CHEMISTRY COMMUNITY

Why does one need to balance reactions?

The law of conservation of mass states that the total mass of the reactants must equal the total mass of the products. Mass cannot be created or destroyed. Therefore, there must be the same number of each atom on both sides of the reaction.

Thank you so much. One last thing, Dr. Lavelle mentioned in class that this might not always be true. Why?

This law is always true for chemical reactions, however not true for nuclear reactions where atoms can be converted to energy.

It is important to balance chemical reactions because when performing experiments/reactions it is important to know: 1.what you need/what you'll get and 2. how much. When you write out a unbalanced chemical reaction it tells you what you need/what you'll get from the reaction, but there is no guarantee that it will be telling the correct amounts of each element/molecule involved in the reaction (this is because chemical reactions follow the Law of Conservation of Mass: within chemical reactions the #of atoms on the left = the #of atoms on the right). To resolve this you balance the chemical reaction.

Must the states of matter always be written in a chemical equation? (s,l,aq)

It's good practice to always write the states of matter for each reactant and product in a chemical equation. It allows one to understand the context of how the reaction is occurring, and more importantly can help indicate which type of chemical reaction is occurring. For example precipitate reactions will have reactants that are aqueous but a product that is solid.

Chemical reactions must be balanced because of the Law of Conservation of Mass.

Total Mass Before = Total Mass After

Like Professor Lavelle stated, it's kind of like saying "4x=5x" in a math equation. If you don't balance a chemical reaction, then t's a false equation. You need to balance an equation to accurately know how much certain moles of reactants will render certain moles of product.

The Law of Conservation of Mass says that mass cannot be created or destroyed during chemical reactions. This means there must be an equal number of atoms before and after the chemical reactions.

This means that if an equation is not balanced, it's not a real chemical reaction that could occur.

We need to balance chemical reactions for them to have any practical relevance in the problem we're doing.

Have you guys been showing all of the work when you do these problems for homework and practice? Is it better to show each step when you add a stoichiometric coefficient or do you just use the same equation and balance it all at once?

Balancing equations is super important because of the Law of Conservation of Mass (Lavoisier). The total mass before equals the total mass after the reaction. This is because atoms are neither created nor destroyed. Therefore, chemical equations (reactants --> products) must always be balanced.

rachel liu 3k wrote:Must the states of matter always be written in a chemical equation? (s,l,aq)

Yes, the states of matter should always be written in order to visualize the equation in the context of the problem.

ALWAYS ! It is best to never assume that an equation is balanced and check... when tests come it is possible that the reaction will not be balanced.

Is there a particular order we have to list our products and reactants?

In what types of questions would we have to specify the state (s,g,l)of the product or reactant?

quresh3E wrote:Is there a particular order we have to list our products and reactants?

In writing a chemical equation, there is no specified order in which we should write the reactants and products. As long as the equations are balanced, and display what is being asked in the problem, you are all set!

Law of Conservation of Mass

MASS IS NOT CREATED NOR DESTROYED, IT IS TRANSFORMED. Consecuently, you need to maintain the same amount of mass at the end the reaction.

Does anyone have any tips for balancing reactions? i.e. what elements should we be looking to balance first?

This is important because the Law of Conservation of Mass states that total mass before (reactants) must equal total mass after (products). In addition, when conducting experiments, you need to know how many moles of each chemical you need to create a reaction.

The law of conservation of mass refers to chemical reactions, which is why in nuclear reactions, this is not true. The law states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products. This means that matter cannot be created or destroyed, and so the amount of each element must be equal on both the reactant and the product side of the chemical equation.

It's important to balance chemical equations because aside from the Law of Conservation of Mass where matter can not be created nor destroyed, you need to have the correct molar ratio in order to be able to conduct any sort of stoichiometric problem.

Chemical reactions have to be balanced in order to satisfy the law of conservation of matter which states that matter is neither created nor destroyed in a closed system. Therefore, the amount of element in the reactant and poduct sides have to be equal.

"In what types of questions would we have to specify the state (s,g,l)of the product or reactant?"
In thermodynamic equations where you are dealing with entropy, it is extremely important to specify the states of the products and the reactants as it is the only way for you to see if the system has become more ordered or disordered compared to the original state. Specifying the states is also important in writing the equilibrium constant where solids are not included.

105099972 wrote:Does anyone have any tips for balancing reactions? i.e. what elements should we be looking to balance first?

You can start with the element that is the least abundant in the reaction and then move forward to the more abundant ones.

According to the Law of Conservation of Mass, matter cannot be created nor destroyed, and therefore, when balancing a reaction, you must have the same amount of moles on both the reactants and products side in accordance with the conservation of mass.

The law of conservation of mass states that mass cannot be created are destroyed and the reactants and products must have the same mass.