 8.0000 g/mL for austenitic stainless steel.
Provides four-decimal-place gravimetric mass measurement (±0.0001 g repeatability) with an electromagnetic force restoration transducer, anti-vibration granite slab base, internal motorized calibration weights, and a draft shield glass chamber to prevent convective air currents from perturbing microgram mass registrations.
Delivers variable volumetric aliquots of liquid with certified Class A volumetric tolerance (±0.05 mL), featuring an ungreased PTFE straight-bore stopcock, permanently etched Schellbach blue-line backing for parallax-free meniscus alignment, and uniform borosilicate 3.3 glass capillary geometry.
Determines absolute liquid volume through hydrostatic confinement in a calibrated borosilicate flask fitted with a ground-glass stopper pierced by a precision central capillary tube, allowing excess liquid and thermal expansion overflow to be wiped flush with optical reproducibility.
Acts as the tared gravimetric receptacle inside the analytical balance chamber, equipped with a polished ground-edge watch glass cover to eliminate volatile evaporative mass loss during prolonged series of volumetric liquid additions.
Monitors the thermal equilibrium temperature of the aqueous test stock and ambient laboratory air, permitting precise temperature compensation against the Tilton-Taylor thermodynamic equation of state for liquid water.
Measures ambient atmospheric pressure P_atm (kPa), dry-bulb temperature, and relative humidity (% RH) to calculate local moist air density ρ_air via the CIPM-2007 air density formulation for exact Archimedean buoyancy corrections.
Determine the density of pure deionized water with high analytical precision across systematic volumetric increments from 5.0 mL to 35.0 mL using an electronic analytical balance (±0.0001 g) and Class A volumetric glassware, evaluate buoyant air displacement corrections, and extract density via ordinary least-squares linear regression. Suggested independent volumetric settings: 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, 35.0 mL.
Thoroughly clean the Class A 50.00 mL burette, receiving weighing beaker, and pycnometer using warm laboratory detergent followed by an acid wash and three rinses with 18.2 MΩ·cm deionized water. Inspect the internal glass walls to ensure a continuous, uniform water film without droplet bead formation. Pre-rinse the burette twice with 5 mL aliquots of the temperature-equilibrated deionized water stock to prevent dilution.
Inspect the spirit leveling bubble at the rear of the analytical balance and adjust the threaded leveling feet until the bubble is centered within the target ring. Activate the internal motorized calibration cycle to compensate for local gravitational acceleration. Place the clean, dry receiving beaker and watch glass inside the balance draft chamber, close all sliding doors, allow temperature equilibration for 120 seconds, and depress the Tare bar to register exactly 0.0000 g.
Fill the burette above the 0.00 mL line with deionized water equilibrated to 20.0 °C. Open the PTFE stopcock rapidly to flush all trapped air bubbles from the delivery tip, ensuring a continuous column of liquid. Carefully drain the liquid until the bottom of the curved concave meniscus aligns tangentially with the 0.00 mL graduation mark, observing horizontally through a magnifying lens against a white/black reading card to eliminate optical parallax error.
Position the delivery tip of the burette just inside the neck of the tared weighing beaker without contacting liquid or walls. Slowly dispense an aliquot of exactly 5.0 mL into the beaker, touching the tip lightly against the inner wall to transfer the hanging droplet. Close the watch glass, insert the beaker into the balance chamber, close the draft shields, wait 15 seconds for mechanical stabilization, and record the displayed net mass m in the observation ledger.
Without emptying the receiving beaker, dispense consecutive cumulative volumetric increments corresponding to total delivered volumes of 10.0, 15.0, 20.0, 25.0, 30.0, and 35.0 mL. After each incremental delivery, close the balance draft shield, record the stable four-decimal net mass m, and verify that the laboratory ambient air temperature remains stable at 20.0 ± 0.2 °C.
Compile the paired dataset (V, m). Apply the CIPM buoyancy formula to calculate true vacuum mass m_vac for each trial. Construct a scatter plot of net mass m versus volume V. Perform ordinary least-squares linear regression to determine the experimental slope m_slope, intercept b, coefficient of determination R², and standard error. Compare the empirical slope with the international CIPM density reference value for pure water at 20.0 °C (0.99820 g/mL).
Points are your recorded gravimetric observations. The regression line validates the linear mass-volume proportionality and extracts density.
| # | Dispensed liquid volume V (mL) (mL) | Net liquid mass m (g) | Dispensed volume V (mL) | Net liquid mass m (g) | Remove |
|---|
No readings yet. Dispense and weigh a volumetric aliquot to record it.