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2 years ago

Which of the following is an example of a chemical change?

Chemistry

1 answer:

alexdok [17]2 years ago

3 0

Answer:

Dissolving sugar in water, burning paper, and melting gold are all chemical changes

Explanation:

The action cannot be reversed, or undone. Therefore it is a chemical change.

Boiling water is a physical change.

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the half of an oxidation-reduction reaction shows the iron gains. what does this electron gain mean for iron.

Nataly [62]

The correct answer is option C, that is, it is reduced.

In reduction and oxidation reactions, reduction refers to the loss of an oxygen atom from a molecule or the gaining of one or more electrons. A reduction reaction is observed from the perspective of the molecule being reduced, as when one molecule gets reduced, another one gets oxidized. The complete reaction is called a redox reaction.

In the given case, iron gains electrons mean that it is reduced.

3 0

2 years ago

Enter a balanced equation for the reaction between solid silicon dioxide and solid carbon that produces solid silicon carbide an

givi [52]

Answer:

SiO2(s) + 3C(s) ------> SiC(s) + 2CO(g)

Explanation:

The formula for silicon oxide is SiO2 and carbon is C. silicon carbide is SiC

and carbon monoxide is CO.

An arrow is always used to separate the reactants (left) and products (right).

A balanced equation must contain equal number of atoms in each side of the equation.

For example in the equation above, there are 1 atom of silicon appears on each side; 2 atoms of oxygen and three atoms of carbon.

3 0

3 years ago

Microwave radiation has a wavelength on the order of 1.0 cm. Calculate the frequency and the energy of a single photon of this r

denis23 [38]

Answer :

(1) The frequency of photon is, $3\times 10^{10}Hz$

(2) The energy of a single photon of this radiation is $1.988\times 10^{-23}J/photon$

(3) The energy of an Avogadro's number of photons of this radiation is, 11.97 J/mol

Explanation : Given,

Wavelength of photon = $1.0cm=0.01m$ (1 m = 100 cm)

(1) Now we have to calculate the frequency of photon.

Formula used :

$\nu=\frac{c}{\lambda}$

where,

$\nu$ = frequency of photon

$\lambda$ = wavelength of photon

c = speed of light = $3\times 10^8m/s$

Now put all the given values in the above formula, we get:

$\nu=\frac{3\times 10^8m/s}{0.01m}$

$\nu=3\times 10^{10}s^{-1}=3\times 10^{10}Hz$ $(1Hz=1s^{-1})$

The frequency of photon is, $3\times 10^{10}Hz$

(2) Now we have to calculate the energy of photon.

Formula used :

$E=h\times \nu$

where,

$\nu$ = frequency of photon

h = Planck's constant = $6.626\times 10^{-34}Js$

Now put all the given values in the above formula, we get:

$E=(6.626\times 10^{-34}Js)\times (3\times 10^{10}s^{-1})$

$E=1.988\times 10^{-23}J/photon$

The energy of a single photon of this radiation is $1.988\times 10^{-23}J/photon$

(3) Now we have to calculate the energy in J/mol.

$E=1.988\times 10^{-23}J/photon$

$E=(1.988\times 10^{-23}J/photon)\times (6.022\times 10^{23}photon/mol)$

$E=11.97J/mol$

The energy of an Avogadro's number of photons of this radiation is, 11.97 J/mol

3 0

3 years ago

Read 2 more answers

You inoculate a bacterium into three tubes of nutrient broth medium containing added salt: 0.5% NaCl, 5% NaCl, and 15% NaCl. Aft

g100num [7]

Answer:

Halophile.

Explanation:

Halophile microorganisms are microorganisms that require very large amounts of NaCl. If the concentration of NaCl is very little, there will be no growth. Ih this case, given that it grows between 5% and 15%, it can be considered a moderate halophile.

5 0

3 years ago

[Rn] 7s25f6d4<br> Which element is denoted

Colt1911 [192]

Answer:

Explanation:

[Rn] 7s25f6d4

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4 0

3 years ago