Using standard heats of formation, calculate the standard enthalpy change for the following reaction.
4HCl(g) + O2(g)—>2H2O(g) + 2Cl2(g)

the oxidation number of copper in copper oxide is 2...

Answer: +2

Explanation: Copper has a +2 oxidation number in CuO.

This is due to the fact that oxygen has an oxidation number of 2, and the entire chemical has a neutral charge. Consequently, the following equation can be used to determine copper's oxidation number:

(+2) + (-2) = 0

In order to counteract the -2 oxidation number of oxygen in CuO, copper must have an oxidation number of +2.

Answer:

3.6782514841

Explanation:

6.43x106=681.58

1.7x109= 185.3

681.58/185.3= 3.6782514841

The concentrations of PCI, (g) and PC1, (g) at equilibrium are 0.00155 mol/L and 0.0565 mol/L respectively.

The given chemical equation is:

PCI, (g) ⇌ PC1, (g) + Cl₂(g)

The equilibrium constant K is given as K = 1.80 at 250 °C.

Let x be the concentration (in mol/L) of PCI, (g) that reacts to form PC1, (g) and Cl₂(g) at equilibrium. The initial concentration of PC1, (g) is 0.2836 mol in a 3.65 L reaction vessel, which gives an initial concentration of [PC1, (g)] = 0.2836 mol/3.65 L = 0.0777 mol/L.

At equilibrium, the concentration of PC1, (g) will be (0.0777 - x) mol/L, and the concentration of Cl₂(g) will also be x mol/L.

Using the equilibrium constant expression, write:

K = [PC1, (g)][Cl₂(g)]/[PCI, (g)]

Substituting the values and expressions in terms of x:

1.80 = (0.0777 - x)x/[PCI, (g)]

Solving for [PCI, (g)]:

[PCI, (g)] = (0.0777 - x)x/1.80

Since the total volume of the reaction vessel is 3.65 L, the total number of moles at equilibrium is:

n_total = [PCI, (g)] + [PC1, (g)] + [Cl₂(g)]

n_total = (0.0777 - x)x/1.80 + 0.0777 mol/L + x mol/L

At equilibrium, the reaction quotient Qc will have the same form as the equilibrium constant expression:

Qc = [PC1, (g)][Cl₂(g)]/[PCI, (g)]

At equilibrium, Qc = K, so we can solve the equilibrium constant expression for [PCI, (g)]:

[PCI, (g)] = [PC1, (g)][Cl₂(g)]/K

Substituting the concentrations in terms of x:

(0.0777 - x)x/1.80 = (0.0777 - x)x/K

Solving for x:

x = 0.0212 mol/L

Substituting this value of x in the expressions for the concentrations at equilibrium:

[PC1, (g)] = 0.0777 - x = 0.0565 mol/L

[Cl₂(g)] = x = 0.0212 mol/L

[PCI, (g)] = (0.0777 - x)x/1.80 = 0.00155 mol/L

Therefore, the concentrations of PCI, (g) and PC1, (g) at equilibrium are 0.00155 mol/L and 0.0565 mol/L, respectively.

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Answer:

1.44 g

Explanation:

1. get number of nitrogen atoms in 9.79 grams of nitrogen

1 mole of Nitrogen is 6.022 x 10^23 atoms N which is = 14.01g N

2.

if 6.022 x 10^23 atoms of Nitrogen is 14

then x atoms  of Nitrogen is 9.79

3.

6.022 x 10^23/ x = 14/9.79 ->

x = 8.431 x 10^24 / 9.79 =

8.61799714478 x 10^23

4.

8.61799714478 x 10^23 atoms of N

6.022 x 1023 atoms of H have a mass of 1.008g, so

8.61799714478 x 10^23 atoms of H have a mass of (1.008/6.022 x 1023) x 8.61799714478 x 10^23) = 1.44250051072175g

1.44 g

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Answer:  588.9 lbs

Explanation:  1 lb = 0.454 kg

(267.1kg)*(1 lb/0.454 kg) = 588.9 lbs

Answer:

quartz

Explanation:

The correct option would be quartz.

Allotropy is a phenomenon that describes the natural existence of the same element in different forms with different physical characteristics. Allotropes are therefore different forms of the same element.

Carbon as an element has several allotropes which include diamond, graphite, graphene, amorphous carbon, and fullerenes. Quartz is a crystalline solid that is composed of silicon dioxide and not carbon.

Hence, all the options are carbon allotropes except quartz.

Answer:

Atmospheric Pressure:

- It is the force exerted on a surface by the air above it as gravity pulls it to Earth. Atmospheric pressure is commonly measured with a barometer. In a barometer, a column of mercury in a glass tube rises or falls as the weight of the atmosphere changes.

