Which of the following must be true about a reaction if it is only spontaneous at high temperatures?

It is exothermic, with both negative enthalpy and entropy changes.

It is endothermic, with both positive enthalpy and entropy changes.

It is exothermic, with a negative enthalpy and positive entropy change.

It is endothermic, with a positive enthalpy and negative entropy change.


2. If the reaction between two solutions has a positive enthalpy change, which of the following best describes the reaction? (2 points)

It is exothermic and heat is added to the system.

It is endothermic and heat is added to the system.

It is exothermic and heat is lost to the surroundings.


3) Which statement below best describes the relationship of the reaction below? (2 points)
3A + B yields 2AB

The rate of formation of AB is twice the disappearance of A.

For every two AB produced, the reaction requires three A.

The rate of disappearance of A is two times the formation of AB.

4) Describe how you would use the information depicted on the potential energy diagram below to determine the amount of required activation energy and the enthalpy change of the reaction. (2 points)
(see chart)

Answer: $1338.16

Explanation: Total cost of stock= $2568

Total cost of stock including the brokerage [tex]=2568+\frac{0.5}{100}\times {2568}=2580.84[/tex]$

Selling price of stock = $3928

Selling price of stock including trading fee=($3928-$7)=$3919

Net Proceeds = Net selling price of stock - Cost Price of stock

Net Proceeds = ($3919 - $2580.84) = $1338.16

Eleanor's net proceeds from the sale of stock after accounting for the purchase broker's fee and the selling fee are $3908.16.

Eleanor initiated two transactions: purchasing and selling stock. When eleanor purchased $2568 worth of stock, she paid a broker's fee of 0.5%, which is calculated as $2568 x 0.5% = $12.84. Later, when the stock price increased to $3928 and she sold the stock, she incurred a flat fee of $7 from an online broker. The gross proceeds from the sale are $3928.

The net proceeds need to account for both the initial broker's fee and the selling fee. Therefore, her net proceeds are:

As a result, Eleanor's net proceeds are calculated as follows:

Net proceeds = $3928 - $12.84 - $7 = $3908.16

Therefore, the Net proceeds is $3908.16.

Answer:

The force will change as the net force applied will increase.

Explanation:

If you are pushing on a door really hard, trying to make it slide open and if your friend is also stand behind you and contributes to help you push towards the door, then the overall force will change as the net amount of force applied will increase.

This is an example of Newton's second law according to which you need more force to move an object with heavier mass.

F = ma

Therefore, the force applied by you and your friend will add and the net force applied will be increased.

Physical properties.

Answer is:  Fluorine and chlorine, because they are both halogens.

Halogen elements are in group 17: fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). They are very reactive and easily form many compounds.

In the gaseous state halogens form diatomic covalent molecules.

Halogen diatomic molecules (halogen means "salt producing") in the gaseous state in room temperature are fluorine (F₂) and chlorine (Cl₂).

Both molecules have single covalent bond and they are very reactive.

Halogens need to gain one electron to have electron cofiguration like next to it noble gas. For example, fluorine has 9 electrons and it gain easily one electron in chemical reaction to have electron configuration like noble gas neon (Ne) with 10 electrons.

Answer:

Fluorine and chlorine, because they are both halogens

Explanation:

i think that the answer is d. millions of small rocky objects

Millions of small rocky objects called asteroids orbit the Sun in a belt between Mars and Jupiter.

D. millions of small rocky objects

Not necessarily.

Isomers might differ in polarities. They will end up with different physical properties such as melting points.

Example:

Both 1,4- and 1,2-dichlorobenzene contains two chlorine atoms connected to a benzene ring. The two molecules are structural isomers.

The two chlorine atoms are adjacent to each other in the 1,2 isomer. The molecule is asymmetric and polar.

The two chlorine align with an axis of symmetry in the 1,4 isomer. The molecule is symmetric. The dipoles would cancel out to produce a nonpolar molecule.

