a compound differs from a mixture in that a compound: a. contains only one element b. varies in chemical composition depending on the size of the sample c. has a definite composition d. can be classified as either heterogeneous or homogeneous

If a  sample of metal has a mass of 2272 grams. Its dimensions are 5 cm by 5 cm by 8 cm, then the density of the sample of the metal would be 11.36 grams / centimeter³.

It can be defined as the mass of any object or body per unit volume of the particular object or body.

ρ = mass / volume

As given in the problem sample of metal has a mass of 2272 grams. Its dimensions are 5 cm by 5 cm by 8 cm.

The density of the metal  = 2272 / (5 × 5× 8)

                                         = 11.36 gram / cm³

Thus, the density of the metal would be 11.36 grams / cm³.

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Answer:

CaCO3

Explanation:

Pure calcite has the composition CaCO3. However, the calcite in limestone often contains a few percent of magnesium. Calcite in limestone is divided into low-magnesium and high-magnesium calcite, with the dividing line placed at a composition of 4% magnesium. High-magnesium calcite retains the calcite mineral structure, which is distinct from that of dolomite, MgCa(CO3)2.[18] Calcite can also contain small quantities of iron and manganese.[19] Manganese may be responsible for the fluorescence of impure calcite, as may traces of organic compounds

The orbital diagram shows us the number of electrons that can be found in the atom.

We know that the orbital is a region in pace where there is a high probability of finding the electron. We also know that the filling of the electrons into the respective orbitals where they fall in can be done by the use of the Aufbau principle.

According to the Aufbau principle, it is clear that in the filling of the electrons into the orbitals, the orbitals that are lesser in energy are first filled. The orbitals that are lesser in energy are always found quite close to the nucleus.

This implies that the relative energies of the orbitals would tend to increase as we move away from the nucleus. In other words, the nucleus is the part of the atom that would be at the lowest energy. The orbital diagram of iron by the use of the Aufbau principle have been shown in the image attached to this answer.

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Beryllium, the first element in group 2, has an atomic number of 4. The second element in this group has an atomic number of 12.

In the field of chemistry, atomic number can be described as the number of protons that is present in the nucleus of an atom.

The atomic number of Beryllium is 4 as it has 4 protons in its nucleus.

The second member of the group 2 elements in the periodic table is Magnesium. Magnesium has an atomic number of 12 because it has 12 protons in its nucleus.

The atomic number is represented by the letter Z usually. The atomic number is usually mentioned in a periodic table at the top-left.

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There are two chiral centers in the ethambutol molecule, but only three possible stereoisomers (structures attached below).

In general, the number of stereoisomers of a chiral molecule is 2ⁿ, where n is the number of chiral centers, so for ethambutol it should be 2² = 4. However, if the molecule is symmetrical (in this case it has a plane of symmetry), then there is an R,S-isomer that is not optically active as a whole because the chiral centers cancel each other out. This is a so-called meso-isomer. So, in the end, we have two enantiomers (R,R- and S,S-) and a meso-isomer, giving us three stereoisomers in total.

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Answer:

Explanation:

so

The partial pressure of oxygen in such conditions is equal to 160 mm Hg.

As the percentage of oxygen in the air is 21 percent, the mole fraction of oxygen in the air can be calculated as follows;

mole fraction of oxygen in air = 21 ÷ 100 = 0.21

Now we can determine the partial pressure of oxygen by using the equation given by Raoult's law as follows;

partial pressure of oxygen = total pressure of air × mole fraction of oxygen

As the atmospheric pressure at sea level is stated to be 760 mm hg and the calculated value of the mole fraction of oxygen is 0.21, substituting these values in the equation as follows;

partial pressure of oxygen = 760 mm hg × 0.21

partial pressure of oxygen = 160 mm hg

Therefore, the partial pressure of oxygen is calculated to be 160 mm hg.

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Taking into account the reaction stoichiometry, a mass of 7.57 grams of MgBr₂ is formed when one grams of magnesium reacts with 5 g of bromine.

