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Learning Objective
Define the law of conservation of mass
Key Points
The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.
According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.
Terms
reactantAny of the participants present at the start of a chemical reaction. Also, a molecule before it undergoes a chemical change.
law of conservation of massA law that states that mass cannot be created or destroyed; it is merely rearranged.
productA chemical substance formed as a result of a chemical reaction.
History of the Law of the Conservation of Mass
The ancient Greeks first proposed the idea that the total amount of matter in the universe is constant. However, Antoine Lavoisier described the law of conservation of mass (or the principle of mass/matter conservation) as a fundamental principle of physics in 1789.
Antoine LavoisierA portrait of Antoine Lavoisier, the scientist credited with the discovery of the law of conservation of mass.
This law states that, despite chemical reactions or physical transformations, mass is conserved — that is, it cannot be created or destroyed — within an isolated system. In other words, in a chemical reaction, the mass of the products will always be equal to the mass of the reactants.
The Law of Conservation of Mass-Energy
This law was later amended by Einstein in the law of conservation of mass-energy, which describes the fact that the total mass and energy in a system remain constant. This amendment incorporates the fact that mass and energy can be converted from one to another. However, the law of conservation of mass remains a useful concept in chemistry, since the energy produced or consumed in a typical chemical reaction accounts for a minute amount of mass.
We can therefore visualize chemical reactions as the rearrangement of atoms and bonds, while the number of atoms involved in a reaction remains unchanged. This assumption allows us to represent a chemical reaction as a balanced equation, in which the number of moles of any element involved is the same on both sides of the equation. An additional useful application of this law is the determination of the masses of gaseous reactants and products. If the sums of the solid or liquid reactants and products are known, any remaining mass can be assigned to gas.
Answer:
52.5 g
Explanation:
Density= mass/volume
Rearranging the equation gives us m= d(V)
m= d(V)
m= (10.5 grams/cm^3)(5 cm^3)
m= 52.5 g
Answer:
Dana filtered the sample and larger granules of the sample were left behind.
Explanation:
If a substance is pure, it will have a uniform composition throughout. It will not separate into particles of various sizes.
One of the characteristics of pure substances is that they are homogeneous. A mixture is definitely made up of particles of various sizes.
Since the particles was filtered and larger granules were left behind, the sample has been separated by a physical method (filtration). Only a mixture can be separated by physical methods. It is not a pure substance.
The amount of heat needed to melt 423 g of water at 0°C is 141282 J
The heat required to melt water can be obtained by using the following formula:
<h3>Q = mL </h3>
Q is the heat required.
L is the latent heat of fusion (334 J/g)
m is the mass.
With the above formula, we can obtain the heat required to melt the water as illustrated below:
Mass of water (m) = 423 g
Latent heat of fusion (L) = 334 J/g
<h3>Heat (Q) required =? </h3>
Q = mL
Q = 423 × 334
<h3>Q = 141282 J</h3>
Therefore, the amount of heat needed to melt 423 g of water at 0°C is 141282 J
Learn more: brainly.com/question/17084080
