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3 years ago

What is a chemical change??

Chemistry

1 answer:

alina1380 [7]3 years ago

4 0

<span>Chemical change is any change that results in the formation of new chemical substances. </span>

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Molodets [167]

False. The answer is liter. kilo is the base (liter) times 1000. it would make no sense.

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3 years ago

Determine which of the following pairs of reactants will result in a spontaneous reaction at 25°C. None of the above pairs will

Alla [95]

Answer:

Only $Fe^{3+}+Mg$ gives spontaneous reaction.

Explanation:

A redox reaction will be spontaneous if standard reduction potential ( $E^{0}$ ) of the reaction is positive. Because it leads to negative standard gibbs free energy change ( $\Delta G^{0}$ ), which is a thermodynamic condition for spontaneity of a reaction.

$E^{0}=E^{0}(reduction)-E^{0}(oxidation)$

Where $E^{0}(reduction)$ and $E^{0}(oxidation)$ represents standard reduction potential of reduction half cell and standard reduction potential of oxidation half cell.

(1) Oxidation: $Mg-2e^{-}\rightarrow Mg^{2+}$ ; $E_{Mg^{2+}\mid Mg}^{0}=-2.38V$

Reduction: $Fe^{3+}+3e^{-}\rightarrow Fe$ ; $E_{Fe^{3+}\mid Fe}^{0}=-0.04V$

So, $E^{0}=E_{Fe^{3+}\mid Fe}^{0}-E_{Mg^{2+}\mid Mg}^{0}=(-0.04+2.38)V=2.34V$

Hence this pair will give spontaneous reaction.

(2) Similarly as above, $E^{0}=E_{Pb^{2+}\mid Pb}^{0}-E_{Au^{+}\mid Au}^{0}=(-0.13-1.69)V=-1.82 V$

Hence this pair will give non-spontaneous reaction.

(3) Similarly as above, $E^{0}=E_{Ag^{+}\mid Ag}^{0}-E_{Br_{2}\mid Br^{-}}^{0}=(0.80-1.07)V=-0.27 V$

Hence this pair will give non-spontaneous reaction.

(4) Similarly as above, $E^{0}=E_{Li^{+}\mid Li}^{0}-E_{Cr^{3+}\mid Cr}^{0}=(-3.04+0.74)V=-2.30 V$

Hence this pair will give non-spontaneous reaction.

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3 years ago

What kinds of information does a structural formula reveal about the compound it represents

stiv31 [10]

Answer:

In organic chemistry, the structural formula shows the bonding and general layout of the molecule.

Explanation:

It can also help in naming the molecule, as many compounds with the same molecular formula have different structural formulas, for example cycloalkanes and alkenes, or aldehydes and ketones.

It tells us about the constituents of the compound, or in other words, the functional groups present. This enables us to predict what kind of properties the compound has and what kind of reactions it can undergo.

It can also help us determine the stereochemistry (shape and spatial orientation) of the compound. This is especially important in organic chemistry and organic chemstry, since certain important reactions will proceed if and only if a molecule with the right shape is employed.

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3 years ago

13. Would you expect oxygen to form a cation or anion? How many electrons would it gain or lose? Why?

netineya [11]

Answer: C)Anion, it would gain 2 electrons to satisfy the octet rule.

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

The electrons are filled according to Afbau's rule in order of increasing energies and thus the electronic configuration of oxygen with 8 electrons is

$O:8:1s^22s^22p^4$

The cation is formed by loss of electrons and anions are formed by gain of electrons.

In order to complete its octet and get stable, it gains 2 electrons and thus would form an anion.

$O^{2-}:10:1s^22s^22p^6$

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3 years ago

What are the 3 types of evidence of Pangaea? *

seraphim [82]

Explanation:

fit of the continents, paleoclimate indicators, truncated?

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2 years ago