what do you mean by PCM​

Answer:

47.25 moles

Explanation:

First we find the amount of O2 in mass in air

That will be = (21/100) x 3.6

This will give us=0.756 kg

Now we want to find the moles, so we convert this mass into grams since we are going to be working with grams= 0.756 x 1000 = 756 grams

Now, to find the number of moles:

moles= mass / molar mass

in this case mass is 756 grams and molar mass of oxygen is 16

So, the mass divided by molar mass would be =756/16= 47.25 moles of O2

Answer:

answers is -d

Explanation:

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Answer:

Answer: When water freezes, water molecules form a crystalline structure maintained by hydrogen bonding. Solid water, or ice, is less dense than liquid water. Ice is less dense than water because the orientation of hydrogen bonds causes molecules to push farther apart, which lowers the density.

Explanation:

Answer:120

Explanation: I think

Answer:

1321.177 grams.

Explanation:

each mole of carbon is 12.0107 grams.

Answer: The molecular weight of tris buffer is 121 g/mol

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in L

moles of tris buffer = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{12.1g}{Mg/mol}[/tex]

Now put all the given values in the formula of molality, we get

[tex]0.1=\frac{12.1g}{Mg/mol\times 1L}[/tex]

[tex]M=121g/mol[/tex]

Therefore, the molecular weight of tris buffer is 121 g/mol

Answer:

780 moles e⁻

Explanation:

N⁺⁵ in NO₃⁻ requires 2(5e⁻)  => 1/2 mole N₂(g)

That is, NO₃⁻ + 2(5e⁻/mole N₂ formed) => 1/2N₂

NO₃⁻ + 10e⁻/mole N₂ formed => 1/2N₂

∴ 78 mole NO₃⁻ requires 780 moles e⁻  => 1/2(78) moles N₂ = 39 moles N₂

Denitrification is the reduction of nitrate to dinitrogen gas. It is achieved by denitrifying organism According to stoichiometry, 390 moles of electrons are required to reduce  78 moles of nitrate to dinitrogen gas.

The equation of denitrification;

2 NO3− + 10 e− + 12 H+ → N2 + 6 H2O

From this equation;

2 moles of nitrate requires 10 moles of electrons

78 moles of nitrate requires 78 * 10/2 = 390 moles of electrons

Hence, 390 moles of electrons are required to reduce  78 moles of nitrate to dinitrogen gas.

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Answer:

10.53 moles ZnCl2

Explanation:

Answer:

Approximately [tex]4.92[/tex].

Explanation:

Initial volume of the solution: [tex]V = 190.0\; \rm mL = 0.1900\; \rm L[/tex].

Initial quantity of [tex]\rm NH_3[/tex]:

[tex]\begin{aligned} n({\rm NH_3}) &= c({\rm NH_3}) \cdot V({\rm NH_3}) \\ &= 0.3733\; \rm mol \cdot L^{-1} \times 0.1900\; \rm L \\ &\approx 0.154375\; \rm mol\end{aligned}[/tex].

Ammonia [tex]\rm NH_3[/tex] reacts with hydrochloric [tex]\rm HCl[/tex] acid at a one-to-one ratio:

[tex]\rm NH_3 + HCl \to NH_4 Cl[/tex].

Hence, approximately [tex]n({\rm HCl}) = 0.154375\; \rm mol[/tex] of [tex]\rm HCl\![/tex] molecules would be required to exactly react with the [tex]\rm NH_3\![/tex] in the original solution and hence reach the equivalence point of this titration.

Calculate the volume of that [tex]0.3733\; \rm mol \cdot L^{-1}[/tex] [tex]\rm HCl[/tex] solution required for reaching the equivalence point of this titration:

[tex]\begin{aligned}V({\rm HCl}) &= \frac{n({\rm HCl})}{c({\rm HCl})} \\ &\approx \frac{0.154375\; \rm mol}{0.3733\; \rm mol \cdot L^{-1}} \approx 0.413541\; \rm L\end{aligned}[/tex].

Hence, by the assumption stated in the question, the volume of the solution at the equivalence point would be approximately [tex]0.413541\; \rm L + 0.1900\; \rm L \approx 0.6035\; \rm L[/tex].

If no hydrolysis took place, [tex]0.154375\; \rm mol[/tex] of [tex]\rm NH_4 Cl[/tex] would be produced. Because [tex]\rm NH_4 Cl\![/tex] is a soluble salt, the solution would contain [tex]0.154375\; \rm mol\![/tex] of [tex]\rm {NH_4}^{+}[/tex] ions. The concentration of [tex]\rm {NH_4}^{+}\![/tex] would be approximately:

[tex]\begin{aligned}c({\rm {NH_4}^{+}}) &= \frac{n({\rm {NH_4}^{+}})}{V({\rm {NH_4}^{+}})}\\ &\approx \frac{0.154375\; \rm mol}{0.6035\; \rm L} \approx 0.255782\; \rm mol \cdot L^{-1}\end{aligned}[/tex].