In first place, the balanced reaction is:

Mg  + Br₂ → MgBr₂

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

The limiting reagent is one that is consumed first in its entirety, determining the amount of product in the reaction. When the limiting reagent is finished, the chemical reaction will stop.

To determine the limiting reagent, it is possible to use a simple rule of three as follows: if by stoichiometry 24.31 grams of Mg reacts with 159.8 grams of Br₂, 1 grams of Mg reacts with how much mass of Br₂?

mass of Br₂= (1 grams of Mg× 159.8 grams of Br₂) ÷24.31 grams of Mg

mass of Br₂= 6.57 grams

But 6.57 grams of Br₂ are not available, 5 grams are available. Since you have less mass than you need to react with 1 grams of Mg, Br₂ will be the limiting reagent.

Considering the limiting reagent, the following rule of three can be applied: if by reaction stoichiometry 24.31 grams of Mg form 184.11 grams of MgBr₂, 1 grams of Mg form how much mass of MgBr₂?

mass of MgBr₂= (1 grams of Mg× 184.11 grams of MgBr₂)÷ 24.31 grams of Mg

mass of MgBr₂= 7.57 grams

Then, a mass of 7.57 grams of MgBr₂ can be produced.

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Low NH₄ and high O₂ conditions are required for nitrogenase expression up-regulated.

control over the transcription of nitrogenase. The transcriptional control of nitrogen fixing is influenced by the oxygen and ammonium levels in the surrounding air. Because the nitrogenase components are oxygen labile, it is advantageous for bacteria to limit transcription when oxygen concentrations are high.

Reversible mono-ADP-ribosylation of the Fe protein, one of nitrogenase's components, regulates the enzyme's activity. The electrons necessary for the reduction of molecular nitrogen are supplied by this protein to the MoFe protein, the other component.

The enzyme nitrogenase turns nitrogen into ammonia. Some prokaryotes include it. Biological nitrogen fixation is the conversion of dinitrogen to ammonia by living things. The enzyme nitrogenase facilitates the transformation of nitrogen into ammonia.

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1) The reaction is exothermic and heat is a product

2) The color would turn to pink.

Let us recall that an endothermic reaction is one in which the increase in the temperature of the system would drive the forward reaction. This implies that the equilibrium would shift to the right when the set up is heated. Since the color of the solution changes to blue when heated hence the reaction is exothermic.

If you removed heat by placing the solution in the ice bath, we can see that we have removed the heat thus we expect that the reverse reaction would take place and the color would change to pink.

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The molarity of the bromide ion is 0.882 M .

Molar concentration is a measure of the attention of a chemical species, specially of a solute in an answer, in phrases of amount of substance in keeping with unit quantity of solution.

In chemistry, the maximum typically used unit for molarity is the number of moles consistent with liter, Molarity refers to the attention of a compound or ion in a solution, and normality refers back to the molar attention handiest of the acid aspect or handiest of the base component of the solution. therefore, normality gives know-how of the solution's concentration in acid-base reactions.

Pb⁺² + 2Br⁻ => PbBr₂

19.38 ml × 0.5690 M = 11.03 millimoles of Pb⁺²

millimoles of Br⁻  = 2 × millimoles of Pb⁺²

                           = 2 × 11.03

                           = 22.06 millimoles of Br⁻

= 22.06 millimoles/25 ml

molarity = 0.882 M in Br⁻.

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''They carry energy''. is the right statement about waves.

A wave is defined as a disturbance in a medium that carries energy without any movement of particles. It may take elastic deformation, a variation of pressure, electric intensity, magnetic intensity, electric potential, and temperature. There are three types of waves i.e. matter waves, mechanical waves, and electromagnetic waves.

All types of waves have the same basic properties of reflection, refraction, diffraction, and interference. All waves have a wavelength, frequency, speed, and amplitude. A wave can be explained by its length, amplitude, and frequency. All waves transfer energy from one place to another, they can also be reflected as well as refracted.

So we can conclude that option A is the right answer about the waves.

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The true statement about the reaction is that the reaction reaches equilibrium around 1.5 seconds.