Dipole-dipole interactions are typically stronger than induced dipole in isomers. As a result, the 1,2 isomer has a higher melting point.

Answers:  

p(NO) = 0; p(O₂) = 0.300 atm; p(NO₂) = 0.400 atm  

Step-by-step explanation:  

Step 1. Moles of NO  

pV = nRT  

n = (pV)/(RT)  

p = 0.500 atm  

R = 0.082 06 L·atm·K⁻¹mol⁻¹  

T = (22 + 273.15)  

T = 295.15 K  

n = (0.500 × 6.00)/(0.082 06 × 295.15)  

n = 3.00/24.22  

n = 0.1239 mol  

===============  

Step 2. Moles of O₂  

p = 2.50 atm  

V = 1.50 L  

n = (2.50 × 1.50)/24.22  

n = 3.75/24.22  

n = 0.1548 mol  

===============  

Step 3. Identify the limiting reactant  

             2NO  +   O₂  ⟶  2NO₂  

n/mol: 0.1239  0.1548  

Calculate the moles of NO₂ we can obtain from each reactant.    

From NO:  

The molar ratio of NO₂: NO is 2:2

Moles of NO₂ = 0.1239 × 2/2  

Moles of NO₂ = 0.1239 mol NO₂  

From O₂:  

The molar ratio of NO₂: O₂ is 2:1.  

Moles of NO₂ = 0.1548 × 2/1  

Moles of NO₂ = 0.3097 mol NO₂  

NO is the limiting reactant because it gives the smaller amount of NO₂.  

===============  

Step 4. Moles of each species after reaction  

               2NO  +       O₂  ⟶  2NO₂  

I/mol:     0.1239      0.1548         0  

C:/mol: -0.1239     -0.06193  +0.1239  

F/mol:        0          0.0929      0.1239  

===============  

Step 5. Partial pressure of NO  

p(NO) = 0  

===============  

Step 6. Partial pressure of O₂  

pV = nRT  

p = (nRT)/V  

V= 6.00 + 1.50  

V = 7.50 L  

p = (0.0929 × 24.22)/7.50  

p = 2.25/7.50  

p = 0.300 atm

===============  

Step 7. Partial pressure of O₂  

p = (0.1239 × 24.22)/7.50  

p = 3.00/7.50  

p = 0.400 atm  

p(NO) = 0; p(O₂) = 0.300 atm; p(NO₂) = 0.400 atm  

The partial pressure of NO is 0 atm, and [tex]\rm NO_2[/tex] is 0.400 atm at the end of the reaction.

The concentration of NO and [tex]\rm O_2[/tex] initially are;

By ideal gas equation:

PV =nRT

P = pressure

V = volume

n = moles

R = constant = 0.0816 L.atm/mol.K

T = temperature = 22 [tex]\rm ^\circ C[/tex] = 273 + 22 K = 295 K

Moles of NO = [tex]\rm \frac{PV}{RT}[/tex]

Moles of  NO = [tex]\rm \frac{0.5\;\times\;6}{0.0816\;\times\;295}[/tex]

Moles of NO = 0.1239 moles

Moles of [tex]\rm O_2[/tex] = [tex]\rm \frac{2.50\;\times\;1.50}{0.0816\;\times\;295}[/tex]

Moles of [tex]\rm O_2[/tex] = 0.1548 moles

The reaction will be:

[tex]\rm 2\;NO\;+\;O_2\;\rightarrow\;2\;NO_2[/tex]

2 moles of NO gives 2 moles of [tex]\rm NO_2[/tex]

So, 0.1239 moles of NO gives 0.1239 moles of [tex]\rm NO_2[/tex]

1 mole of [tex]\rm O_2[/tex] gives 2 moles of [tex]\rm NO_2[/tex]

0.1548 moles of [tex]\rm O_2[/tex] gives 0.3097 moles of [tex]\rm NO_2[/tex]

Since No produces smaller amount of [tex]\rm NO_2[/tex], it is the limiting factor.

