The quantatum mechanical model of an atom uses atomic orbitals to describe what

Answer:

All atoms of a specific element are identical in mass, size, and other properties. However, atoms of different element exhibit different properties and vary in mass and size. Atoms can neither be created nor destroyed. Furthermore, atoms cannot be divided into smaller particles.

Answer:

Explanation:

Here, we want to get the number of moles in the given mass

Mathematically:

The molar mass of CaCO3 is 100 g/mol

The number of moles is thus:

When hydrogen (H+) and chlorine (Cl-) are mixed, they are called hydrochloric acid.

Hydrochloric acid is prepared by combining the gaseous hydrogen chloride with water. Due to the corrosive nature of the acid, ceramic, glass, or tantalum apparatus is used. Hydrochloric acid is also known as muriatic acid. It is also known as an aqueous solution of hydrogen chloride. It is a colorless solution with a pungent smell. It is classified as a strong acid because of more hydrogen atoms. It is a part of the gastric acid that is present in the digestive systems of animal species such as humans. Hydrochloric acid is an important laboratory and industrial chemical.

So we can conclude that hydrochloric acid is formed when hydrogen and chlorine are mixed.

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Answer:

c

Explanation:

V atery few members of the public have heard of a case dealing with forensics. The use of forensics is more popular with the public and law enforcement. Colleges have stopped offering courses and majors in forensic science.

answer and explanation

we are given initial values of temperature, pressure and volume as well as the final value of temperature and pressure and we are asked to find the final volume.

we can do this using the combined gas equation

P1V1/T1 = P2V2/T2

when we plug in the values we get:

(6atm x78L)/53K = (85atm x V2/17K

8.83 = 85atm x V2 / 17K

V2 = 1.77 Liters

The easiest way to tell which layer is wich, while performing the extraction experiment is to run a little test.

The test will consist on mixing a sample of both layers in different recipients with water.

After mixing them, the recipient with a homogeneous phase will have the aqueous layer, and the other one will be the organic layer.

Answer: The layer on top.

Explanation:

Assuming you were completing an extraction experiment and had a setup similar to the one below then the organic layer will float on top of the aqueous since most non-halogenated organic solvents have a density of less than 1.

Answer: ΔT = 62.98

Explanation:

This can be done using Gay Lusac's Law which states that Pressure is proportional to temperature

So, we take p1 = 4.62 atm, t1 = (27+273)°K, p2 = 5.59 atm, t2=?

now, P1/T1 = P2/T2

From here find out T2 which would be in Kelvin and then subtract 273 to convert it into celsius. Then find the difference between T1 and T2 and you should have your answer.

Given the hypothetical thermochemical equation, expressed as:

We are to find the enthalpy change (ΔH ) for the reaction 2C → 3 A + B.

• You can see that the, given reaction, 2C → 3 A + B is the, reverse ,of the thermochemical equation 3 A + B → 2 C.

• Since the ,reverse reaction is possible,, the reaction enthalpy has the ,same numerical value, but with the, ,opposite sign

Therefore, the enthalpy change ∆H, in kJ/mol, be for the reaction 2 C → 3 A + B is -65.5kJ/mol

Answer

The pressure of the sample is 1.47 atm

Explanation

Given:

Moles, n = 1.31 mol

Volume, V = 24.6 L

Temperature, T = 336 K

The ideal gas constant, R = 0.0821 L*atm/mol*K

What to find:

Pressure, P of the sample.

Step-by-step solution:

Pressure, P of the sample can be calculated using the ideal gas equation.

Put the values of the parameters into the formula, we have;

The pressure of the sample is 1.47 atm

• The bond that exist between the CCl4 compound ,forms a covalent bond ,, this can be illustrated in the diagram below:

• We can see that it contains four non-polar covalent bond between carbon and chloride

In order to solve this question we need to set up the properly balanced equation first:

CaCO3 + 2 HCl -> CaCl2 + H2O + CO2

Now that our reaction is properly balanced, we have to find the limiting reactant in order to find how much mass of CaCl2 will be produced

We have:

10.0 g of CaCO3, molar mass = 100.086 g/mol

15.0 g of HCl, molar mass = 36.46 g/mol

Now we need to find the number of moles of the reactants, and see if the amount available of the other reactant is the one needed to react.

CaCO3:

100.086g = 1 mol

10g = x moles

x = 0.099 moles of CaCO3

According to the molar ratio, the CaCO3 and HCl will have a relationship in which we will always need 2 times more HCl than CaCO3, therefore if we have 0.099 moles of CaCO3, we will need 0.198 moles of HCl in order to proceed with the reaction, but we don't know if that is the right amount, let's check:

HCl:

36.46g = 1 mol

15.0g = x moles

x = 0.411 moles of HCl, this means that we have an excess of HCl, since we only need 0.198 moles in order to react with CaCO3. Therefore Calcium carbonate is the limiting reactant.

