How to compare viscosity

Updated December 06, 2020

By Timothy Banas

Liquid viscosity is a measure of the internal friction of a liquid. Liquids with high viscosities flow slowly, whereas low viscosity liquids flow quickly. Lava has a relatively high viscosity; water has a relatively low one. You can measure the viscosity of a liquid by measuring the velocity of a sphere as it falls through the liquid. The velocity of the sphere, combined with the relative densities of the sphere and the liquid, can be used to calculate the viscosity of the liquid.

By measuring the speed of a metal ball dropped in a container of liquid, you can determine the liquid's viscosity.

Measure the mass of your ball, using your balance. For instance, suppose the mass of the ball is 0.1 kilograms (kg).

Find the radius of the ball by first measuring the diameter (distance of a straight line through the ball at the widest part). Divide the diameter by 2; this gives the radius of your ball. Calculate the volume of the ball by plugging the radius into the equation for the volume of a sphere. Suppose the ball bearing has a radius of 0.01 meter (m). The volume would be:

V=\frac{4}{3} \pi r^3 = \frac{4}{3} \pi 0.01^3 =0.00000419\text{ m}^3

Calculate the density of the ball by dividing its mass by its volume. The density of the ball in the example would be:

d=\frac{0.1}{0.00000419}=23,866\text{ kg/m}^3

Measure the mass of your graduated cylinder when it is empty. Then measure the mass of your graduated cylinder with 100 millilters (mL) of liquid in it. Suppose the empty cylinder had a mass of 0.2 kg, and with fluid its mass was 0.45 kg.

Determine the mass of the fluid by subtracting the mass of the empty cylinder from the mass of the cylinder with the fluid. In the example: Mass of liquid = 0.45 kg - 0.2 kg = 0.25 kg

Determine the density of the fluid by dividing its mass by its volume. Example:

d=\frac{0.25\text{ kg}}{100\text{ mL}}=0.0025 \text{ kg/mL}=2,500\text{ kg/m}^3

​1 mL is equal to 1 cm3 and ​1 million cubic centimeters equal 1 cubic meter

Fill your tall graduated cylinder with the liquid so it is about 2 cm from the top of the cylinder. Use your marker to make a mark 2 cm below the surface of the liquid. Mark another line 2 cm from the bottom of the cylinder.

Measure the distance between the two marks on the graduated cylinder. Suppose that the distance is 0.3 m.

Let the ball go on the surface of the liquid and use your stopwatch to time how long it takes for the ball to fall from the first mark to the second mark. Suppose it took the ball 6 seconds (s) to fall the distance.

Calculate the velocity of the falling ball by dividing the distance it fell by the time it took. In the example:

v=\frac{0.3\text{ m}}{6\text{ s}}=0.05\text{ m/s}

Calculate the viscosity of the liquid from the data you have collected:

\text{viscosity}=\frac{2(\text{ball density}-\text{ liquid density})ga^2}{9v}

where g = acceleration due to gravity = 9.8 m/s2 a = radius of ball bearing v = velocity of ball bearing through liquid

Plug your measurements into the equation to calculate the viscosity of the liquid. For the example, the calculation would look like this:

\text{viscosity}=\frac{2(23,866-2,500)(9.8)(0.01)^2}{9(0.05)}=93.1\text{ pascal seconds}

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We can compare roughly the viscosity of two liquids by filling two measured cylinders with each of them, and allowing identical small steel ball bearings to fall through each liquid. The ball bearing falls slower through the liquid with higher viscosity.

How is viscosity determined?

The viscous properties of a liquid or amorphous solid are primarily determined by inter-particle forces within the solution, including friction and attraction between molecules in the macrostructure. ... This property is density-dependent and is measured in square meters per second (m2/s).

How do you measure viscosity in an experiment?

Have students calculate the density of the fluid.

1. Weigh the empty graduated cylinder.
2. Fill the cylinder with fluid, and record the volume.
3. Weigh the full graduated cylinder. Subtract the mass of the empty graduated cylinder to determine the mass of the fluid.
4. The density of the fluid is the mass over the volume.

What liquid has lowest viscosity?

Water, gasoline, and other liquids that flow freely have a low viscosity. Honey, syrup, motor oil, and other liquids that do not flow freely, like those shown in Figure 1, have higher viscosities.

What liquid has the highest viscosity?

Honey is between 2,000 and 10,000 times more viscous than water. Some fluids are so viscous they appear to be solid and yet, over time, slowly flow. One of the most viscous liquids known is pitch, also known as bitumen, asphalt, or tar.

30 related questions found

Explanation: Here Oil is the most viscous liquid. The liquid with the most intermolecular force is high viscous. viscosity is how smoothly a liquid flows and how hardly the liquid flows it is highly viscous.

Honey, for instance, has a viscosity between 2.54 and 23.4 Pa · s (at 25°C, depending on moisture and sugar composition) [46] , while blood has 4 mPa · s [47]. ... ... Honey, for instance, is much more viscous at lower temperatures [46] .

Dynamic viscosity: The SI physical unit of dynamic viscosity (μ) is the Pascal-second (Pa s), which is identical to 1 kg m−1 s−1. The physical unit for dynamic viscosity in the centimeter gram second system of units (cgs) is the poise (P), named after Jean Poiseuille.

To measure the viscosity of a sample liquid. Introduction: Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.

The unit of viscosity is newton-second per square metre, which is usually expressed as pascal-second in SI units.

Therefore, viscosity is dimensionally represented as [M1 L-1 T-1].

Types of Viscosity & When to Apply Them

• Dynamic (absolute) viscosity – the measurement of the fluid's internal resistance to flow when force is applied.
• Kinematic viscosity – refers to the ratio of dynamic viscosity to density, or a measurement of the viscosity of a fluid in motion.

So, we can say that intermolecular forces decide the viscosity of the fluid. - In water, only water molecules are there. ... That results in the resistance to the deformation in the fluid. So, we can say that due to more intermolecular forces, honey is more viscous than water.

What liquids are less viscous than water? 8cST) fluid. ... Acetone has a viscosity 3x less than water but weighs 2.5 times more.

Water has higher viscosity than methanol because intermolecular forces (hydrogen bonding) are stronger in water than in methanol.

Viscosity is a physical characteristic of fluids that demonstrates resistance to motion or flow. Water is an example of a low viscosity (thin) liquid, while toothpaste is an example of a high viscosity (thick) liquid.

Water, for example, is very thin; therefore, it has a low viscosity. Ketchup, on the other hand, is much thicker than water (as evidenced by the difficulty in getting it out of a glass bottle). This thickness means that ketchup has a higher viscosity than water. ... Because ketchup is a non-Newtonian fluid.

The viscosity of honey generally decreases with the increase in the temperature. ... Most of the honeys were reported to have Newtonian fluid like characteristics, whereas, some honey has been reported as non-Newtonian fluids [13].

One of the reasons it took so long to identify tar pitch as the slowest-moving liquid on the planet is because it looks like a solid at room temperature. Liquids share specific properties whether they flow quickly or agonizingly slowly.

The main ingredients of your final recipe probably consisted of corn syrup diluted with water and thickened with flour. This particular mixture resembles the flow of blood quite well because it has a similar viscosity, or resistance to flow.

We're home to the famous Pitch Drop experiment, which holds the Guinness World Record for the longest-running laboratory experiment. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar that is the world's thickest known fluid and was once used for waterproofing boats.

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