Question

The sink-float method is often used to identify the type of glass material found at crime scenes by determining its density.

Answer 1

Answer:

Glass that will sink

• alkali zinc borosilicate with a density of 2.57 g/mL in a solution with a density of 2.46 g/mL

• potash soda lead with a density of 3.05 g/mL in a solution with a density of 1.65 g/mL

Glass that will float

• soda borosilicate with a density of 2.27 g/mL in a solution with a density of 2.62 g/mL

• alkali strontium with a density of 2.26 g/mL in a solution with a density of 2.34 g/mL

Glass that will not sink or float

• potash borosilicate with a density of 2.16 g/mL in a solution with a density of 2.16 g/mL

Explanation:

Density is the property of matter that states the ratio of the amount of matter, its mass, to the space occupied by it, its volume.

So, the mathematical expression for the density is:

• density = mass / volume

By comparing the density of a material with the density of a liquid, you will be able to determine whether object will float, sink, or do neither when immersed in the liquid.

The greater the density of an object the more it will try to sink in the liquid.

As you must have experienced many times an inflatable ball (whose density is very low) will float in water, but a stone (whose denisty is greater) will sink in water.

The flotation condition may be summarized by:

• When the density of the object < density of the liquid, the object will float

• When the density of the object = density of the liquid: the object will neither float nor sink

• When the density of the object > density of the liquid: the object will sink.

Glass that will sink

• alkali zinc borosilicate with a density of 2.57 g/mL in a solution with a density of 2.46 g/mL, because 2.57 > 2.46.

• potash soda lead with a density of 3.05 g/mL in a solution with a density of 1.65 g/mL, because 3.05 > 1.65.

Glass that will float

• soda borosilicate with a density of 2.27 g/mL in a solution with a density of 2.62 g/mL, because 2.27 < 2.62.

• alkali strontium with a density of 2.26 g/mL in a solution with a density of 2.34 g/mL, because 2.26 < 2.34.

Glass that will not sink or float

• potash borosilicate with a density of 2.16 g/mL in a solution with a density of 2.16 g/mL, because 2.16 = 2.16