Which reaction below is a physical change?
a. CH4​(g) + 2O2​(g) → CO2​(g) + 2Hs​O(l)
b. CaO(s) + H2​O(l)→ Ca(OH)2​(s)
c. H2​O (l) → H2​O(s)
D. 2Hs​O (l) → 2H2​(g) + O2​(l)

Answers

Answer 1

Answer:

c. H₂​O (l) → H₂​O(s)

Explanation:

The correct answer is option C: The molecular formulas for the substance(s) on the left side of the equation and on the right side of the equation are identical. This means that there was not a chemical change, but a physical one.

In this concrete example, what happened was a change of states of matter: from liquid (l) to solid (s).

Other reactions have different molecular formulas on both sides of the equation, thus they represent chemical changes.


Related Questions

5. What is the pH of a solution with p0H= 8.5? Is this an acid, base, or neutral?

Answers

Answer:

pH = 5.5 and it is an acid

Explanation:

Fr the question given above, the following data were obtained:

poH = 8.5

pH =?

pH + pOH = 14

pH + 8.5 = 14

Collect like terms

pH = 14 – 8.5

pH = 5.5

pH scale reads as follow:

0 to 6 => Acidic

7 => Neutral

8 to 14 => Basic

With the above pH scale, we can conclude that the solution with pH 5.5 is acidic.

number of atoms per unit cell in face centred cube is




Answers

Answer:  4 atoms is the answer. I hope it helped you.

Explanation:

Identify the products formed in this Brønsted-Lowry reaction. HCO−3+HBrO↽−−⇀acid+base

Answers

Answer:

[tex]HCO^-_3+HBrO\rightleftharpoons H_2CO_3+BrO^-[/tex]

Explanation:

Hello there!

In this case, according to the Brønsted-Lowry theory of acids, it is possible to realize that HBrO acts as the Brønsted-Lowry acid as it has a free hydrogen to give away to HCO₃⁻ which acts as the Brønsted-Lowry base able to accept the incoming hydrogen; therefore, the Brønsted-Lowry reaction is:

[tex]HCO^-_3+HBrO\rightleftharpoons H_2CO_3+BrO^-[/tex]

Best regards!

In the Brønsted-Lowry reaction between HCO⁻₃ and HBrO, the formed acid is H₂CO₃ and the formed base is BrO⁻.

According to Brønsted-Lowry acid-base theory:

An acid is a substance that donates H⁺.A base is a substance that accepts H⁺.

Let's consider the following Brønsted-Lowry reaction.

HCO⁻₃ + HBrO ⇄ acid + base

HBrO can only donate H⁺, so it is an acid.HCO⁻₃ can accept or donate H⁺. Here, it will accept the H⁺ donated by HBrO and behave as a base.

The resulting reaction is:

HCO⁻₃ + HBrO ⇄ H₂CO₃ + BrO⁻

H₂CO₃ can donate H⁺ so it is an acid.BrO⁻ can accept H⁺ so it is a base.

In the Brønsted-Lowry reaction between HCO⁻₃ and HBrO, the formed acid is H₂CO₃ and the formed base is BrO⁻.

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What is the pH of 0.42M aniline?

Answers

Answer:

Kb=x^2/0.42-x (eqn to calculate)

basicity (pkb) 9.3

Explanation:

There are about 26 deuterium atoms for every million hydrogen atoms across the universe, but it is six times as prevalent in the water on Earth and in other solar system bodies. Deuterium has one more ———— than hydrogen.


A. Ionic pair
B. Hydrogen bond
C. Proton
D. Electron
E. Neutron

Answers

Answer:

Option E

Deuterium has one more neutron than hydrogen

Explanation:

Deuterium is an isotope of Hydrogen and hence there will variation in the number of neutron

Hydrogen has 0 neutron

Deuterium has 1 neutron and

Tritium has 2 neutron

Thus option E is correct

In the universe, there are approximately 26 deuterium atoms for every million hydrogen atoms. Deuterium has one more neutron than hydrogen.

The correct option is E.

What is deuterium?

Deuterium is a stable isotope of hydrogen, whose atomic weight is 2.014.

It is also called heavy hydrogen, and it contains one neutron and one proton.

In nuclear fusion reactors, deuterium is employed as a tracer, while in heavy water moderated fission reactors, it is utilized to slow down neutrons.

Thus, the correct option is E.