However, because [tex]\rm NH_3 \cdot H_2O[/tex] is a weak base, its conjugate [tex]\rm {NH_4}^{+}[/tex] would be a weak base.

[tex]\begin{aligned}pK_{\rm a}({{\rm NH_4}}^{+}) &= pK_{\rm w} - pK_{\rm b}({\rm NH_3})\\ &\approx 13.99 - 4.75 = 9.25\end{aligned}[/tex].

Hence, the following reversible reaction would be take place in the solution at the equivalence point:

[tex]\rm {NH_4}^{+} \rightleftharpoons NH_3 + H^{+}[/tex].

Let [tex]x\; \rm mol \cdot L^{-1}[/tex] be the increase in the concentration of [tex]\rm H^{+}[/tex] in this solution because of this reversible reaction. (Notice that [tex]x \ge 0[/tex].) Construct the following [tex]\text{RICE}[/tex] table:

[tex]\begin{array}{c|ccccc} \textbf{R}& \rm {\rm NH_4}^{+} & \rightleftharpoons & {\rm NH_3}& + & {\rm H}^{+}\\ \textbf{I} & 0.255782 \; \rm M \\ \textbf{C} & -x \;\rm M & & + x\;\rm M & & + x\; \rm M \\ \textbf{E} & (0.255782 - x)\; \rm M & & x\; \rm M & & x\; \rm M\end{array}[/tex].

Thus, at equilibrium:

[tex]\displaystyle \frac{[{\rm NH_3}] \cdot [{\rm H^{+}}]}{[{ \rm {NH_4}^{+}}]} = 10^{pK_\text{a}({\rm {NH_4}^{+}})}[/tex].

[tex]\displaystyle \frac{x^2}{0.255782 - x} \approx 10^{-9.25}[/tex]

Solve for [tex]x[/tex]. (Notice that the value of [tex]x\![/tex] is likely to be much smaller than [tex]0.255782[/tex]. Hence, the denominator on the left-hand side [tex](0.255782 - x) \approx 0.255782[/tex].)

[tex]x \approx 1.19929 \times 10^{-5}[/tex].

Hence, the concentration of [tex]\rm H^{+}[/tex] at the equivalence point of this titration would be approximately [tex]1.19929 \times 10^{-5}\; \rm M[/tex].

Hence, the [tex]pH[/tex] at the equivalence point of this titration would be:

[tex]\begin{aligned}pH &= -\log_{10}[{\rm {H}^{+}}] \\ &\approx -\log_{10} \left(1.19929 \times 10^{-5}\right) \approx 4.92\end{aligned}[/tex].

they are impacted because people loose their home due to the wreckage that has happend and landscapes are ruined due to landslides

Answer:

Well the landscape is torn up, it goes through quite a bit of damage. the plants, animals, and water are all affected by it. when a earth quake hits it destroyes most everything, houses fall into the ground and are destroyed, people die. Earthquakes destry electrical wires and many other things

Explanation:

Sorry I did not answer it full, but you can look it up online.

Answer:

the distillate (D) and the bottoms (B) products flow rates are;

B = 72.1875 kmol/hr

D = 37.8125 kmol/hr

Explanation:

Given the data in the question;

as illustrated in the image below;

F1 stream, ( 90 kmol/hr ) contains 42 mol% p-xylene and Feed 2 ( 20 kmol/hr) contains 9mol% p-xylene, so;

more volatile → p-xylene

less volatile → o-xylene

now, Overall balance;

F1 + F2 = D + B

90 + 20 = D + B

D + B = 110    ------------- let this be equation 1

p-xylene. component balance;

0.42F1 + 0.09F2 = 0.99D +  0.03B

0.42(90) + 0.09(20) = 0.99D +  0.03B

37.8 + 1.8 = 0.99D +  0.03B

0.99D +  0.03B = 39.6 --------------- let this be equation 2

from equation 1 and 2

input (D = 110 - B) into equation 2

0.99(110 - B) +  0.03B = 39.6

108.9 - 0.99B + 0.03B = 39.6

108.9 - 39.6 = 0.99B - 0.03B

69.3 = 0.96B

B = 69.3 / 0.96

B = 72.1875

now, input B = 72.1875 into equation 1

D + B = 110

D + 72.1875 = 110

D = 110 - 72.1875

D = 37.8125

Therefore, the distillate (D) and the bottoms (B) products flow rates are;

B = 72.1875 kmol/hr

D = 37.8125 kmol/hr

Answer:

The mass of oxygen the container must have is 150.85 g.