Now that we know which one is the limiting reactant, we can find the mass produced of CaCl2.

Again the molar ratio is important here, but know, we will always have the same number of moles for CaCO3 and CaCl2, 1:1 will be the molar ratio, therefore if we have 0.099 moles of CaCO3, we will also have 0.099 moles of CaCl2, using its molar mass, 110.978g/mol, we can find the final mass

CaCl2:

110.978g = 1 mol

x grams = 0.099 moles

x = 11.0 grams (it is actually 10.986 grams, but I have rounded up to 11 grams)

Explanation:

We form a supersaturated solution. At 45 °C the solution has more potassium nitrate that can be dissolved. The recrystallization of the excess dissolved solute can be started inserting a crystal that is called seed crystal.

Answer: seed

The pH of a 0.670 M solution of Ca(NO₂)₂ is 1.76

When HNO₂ dissociates, it forms H⁺ and NO₂⁻ ions.

HNO₂ ==> H⁺ + NO₂⁻

Ka of HNO₂ = [H⁺] [NO₂⁻] / [HNO₂] = 4.5× 10⁻⁴

Let’s take x for unknown

4.5 x 10⁻⁴ = (x)(x) / 0.670

4.5 x 10⁻⁴ = x² / 0.670

x² = 3.015 x 10⁻⁴

x = 1.74 x 10⁻²

[H⁺] = 1.74 x 10⁻² M

pH is the measurement of the acidity or basicity of a compound. It ranges from  0 to 14

Therefore, the pH of a 0.670 M solution of Ca(NO₂)₂ is

pH = -log [H⁺]

pH = -log 1.74 x 10⁻²

pH = 1.76

The pH of a 0.670 M solution of Ca(NO₂)₂ is 1.76 which lies in the acidic range (0 to 7)

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The final pressure of the gas when the sample gas is administered to a new volume of 10.0 L at 20.2℃ would be 0.245 atm.

The problem here has to do with the combined gas law. The law is mathematically expressed as:

[tex]p_1v_1/t_1[/tex] =[tex]p_2v_2/t_2[/tex]

Where [tex]p_1[/tex] = initial pressure, [tex]v_1[/tex] = initial volume, [tex]t_1[/tex] = initial temperature, [tex]p_2[/tex] = final pressure, [tex]v_2[/tex] = final volume, and [tex]t_2[/tex] = final temperature.

In this case,

Rearranging the combined gas equation:

[tex]p_2[/tex] = [tex]p_1v_1t_2/t_1v_2[/tex]

Substituting the different variables:

[tex]p_2[/tex] = 1.2 x 6.02 x 20.2/59.5 x 10.0

      = 145.9248/595

      = 0.245 atm

Thus, the final pressure of the sample gas will be 0.245 atm.

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We have to find the molarity of a solution of Magnesium Fluoride. The definition of molarity is:

Molarity = moles of solute/Volume of solution in L

Our solute is MgF₂:

Molarity = moles of MgF₂ / L of solution

From the problem we know that the volume of the solution that the chemist prepared is 250. mL, we will have to convert that into L.

We know that there are 1000 mL in 1 L. So:

1 L = 1000 mL

250. mL = 250. mL * 1 L/1000 mL = 0.250 L

Volume of solution in L = 0.250 L

Now we have to find the number of moles of MgF₂ that the chemist added. From the problem we know the mass of MgF₂ added. Let's convert it to g:

1000 mg = 1 g

mass of MgF₂ = 6-73 mg

6.73 mg = 6.73 mg * 1 g/1000 mg = 0.00673 g

mass of MgF₂ = 0.00673 g

When we want to find the number of moles that we ave in a certain amount of a compound, we have to use the molar mass. Let's find the molar mass of MgF₂.

According to the periodic table the atomic mass of Mg is 24.3 amu and the atomic mass of F is 19 amu. So the molar mass of MgF₂ is:

molar mass of MgF₂ = 24.3 + 2 * 19 = 62.3 g/mol

molar mass of MgF₂ = 62.3 g/mol

Using the molar mass we can find the number of moles that we have in 6.73 mg or 0.00673 g of MgF₂:

moles of MgF₂ = 0.00673 g/(62.3 g/mol)

moles of MgF₂ = 1.08 * 10^-4 moles

So the chemist added 1.08 * 10^-4 moles of MgF₂ in 0.250 L of solution. Then the molarity of the solution is:

Molarity = moles of solute/Volume of solution in L

Molarity = 1.08 * 10^-4 moles/0.250 L

Molarity = 4.32 * 10^-4 M

So the answer to our problem is 4.32 * 10^-4 M

If the wavelength of green light from a traffic signal is approximately 5.2 ×10⁷ m , then the frequency of the light would be 5.769 × 10¹⁶ Hz .