Explanation:

Hope this helps

Answer:

Propane gas plus oxygen gas produces water and carbon dioxide.

Explanation:

This is the initial chemical equation: C3H8 + O2 = CO2 + H2O

This is the balanced chemical equation: C3H8 + 5 O2 = 3 CO2 + 4 H2O

C3H8 + O2 → CO2 + H2O

C3H8 + 5O2 → 3CO2 + 4H2O

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Answer: Microphones are a type of transducer - a device which converts energy from one form to another. Microphones convert acoustical energy (sound waves) into electrical energy (the audio signal). Different types of microphone have different ways of converting energy but they all share one thing in common! Furthermore, Example 1: Crushing a can.

Type of change:

Developmental – May be either planned or emergent; it is first order, or incremental. ...

Transitional – Seeks to achieve a known desired state that is different from the existing one. ...

Transformational – Is radical or second order in nature.

Answer:

The number of these organisms in the soil would decrease.

Explanation:

There are 15.4 equivalents of chloride ion present in the solution

We need to multiply the total number of moles of chloride ion in the solution by the number of equivalents.

The molar mass of NaCl is 58.44 g/mol, so 3.5 mol of NaCl contains :

3.5 mol NaCl x 2 mol Cl⁻/1 mol NaCl = 7 mol Cl⁻

Similarly, the molar mass of MgCl₂ is 95.21 g/mol, so 4.2 mol of MgCl₂ contains:

4.2 mol MgCl₂ x 2 mol Cl⁻/1 mol MgCl₂ = 8.4 mol Cl⁻

Therefore, the total number of moles of chloride ion in the solution is:

7 mol Cl⁻ + 8.4 mol Cl⁻ = 15.4 mol Cl⁻

By dividing the total number of moles by the number of equivalents per mole, we can finally determine how many equivalents of the chloride ion there are. There is one equivalent of the chloride ion per mole since it has a valency of -1.

15.4 mol Cl⁻ x 1 eq/mol = 15.4 eq

So there are 15.4 equivalents of chloride ion present in the solution.

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Answer:

A weak acid will partially dissociate. A strong acid will almost completely dissociate.

Explanation:

This means that the H+ will "fall" off of the molecule and bind to H2O, forming H3O+

The pH will drop regardless, but moreso for a strong acid, as the H3O content rises, also moreso for a strong acid.

The pH or the concentration of hydronium ion will change as per the dissociation of ions in an acid.

Acids are those substances that donate a proton. There are two types of acids. Weak acid is the one that dissociates partially while a strong acid dissociates completely into ions.

Thus, the pH will change and depend upon the capacity to donate proton.

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The statements that best support the student’s claim is that

A cell is described as the smallest unit that can live on its own and that makes up all living organisms and the tissues of the body.

A cell has three main parts which include :

The cell membrane surrounds the cell and controls the substances that go into and out of the cell.

In conclusion, Cells are the basic building blocks of all living things.

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The concentration by% m/v if 67 g are dissolved to make 1.2 L of solution is 5.58%.

A homogenous mixture of two or more substances is referred to as a solution, where one of the substances is referred to as the solute and the other as the solvent. The solute particles are evenly dispersed throughout the solvent in a solution, forming a single phase with constant characteristics throughout the mixture.

Divide the solute's mass (in grams) by the solution's volume (in milliliters) to get the concentration of a solution in percent m/v (mass/volume). Then multiply the result by 100%.

In this instance, 1.2 L of solution, or 1200 mL, contains 67 g of solute that has been dissolved in it.

The% m/v concentration is therefore:

(67 g / 1200 mL) x 100% = 5.58%

The concentration by% m/v is 5.58%.

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Answer:

   A + B = AB is an example of a synthesis reaction

Explanation:

The number of moles of the gas at 77°C and 1.33 atm occupies a volume of 50.3 L is 2.35 moles. It can found with the help of Ideal gas equation.

The ideal gas equation is formulated as : PV = nRT.

In this equation, P refers to the pressure of the ideal gas, V is the volume of the ideal gas, n is the total amount of ideal gas that is measured in terms of moles, R is the universal gas constant, and T is the temperature.

Given ;

We know ;

Formula used ;

n = PV / RT

n = 1.33 x 50.3 / 0.081 x 350k

  =  2.35 moles.

Hence, The number of moles of the gas at 77°C and 1.33 atm occupies a volume of 50.3 L is 2.35 moles

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Answer:

A small amount of chemical splashes in Frank's eye. What should happen next? Frank should go to the eyewash station while his lab partner tells the teacher what happened.

