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### Law of Conservation of Mass

Posted: Mon Oct 01, 2018 6:08 pm
Anyone willing to give a simpler definition of the Law of Conservation of Mass?

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 6:19 pm
It's literally what happens at the beginning (or the mass at the start (mass initial)) is going to be equal to the mass final. This is usually done as was done in lecture today where we were given n = Moles*liters and given a question would just plug in the given values of of (M)*(v-liters) initial and equal to the final result. It's kind of like the physics conservation of energy law if you're familiar with that, except this is chem and it deals with mass rather than energy. It's just saying that mass initial will equal mass final and this correlates to the key concept regarding diluting a solution because the amount of for example salt in a cup of water, you can always add more water but the amount of salt will remain the same even if dissolved. I'm not sure if this answered your question, but I genuinely hope this helps clarify it at least.

### Re: Law of Conservation of Mass  [ENDORSED]

Posted: Mon Oct 01, 2018 6:32 pm
This is as simple as it gets: mass can not be created and mass cannot be destroyed. There will always be the same amount mass before and after a chemical reaction since mass cannot be created nor destroyed.

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 7:25 pm
Yes, basically the total mass before a reaction is always equal to the total mass after. Also I liked this concept too: in chemical reactions, atoms are not created or destroyed; they are rearranged.

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 8:09 pm
It's basically that mass can't be created nor destroyed. The matter may not change, there is just a rearrangements of atoms in a chemical reaction with the same mass in both the product and the reactants.

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 8:22 pm
The Law of conservation of Mass means that the mass of an equation can not be created or destroyed. Therefore, the mass in the reactants (left side) should be the same as the mass in the products (right side).

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 8:32 pm
Everything the people said above me is correct: You cannot lose or gain mass in a chemical reaction. I know we are not at nuclear reactions, but this the law of conservation of mass only applies to chemical reactions.
We can use combustion of propane (C3H8) as an example of a chemical reaction.

The rxn would look like this:
C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(l)

The equation is balanced because mass is neither created or destroyed in the process. The amount of carbon atoms on the left side equals the amount of carbon atoms on the right (3 Carbon atoms). The amount of hydrogen atoms on the left side equals the amount of hydrogen atoms on the right (8 Hydrogen atoms). The amount of oxygen atoms on the left side equals the amount of oxygen atoms on the right (10 Oxygen atoms).
Hope this helps

### Re: Law of Conservation of Mass

Posted: Mon Oct 01, 2018 9:44 pm
The easiest way to understand the Law of Conservation of Mass is that matter is neither created nor destroyed. This means that in a chemical equation, the number of reactant atoms are equal to the number of product atoms. The Law of Conservation on Mass is one of the key concepts in understanding how to balance chemical equations.