Density can be defined as the relationship between the mass of a given material and the volume it occupies. There is a formula that expresses this relationship:
d = m
V
The International System of Units – the SI defines the unit. density as (kg/m³), that is, kilogram per cubic meter.
However, the most used definitions are g/mL and g/cm³. Speaking of definitions, it is important to remember that 1 Ml is equivalent to 1 cm³.
Density can express one substance or several. substances involved in a matter. Want an example? The water has. density defined as 1.00 g/cm³. That means for every 1cm³ of water. or 1mL, there is 1.0g of water.
However, when there are mixed substances, the density. varies depending on the amounts of mixing involved. For example: middle. liter of a solution + 50 grams of salt and 500 g of water; We can define this one. density using the following formula:
d=m
v
d= 550g → (mass of salt + mass of. Water)
500ml
d=1.1 g/ml
Temperature also directly affects the density of the substance. Again using the example of water, if the temperature drops below 0°C, ice becomes less dense than liquid water. That's why ice floats in a glass of water. On the other hand, if we put ice in a glass with alcohol, the ice sinks because the density of ethanol is lower than that of ice.
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Index
É. It is important that we know the concept of density so that we can easily identify it. if there has been any tampering with products we use on a daily basis. For example, it is possible to identify if the fuel is adulterated or if the milk has it. adding water to its composition.
For. correctly identify whether a product is tampered with or not, there is one. device called hydrometer. Through this device, it is easy to know if. there are components added to a product that should be pure.
As we've already seen, density is the concentration of matter in one. certain volume. To measure this physical property you need to consider a. interaction between the mass of a material and the volume it occupies.
A quirk about density is that two pounds of sponge. they weigh exactly the same as two kilos of lead. Unconsciously, we hang. to the thought that two pounds of lead weigh more than two pounds of. sponge because we know lead is heavier.
But if both weigh two kilos it is because of the volume of. materials is different, which changes the density of both. To get the same. weight, sponge volume will be much larger than that of lead, because the same. has the highest density.
Acetone, gasoline and wood materials float in water, as the density of these materials is lower than that of water, according to the table. above.
If the same amount of mass of ethanol e. mercury, each in an unidentified vial, the density of the. mercury is higher than ethanol, so the bottle containing ethanol is higher. full.
We've already seen a little bit about the formula. Now let's go deeper into the subject.
Source: Chemistry for love.
The expressions that characterize the density are: gram per cubic centimeter (g/cm3), kilogram per cubic meter (kg/m3) or in gram per milliliter (g/mL).
Average Density of Materials in g/cm3
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The expression density is usually related to. absolute density, which is the result of dividing the mass over the volume of one. material.
The relative density, on the other hand, has another calculation formula, respecting it. the comparative relationship between the density of one material with that of another. Here's a. formula for calculating relative density:
DR = Psubstance/Preference
As explained by Wikipedia, see what the density. relative means:
“In this expression, DR is. the relative density, ρsubstance is the density of the substance being measured and ρ. reference is the reference density. In this expression the Greek letter rho. denotes density.
The stuff of. reference can be indicated using the indices: DRsubstance/reference, which means the relative density of the substance in relation to the reference.
Relative density or. specific gravity[1][2] is the ratio of the density (mass of a unit of. volume) of a substance and the density of a given reference material. THE. expression “specific gravity” generally means a density. relative with respect to water. The term relative density is many times. preferred in modern scientific usage.
If the density. The relative value of a substance is less than 1 so it is less dense than a. reference and if it is greater than 1 then it is denser than the reference. If. the relative density is exactly equal to 1 so the densities are equal, that is, equal volumes of the two substances have the same mass. If the material of. reference is water, a substance with a density (or gravity. specific) less than 1 will fluctuate. For example, an ice cube, with a. density of about 0.91, will fluctuate. In turn, a substance with a. relative density greater than 1 will sink.
The temperature and a. pressure must be specified for both the sample and a. reference. The pressure is almost always 1 atm equal to 101,325 kPa. When not, it is more usual to specify the density directly. Temperatures for both sample. and benchmark, vary from sector to sector. In British breweries a. specific gravity, as specified above, is multiplied by 1000.[3] Specific gravity is commonly used in industry as a simple means of. obtaining information on the concentration of solutions of various materials, such as brines, sugar solutions (syrups, juices, honeys, etc.) and acids.”
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