Explanation:

Brainlist

In this question, we are presented with a substance X with a solubility of 52.6 g/L, which means that in every 1 liter of volume, we will dissolve 52.6 grams of it at 10°C. Now the question asks about the volume for 43.0 grams at the same temperature:

52.6 grams = 1 Liter

43.0 grams = x Liters

52.6x = 43.0

x = 43.0/52.6

x = 0.817 Liters of volume

The balanced chemical equation for the combustion of propane with oxygen is: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

To balance the equation, first balance the carbon atoms on both sides of the equation. There are three carbon atoms in the propane molecule and three in the carbon dioxide molecule, so balance the carbon atoms by putting a coefficient of 3 in front of the CO₂ molecule.

C3H8 + 5O2 → 3CO₂

Next, balance the hydrogen atoms. There are eight hydrogen atoms in the propane molecule and four in the water molecule, so balance the hydrogen atoms by putting a coefficient of 4 in front of the H₂O molecule.

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Finally, balance the oxygen atoms. There are five oxygen atoms on the left side and 10 on the right side, so balance the oxygen atoms by putting a coefficient of 5 in front of the O₂ molecule.

Therefore, the correct whole number coefficient for propane, C3H8, is 1.

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The statement is correct. The photoelectric effect refers to the phenomenon where electrons are ejected from the surface of a material when it is exposed to light. The frequency of light striking an electron in a metal must be above the threshold frequency in order for the photoelectric effect to occur.

The statement is correct. The photoelectric effect refers to the phenomenon where electrons are ejected from the surface of a material when it is exposed to light. However, for the photoelectric effect to occur, the frequency of the incident light must be above a certain threshold frequency.

The threshold frequency is the minimum frequency of light required to dislodge electrons from the material. Below this threshold frequency, regardless of the intensity or duration of the light, no electrons will be emitted.

This behavior can be explained by the particle-like nature of light, where light is composed of discrete packets of energy called photons. The energy of a photon is directly proportional to its frequency. Only photons with energy greater than or equal to the binding energy of the electrons in the material can dislodge them.

Therefore, the frequency of light striking an electron in a metal must be above the threshold frequency in order for the photoelectric effect to occur.

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A balanced equation may be used to describe this reaction:

HC=C(aq) + H2O(l) ⇌ H3C+C-(aq) + OH-(aq)

The Brnsted-Lowry hypothesis is an acid-base reaction theory that was separately proposed in 1923 by Johannes Nicolaus Brnsted and Thomas Martin Lowry. In a chemistry, a Brnsted-Lowry base is a molecule or ion that accepts a hydrogen ion. Because a hydrogen ion is often referred to as a proton, acids and bases are proton donors and acceptors, according to the Brnsted-Lowry definition.

Here,

The acetylide ion (HC=C) acts as a Brønsted-Lowry base in water, accepting a proton from water to form an acetylene cation (H3C+C-):

HC=C + H2O ⇌ H3C+C- + OH-

This reaction can be written as a balanced equation:

HC=C(aq) + H2O(l) ⇌ H3C+C-(aq) + OH-(aq)

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There are numerous ways to determine whether lead is present in an ore. Atomic absorption spectroscopy is a popular approach. With this method, an ore sample is dissolved in acid and then atomized in a flame or plasma.

The sample's atoms will absorb light at particular wavelengths that are peculiar to the element under investigation. The amount of light absorbed can be used to calculate how much lead is present in the sample. Inductively coupled plasma mass spectrometry and X-ray fluorescence spectroscopy are further techniques. It is crucial to remember that these procedures call for specialized tools and training, thus they ought to only be carried out in a lab by qualified experts.

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Answer:

D

Explanation:

Because a metal must reactive and able to conduct

Answer:

B.Conductivity and ductility

Explanation.

Some metals are conductive and are ductile

Conductivity is the ability to have an electric flow

Ductility is the ability to bend

Answer:

A full.

Explanation:

An electron needs to have a full octet do not need any more electrons. So the correct option is D.

The s and p electrons in the outermost shell are valence electrons. Core electrons are those found in the inner shell. Valence electrons are little subatomic particles that we come across as we examine and investigate an element's atom. We can trace the valence electrons and forecast the sorts of bonds with the aid of Lewis structures.

The majority of valence electrons are negatively charged particles, and they are all grouped in various orbitals or shells. Additionally, these electrons are in charge of how atoms interact with one another and create chemical bonds.

However, not every electron belongs to an atom. A chemical bond or molecule can only be created by the electrons that are found in the outermost shell. Valence electrons are the name given to this sort of electron.

Therefore the correct option is D.

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Answer:

0.15 g of CuSO4.

Explanation:

What is given?

Concentration of CuSO4 = 0.00095 mol/L.

Liters of solution = 1 L.