We say that a reaction is reversible if the reaction can proceed both in the forward and the reverse directions. Let us recall that it is possible for a reversible reaction to attain a status of dynamic equilibrium. The status of dynamic equilibrium is the status where the rate of the forward reaction is equal to the rate of reverse reaction.

If we look at the graph as we have it we would notice that there is such a point of dynamic equilibrium as we survey the system around 1.5 seconds.

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The true statement about the reaction is the reaction reaches equilibrium around 1.5 seconds. Thus option D is correct.

Reversible reaction is defined as a reaction in which the transformation of both reactants and products into one another takes place simultaneously.

If a response may occur in both the forward and reverse directions, we say that it is reversible. Let's not forget that a reversible reaction can reach a state of dynamic equilibrium. The condition known as dynamic equilibrium occurs when the forward reaction rate and the backward reaction rate are equal.

If we were to examine the graph as it currently stands, we would see that the system reaches a point of dynamic equilibrium after 1.5 seconds of observation.

Thus, the true statement about the reaction is the reaction reaches equilibrium around 1.5 seconds. Thus option D is correct.

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The percent composition are the percent in mass of each atom in the molecule.

Since we know that the molar mass of the substance is 334.0 g/mol, we can use it to figure out how much of each atom we have per molecule.

Starting from carbon, we know it is 75.42% of the mass.

In 1 mol of the substance, there are 334.0 g, 75.42% of which is from carbon atoms.

So, in 1 mol of the substance, there are the following mass of carbon:

The aromic mass of the carbon atom is 12.0107 g/mol.

That is, in 1 mol of the substance -> 251.9028 g of C.

That mass of carbon is equivalent to:

So, in 1 mol of the substance -> 251.9028 g of C -> 21 mol of C. This means that for each molecule of the substance we have 21 atoms of carbon.

Now, we can just repeat the process for Hydrogen, Nitrogen and Oxygen.

Hydrogen has an atomic mass of 1.00794 g/mol, and the percent composition of it is 6.63%, so:

So, for each molecule of the substance there are 22 atoms of hydrogen.

Nitrogen has an atomic mass of 14.0067 g/mol, and the percent composition of it is 8.38%, so:

So, for each molecule of the substance there are 2 atoms of nitrogen.

Oxygen has an atomic mass of 15.9994 g/mol, and the percent composition of it is 9.57%, so:

So, for each molecule of the substance there are 2 atoms of oxygen.

To summarize, we have, for each molecule of the substance:

- 21 carbon

- 22 hydrogen

- 2 nitrogen

- 2 oxygen

So, the molecular form of the substance is C₂₁H₂₂N₂O₂.

Answer:

The second element in group 2 has an atomic number of 12.

We can describe atomic number as the number of protons that are present in the nucleus of an atom. The number of protons is equal to the number of electrons, hence the atomic number is the number of protons or the number of electrons in an atom.

Beryllium has an atomic number of 4 because the element Beryllium has 4 protons.

In the periodic table, you will find that the second element in group 2 is Magenium. The atomic number of Magnesium is 12 because Magnesium has 12 protons in the nucleus of its atom.

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Answer:

as they use multiple bulbs in conjunction chandeliers don't need higher watt bulbs and are usually not used as often as other lights  

Explanation:

hope this helps

Answer

AlBr₃ is the limiting reactant

Explanation

Mass of AlBr₃ = 23.45 g

Mole of AlBr₃ = Mass/molar mass = 23.46 g/266.69 g/mol = 0.08797 mol

Mass of Na₂O = 34.57 g

So mole of Na₂O = mass/molar mass = 34.57 g/61.9789 g/mol = 0.5578 mol

Mole ratio of AlBr₃ to Na₂O = (0.08797/0.08797) : (0.05578/0.08797) = 1:6

To know the limiting reactant, write a chemical equation for the reaction and compare the reactant mole ratio in the equation with the mole ratio above.

