Viscosity Of A Solution Calculator

Work out viscosity of a solution instantly with clear inputs, formula shown and shareable results.

About Viscosity Of A Solution Calculator

A capillary viscometer measures flow times, and their ratio is the relative viscosity - no absolute calibration needed as long as densities are close. Subtracting one gives the specific viscosity, the fractional thickening caused by the solute, and dividing that by concentration gives the reduced viscosity. Extrapolating reduced viscosity to zero concentration yields intrinsic viscosity, which is how polymer molar mass is measured.

Formulas

Relative and specific viscosity

eta(rel) = t / t0, eta(sp) = eta(rel) - 1

Reduced and inherent viscosity

eta(red) = eta(sp) / c, eta(inh) = ln(eta(rel)) / c

Worked example

With the default values below, Viscosity Of A Solution Calculator returns Reduced Viscosity of 0.8333. Change any input above and every figure here is recalculated in your browser.

Inputs used

Flow time of the solutionminimum 0 s: 85 s
Flow time of the pure solventminimum 0 s: 60 s
Solution concentrationminimum 0 g/dL: 0.5 g/dL

Results

Reduced Viscosity: 0.8333 dL/g
Relative Viscosity: 1.4167
Specific Viscosity: 0.4167
Inherent Viscosity: 0.6966 dL/g

Step by step

1Values used
2Relative and specific viscosity
3Reduced and inherent viscosity
4Reduced Viscosity= 0.8333 dL/g
5Relative Viscosity= 1.4167
6Specific Viscosity= 0.4167
7Inherent Viscosity= 0.6966 dL/g

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does this ignore density?

Because for dilute solutions the density ratio is within a fraction of a percent of one, and it cancels in the flow-time ratio.

How do I get intrinsic viscosity from this?

Measure reduced viscosity at several concentrations and extrapolate the straight line back to zero concentration - the intercept is the intrinsic viscosity.