RAM (Cu) = 63.

RAM (S) = 32.

RAM (O) = 16.

Step-by-step solution:

Let's see the formula of molarity (concentration of solution):

And we want to find the moles of solute to calculate the weight of copper sulfate. The statement is telling us that we're going to use 1 liter of solution, so let's solve for 'moles of solute' and replace the given data (molarity of CuSO4 solution = concentration of CuSO4 = 0.00095 mol/L and liters of solution = 1L):

Now, we have to convert 0.00095 moles of CuSO4 to mass and here we're going to use the RAM (relative atomic mass)

First, let's calculate the RAM of CuSO4 by doing an algebraic sum with the given RAMs. You can see that we have 1 Cu, 1 S, and 4 O, so the calculation will look like this:

The RAM of CuSO4 is 159. The value of RAM is equivalent to molar mass, but the difference is that the molar mass has the units of g/mol, so, in this case, the molar mass of CuSO4 is 159 g/mol. So now, the conversion from moles to grams will be:

The answer is that they have to weigh out 0.15 g of CuSO4.

Ammonia (\(NH_3\)) and ammonium chloride (\(NH_4Cl\)) mixture could be a useful buffer in a solution. Option C

A buffer is a solution that can resist changes in pH when small amounts of acid or base are added. It consists of a weak acid and its conjugate base or a weak base and its conjugate acid. The buffer system works by the principle of Le Chatelier's principle, where the equilibrium is shifted to counteract the changes caused by the addition of an acid or a base.

In option A, acetic acid (\(CH_3CO_2H\)) is a weak acid, but hydrochloric acid (HCl) is a strong acid. This combination does not form a buffer because HCl is completely dissociated in water and cannot provide a significant concentration of its conjugate base.

Option B consists of sodium hydroxide (NaOH), which is a strong base, and elemental sodium (Na), which is a metal. This combination does not form a buffer as there is no weak acid-base pair involved.

Option D contains acetic acid (\(CH_3CO_2H\)), a weak acid, and ammonia (\(NH_3\)), a weak base. Although they are weak acid and base, they do not form a buffer system together as they are both weak acids or bases and lack the required conjugate acid-base pair.

Option C, ammonia (\(NH_3\)), is a weak base, and ammonium chloride (\(NH_4Cl\)) is its conjugate acid. This combination can form a buffer system. When ammonia reacts with water, it forms ammonium ions (NH4+) and hydroxide ions (OH-).

The ammonium ions act as the weak acid, while the ammonia acts as the weak base. The addition of a small amount of acid will be counteracted by the ammonium ions, and the addition of a small amount of base will be counteracted by the ammonia, thus maintaining the pH of the solution relatively stable.

Therefore, option C, consisting of ammonia (\(NH_3\)) and ammonium chloride (\(NH_4Cl\)), is the suitable mixture that could be a useful buffer in a solution.

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Answer:

6F2 ( g ) + 2Ga2O ( aq ) → 4GaF3 + O2

F is more reactive than O, so F displaces O from Ga2O and forms GaF3.

Ga has a valency of 3, it need 3 electrons to get complete electronic configuration.

F has a valency of 1,

3 F atoms constitutes 3 electrons.

So, GaF3.

And hence, the chemical equation is balanced on both sides.

Answer:

interact with each other through London dispersion forces.

Answer:

0 degrees Celsius

Explanation:

Answer:

Water changes from a liquid to a solid at 0° Celsius

Explanation:

Hund's first and second rules describe how electrons are arranged in an atom's orbitals. Hund's first rule states that when electrons occupy orbitals of equal energy (such as the three p orbitals in a given shell), they will each first occupy separate orbitals before any orbital receives a second electron. This means that electrons will always try to maximize their spin, with one electron in each orbital having the same spin before any pairing occurs.

Hund's second rule states that if two or more orbitals of the same energy level are available, electrons will occupy empty orbitals before they pair up in an orbital that already has an electron.

Now, let's look at the orbital notation for sulfur. The atomic number of sulfur is 16, which means it has 16 electrons.

The orbital notation for sulfur would be:

1s² 2s² 2p⁶ 3s² 3p⁴

This indicates that sulfur has two electrons in the 1s orbital, two electrons in the 2s orbital, and six electrons in the 2p orbital, fully occupying all three 2p orbitals with two electrons in each and spinning in the same direction. Sulfur also has two electrons in the 3s orbital and four electrons in the 3p orbital, with a single electron in each of the three 3p orbitals and the fourth 3p orbital being half-filled. The half-filled 3p orbital is a consequence of Hund's rule, which predicts that electrons will fill each of the three 3p orbitals with one electron before any two orbitals receive a second electron.