Explanation:

Given;

mass of the oxygen, m₁ = 44.5 g

initial pressure of the gas, P₁ = 2.3 atm

final pressure of the gas, P₂ = 7.8 atm

Atomic mass of oxygen gas, = O₂ = 16 x 2 = 32 g

initial number of moles of oxygen in the container, n₁ = 44.5/32 = 1.39

let the final number of moles of oxygen = n₂

Apply ideal gas equation;

PV = nRT

[tex]\frac{PV}{Rn} = T\\\\since \ temperature\ T \ is \ constant;\\\\\frac{P_1V}{Rn_1} = \frac{P_2V}{Rn_2}\\\\\frac{P_1}{n_1} = \frac{P_2}{n_2} \\\\n_2 = \frac{n_1P_2}{P_1} \\\\n_2 = \frac{1.39 \times 7.8}{2.3} \\\\n_2 = 4.714 \ moles[/tex]

The mass of the oxygen in grams is calculated as;

m₂ = 4.714 x 32g

m₂ = 150.85 g

Therefore, the mass of oxygen the container must have is 150.85 g.

Answer:

A liquid freezes into a solid or any other state change is a physical change. Bubbles are produced upon mixing two solutions is a Chemical change as gas formed. a precipitate is formed from two solutions is a Chemical change  The conversion of a substance to another compound over time leads to a color change of the substance due to the insolubility of the compound.

It is a chemical change or properties. A solution that heats up upon mixing with another is a Chemical change known as an exothermic reaction. dissolving the substance in a liquid is a physical change physical that can be regained by evaporation or crystalization.

Answer: The formula for the precipitate formed is [tex]ZnCO_3[/tex]

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.  

A double displacement reaction in which one of the product is formed as a solid is called as precipitation reaction.

The balanced chemical equation when aqueous solutions of zinc chloride and sodium carbonate are mixed:

[tex]ZnCl_2(aq)+Na_2CO_3(aq)\rightarrow ZnCO_3(s)+2NaCl(aq)[/tex]

Answer:

Thicker rings indicate a longer or faster growing season. This means that the temperature was high for a longer time and allowed the tree to grow more. Smaller rings show shorter or slower growing seasons which means either the temperature was low or the tree didn't have enough water to grow very much.

Explanation:

Hoped that helped!

Answer:

strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other.

Explanation:

In liquids, the attractive intermolecular forces are strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other.

Intermolecular forces are the forces of repulsion or attraction.

Intermolecular forces lie between atoms, molecules, or ions. Intramolecular forces are strong in comparison to these forces.

In liquids, the attractive intermolecular forces are strong enough to hold

molecules relatively close together but not strong enough to keep

molecules from moving past each other.

Liquid is a state of matter in which the atoms are relatively close to each

other but less than that of solids which are densely and tightly packed.

The intermolecular force in liquids are strong enough to hold them together

which makes them less easily compressible but not strong enough to keep

them from moving or gliding past each other because they aren't tightly

packed.

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Answer:

2NaN₃ → 2Na + 3N₂

Explanation:

First we use the information given by the problem to write an unbalanced equation:

There are 3 N atoms on the left side and only 2 on the right, to remedy that we put a 2 coefficient on NaN₃ and a 3 coefficient on N₂:

Now there are 6 N atoms on both sides of the equation. What's left is to balance Na atoms:

The equation is now balanced.

The properly balanced chemical equation for this chemical reaction is given by [tex]2NaN_3 \rightarrow 2Na + 3N_2[/tex]

A balanced chemical equation can be defined as a chemical equation wherein the number of atoms on the reactant side (left) is equal to the number of atoms on the product side (right).

In this scenario, Sodium azide ([tex]NaN_3[/tex]) undergoes a decomposition reaction due to an electrical impulse, which causes it to produce elemental sodium and nitrogen gas.

The properly balanced chemical equation for this chemical reaction is given by:

                                      [tex]2NaN_3 \rightarrow 2Na + 3N_2[/tex]

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Answer:

Ammonia

Explanation:

Both amines and amides are structurally similar to ammonia, the difference is the introduction of a carbon into the structure.

Answer:

[tex]KClO_3[/tex]

Explanation:

Hello!

In this case, as we know the mass of the total sample, we can first compute the mass of oxygen:

[tex]m_O=22.9g-7.33g-6.65g=8.92g[/tex]

Next, we compute the moles of each element:

[tex]n_K=\frac{7.33g}{39.9g/mol}= 0.184mol\\\\n_{Cl}=\frac{6.65g}{35.45g/mol}=0.188mol \\\\n_O=\frac{8.92g}{16.00g/mol} =0.5575mol[/tex]

Now, we divide the moles by 0.184 moles, the fewest ones, to obtain:

[tex]K=\frac{0.184}{0.184}=1.0 \\\\Cl=\frac{0.187}{0.184}=1.0\\\\O=\frac{0.5575}{0.184} =3.0[/tex]

Therefore, the empirical formula is:

[tex]KClO_3[/tex]

Regards!