Partial pressure of NO = 0 since it is completely used.

Partial pressure of [tex]\rm NO_2[/tex] = [tex]\rm \frac{nRT}{V}[/tex]

n = 0.1239 moles

Total volume = 6 + 1.50

V = 7.5 L

Partial pressure of [tex]\rm NO_2[/tex] = [tex]\rm \frac{0.0929\;\times\;0.0816\;295}{7.5}[/tex]

Partial pressure of [tex]\rm NO_2[/tex] = 0.400 atm

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Rain.

I finished the Future Diary im so sad seeing Yuki and Yuno for the last time. Im listening to the saddest song in the OST called "Here with you" im literally crying D:

the wavelength  of electromagnetic radiation  having a frequency  of 1.37 × 10¹⁵  is  2.18 ×  10⁻⁷

  calculation

wavelength = speed of light/ frequency

speed  of light = 3.0  × 10⁸ m/sec

 frequency=  1.37  × 10¹⁵ hz = 1.37× 10¹⁵ 1/sec

wavelength  = (3.0 × 10⁸ m/sec) / (1.37  × 10¹⁵ 1/sec)

 = 2.18 × 10 ⁻⁷ m

Answer:

D. It is found in the nucleus of a cell.

Explanation:

Friedrich Miescher first discovered DNA as a biomolecule. He isolated nuclein in which DNA is wrapped around cellular proteins such as Histones. Many years after Miescher's discovery it was proved that DNA is the hereditary material in cells. In the times of Miescher proteins were believed to be the molecules of hereditary.

The important property of DNA that Friedrich Miescher discovered is that it is made partly of sugar molecules. Option A.

Friedrich Miescher discovered an essential property of DNA, revealing that it contains sugar molecules. In the late 1800s, he isolated a substance from cell nuclei that contained both phosphorus and nitrogen.

Later recognized as DNA, this discovery laid the foundation for understanding the molecular composition of genetic material.

While options B, C, and D are also relevant aspects of DNA's structure and location, it was Miescher's identification of DNA's sugar component that marked a pivotal step in unraveling the molecule's role in inheritance and genetics.

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NaCl and H2O.

The products are typically the elements/compounds on the right side of the equation or the right side of the arrow. The left side of the arrow would be the reactants of the equation.

Hope this helps!

Answer:

NaCl and H2O

Explanation:

Answer:

See below.  

Step-by-step explanation:

The graph (shown below) is a series of four lines.

Each line starts at a high value and decreases as the atomic number increases  

They are like a series of waves in which the amplitude rises and falls periodically as the waves go by.

In chemical terms, we would say that the atomic radius varies periodically with increasing atomic number.

The atomic radius graph shows periodicity through patterns of increasing and decreasing atomic sizes. As you move left to right in a period, atomic radius decreases, while it increases as you move down a group.

The atomic radius graph from element 1 to 36 shows periodicity by illustrating the regular patterns in the sizes of atoms across different periods and groups on the periodic table. Within each period, the atomic radius decreases as the atomic number (Z) increases, as seen in the trend from potassium (K) to krypton (Kr). Conversely, within a group, such as the alkali metals, the atomic radius increases with the atomic number. This is depicted by the graph's jagged line that peaks at the locations of alkali metals and has minima at the noble gases. The largest atoms are found in the lower left corner of the periodic table and the smallest in the upper right corner.

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Answer:

It will not dissolve. More crystals will separate from the solution.  

Step-by-step explanation:

If you add a crystal of ammonium nitrate to a supersaturated solution of the solute, it will not dissolve.  

Instead, it will act as a "seed" on which more ammonium nitrate crystals will form.

They will separate from the solution as long, colourless, needle-like crystals until the solution is no longer supersaturated.

Adding a crystal of ammonium nitrate to a supersaturated solution likely causes crystallization instead of further dissolving, as the solution already has more solute than equilibrium allows.

