2 March 2024

the gram molecule It is a unit of measurement used in chemistry to express the amount of substance of a certain molecule. This unit of measure is also called mole-gram, and is the weight in grams of one mole of molecules (6.022×1023 molecules) of a chemical substance. It is determined by expressing the molecular weight in grams.

In this article we invite you to learn more about the gram molecule, and what is its role in modern chemistry.

Importance of the gram molecule

The gram molecule is important because it allows us to perform precise calculations in chemistry modern, especially in the dosage of substances in a chemical preparation.

This unit of weight has great chemical relevance for one gram atom of any substance contains approximately six hundred thousand trillion atoms. This unit is used to perform chemical calculations related to the quantity and mass of substances.

Calculations related to the gram molecule

exist two types of calculations related to the gram molecule: the calculation of the amount of substance in gram molecules and the calculation of the mass from the amount of substance.

Below we detail each of these examples:

Calculation of the amount of substance in gram molecules

To calculate the amount of substance in gram molecules, it is necessary to know Avogadro’s number, which is equal to 6.02×10^23. This number tells us the number of molecules present in a sample of a given substance.

Therefore, to calculate the amount of substance in gram molecules, divide the amount of substance in molecules by Avogadro’s number.

Calculation of mass from the amount of substance

To calculate mass from the amount of substance, you can use the relationship between mass, amount of substance, and molar mass.

The formula to calculate the mass is: m=n*M, where m is the mass in grams, n is the amount of substance in moles and M is the molar mass in grams per mole.

The molar mass of a substance can be found in the Periodic table of elements for pure elements, or can be calculated by adding the molar masses of the elements that make up a molecule for chemical compounds.

What is gram molecular volume?

This value is the volume occupied by one mole of molecules in a gas perfect, under normal conditions of temperature and pressure. It is important to mention that the molecular volume can vary depending on the temperature and pressure.

What is gram molecule in chemistry?

In chemistry, a gram molecule known as a mole, is the unit of measure for the amount of substance. One mole contains exactly 6.02214076 × 10²³ elementary entities, which can be atoms, molecules, ions, or other small particles. This value is determined by expressing the molecular weight in grams.

The term molecule-gram It was formerly used in chemistry to refer to a mole of molecules. For example, a gram molecule of water is 18 grams (H₂O = 1 + 1 + 16 = 18 g).

What is gram molecular mass?

molecular mass is the sum of the atomic masses of the atoms in a molecule of a substance. This value is calculated by adding the atomic masses of the elements of the substance, each one multiplied by its subscript (written or implied) in the molecular formula.

Molecular mass units are also atomic mass units. For example, the molecular mass of water (H₂O) is 18 Da (Dalton), because it contains two hydrogen atoms (2 x 1 Da) and one oxygen atom (16 Da).

Applications of the gram molecule

The mole, also known as the gram molecule, widely used in chemistry as a convenient way to express amounts of reactants and products of chemical reactions.

In addition to its use in chemistry, the mole also it is used in other fields such as physics and biology to express quantities of particles or entities. It is a fundamental unit in the International System of Units (SI) and is used in many scientific calculations and measurements.

Practical examples of gram molecule

Here are several practical examples of the use of the gram molecule:

For calculate the mass of a reactant necessary for a chemical reaction, the relationship between moles and mass can be used.

  1. For example: a reaction requires 2 moles of hydrogen (H₂). The required mass of hydrogen can be calculated by multiplying the number of moles by the molar mass of hydrogen (2 g/mol), giving 4 g of hydrogen.

For prepare a concentration solution known, the relationship between moles and volume can be used.

  1. For example: to prepare 1 L of a 0.5 mol/L sodium chloride (NaCl) solution. The number of moles of NaCl needed can be calculated by multiplying the concentration by the volume (0.5 mol/L x 1 L = 0.5 mol). Then convert the moles to mass using the molar mass of NaCl (58.44 g/mol), which gives 29.22 g of NaCl.

For determine the empirical formula of a compound From experimental data, moles can be used to convert the masses of different elements into relative numbers of atoms.

  1. For example: analysis of a compound shows that it contains 40 g of calcium, 12 g of carbon, and 48 g of oxygen. The relative number of atoms of each element can be calculated by dividing each mass by the respective atomic mass. This is equal to (40 g Ca / 40 g/mol = 1 mol Ca, 12 g C / 12 g/mol = 1 mol C, 48 g O / 16 g/mol = 3 mol O), which gives the empirical formula CaCO₃.

Dosage of substances in a chemical preparation

The dosage of substances in a chemical preparation that depends on the chemical reaction in question and the amounts of reactants and products desired. Dose can be calculated using chemical reaction equations and relationships between moles, mass, volume, and concentration.

For example: you want to prepare a hydrochloric acid solution (HCl) from concentrated hydrochloric acid (37% by mass, density 1.19 g/mL) and water. The volume of concentrated acid required can be calculated using the relationship between the mass concentration and the molar concentration.

The molar concentration of the concentrated acid is 37% x 1.19 g/mL / 36.46 g/mol = 12.1 mol/L.

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