How can you distinguish between a physical change and a chemical change?

Chemistry

1 answer:

AleksAgata [21]3 years ago

8 0

Answer:

Physical Change

When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged.
Physical change is a temporary change.
A Physical change affects only physical properties i.e. shape, size, etc.
A physical change involves very little to no absorption of energy.
Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. .
In a physical change, no new substance is formed.
Physical change is easily reversible i.e original substance can be recovered.

Chemical Change

When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances.
.A chemical change is a permanent change.
Chemical change both physical and chemical properties of the substance including its composition
During a chemical reaction, absorption and evolution of energy take place.
A few examples of chemical change are digestion of food, burning of coal, rusting, etc.
A chemical change is always accompanied by one or more new substance(s).
Chemical changes are irreversible i.e. original substance cannot be recovered.

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Rzqust [24]

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2 years ago

A reversible reaction is one where A) there are large changes in the net free energy from substrate to product. B) there is litt

laila [671]

Answer:

A reversible reaction is one where B) there is little change in the net free energy between substrate and product.

Explanation:

A reversible reaction is one that reagents are transformed into products and at the same time products are transformed into reagents. That is to say that as the products appear in the reaction, they can react with each other by regenerating the reagents again. It is represented by a double arrow, indicating that the reaction can be carried out both in one direction and the other way around.

At the start of the reaction, there is a large amount of reagents. As time goes by, that amount decreases and speed too.

On the other hand, at the beginning of the reaction there are no products. As the reaction happens, the products are being formed and their speed will increase to match the speed of the reagents. When the rates of products and reagents are equal and constant, it is possible to say that the reaction is in chemical equilibrium. At this point, both reactions continue to happen, but the total concentrations of reagents and products no longer change.

The Gibbs free enthalpy or free energy of a system is a measure of the amount of usable energy (energy that a job can perform) in that system.

When a reaction system is in chemical equilibrium, it is in the lowest possible energy state (it has the lowest possible free energy). If a reaction is not in equilibrium, it will move spontaneously towards it because that allows it to reach a state of lower and more stable energy. Then when the reaction moves towards equilibrium, the free energy of the system decreases more and more.

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3 years ago

How many grams of mercury can be produced if 18.0 g of mercury (11) oxide decomposes?

NARA [144]

Answer:

18.0 g of mercury (11) oxide decomposes to produce 9.0 grams of mercury

Explanation:

Mercury oxide has molar mass of 216.6 g/ mol. It gas a molecular formula of HgO.

The decomposition of mercury oxide is given by the chemical equation below:

2HgO ----> 2Hg + O₂

2 moles of HgO decomposes to produce 1 mole of Hg