While verifying the law of conservation of mass Smith added 3.5g of magnesium (3) metal into 14 g of hydrochloric acid. The mass of magnesium chloride formed is 13.8g, what is the mass of hydrogen gas eliminated, if the law of conservation of mass is true?
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Answer:
Chemistry is basically taking 'stuff' (the reactants) and changing it and separating out 'different stuff' (the products).
In a chemical change, the atoms of the reactants are rearranged to give the products.
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The atoms remain the same elements BUT are arranged or bonded in a different way in the products.
In the 'picture equation' above, just look at how the copper, carbon, oxygen, hydrogen and sulfur atoms are changed in their arrangement from reactants on the left, to products to the right of the arrow - indicating the direction of chemical change.
So, what about the relative mass of all the products compared to the total mass of the original reactants?
Read on .... !!!
What is the Law of Conservation of Mass?
When elements and compounds react to form new products, mass cannot be lost or gained.
"The Law of Conservation of Mass" definition states that "mass cannot be created or destroyed, but changed into different forms".
So, in a chemical change, the total mass of reactants must equal the total mass of products whatever the physical state of the reactants and products.
The law of conservation of mass can also be stated as "no atoms can be lost or made in a chemical reaction", which is why the total mass of products must equal the total mass of reactants you started with.
By using this law, together with atomic and formula masses, you can calculate the quantities of reactants and products involved in a reaction and the simplest formula of a compound
One consequence of the law of conservation of mass is that In a balanced chemical symbol equation, the total of relative formula masses of the reactants is equal to the total relative formula masses of the products.
You can see this in the examples worked out for you ...
... so, this page just explains how to do simple reacting mass calculations based on the reaction equation and applying the Law of Conservation of Mass,
but first, by at least one clearly observed experiment, that the Law of Conservation of Mass holds good, even in the humble school or college laboratory! see diagram below and read on. ...
See also Section 5. which shows how to use this law to get to a compound's formula too
... before tackling the first calculations based on the Law of Conservation of mass, its worth describing a simple experiment to demonstrate the validity of the law. The experiment is illustrated in the diagram above and represents an enclosed system, where