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SVETLANKA909090 [29]
4 years ago
8

Which statement is true?

Chemistry
2 answers:
MissTica4 years ago
8 0

Answer:

The correct answer is in an exothermic reaction the energy of the product is less than the energy of the reactants.

Explanation:

Exothermic reaction is a type of reaction that generates heat.As a result in case of an exothermic reaction the energy of the reactant is more than the energy of the product.

       That"s why the enthalpy change in an exothermic reaction is always positive .

lorasvet [3.4K]4 years ago
7 0

The correct answer is C. In an exothermic reaction, the energy of the products is less than the energy of the reactants.

Explanation:

A chemical reaction is a process during which two or more substances interact and form new products. In these, the first substances are known as the reactants while the substances at the end of the reaction are the products. Moreover, reactions often involve a change in the energy of substances this known as enthalpy.

In the case of exothermic reactions in which energy or heat is released, the enthalpy is negative, this means, the energy in the products is less than in the reactants because during the chemical reaction substances release energy. This makes option C correct. On the other hand, in endothermic reactions, energy is absorbed, and therefore it is expected energy in the products is more than the one in the reactants.

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Why is it important to living things that water is bonded by h bond and not by covalent or ionic one
nexus9112 [7]
Because im pretty sure the molecules would just fall apart like salt which is ionic
8 0
3 years ago
Find the number of CoCl2 units present in a 0.78 mol sample.
stich3 [128]

\qquad\qquad\huge\underline{{\sf Answer}}

Here we go ~

1 mole of \sf{ COCl_2} has 6.022 × 10²³ molecules of the given compound.

So, 0.78 mole of \sf{COCl_2} will have ~

\qquad \sf  \dashrightarrow \: 0.78 \times 6.022 \times 10 {}^{23}

\qquad \sf  \dashrightarrow \:  \approx4.7 \times 10 {}^{23}  \:  \:  \: molecules

5 0
3 years ago
3. What is the energy of a photon whose frequency is 5.2 x 1015 Hz? Use the equation: E = hxv
anzhelika [568]

Answer:

3. 3.45×10¯¹⁸ J.

4. 1.25×10¹⁵ Hz.

Explanation:

3. Determination of the energy of the photon.

Frequency (v) = 5.2×10¹⁵ Hz

Planck's constant (h) = 6.626×10¯³⁴ Js

Energy (E) =?

The energy of the photon can be obtained by using the following formula:

E = hv

E = 6.626×10¯³⁴ × 5.2×10¹⁵

E = 3.45×10¯¹⁸ J

Thus, the energy of the photon is 3.45×10¯¹⁸ J

4. Determination of the frequency of the radiation.

Wavelength (λ) = 2.4×10¯⁵ cm

Velocity (c) = 3×10⁸ m/s

Frequency (v) =?

Next, we shall convert 2.4×10¯⁵ cm to metre (m). This can be obtained as follow:

100 cm = 1 m

Therefore,

2.4×10¯⁵ cm = 2.4×10¯⁵ cm × 1 m /100 cm

2.4×10¯⁵ cm = 2.4×10¯⁷ m

Thus, 2.4×10¯⁵ cm is equivalent to 2.4×10¯⁷ m

Finally, we shall determine the frequency of the radiation by using the following formula as illustrated below:

Wavelength (λ) = 2.4×10¯⁷ m

Velocity (c) = 3×10⁸ m/s

Frequency (v) =?

v = c / λ

v = 3×10⁸ / 2.4×10¯⁷

v = 1.25×10¹⁵ Hz

Thus, the frequency of the radiation is 1.25×10¹⁵ Hz.

8 0
3 years ago
Which element has a larger atomic radius than sulfur? chlorine cadmium fluorine oxygen
zhuklara [117]

Answer:

  • <u>Cadmium has larger atomic radius than sulfur.</u>

Explanation:

Down a period, atomic radii decrease from left to right due to the increase in the number of protons and electrons across a period: when a proton is added the pull of the electrons towards the nucleus is larger, so the size of the atom decreases.

Hence, you can compare the elements that belong to a same period and predict that the atom with lower atomic number (number of protons) will haver larger atomic radius. With that:

  • Oxygen and fluorine are in the period 3, being oxygen to the left of fluorine, so oxygen is larger than fluorine.

  • Sulfur and chlorine are in the period 4, being sulfur to the left of chlorine, so sulfur is larger than chlorine.

Now see whan happens down a group. Atomic radius increases from top to bottom within a group due to electron shielding. That permits you to compare the size of the elements in a group:

  • Fluorine and chlorine are in the same group (17), with chlorine directly below fluorine, so the atomic radius of chlorine is larger than the atomic radius of fluorine.

  • Sulfur and oxygen are in the same group (16), with sulfur directlly below oxygen, so sulfur the atomic radius of sulfur is larger than the atocmi radius of oxygen.

So far, you can rank the atomic radius of sulfur, chlorine, fluorine, and oxygen, in increasing order as:

  • O < F < Cl < S, concluding that O, F, and Cl have smaller atomic radius than S.

Cadmiun, Cd, is to the left and below sulfur, so both electron shielding (down a group) and increase of the number of protons (down a period) lead to predict the cadmium has a larger atomic radius than sulfur.

8 0
3 years ago
Why is oxygen written with a subscript 2 in CO2?
Alexeev081 [22]

Answer:

Explanation:

the answer is b

6 0
4 years ago
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