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garri49 [273]
2 years ago
5

Which one of the following statements BEST describes a chemical reaction?

Chemistry
1 answer:
Natalija [7]2 years ago
8 0

Answer: The correct statement is (A new substance is formed and the process can usually NOT be undone.)

Explanation:

A chemical reaction is simply defined as the reaction between two or more elements in which a new substance is formed and the process can usually not be undone. Different types of chemical reaction includes:

-- combination reaction: this occurs when two or more reactants form a product. For example: In the burning of coal, It combines with oxygen to produce carbon dioxide. Also in the burning of wood, carbon dioxide is given off and ashes are formed. Because new substance is being formed, they often can't be undone. The ashes formed can't be changed back into wood. Other types of chemical reaction are listed below.

-- Decomposition reaction

-- Single displacement reaction

-- Double displacement reaction

-- combustion reaction

-- Redox reaction

For the product of a chemical reaction to be undone (reversed), it has to undergo another chemical process different from the one that produced it.

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I think it is the third statement
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steposvetlana [31]
Part (a) :
H₂(g) + I₂(s) → 2 HI(g)
From given table:
G HI = + 1.3 kJ/mol
G H₂ = 0
G I₂ = 0
ΔG = G(products) - G(reactants) = 2 (1.3) = 2.6 kJ/mol

Part (b):
MnO₂(s) + 2 CO(g) → Mn(s) + 2 CO₂(g)
G MnO₂ = - 465.2
G CO = -137.16
G CO₂ = - 394.39
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ΔG = G(products) - G(reactants) = (1(0) + 2*-394.39) - (-465.2 + 2*-137.16) = - 49.3 kJ/mol

Part (c):
NH₄Cl(s) → NH₃(g) + HCl(g)
ΔG = ΔH - T ΔS
ΔG = (H(products) - H(reactants)) - 298 * (S(products) - S(reactants))
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      = 176.15 kJ - 84.78 kJ = 91.38 kJ 
 





 
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Why is all matter affected by gravity ​
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Answer:

Explanation:

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Explanation:

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The earth is most heavier than all other matter that's why all matter pulls towards the earth.

For example;

when we walk on the earth, it pull us. Our mass is less as compared to the earth that's why we fall back on the earth instead of moving upward because our pull is negligible because of greater difference in masses. The earth mass is very high.

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5 0
3 years ago
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My name is Ann [436]

Answer:

There are no specific equations but here what i can give you:

1. Synthesis -- A synthesis reaction is a chemical change in which two or more substances react to form a single new substance.

In all synthesis reactions, there is a single product that is a compound!

2. Decomposition -- A decomposition reaction is a chemical change in which a single compound breaks down into two or more simpler products. (This is the opposite of synthesis reactions!)

Most decomposition reactions require energy in the form of heat, light, and electricity.

3. Single Replacement -- A single-replacement reaction is a chemical change in which one element replaces a second element in a compound. You can identify a single-replacement reaction by noting that both the reactants and the products consist of an element and a compound.

4. Double Replacement -- A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds.

For a double replacement reactions to occur, one of the following is usually true:

- One of the products is only slightly soluble and precipitates from solutions.

- One of the products is a gas.

- One product is a molecular compound such as water.

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A combustion reactant always involves oxygen as a reactant. (If the supply of oxygen is limited, then the combustion will not be complete.)

The other reactant is a hydrocarbon, which is a compound composed of hydrogen and carbon and the complete combustion of a hydrocarbon produces CO2 and H2O.

Hydrocarbons include methane, propane, and butane.

I really hope this helps you!

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