It can be understood in terms of the distance between any two similar successive points across any wave for example wavelength can be calculated by measuring the distance between any two successive crests.

C = λν

The frequency of the green light = 3 × 10⁸ / 5.2 ×10⁷

                                                       = 5.769 × 10¹⁶ Hz

Thus , If the wavelength of green light from a traffic signal is approximately 5.2 ×10⁷ m , then the frequency of the light would be 5.769 × 10¹⁶ Hz .

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According to the explanation given in the previous session, now we have hexane in an organic compound with the solubility of 0.520 g/mL at 25°C. We need to find the value of volume at 120.0 mg

1 gram = 1000 mg

120.0 mg = 0.12 grams

Now we can calculate the volume:

0.520g = 1 mL

0.12g = x mL

0.520x = 0.12

x = 0.12/0.520

x = 0.231 mL is the volume for this compound

In simple terms a covalent bond is when we have sharing of electrons, which means there is no polarity being formed when the elements are bonded, this is more likely to occur with atoms with high electronegativity, or same pair of elements, like O2, where we have O - O (Oxygen bonded with Oxygen), since they have the same electronegativity, there is no charge being formed

The same can not be told for ionic bonds, where we have very different elements being bonded together, with a big electronegativity difference, which means we have polarity being formed (which basically means that we have charge in the compound)

One way to find out if a compound is covalent or ionic is by checking their positions in the periodic table, for example, let's analyze our question

We have:

A) Fluorine - Fluorine, here we have a classical example of covalent bond, since there is no "stronger" element, pulling the electrons towards its side, they are the same, hence, the same strength

B) Carbon - Chlorine, we have two non-metals, with a relatively high electronegativity each one of them, so there is ions being formed, therefore it is covalent

C) Potassium - Oxygen, in this case we have a metal and non-metal bonding together, and since potassium has only 1 electron in its valence shell, it will easily give up this electron to another element, therefore K will receive a positive charge (which means loss of electron) and oxygen will receive a negative charge (which means gain of electron), and this is an ionic bond

D) Oxygen - nitrogen is the same case as letter B

It is also possible to check an electronegativity table, in which there are some rules that helps you understand if a compound is more likely to be covalent or ionic

The existence of isotopy shows that the atoms of the same element are not exactly alike.

Recall that the atom is the simplest particle of a substances that is able to take part in a chemical reaction. Note that the empirical study of the atom became much more common after the study of John Dalton that led to the Dalton Atomic Theory.

Now, one of the postulates of the theory is the atoms of the same elements are exactly alike in all respects and are different from the atoms of other elements. The existence of isotopy have shown that the atoms of the same element could be different and behave slightly differently from each other.

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Subtract the numbers and write the power 10^3

The answer is 8.3x10^3

Was a bit lengthy but I guess you do it like this?

Step 1: Write and balance the equation:

3 NaCl + Al(NO3)3 → AlCl3 + 3 NaNO3

Step 2: We need to find the limiting and excess reactant. For this, we need to look at the stoichiometric ratio between the reactants:

3 moles of NaCl reacts with 1 mole of Al(NO3)3.

Now we do a rule of 3 for both.

For 9 moles of NaCl:

3 moles of NaCl --- 1 mole of Al(NO3)3

9 moles of NaCl --- x mole of Al(NO3)3

3x = 9

x = 3 moles of Al(NO3)3

For 4 moles of Al(NO3)3:

3 moles of NaCl --- 1 mole of Al(NO3)3

x moles of NaCl --- 4 moles of Al(NO3)3

x = 12 moles of NaCl

As we can see, to react with 4 moles of Al(NO3)3 we should have 12 moles of NaCl, but we have just 9. So the NaCl is the limiting reactant and the excess reactant is Al(NO3)3.

Step 3: We need to look at the stoichiometric ratio between the limiting reactant (NaCl) and NaNO3:

3 moles of NaCl --- 3 moles of NaNO3

9 moles of NaCl --- x moles of NaNO3

x = 9 moles of NaNO3

Answer: The maximum amount of NaNO3 that was produced during the experiment is 9 moles.

Answer:

Explanation:

Here, we want to get what will happen when an Atthenius base interacts with water

By definition, an Arrhenius base increases the concentration of hydroxide ions in aqueous solutions

What this simply mean is that when an Arrhenius base comes in contact with water, the solution is expected to have an increase in the concentration of hydroxide ion. This can be measures pH wise and we expect an increase in the pH of the solution from 7

The chemical element which magnesium would combine with in order to attain a subscript of 3 is nitrogen which result in the formation magnesium nitride ( Mg₃N₂ )

Magnesium is a metallic element which belongs to group 2 and and has a valence electron of 2. This means that in an electrovalent combination, magnesium loses 2 valence electrons to nitrogen to become Mg2+ ion. To complete this bonding, nitrogen which has 5 valence electrons accepts 3 of Mg2+ ions in addition with with its two N3− ions to form magnesium nitride. When this happens, magnesium then attains a subscript of 3.