Answer:

0.0258 mol Answer .......

Answer:

A forensic palynologist is a spore and pollen expert that helps solve crimes.

The case that Mildenhall worked on was about a murder that involved a prostitute. The police couldn’t find a trace to help solve the case, so they called Mildenhall to help with pollen clues. He was able to find trace evidence in the pollen, which helped police connect the victim to a gang hangout by the crime scene.

A forensic palynologist can help with a criminal investigation by comparing pollen from the suspect and the victim using a comparison microscope to determine if the pollen matches.

The challenges of using a forensic palynologist in a criminal investigation are that judges and juries may have a hard time understanding palynologists.

Explanation:

Answers of the following points regarding forensic palynologist are given below:

This is a internal branch of palynology that deals with the relationship among different objects to prove or disprove, which may belongs to both criminal and civil cases.

(1). Forensic palynologist is a person who do the case study of the crime seen,  and deals with a spore and pollen.

(2). Mildenhall worked on a murder case in New Zealand where a prostitute was involved. Police were not able to solve the crime, so they called Mildenhall to help with pollen clues. Mildenhall who is a spore and pollen expert was able to study the pollen clues and gave hint to the police as they were do further process to connect with the victim.

(3). A forensic palynologist by comparing the pollen clues from the crime scene and the victim, can help with a criminal investigation by using a comparison microscope to determine if the pollen matches.

(4). As forensic palynology is a science study which can not be general understand by normal people; so that judges, juries and advocates may have a hard time understanding palynologists and this is the challenges of using a forensic palynologist in crime investigations.

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Answer:

Option C

Explanation:

Pure  germanium is  a bad conductors of electricity. It is so because its valence band is full and its outer electrons are attached through covalent bond  is a diamond like framework. In metallic sense, it is neither a conductor nor an insulator but a semiconductor. It has a small band gap of 0.7eV.

Hence, option C is correct

Answer: Light, Chemical

Explanation: This is the answer because "photosynthesis takes place in two stages: the light-dependent reactions and the Calvin cycle. In the light-dependent reactions, which take place at the thylakoid membrane, chlorophyll absorbs energy from sunlight and then converts it into chemical energy with the use of water." - source https://opentextbc.ca/

In the photosynthesis the energy starts as Light energy and ends up as Chemical Energy. Hence option (D) is correct

The process by that inexperienced plants and a few different organisms use daylight to synthesize nutrients from carbonic acid gas and water. chemical action in plants usually involves the inexperienced pigment and generates element as a by-product.

Photosynthesis may be a method employed by plants and different organisms to convert lightweight energy into energy that, through internal respiration, will later be discharged to fuel the organism's activities.

photosynthesis takes place in 2 stages: the light-dependent reactions and also the Calvin cycle. within the light-dependent reactions, that manifest itself at the thylakoid membrane, pigment absorbs energy from daylight and so converts it into energy with the employment of water.

Therefore, In the photosynthesis the energy starts as Light energy and ends up as Chemical Energy. Hence option (D) is correct

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#SPJ2

Answer:

the subject of a talk, piece of writing, exhibition, etc.; a topic.

Explanation:

Answer:

1 NH4NO3(s) → 1 N2(g) + 4 H2O(g) + 2 O2(g)

Explanation:

Answer:

Explanation:

The main difference between these two is that a star has a solid rock and gas surface, while a comet has tail of dust and gas. A star is a giant mass of rock and gas that follows a set eliptical path. Comets on the other hand are made of ice and dust with some gases and usually travel in a straight path. This is why they have a tail of dust and gas which is the ice burning up behind it as it travels at extremely high speeds.

Answer: A: A star has a solid rock and gas surface, while a comet has tail of dust and gas.

Explanation:

1.54 × 10²⁴ atoms He

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Atomic Structure

Stoichiometry

Step 1: Define

[Given] 2.56 moles He

[Solve] atoms He

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

1.54163 × 10²⁴ atoms He ≈ 1.54 × 10²⁴ atoms He

Answer:

c. water is added to coffe until the solution becomes clear

Answer:

c

Explanation:

Water is added to coffee until the solution becomes

clear.

Answer:

Noble gases are sometimes called "inert gases." What can you infer about the meaning of the word "inert" in chemistry? It refers to substances that easily lose electrons. It refers to substances that do not react with other substances. It refers to substances that have strong electrochemical charges.

Explanation: