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2 years ago

Why are chemical changes considered "unseen?"

2 answers:

6 0

<span>Chemical changes are considered unseen because they occur at the atomic level, changing the actual structure of the thing. This is in comparison to a physical change, which is visible.</span>

Andrej [43]2 years ago

5 0

Chemical changes are considered unseen because they occur at the atomic level, changing the actual structure of the thing.

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Hey can someone help me and show work please

Ivahew [28]

Answer: 2.54g

Explanation:

Molar Mass of H2O2 = (2x1) + (2x16) = 34g/mol

1mole (34g) of H2O2 contains 6.02x10^23 molecules

Therefore Xg of H2O2 will contain 4.5x10^22 molecules i.e

Xg of H2O2 = (34x4.5x10^22)/6.02x10^23 = 2.54g

5 0

3 years ago

Identify the atoms that are oxidized and reduced, the change in the oxidation state for each, and oxidising and reducing agents

KATRIN_1 [288]

Answer:

Explanation:

a) $Mg + NiCl_2 \rightarrow MgCl_2 + Ni$

Oxidation state of Mg changes to 0 to +2.

Oxidation state of Ni changes to +2 to 0.

Oxidation state of Cl does not change.

So, Mg is oxidized, Ni is reduced.

Mg acts as reducing agent and $NiCl_2$ acts as oxidizing agent.

b) $PCl_3 + Cl_2 \rightarrow PCl_5$

Oxidation state of P changes to +3 to +5.

Oxidation state of Cl changes to 0 to -1.

So,

P is oxidized and Cl is reduced.

$PCl_3$ acts as reducing agent and $Cl_2$ acts as oxidizing agent.

c) $C_2H_4 + 3O_2 \rightarrow 2CO_2 + 2H_2O$

Oxidation state of C changes to -2 to +4.

Oxidation state of O changes to 0 to -2.

Oxidation state of H does not change.

So,

C is oxidized and O is reduced.

$C_2H_4$ acts as reducing agent and $O_2$ acts as oxidizing agent.

d) $Zn + H_2SO_4 \rightarrow ZnSO_4 + H_2$

Oxidation state of Zn changes to 0 to +2.

Oxidation state of H changes to +1 to 0.

Oxidation state of S and O do not change.

So, Zn is oxidized, H is reduced.

Zn acts as reducing agent and $H_2SO_4$ acts as oxidizing agent

e) $K_2S_2O_3 + I_2 \rightarrow K_2S_4_O6 + 2KI$

Oxidation state of S changes to +2 to +2.5.

Oxidation state of I changes to 0 to -1.

Oxidation state of K and O do not change.

So, S is oxidized, I is reduced.

$K_2S_2O_3$ acts as reducing agent and $I_2$ acts as oxidizing agent.

f) $3Cu + 8HNO_3 \rightarrow 3Cu(NO_3)_2 + 4H_2O+2NO$

Oxidation state of Cu changes to 0 to +2.

Oxidation state of N changes to N +5 to +2.

Oxidation state of H and O do not change.

So, Cu is oxidized, N is reduced.

Cu acts as reducing agent and $HNO_3$ acts as oxidizing agent

8 0

2 years ago

How are different elements distinguishable from one another? (Check all that apply.)

Kazeer [188]

The correct answer to this question is the unique atomic number which would be B

7 0

2 years ago

How many grams of mgcl2 are contained in 500 grams of a 1.0% solution

GarryVolchara [31]

1. Julie had saved 105 coins from her daily allowance. If the coins consist of 5-peso coins and 10-peso coins amounting to ₱950, how many of each kind of coin did she have?

5 0

2 years ago

Atoms of arsenic (As) are often added to silicon (Si) in a process called doping to change the conductivity of the silicon. How

Basile [38]

Answer:

B.) An atom of arsenic has one more valence electron and more electron shells than an atom of silicon, so the conductivity decreases because the arsenic atom loses the electron.

Explanation:

Silicon is located in the 3rd row and 14th column in the periodic table. Arsenic is located in the 4th row and 15th column in the periodic table. This means that arsenic has one more valence electron than silicon. Since arsenic is located one row down from silicon, its valence electrons occupy higher energy orbitals.

Silicon maintains a crystal-like lattice structure. Each silicon atom is covalently connected to assume this shape. When silicon gains one extra electron from arsenic, it experiences n-type doping. This new electron is not tightly bound in the lattice structure. This allows it to move more freely and conduct more electricity. This can also be explained using band gaps. Silicon, which previously had an empty conduction band, now has one electron in this band. This lowers the band gap between the conduction and valence bands and increases conductivity.

5 0

2 years ago