Featured contributor PhD Applied Physics; former research associate at a national metrology lab.

Dr. Helena Ortiz

Senior Reviewer, Science & Engineering

0 calculators 0 articles Member since Jun 2026

About

Helena is the senior technical reviewer for physics, chemistry, and unit-conversion calculators. She is the last pair of eyes on every formula — checking constants, units, and edge cases against primary sources and standards bodies.

She holds a PhD in Applied Physics and previously held a research post at a national metrology lab.

Areas of expertise

Physics Chemistry Unit conversion Measurement standards

Education & credentials

BSc Physics — Universidad Complutense de Madrid
PhD Applied Physics — Stanford University

Chemistry

Electroplating Mass Deposited (Faraday's Law) Calculator

Compute the mass of metal deposited at the cathode during electroplating from the current, time, molar mass of the metal...

basic

17,664 3.9 1 min

Chemistry / Reactions

Bond Energy Reaction Calculator

Estimate the enthalpy change of a reaction from average bond energies: ΔH ≈ Σ (bonds broken in reactants) − Σ (bonds for...

basic

24,317 5.0 1 min

Chemistry

Dalton's Law Partial Pressure Calculator

Calculates partial pressures for up to four gas components in a mixture using Dalton's Law and mole fractions.

basic

11,153 4.8 1 min

Physics

Thin-Lens Magnification from Image and Object Distance Calculator

Compute the linear (transverse) magnification of an image formed by a thin lens or spherical mirror from the object dist...

basic

7,177 4.7 1 min

Physics

Schwarzschild Radius Calculator

Compute the Schwarzschild (event horizon) radius of a non-rotating black hole from its mass using r_s = 2 · G · M / c²,...

basic

6,404 3.9 1 min

Chemistry

pKa ↔ pKb Conversion Calculator

Convert between the acid dissociation constant exponent pKa and its conjugate-base counterpart pKb using the water relat...

basic

5,073 4.9 1 min

Chemistry

Equivalent Weight Calculator

Compute the equivalent weight (also called gram-equivalent) of a substance from its molecular weight and its valence fac...

basic

7,451 4.4 1 min

Chemistry

Ka from pH of Weak Acid Calculator

Back-calculate the acid-dissociation constant Ka of a weak monoprotic acid from a measured pH and the initial concentrat...

basic

12,102 4.8 1 min

Physics / Electricity

RC Low-Pass Cutoff Frequency Calculator

Compute the −3 dB cutoff frequency of an RC low-pass (or high-pass) filter from the resistor and capacitor values, plus...

basic

764 4.8 1 min

Physics

Brewster's Angle & Refractive Index Calculator

Calculates Brewster's angle for complete polarisation of reflected light from the refractive indices of two media.

basic

1,109 4.4 1 min

Chemistry / Solutions

Common-Ion Effect Solubility Calculator

Compute the new molar solubility of a 1:1 salt MA in a solution that already contains a common-ion concentration [A⁻], u...

basic

11,912 4.1 1 min

Chemistry / Solutions

Boiling Point Elevation Calculator

Calculates the boiling point elevation of a solution using the van't Hoff factor, ebullioscopic constant and molality.

basic

23,119 4.7 1 min

Showing 289 to 300 of 504 results

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Reviewed by Dr. Helena Ortiz

These calculators were technically reviewed by Dr. Helena Ortiz for accuracy.

Chemistry / Reactions

Equilibrium Constant Calculator

Compute the equilibrium constant K_c from the concentrations of two products (with stoichiometric coefficients 1) divide...

basic

5,060 4.0 1 min

Conversions / Length

Length Converter

Convert between meters, kilometers, miles, feet, inches, and yards.

Featured basic

4,965 4.2 1 min

Chemistry / Solutions

Combined Gas Law Calculator

Find the missing pressure, volume, or temperature using the combined gas law for a fixed amount of gas.

basic

5,360 4.2 1 min

Physics / Electricity

Capacitance Calculator

Compute the capacitance of a parallel-plate capacitor from plate area, plate separation, and the dielectric constant.

basic

12,524 4.1 1 min

Chemistry / Solutions

pOH Calculator

Compute pOH from hydroxide ion concentration and the matching pH at 25 °C.

basic

18,221 4.2 1 min

Ecology / Carbon Footprint

Carbon Footprint Calculator

Estimate your annual personal CO₂e footprint from home energy, driving, flying, and diet — with adjustable emission fact...

Featured basic

15,826 4.9 1 min

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Browse categories

Dr. Helena Ortiz

Electroplating Mass Deposited (Faraday's Law) Calculator

Bond Energy Reaction Calculator

Dalton's Law Partial Pressure Calculator

Thin-Lens Magnification from Image and Object Distance Calculator

Schwarzschild Radius Calculator

pKa ↔ pKb Conversion Calculator

Equivalent Weight Calculator

Ka from pH of Weak Acid Calculator

RC Low-Pass Cutoff Frequency Calculator

Brewster's Angle & Refractive Index Calculator

Common-Ion Effect Solubility Calculator

Boiling Point Elevation Calculator

Reviewed by Dr. Helena Ortiz

Equilibrium Constant Calculator

Length Converter

Combined Gas Law Calculator

Capacitance Calculator

pOH Calculator

Carbon Footprint Calculator