If a crystal of ammonium nitrate is added to a supersaturated ammonium nitrate solution, it is likely to initiate crystallization rather than dissolve because the solution already contains more dissolved solute than can be maintained at equilibrium. Supersaturated solutions are unstable, and the introduction of a seed crystal often precipitates rapid crystallization. Ammonium nitrate is known to dissolve in water endothermically, and while it will dissolve to reach a saturation point, once a solution is supersaturated, additional solid will not dissolve and will instead cause the excess solute to crystallize out of the solution.

 The atomic number increases moving left to right across a period and subsequently so does the effective nuclear charge. Therefore, moving left to right across a period the nucleus has a greater pull on the outer electrons and the atomic radii decreases.

Valence is the same in every family... except for transition metals, it goes from 1-8

dk if that helped

the correct answer is "all members within any period"

Answer:  D) The lead (II) nitrate is the reaction's limiting reactant.

Explanation:

[tex]\text{no of moles of iron(III) chloride}={\text{Molarity}\times {\text{Volume in L}}[/tex]

[tex]\text{no of moles of iron(III) chloride}={0.100M}\times {0.05L}=5\times 10^{-3}[/tex]

[tex]\text{no of moles of lead nitrate}={\text{Molarity}\times {\text{Volume in L}}[/tex]

[tex]\text{no of moles of lead nitrate}={\text{0.100M}\times {0.05L}=5\times 10^{-3}[/tex]

[tex]2FeCl_3+3Pb(NO_3)_2\rightarrow 2Fe(NO_3)_3+3PbCl_2[/tex]

As can be seen from the balanced chemical equation,  3 moles of lead nitrate react with 2 moles of ferric chloride.

Thus [tex]5\times 10^{-3}[/tex] moles of lead nitrate react with [tex]=\frac{2}{3}\times {5\times 10^{-3}}={3.33\times 10^{-3}}[/tex] of ferric chloride.

[tex]5\times 10^{-3}-{3.33\times 10^{-3}}=1.67\times 10^{-3}[/tex]moles of ferric chloride will be left unreacted.

Limiting reagent is the reagent which limits the formation of product. Excess reagent is one which is in excess and thus remains unreacted.

Thus lead nitrate is the limiting reagent and ferric chloride is the excess reagent.

Picture A and B are examples of pure substances.

Classifying substances based on composition, without seeing the pictures but assuming the guideline of uniform composition defining pure substances, the culmination is that if both Pictures B and D exhibit uniform compositions, they should be categorized as pure.

This discussion refers to the subject of Chemistry which involves classifying substances based on their composition. Without access to actual images, supposing we have a comprehension of the classification criteria: pure substances consist of a single type of particles whereas mixtures are composed of, more so, diverse particle types. If we take pure substance as uniform in composition, and Picture B and Picture D exhibit that characteristic, then the answer should be 'Pictures B and D are examples of pure substances'.

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Answer: The number is 2.

Explanation: The molecular formula of water is [tex]H_2O[/tex]. It contains two atoms of hydrogen and one atom of oxygen.

Thus there is an odd number of oxygen atom. To make the atoms even , with the smallest number, we multiply the formula by 2. The number of oxygen atoms in 2[tex]H_2O[/tex] will be 2 , which is an even number.

Answer:

B. A harmful compound can become harmful when its elements are seperated.

Explanation:

In the question, common table salt, NaCl was the illustration.

NaCl is a crystalline solid whjch has different benefits like for preservation, add taste to foods etc. NaCl is generally consumed by humans daily and is found readily. This goes to show that NaCl is a harmless compound but the individual elements that is, Soduim and Chlorine gas,

2Na + Cl2 --> NaCl

Soduim metal is a reactive and unstable element with 1 (valence) electron in its outer shell. Hence why the reaction of sodium strips with water is explosive.

Chlorine gas is very poisonous, unstable as well as reactive because of the 7 (valence) electrons in its outermost shell.

