How to transfer the amount in weight of : Information for students

How to transfer the amount in weight of : Information for students
You will need:
  • Paper
  • Handle Table
  • density substances
# 1

Very often at school at lessons of physics or chemistry are considered problem of finding the mass of a substance.Problems of this kind are very practical, because in real life with the weight and volume calculations we encounter every day.How many liters in the bottle?What's harder: petrol or water?How much will it weigh a full canister of acetone?Answers to all these questions can be obtained by knowing how to translate the volume into mass and vice versa.

# 2

In physics and chemistry of the substance is characterized not only by their number, but also its density.Density - is a constant (for each substance is its own), which is calculated by dividing the mass of a substance to its volume.weight and volume measurements are carried out under normal conditions (20 degrees Celsius, 760 mm. Hg) and recorded in a special table of densities.

# 3

Sometimes scientists to calculate the density necessary to resort to such a bag

of tricks, how to calculate the molar mass of a substance, because in practice it is difficult to weigh the substance or too little.The unit of measurement of density - grams divided by centimeter per cubic meter to cubic or kilogram.In practice, also conveniently measured in kilograms per liter (also known as a cubic decimeter).This value, expressed by the Greek letter rho (ρ).

# 4

Turning to the question of how to find the mass of the density, look at a specific example.Find the mass of copper ingots in the volume of 740 cubic cm.Looking at the table, determine the density of copper is 8.2 (g / cc).Next, multiply the volume by the density: 740 cc..* 8.2 g / cc.cu.= 0.8, the obtained results always need to be reversed in the SI system.This is roughly equal to 6.6 kilograms.

# 5

A similar problem is how to find a lot of knowing the volume.It is also necessary to multiply the volume by the density of matter.Consider a more complex task.Brass bar volume of 0.8 cubic decimeters was placed in an empty two-liter capacity, the rest is filled with water.Find the mass of the contents of a two-liter tank, the mass of the container can be neglected.To begin with we find the volume of water: 2 liters - 0.8 liters (ie a liter cubic dm =....) = 1.2 liters.

# 6

Let us turn to the problem of how to find a lot of water and brass.The density of water is 1 kg / liter, so the mass is equal to 1 * 1.2 = 1.2 kg.The average density of brass is equal to 8.5 kg / liter, hence the mass of 0.8 liters will be equal to 0.8 * 8.5 = 6.8 kg.Next, we add up the calculated mass: 1.2 kg + 6.8 kg = 8 kg.The problem is solved.Table densities can always be found in every school library or on the Internet.