Question

Выразить массу молекулы воды в килограммах, если известно ,что ее относительная молекулярная масса равна 18а.е.м

Answer 1

Чтобы найти массу молекулы воды неоходимо молярную массу разделить на число Авагадро. Молярная масса равна 0,018  кг/моль, ачисло Авагадро равно

6*1023 1/моль

и получится ответ

3*10-26 кг

Answer 2

Calculation of the Mass of a Water Molecule

To calculate the mass of a water molecule in kilograms, we need to know its relative molecular mass. In this case, the relative molecular mass of water is given as 18 atomic mass units (a.m.u.).

The relative molecular mass of a substance is the average mass of its molecules compared to the mass of a carbon-12 atom, which is assigned a mass of exactly 12 atomic mass units. Therefore, the relative molecular mass of water (H2O) being 18 a.m.u. means that the average mass of a water molecule is 18 times the mass of a carbon-12 atom.

To convert the relative molecular mass of water to kilograms, we need to know the mass of one mole of water molecules. One mole of any substance contains Avogadro's number of particles, which is approximately 6.022 x 10^23 particles per mole.

The molar mass of water can be calculated by multiplying the relative molecular mass by the molar mass constant, which is approximately 1 gram per mole. Therefore, the molar mass of water is 18 grams per mole.

To convert grams to kilograms, we divide by 1000. Therefore, the mass of one mole of water molecules is 0.018 kilograms.

Since one mole of water molecules contains Avogadro's number of particles, the mass of a single water molecule can be calculated by dividing the molar mass by Avogadro's number.

Let's calculate the mass of a water molecule in kilograms:

Mass of one mole of water molecules = 0.018 kilograms Avogadro's number = 6.022 x 10^23 particles per mole

Mass of a water molecule = (Mass of one mole of water molecules) / (Avogadro's number)

Mass of a water molecule = 0.018 kilograms / (6.022 x 10^23 particles per mole)

Therefore, the mass of a water molecule is approximately 2.991 x 10^-26 kilograms.

Please note that this calculation is an approximation and assumes that the water molecule is composed of two hydrogen atoms and one oxygen atom, each with a mass of 1 atomic mass unit (a.m.u.) and 16 a.m.u., respectively.