2AlBr₃ + 3 Na₂O -----> Al₂O₃ + 6NaBr

Mole ratio in the equation = 2:3

Comparing the mole ratio, AlBr₃ will be the first to be completely consumed.

Therefore, AlBr₃ is the limiting reactant

Answer:

0.1498 g of O2.

Explanation:

The Behavior of Gases => Ideal Gas Law.

The ideal gas law is a single equation that relates the pressure, volume, temperature, and the number of moles of an ideal gas, which is:

where P is pressure in atm, V is the volume in liters, n is the number of moles, R is the ideal gas constant (0.082 L*atm/mol*K), and T is the temperature in the Kelvin scale.

So we have to convert pressure from 700.0 mmHg to atm, volume from 120.0 mL to L, and 15 °C to K.

Let's convert pressure taking into account that 1 atm equals 760 mmHg, like this:

Remember that 1 L equals 1000 mL, so 120.0 mL would be equal:

And the conversion from °C to K is just sum °C with 273, so 15 °C in K is:

Finally, we can use the ideal gas formula, solving for 'n' (number of moles) and replacing the data that we have, as follows:

Now, the final step is to convert 4.680 x 10⁻³ moles of O2 to grams using the molar mass of O2 that can be calculated using the periodic table, which is 32 g/mol. The conversion will look like this:

The answer would be that there are 0.1498 g of O2.

The volume of 3.75 moles of oxygen gas at STP is 84.05L.

The volume of a gas can be calculated using the ideal gas law equation as follows:

PV = nRT

Where;

At standard temperature and pressure (STP), the temperature and pressure of an ideal gas is 273K and 1 atm respectively.

1 × V = 3.75 × 0.0821 × 273

V = 84.05L

Therefore, 84.05L is the volume of the ideal oxygen gas.

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The pH of the solution after 28.0 ml of NaOH have been added to the acid exists 0.85.

The balanced reaction between base and acid exists;

NaOH + HCl → NaCl + H₂O

NaOH exists a strong base and HCl exists a strong acid therefore complete dissociation. Stoichiometry of acid to base exists 1: 1.

The number of moles of base added - 0.5 M /1000 mL/L × 28.0 mL = 0.014 mol

the number of acid moles present - 0.5 M /1000 mL/L × 50.0 mL = 0.025 mol.

acid reacts with base 1: 1 ratio

Therefore excess amount of acid present - 0.025 - 0.014 = 0.011 mol

Total volume = 50.0 + 28.0 = 78.0 mL

[H⁺] = 0.011 mol/0.078 L = 0.14 M

Therefore, pH = -log [H⁺]

substitute the values in the above equation, we get

pH = -log(0.14)

simplifying the above equation, we get

pH = 0.85.

Therefore, the pH of the solution after 28.0 ml of NaOH have been added to the acid exists 0.85.

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Answer: As you hold cold milk.... travels to your hand

Explanation:

Cold and hot are compared to your own body temperature. So yeah that's kind of off topic but yeah. Anyways, to the explanation: so, this can be tested--obviously--by literally doing what the statement says. after you are done holding the milk, you will notice your hand is cold. This is because the milk is cooling down your hand to balance out the temperatures.

The composition of the mixture is 2.5 moles of HI, 0.75-mole I₂, and 0.75 moles of H₂.

The act of combining elements or elements to shape an entire. the ensuing nation or product. manner of being composed; structure: This portrait has an orderly composition. make-up; constitution: His ethical composition becomes impeccable.

A composition can discuss with any innovative painting, be it a quick story, poem, essay, studies paper or a piece of tune. consequently, the principle difference between essay and composition is that essay is a form of composition whereas composition refers to any innovative paintings.

                       H₂ + I₂ = 2HI

initial             2mol  2     0mol

final                                   2.5 mol

limiting reagent is  I₂

2 mole of HI is produced by 1 mole of  I₂

2.5 mole of  I₂ is produced by = 1/2 × 2.5

                                                  = 1.25 mole

The final composition of the mixture = 2.5 moles of HI, 0.75-mole I₂, and 0.75 moles of H₂.

