1.000000e-2
S
1.000000e+2
1/m
1.000000e+0
S/m
1.000000e+0
Ω·m
1.000000e-2
S
1.000000e+2
1/m
1.000000e+0
S/m
1.000000e+0
Ω·m
Electrical conductivity is a fundamental property that quantifies how well a material or solution conducts electric current. The Conductivity Calculator computes conductance (G), specific conductivity (κ), and resistivity (ρ) from measured resistance and cell geometry. In electrochemistry, conductivity measurements are essential for characterizing electrolyte solutions, monitoring water purity, and studying ionic transport phenomena. The conductivity of a solution depends on the concentration, mobility, and charge of dissolved ions. A conductivity cell with known geometry (cell constant = l/A) is used to convert measured resistance into specific conductivity. This calculator handles the fundamental relationships between resistance, conductance, resistivity, and conductivity, providing researchers and students with a quick way to process electrochemical measurements. Understanding conductivity is critical in fields ranging from analytical chemistry and environmental monitoring to industrial process control and battery research.
The calculator uses the fundamental relationships between electrical resistance and conductivity:
$$G = \frac{1}{R}$$
where G is conductance in siemens (S) and R is resistance in ohms (Ω).
The specific conductivity (κ) relates conductance to the cell geometry through the cell constant:
$$\kappa = G \times \frac{l}{A} = \frac{1}{R} \times \frac{l}{A}$$
where l is the distance between electrodes (m) and A is the electrode cross-sectional area (m²). The ratio l/A is called the cell constant with units of m⁻¹.
Resistivity is the inverse of conductivity:
$$\rho = \frac{1}{\kappa} = R \times \frac{A}{l}$$
Conductivity is measured in S/m (SI unit) or often in μS/cm for dilute solutions. Pure water has a conductivity of about 0.055 μS/cm, while seawater has approximately 5 S/m. The cell constant must be determined through calibration with a standard KCl solution of known conductivity.
The conductance value represents the ease with which current flows through the specific cell used. Higher conductance means lower resistance. The specific conductivity (κ) is the intrinsic property of the solution, independent of cell geometry—it allows comparison between different solutions measured in different cells. A higher κ indicates more ions, higher ionic mobility, or both. The resistivity (ρ) is the reciprocal of conductivity and is commonly used in materials science. For aqueous solutions, conductivity typically ranges from 0.055 μS/cm (ultrapure water) to over 100 mS/cm (concentrated acid). If your measured conductivity seems anomalous, verify the cell constant calibration and ensure temperature control, as conductivity increases roughly 2% per °C for most electrolytes.
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A 0.1 M KCl solution measured in a cell with constant 100 m⁻¹ gives a conductivity of 0.667 S/m, consistent with published values near 1.29 S/m at 25°C for 0.1 M KCl.
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A dilute NaCl solution with R = 5000 Ω in a cell with l/A = 100 m⁻¹ yields κ = 0.02 S/m (200 μS/cm), typical of a ~0.001 M NaCl solution.
Conductance (G) is the reciprocal of resistance for a specific measurement cell and depends on cell geometry. Conductivity (κ) is an intrinsic material property obtained by multiplying conductance by the cell constant (l/A). Conductivity allows meaningful comparison between solutions regardless of the cell used.
The cell constant is the ratio l/A (distance between electrodes divided by electrode area), with units of m⁻¹ or cm⁻¹. It is determined by measuring a standard KCl solution of known conductivity and calculating: cell constant = κ_known × R_measured.
Higher temperature increases ionic mobility by reducing solvent viscosity and enhancing thermal motion of ions. Most electrolyte solutions show a conductivity increase of about 1.5–2.5% per °C. Temperature compensation is essential for accurate measurements.
Ultrapure water: ~0.055 μS/cm; tap water: 50–800 μS/cm; 0.1 M KCl: ~12.9 mS/cm; seawater: ~50 mS/cm; 1 M HCl: ~332 mS/cm; concentrated H₂SO₄: ~730 mS/cm at peak concentration.
The SI unit is S/m (siemens per meter). In practice, mS/cm and μS/cm are commonly used. 1 S/m = 10 mS/cm = 10,000 μS/cm. For resistivity, Ω·m or Ω·cm are standard.
Conductivity generally increases with concentration as more ions are available. However, at very high concentrations, ion pairing and increased viscosity reduce mobility, causing conductivity to reach a maximum and then decrease.
Yes, the fundamental relationship κ = G × (l/A) applies to any conductor. For metals, conductivity is extremely high (10⁶–10⁸ S/m), while semiconductors range from 10⁻⁴ to 10⁴ S/m and insulators fall below 10⁻⁸ S/m.
Total Dissolved Solids (TDS) can be estimated from conductivity using the approximation: TDS (mg/L) ≈ κ (μS/cm) × conversion factor (typically 0.5–0.7). The exact factor depends on the dissolved species.
AC current prevents electrolysis and electrode polarization that would occur with DC current. Typical measurement frequencies range from 1–3 kHz for standard solutions to higher frequencies for highly conductive solutions.
Multiply S/m by 10 to get mS/cm, or divide mS/cm by 10 to get S/m. For example, 1.29 S/m = 12.9 mS/cm. Similarly, 1 S/m = 10,000 μS/cm.
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