Learn more about deuterium

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What can be different between products and reactants in a balanced equation?

a) The total mass of products and reactants

b) The total moles of each element present in the reactants and in the products.

c) The number of molecules in the reactants and in the products​​

Answers

Answer:

b) The total moles of each element present in the reactants and in the products.

Explanation:

Hello there!

In this case, since the law of conservation of mass is used to realize that the mass, atoms and molecules of all the species involved in a chemical reaction must be the same at both reactants and products, we can see that a and c stand for those that must be equal; thus, we infer that the moles can be different as they stand for the amount of substance which is related to the mass via molar masses. Therefore, the answer would be b) The total moles of each element present in the reactants and in the products.

Regards!

A car accelerates away from the starting line at 3.6 m/s2 and has the mass of 2400 kg. What is the net force acting on the vehicle?

Answers

Answer:

F = m x a

F = 2400 kg x 3.6 m/s2

F = 8,640 N

Explanation:

A rectangular block has dimension 20m x10mx5m and mass of 400kg calculate the density of the rectangular block

Answers

Answer:

0.4 kg/m^3

Explanation:

v (volume) = 20m x 10m x 5m = 1000 m^3

w (weight) = 400 kg

d (density) = w / v

d = 400 / 1000 = 0.4 kg per cubic meter (kg/m^3)

I apologize if this is a little complex, however all of the math is there, if you're interested then look it over. Otherwise I've provided the answer in the units used for the dimensions and weight provided.

Help help help :/

Please

Answers

super giants have the greatest luminosity!

Is anyone good at chemistry if so can someone help me please ?

(NO LINKS)

Answers

Since pH + pOH = 14, given a pOH of 4.53, our pH would be 14 - 4.53 = 9.47. And since the pH is greater than 7, this solution is basic. So, the correct answer choice would be D.

Please disregard this

Answers

well i need points

Explanation:

thanks

15 The Following statement describes which body system? It also produces blood cells, and stores calcium. It regulates endocrine as well. This specific system uses all bones & joints in your body. A. The Lymphatic System B.The Muscular System C.The Reproductive System D.The Skeletal System​

Answers

the skeletal system. it produces blood cells and stores calcium while regulating endocrine. :)

What is the difference between Benedict’s test and Barfoeds test?

Answers

Answer:

Benedict's test would determine if the sample is a reducing sugar, and Barfoed's test would determine if it is a monosaccharide or disaccharide.

Please help
I need to turn in in 5 min


<3

Answers

i am learning this right now in earth science! the answer is the sun;)

3. Jordan built a model of a neutral helium atom.
Nucleus
Proton
Neutron
Electron
What change would fix the mistake in Jordan's model?

Answers

answer is nucleus bc a helium atom only has protons neutrons and electrons

(d) Other
sugar molecules become
_____ and are carried away from the crystal.
the force of attraction is

Answers

Answer:

liquid

Explanation:

defiantly

5.50 L of a 0.190 M CaCl2M CaCl2 solution
How do you find Grams?

Answers

Answer:

115.891

Explanation:

Molarity is equal to moles/liters so to get moles we multiply molarity by liters, after this we multiply the moles by the total atomic weight of the compound to get grams

What are characteristics of absorption spectra? Check all that apply.
Light is absorbed, which produces characteristic lines.
| Light is emitted, which produces characteristic lines.
Lines are dark on a visible light background.
Lines are brightly colored on a black background.
Lines are produced by electrons being excited.
Lines are produced from electrons returning to a lower energy level.

Answers

Answer:

Light is absorbed, which produces characteristic lines.

Lines are dark on a visible light background.

Lines are produced by electrons being excited.

Explanation:

Edg

The characteristics of absorption spectra light is absorbed, which produces characteristic lines, lines are dark on a visible light background and Lines are produced by electrons being excited.

What is absorption spectra?

The term "absorption spectroscopy" applies to spectroscopic methods that assess how much radiation interacts with a sample and is absorbed as a proportion of frequency or wavelength. The sample takes in photons, meaning energy, from the emitting field.

What are electrons?

The electron would be a subatomic particle with a negative one fundamental charge electric charge. Due to their lack of components or substructure, electrons, which have become part of the lepton particle family's first generation, could be typically regarded to be elementary particles.

The percentage of incoming electromagnetic energy that a material absorbs across a variety of frequencies is displayed in the material's absorption spectrum. In a way, an emission spectrum would be the converse of an absorption spectrum.

To know more about absorption spectrum and electrons

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A common ancestor is an organism that is the
O direct ancestor of two or more different organisms
O direct ancestor of one organism.
O indirect ancestor of two or more different organisms.
O indirect ancestor of one organism.