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Answer:

Examples of synthetic polymers include nylon, polyethylene, polyester, Teflon, and epoxy.

The more the number of theoretical plates, the more easier the separation of a mixture of two liquids.

A measure of column efficiency is the theoretical plates number (N). It describes the number of plates as defined by plate theory and can be used to calculate column efficiency using a computation where the sharper the peaks, the higher the theoretical plate number. The more theoretical plates there are, the more ideal equilibrium stages there are in the system, and the more effective the separation is.

From all of these factors, it is obvious that more theoretical plates suggest greater separation quality since more equilibriums between stationary and mobile phases can be reached. This can be understood by using the example of a set of stairs. The length of each step grows as the number of stairs decreases.

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1.5 atm pressure will be required for neon at 30°C to have the same density as nitrogen at 20°C and 1.0 atm.

The relationship between a gas's pressure P, volume V, and temperature T in the range of low pressures and high temperatures, when the gas's molecules move virtually independently of one another, is known as the ideal gas law, also known as the perfect gas law.

T[tex]_N_e[/tex]​ =30⁰C=(30+273)K=303K

T[tex]_N_2[/tex]​​ =20⁰C=(20+273)K=293K

P[tex]_N_2[/tex] ​ =1.0atm

Ideal gas constant - R=0.0821L⋅atm/ K⋅ mol

The molar mass of

Neon - M[tex]_N_e[/tex]​​=20.18g/mol

Nitrogen - M[tex]_N_2[/tex]​​ ​ =2⋅14.007g/mol=28.014g/mol

Determine the pressure P[tex]_N_e[/tex]​  required for neon at 30⁰C to have the same density (d) as nitrogen at 20⁰C.

d = m/V

We know that

n = m/M

Using the ideal gas law, we get

PV = nRT

PV = m/M *RT

Since

PM/RT = m/V =d

d =  PM/RT

d= [tex]\frac{P_{N_2} M_{N_2}}{R T_{N_2}}[/tex]

d = 1.0 atm * 28.014 g/mol/0.0821L atm/K mol 293K

d = 1.2 g//L

Since both gases have the same density, we can calculate the pressure of neon gas, using

[tex]d=\frac{P_{N e} M_{N e}}{R T_{N e}}[/tex]

[tex]P_{N e}=\frac{d R T_{N e}}{M_{N e}}[/tex]

[tex]P_{N e}[/tex]=1.2g/L . 0.0821L . atm/K.mol.303 K/20.18 g/mol

[tex]P_{N e}[/tex]=1.5 atm

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The metals that are able to displace iron sulfate from solution are magnesium and aluminum.

The electrochemical series is a series that shows the reactivity of the metals. We must note that the order of the reactivity of the metals depends on the electrode potential of the metal. The metals that have a higher electrode potential would tend to react better and faster.

Also note that, the metals that are higher in the electrochemical series are able to displace the metals that are lower in the series from their aqueous solutions. This implies that if we add a metal to a solution that contains a meta that is lower in the electrochemical series, the lower meta is discharged from solution.

As we can see, when we add each of these metals to the iron sulfate solution, the only time that we would be able to have a reaction is when  we add the aluminum or the magnesium metals.

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Acetaldehyde is a toxic compound created in alcohol metabolism.

what is alcohol metabolism?

Alcohol dehydrogenase, an enzyme found in the liver cells, is responsible for the majority of alcohol metabolism (ADH).

Alcohol metabolism is governed by a number of processes.

The two enzymes involved in the most common of these methods are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ADH) (ALDH). These enzymes assist in breaking down the alcohol molecule so that the body can eliminate it. ADH first breaks down alcohol into acetaldehyde, an extremely dangerous molecule and known carcinogen. In a following phase, acetaldehyde is further transformed to acetate, a less active byproduct, for rapid removal. Acetate can then be easily converted into carbon dioxide and water.

The researchers reported that heavy drinking leads to elevated acetaldehyde levels, which leads to inhibited ALDH enzymes, and in turn causes these adverse effects. The alcohol does not properly metabolize.

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