Answer:

the only element above is potassium

Answer: The correct answer is option B.

Explanation: Reactivity of elements is defined as the tendency to loose or gain electrons.

These reactions are a type of single displacement reactions. A single displacement reaction is a type of reaction in which an element displaces another element in a chemical reaction. These are studied with the help of reactivity series.

The element which lies above in the reactivity series can easily displace the element which lies below in the reactivity series.

Option A: This reaction will not yield a stable product because Zinc lies below Aluminium in the reactivity series.

[tex]AlBr_3+Zn\rightarrow \text{No reaction}[/tex]

Option B: This reaction will yield a stable product because Sodium lies above Calcium in the reactivity series.

[tex]CaBr_2+2Na\rightarrow 2NaBr+Ca[/tex]

Option C: This reaction will not yield a stable product because Hydrogen lies below Magnesium in the reactivity series.

[tex]MgBr_2+H_2\rightarrow \text{No reaction}[/tex]

Option D: This reaction will not yield a stable product because Calcium lies below Barium in the reactivity series.

[tex]BaBr_2+Ca\rightarrow \text{No reaction}[/tex]

Option E: This reaction will not yield a stable product because barium lies below Lithium in the reactivity series.

[tex]2LiBr+Ba\rightarrow \text{No reaction}[/tex]

The answer is C, because wind turbines are used to produce electricity, and it's also the most safest way--but they are  expensive.

Answer:

A dipole-dipole refers to an intermolecular force, which takes place in between the two molecules that are polar. They take place when the slight negative terminal of one polar molecule gets fascinated towards the slight positive terminal of another polar molecule. These are weaker bonds in comparison to hydrogen bonds, however, they are stronger in comparison to London dispersion forces.

Dipole interactions are caused by the electrostatic attraction of the partial negative end of a molecule to the partial positive end of another. These interactions include dipole-dipole attractions, and van der Waals forces, such as electric dipoles, induced dipoles, and hydrogen bonding.

Dipole interactions, also referred to as dipole-dipole attractions, are caused by the electrostatic attraction of the partial negative end of one polar molecule for the partial positive end of another. These interactions are part of the larger group of intermolecular attractive forces, or van der Waals forces, which are fundamental to the behavior of liquids and solids.

Electric dipoles form in a system of two equal but opposite charges at a fixed distance apart, such as in an atom or a molecule where the positive and negative charges are displaced by opposing forces. An example of this is a water molecule inside a microwave oven. Induced dipoles also occur, which are temporary dipoles formed when the electrons of an atom or molecule are distorted by the instantaneous dipole of a neighboring atom or molecule.

Dipole interactions also include hydrogen bonding, which occur when hydrogen is bonded to one of the three most electronegative elements: F, O, or N, resulting in exceptionally strong dipoles. These concepts and interactions between particles are fundamental to understanding behavior at a molecular and atomic level in chemistry.

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Answer:

Proteins

Explanation:

Building blocks of proteins are amino acids that are bonded by peptide bonds. The bonded amino acids form a long chain, which is essentially a protein.  Proteins are essential to the body as they control the structure, function, and regulation of the different cells, tissues and organs that make up different organisms. The arrangement of the amino acids are specific to a certain protein.

Answer is:  the number of bromine molecules is 1.35·10²⁴.

n(Br₂) = 2.25 mol; amount of bromine molecules.

Na = 6.022·10²³ mol⁻¹; Avogadro constant.

N(Br₂) = n(Br₂) · Na.

N(Br₂) = 2.25 mol · 6.022·10²³ mol⁻¹.

N(Br₂) = 13.54 ·10²³.

N(Br₂) = 1.35·10²⁴; number of bromine molecules.

Final answer:

The number of bromine (Br2) molecules present in 2.25 mol is calculated by multiplying the moles of substance by Avogadro's number, yielding 1.355 × 10^24 molecules of Br2.