Answers

I think it’s the third option
Hope that is right XD

A common ancestor is an organism that is the direct ancestor of two or more different organisms.

A common ancestor refers to an organism that is shared by multiple organisms, serving as the direct predecessor to those organisms. It is the point in evolutionary history where two or more distinct lineages diverged from a single ancestral lineage. This means that the common ancestor is the starting point from which different species or groups of organisms evolved over time.

In the context of evolution, organisms share common ancestry due to the process of descent with modification. Through genetic inheritance and gradual changes in traits over generations, new species arise from a common ancestor. As these species undergo divergent evolution, they develop distinct characteristics and adaptations, eventually becoming separate lineages.

Hence, the correct option is the direct ancestor of two or more different organisms.

Learn more about evolution here:

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Graphite, an allotrope of carbon, is converted into cubic diamond through a process that may take a billion years or longer. As illustrated above, scientists can make synthetic diamonds using a certain process in about one week. However, these synthetic diamonds have carbon atoms in a hexagonal lattice. Diamonds with a carbon atoms in a cubic lattice are not produced even though they are thermodynamically more stable than hexagonal diamond. Which of the following best justifies why the synthetic process produces hexagonal diamond and not the more thermodynamically stable cubic diamond?

a. The amount of energy required to create new bonds between carbon atoms in cubic diamond is much greater than the amount of energy required to create hexagonal diamond.
b. The amount of energy required to create new bonds between carbon atoms in cubic diamond is much smaller than the amount of energy required to create hexagonal diamond.
c. The activation energy needed to form cubic diamond is much less than the activation energy needed to form hexagonal diamond.
d. The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond.

Answers

Answer:

The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond.

Explanation:

The activation energy refers to the minimum energy that reacting species must possess before they can undergo a particular chemical reaction.

This implies that if species do not possess the activation energy, they hardly undergo a given reaction. The activation energy is the barrier between reactants and products.

Hence, a reaction that has a very high activation energy occurs slowly or may not even occur. The activation energy needed to form cubic diamond is much greater than the activation energy needed to form hexagonal diamond hence the synthetic process produces hexagonal diamond and not the more thermodynamically stable cubic diamond.

Which product forms from the synthesis reaction between lithium (Li) and oxygen (O)?
A. Li2O
B. LiO
C. LiO2
D. Li2O2​

Answers

Answer:

A Li2O

Explanation:

Li has a 1+ charge and O has a 2- charge so to balance the charges there needs to be 2 Li for every 1 O

The product forms from the synthesis reaction between lithium (Li)and oxygen (O) is Li₂O. The correct option is A.

What is synthesis reaction?

Synthesis reaction is the reaction when two or more products combine to form a single product.

An example of a synthesis reaction is the combination of sodium (Na) and chlorine (Cl) to produce sodium chloride (NaCl).

Thus, the correct option is A. Li2O.

Learn more about synthesis reaction

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how are electrons arranged in molecules of compounds?​

Answers

Answer:

electrons are always in the outer shell

When an electron moves, it absorbs or produces energy in the form of photons. Electrons surround the nucleus, which is made up of protons and neutrons, and they all form an atom. The exchange or sharing of electrons between atoms is the main cause of chemical bonding.

Hope this helps you :)

Identify the kind(s) of intermolecular forces that would occur between the solute and solvent in an acetic acid (which is polar and contains an OHOH group) solution. Check all that apply. Check all that apply. dispersion hydrogen bonding ion-dipole dipole-dipole

Answers

Explanation:

The acetic acid is a polar compound. The polar molecules have a positive and negative extreme for this reason they are dipoles. The dipoles can attract other dipoles or ions. So, it can establish ion-dipole and dipole-dipole forces with the solute. In addition, acetic acid has a hydroxyl group that can interact with hydrogens or other very electronegative atoms (oxygen, nitrogen and fluor) forming hydrogen bridge junctions.

what part of of the universe is less than 1 km in diameter

Answers

Answer:

Meteoroids

Explanation:

Meteoroids are the elements of the universe that have the smallest diameter among all elements, reaching less than 1 km in diameter. They are any rocky or metallic body, which exists in space and does not reach more than 100 meters. It is common for meteoroids to fall to earth, but their impact is not as destructive as the impact of other space bodies, due to their tiny size.

The half-life of I-37 is 8.07 days. If 25 grams are left after 40.35 days, how many grams were in the original sample?

