Because the mass of the reactants equal to the mass of the product of a reaction, the number of moles will be conserved.
-I think this is sometime true but I don't know a way to prove that it sometime true. Anyone got an idea ? Thanks
It seldom is true.
examples:
Fe+S=FeS (two moles=1?)
2Fe+O2> 2FeO (three moles=2?)
N2 + O2 > 2NO (two moles=2)
To prove that the number of moles is conserved in a chemical reaction, you need to apply the principle of conservation of mass, also known as the law of conservation of mass.
The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction. In other words, the total mass of the reactants must be equal to the total mass of the products.
To demonstrate that the number of moles is conserved in a reaction, you can follow these steps:
1. Determine the balanced chemical equation for the reaction: A balanced chemical equation shows the reactants on the left side and the products on the right side, with the proper stoichiometric coefficients. For example, the balanced equation for the reaction between hydrogen (H2) and oxygen (O2) to form water (H2O) is:
2H2 + O2 -> 2H2O
2. Calculate the molar masses: Determine the molar masses of all the reactants and products involved in the reaction. The molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). You can find the molar masses of elements from the periodic table and the molar masses of compounds by adding up the molar masses of their constituent atoms.
3. Convert mass to moles: Divide the mass of each substance involved in the reaction by its molar mass to obtain the number of moles. This can be done using the formula:
Moles = Mass / Molar Mass
4. Compare the number of moles: Compare the number of moles for each reactant with the number of moles for each product. If the reaction is balanced, the number of moles of each element on the reactant side should be equal to the number of moles of the same element on the product side.
5. Perform a mass balance calculation: Add up the masses of the reactants and compare them to the sum of the masses of the products. The masses should be equal if the reaction is balanced.
By following these steps, you can confirm that the number of moles is conserved in the reaction, as long as the reaction is balanced. However, it's important to note that there are some cases where moles may not be conserved, such as in nuclear reactions or reactions involving changes in temperature and pressure.
The statement you provided is based on the law of conservation of mass, which states that in a chemical reaction, the total mass of the reactants will always be equal to the total mass of the products.
To prove the conservation of moles, we need to understand the concept of molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol).
Here's a step-by-step explanation to demonstrate the conservation of moles:
1. Determine the balanced chemical equation for the reaction you want to analyze. For example, let's consider the combustion of methane: CH4 + 2O2 -> CO2 + 2H2O.
2. Calculate the molar mass of each substance involved in the reaction. The molar mass of methane (CH4) is approximately 16.04 g/mol, oxygen (O2) is 32.00 g/mol, carbon dioxide (CO2) is 44.01 g/mol, and water (H2O) is 18.02 g/mol.
3. Given a certain mass of reactant, convert the mass to moles by dividing it by the molar mass. For example, if you have 10 grams of methane, divide it by the molar mass of methane (16.04 g/mol) to obtain the number of moles of methane.
4. Use the coefficients of the balanced equation to determine the moles of other substances involved in the reaction. In the example equation, since the coefficient of methane is 1 and the coefficient of carbon dioxide is also 1, if you have 1 mole of methane reacting, you will produce 1 mole of carbon dioxide.
5. Repeat steps 3 and 4 for all the reactants and products in the equation to find the number of moles of each substance.
6. Compare the number of moles of reactants with the number of moles of products. In this case, if you started with 1 mole of methane, you end up with 1 mole of carbon dioxide and 2 moles of water. The total number of moles of reactants (1 mole of methane) is equal to the total number of moles of products (1 mole of carbon dioxide + 2 moles of water).
By performing these calculations, you can demonstrate that the number of moles is conserved in a reaction.