Explanation:

To calculate the number of bromine (Br2) molecules present in 2.25 mol, we need to utilize Avogadro's number, which is approximately 6.022 × 1023 molecules/mol. The number of molecules can be found by multiplying the moles of substance by Avogadro's number.

Here’s the calculation:

Multiply the number of moles of bromine by Avogadro’s number: 2.25 mol × 6.022 × 1023 molecules/mol = 1.355 × 1024 molecules of Br2.

   The volume  at standard  pressure  is 162.5 L

  calculation

The  volume  at Standard pressure (760  mm hg)  is calculated using the Boyle's  law formula

That is P₁V₁ =P₂V₂

where;

P₁=650 mmHg

V₁= 190 L

P₂ = 760 mm hg

V₂ =? L

make   V₂   the formula of the subject  by diving  both side of equation by P₂

V₂  is therefore = P₁V₁/P₂

= {(650 mmHg x 190 L) / 760 mmHg} =162.5 L

Answer : The volume of the gas at standard pressure (1 atm) is, 162.45 L

Solution : Given,

Initial pressure of gas = 650 mmHg = [tex]\frac{650}{760}=0.855atm[/tex]    [tex](1atm=760mmHg)[/tex]

Initial volume of gas = 190 L

Final pressure of gas = 1 atm     (standard pressure is 1 atm)

Formula used : [tex]\frac{P_1}{P_2}=\frac{V_2}{V_1}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas

[tex]P_2[/tex] = final pressure of gas

[tex]V_1[/tex] = initial volume of gas

[tex]V_2[/tex] = final volume of gas

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

[tex]\frac{0.855atm}{1atm}=\frac{V_2}{190L}[/tex]

By rearranging the terms, we get the final volume of the gas.

[tex]V_2=162.45L[/tex]

Therefore, the volume of the gas at standard pressure (1 atm) is, 162.45 L

Answer:

1) Mg; 2)18 g  

Step-by-step explanation:

1) Identify the limiting reactant

We have the masses of two reactants, so this is a limiting reactant problem.  

We know that we will need a balanced equation with masses, moles, and molar masses of the compounds involved.  

Step 1. Gather all the information in one place with molar masses above the formulas and masses below them.  

M_r:      24.30  36.46

               Mg  + 2HCl ⟶ MgCl₂ + H₂

Mass/g:   25        20

Step 2. Calculate the moles of each reactant  

Moles of Mg   = 25 g × 1 mol/24.30 g

Moles of Mg  = 1.03 mol Mg

Moles of HCl = 20 g× 1mol/36.46 g

Moles of HCl = 0.549 mol HCl

Step 3. Identify the limiting reactant  

Calculate the moles of H₂ we can obtain from each reactant.  

From Mg:

The molar ratio is 1 mol H₂:1 mol Mg

Moles of H₂ = 1.03 mol Mg × 1mol H₂/1 mol Mg

Moles of H₂ = 1.03 mol H₂

From HCl:

The molar ratio is 1 mol H₂:2 mol HCl

Moles of H₂ = 0.549 mol HCl × 1 mol H₂/2 mol HCl

Moles of H₂ = 0.274 mol H₂

The limiting reactant is HCl because it gives the smaller amount of H₂.

The excess reactant is Mg.

2) Calculate the mass of Mg remaining

Step 1. Calculate the moles of Mg reacted

The molar ratio is 1 mol Mg: 2 mol HCl

Moles of Mg reacted = 0.549 mol HCl × 1 mol Mg/2 mol HCl

Moles of Mg reacted = 0.274 mol Mg

Step 2. Calculate the mass of Mg reacted

Mass of Mg reacted = 0.274 mol Mg × 24.30 g Mg/1 mol Mg

Mass of Mg reacted = 6.66 g Mg

Step 3. Calculate the mass of Mg remaining

Mass remaining = original mass – mass reacted

Mass remaining = (25 – 6.66) g Mg

Mass remaining = 18 g Mg