Answers

Answer:

800 g

Explanation:

We can express the decay of I-37 using the formula:

Final Mass = Initial Mass * [tex]0.5^{\frac{Time}{Half-Life} }[/tex]

We input the data:

25 g = Initial Mass * [tex]0.5^{(\frac{40.35}{8.07})}[/tex]

And solve for Initial Mass:

25 g = Initial Mass * [tex]0.5^{5}[/tex]25 g = Initial Mass * 0.03125Initial Mass = 800 g

Meaning that out 800 grams of I-37, only 25 will remain after 40.35 days.

PLSSS HELP ASAP!!!!!!!!​

Answers

Answer:

i-dk but A seems most logical to me

Explanation:

Brainliest will be given to correct answer :)
Chemistry II Help please! Last question on my homework and I'm stuck.

Thank you!

Answers

Answer: [tex]\Delta G[/tex] for the reaction   is -90kJ

Explanation:

The balanced chemical reaction is,

[tex]2H_2S(g)+SO_2(g)\rightarrow 3S_{rhombic}(s)+2H_2O(g)[/tex]

The expression for Gibbs free energy change is,

[tex]\Delta G=[n\times G_{products}]-[n\times G_{reactants}][/tex]

Putting the values we get :

[tex]\Delta G=[3\times G_f{S,rhombic}+2\times G_f{H_2O}]-[2\times G_f{H_2S}+1\times G_f{SO_2}][/tex]

[tex]\Delta G=[(3\times 0kJ/mol)+(2\times -229kJ/mol)]-[(2\times -34kJ/mol) +(1\times -300kJ/mol)][/tex]

[tex]\Delta G=-90kJ[/tex]

Thus [tex]\Delta G[/tex] for the reaction[tex]2H_2S(g)+SO_2(g)\rightarrow 3S_{rhombic}(s)+2H_2O(g)[/tex]   is -90kJ

what is the speed of the electromagnetic waves please solve using correct units ill give brainliest.​

Answers

Answer:

3 m

Explanation:

We'll begin by converting 99.9 MHz to Hz. This can be obtained as follow:

1 MHz = 10⁶ Hz

Therefore,

99.9 MHz = 99.9 MHz × 10⁶ Hz / 1 MHz

99.9 MHz = 99.9×10⁶ Hz

Finally, we shall determine the wavelength. This can be obtained as follow:

Frequency (f) = 99.9×10⁶ Hz

Velocity (v) = 3×10⁸ m/s

Wavelength (λ) =?

Velocity = wavelength × frequency

v = λf

3×10⁸ = λ × 99.9×10⁶

Divide both side by 99.9×10⁶

λ = 3×10⁸ / 99.9×10⁶

λ = 3 m

Thus, the wavelength of the electromagnetic wave is 3 m.

Oxidation elements of the numbers H2CO2

Answers

Carbon atoms oxidation number is +2.Hydrogen's oxidation number is +1.Oxygen's oxidation number is -2.

How many liters of nitrogen gas (N₂) are required to produce 7.5 x 10²⁶ molec NH₃ gas with excess of hydrogen gas at STP?

Answers

Answer: The volume of nitrogen gas that is required is 13944 L.

Explanation:

Given values:

Number of molecules of ammonia gas = [tex]7.5\times 10^{26}[/tex]

According to the mole concept:

[tex]6.022\times 10^{23}[/tex] number of molecules are present in 1 mole of a compound

So, [tex]7.5\times 10^{26}[/tex] number of molecules will be present in [tex]\frac{1}{6.022\times 10^{23}}\times 7.5\times 10^{26}=1.245\times 10^3 moles[/tex] of ammonia gas

The chemical equation for the formation of ammonia gas follows:

[tex]N_2 (g) + 3H_2(g) \rightarrow 2NH_3(g)[/tex]

According to the stoichiometry of the reaction:

2 moles of ammonia gas are produced from 1 mole of nitrogen gas

So, [tex]1.245\times 10^3[/tex] moles of ammonia gas will be produced from [tex]\frac{1}{2}\times 1.245 \times 10^3=6.225\times 10^2[/tex] moles of nitrogen gas

At STP conditions:

1 mole of a gas occupies 22.4 L of volume

So, [tex]6.225 \times 10^2[/tex] moles of nitrogen gas will occupy [tex]\frac{22.4 L}{1 mol}\times 6.225\times 10^2 moles=13944 L[/tex] of volume

Hence, the volume of nitrogen gas that is required is 13944 L.

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