A different point of view: a continuous tracing of acid-base titration with fiber-optic sensor

Abstract

Our main aim was to investigate variations in the refractive index of a solution during chemical reaction. The variation of refractive index was measured through the entire acid-base titration process, especially near the equivalence point. To determine the equivalence point, the conductivity of the solution and the refractive index were measured simultaneously. In this preliminary study, sodium hydroxide and hydrochloric acid were used as the base and the acid solution, respectively. To measure the refractive index variation, a fiber-optic refractive index sensor was designed. The fiber-optic probe was dipped into the solution and acted as a refractive index sensor according to Fresnel's fundamental reflection law. A conductometer, a lab-made fiber-optic refractive index sensor ensemble, and a lab-made optical drop counter were each connected to a computer via an analog digital converter and the data acquisition was performed with the LabVIEW program. The equivalence point was derived easily from the refractive index data for the sodium hydroxide solution with different molarities of hydrochloric acid. In our opinion, the measurement of the variation of the refractive index during this kind of chemical reaction is more sensitive than the conductometric measurement.

A Temperature‐Driven, Reversible, Helical‐Handedness Inversion in Peptaibol Analogues Tuned by the C‐Terminal Capping Moiety

“…Assuming a FRET mechanism of quenching, and correcting for the temperature variations of the unperturbed quantum yield and the methanol refractive index, an estimate of the relative variations in interprobe distance can be obtained, thus allowing for more quantitative considerations (Figure ). Both the difference between the two analogues and the temperature‐induced distance variation are relatively small.…”

Interaction Effects on Number Fluctuations in a Bose-Einstein Condensate of Light

“…Both the temperature dependence of the single-photon energy and the heat capacity might depend on the number of dissolved dye molecules, but as the experiments by Klaers et al are performed for small concentrations of dissolved Rhodamine 6G, we expect at least this latter effect to be small. Neglecting the former effect and using typical numerical values for liquid methanol with 1 mmol Rhodamine 6G dissolved [22,23], we obtain an estimate for the interaction strength of g ∼ 10 −9 . This is several orders of magnitude below the only experimental result g ∼ 10 −4 .…”

Temperature compensation of dye doped polymeric microscale lasers

“…This is explained by the fact that the NBA 107 polymer has a linear expansion coefficient and a thermo‐optic coefficient of, respectively, α = 2.2 × 10 −4 °C −1 and β = −2.6 × 10 −4 °C −1 . The solution made with ethanol and rhodamine for the concentration used has a thermos‐optic coefficient of β = −3.435 × 10 −4 °C −1 , as found in the literature . The ethanol alone has β = −4 × 10 −4 °C −1 ; therefore, adding rhodamine 6 g to the solvent, slightly lowers the absolute value of the solution's thermos‐optic coefficient.…”

“…The solution made with ethanol and rhodamine for the concentration used has a thermos-optic coefficient of b 5 23.435 3 10 24 8C 21 , as found in the literature. 15 The ethanol alone has b 5 24 3 10 24 8C 21 ; therefore, adding rhodamine 6 g to the solvent, slightly lowers the absolute value of the solution's thermosoptic coefficient. Figure 4 shows the linear dependence between the optical resonance and the change of resistor temperature.…”