Magnesium nitride is an electovalent or ionic compound and the bond which exist in it is Ionic bond. It is used in the synthesis of ceramic substances.

So therefore, we can confirm from above that when magnesium reacts with nitrogen, it attains a subscript of 3.

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Nitrogen is the chemical element that magnesium would mix with to get a subscript of 3, leading to the production of magnesium nitride.

Chemical elements are defined as a type of atom, including the pure substance made entirely of that type, with a specific number of protons in its nucleus.

Magnesium is a metallic element with a valence electron number of 2, and it is a member of group 2. This indicates that magnesium loses two valence electrons to nitrogen in an electrovalent combination to form the Mg2+ ion. Nitrogen, which has five valence electrons, accepts three Mg2+ ions in addition to its two N3 ions to complete this bonding and create magnesium nitride. Magnesium then achieves a subscript of 3 when this occurs.

Thus, Nitrogen is the chemical element that magnesium would mix with to get a subscript of 3, leading to the production of magnesium nitride.

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Let's analyze each option to find what best fit as an answer:

A - the function of a catalyst is to lower the energy of activation in a reaction, causing it to occur in a faster way. Since this question is not much about energy or kinetics, this would be the best fit, adding a catalyst or not adding it would not be too influential in the shift of the reaction.

B - Increasing the pressure in a reaction containing gases will mostly favor the side with a lower value of moles, smaller amount of moles = less pressure, so if we add more pressure, the reaction will shift towards the side of the products

C - If we treat heat as a reactant, if we add more temperature, it will shift towards the products, to counteract this increase of temperature

D - Adding reactants will favor the reaction to shift towards the products

Therefore the answer is letter A

Answer: One centimeter per month.

Explanation: Technically speaking, human hair grows about 1/2 inch a month or 6 inches a year.  1/2 inch is approx 1.27 centimeters, or in other words, one centimeter a month.  Therefore, that's your answer.

Let me know if I got it right! :)

Answer:

1 centimeter per month

Explanation:

Human hair typically grows 6 inches in a year. Since there's 12 months, we can tell that hair grows 1/2 an inch per month. 1/2 an inch is about 1 cm.

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The sum of coefficients when the above-mentioned equation is balanced is 12.

A chemical equation is a symbolic representation of a chemical reaction where reactants are represented on the left, and products on the right.

A chemical equation is said to be balanced when the number of atoms of each element on both sides of the equation is the same.

According to this question, calcium hydroxide reacts with phosphoric acid as follows:

3Ca(OH)₂ + 2H₃PO4 → Ca₃(PO4)₂ + 6H₂O

The sum of the coefficients of the above balanced chemical equation is 3 + 2 + 1 + 6 = 12.

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Final temperature of the two pieces of metal is 32.25°C

Temprature is the degree of hotness or coldness of the object

Here given data is

Mass of iron = 150 g

Mass of copper = 275 g

Specific heat of iron = 25.09 J/mol°C

Specific heat of copper = 25.46J/mol°C

Temprature in iron = 47°C = initial temprature = T₁

Temprature in copper = 20°C = initial temprature = T₁'

So here we have to find final temprature of  two pieces of metal =?

So, the formula is Q =mcΔT

Q =  (150 g - 275 g) × (25.09 J/mol°C - 25.46J/mol°C) × ( 47°C-20°C )

Q = 125×0.37×27

Q = 243 J

243 J/125×0.37 = 5.25°C = change in temprature

Initial temprature  = 27°C

Final temprature = ?

ΔT = T₂ - T₁

27°C = T₂ - 5.25°C

T₂ = 27°C +  5.25°C

T₂ = 32.25°C

Final temperature of the two pieces of metal is  32.25°C

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Explanation:

An electrolyte has to be capable of of ionizing and CH40 is not.

Therefore, CH40 is not an electrolyte.

Answer:

False

The density of the solid object is obtained to be 2.89 g/mL.

The density is defined as the ratio of the mass to the volume of the object. In this case, the density is to be obtained by the use of the displacement method of the solving the problem.

Mass of the empty cylinder =  50 g

Mass of water and cylinder = 120 g

Mass of water alone = 70 g

Mass of water, cylinder and the object = 250 g

Mass of the object = 250 g - 120 g = 130 g

Volume of the object = 75 mL -  30 mL  = 45 mL

Density of the object = 130 g/45 mL

= 2.89 g/mL

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