Consider the reaction between sodium metal and chlorine gas to form sodium chloride (table salt):2 Na(s) + Cl2 (g) > 2 NaCI(s)If 12.5 g of sodium react with sufficient chlorine, how many grams of sodium chloride should form?1. 12.1 grams2. 1.18 x 10^2 grams3. 15.9 grams4. 3.18 x 10^1 grams5. 51.0 grams

Step 1

The reaction is written and balanced as:

C2H4(g) + 302(g) → 2CO2(g) + 2H2O(g)

Step 2

Oxidation states are analyzed

For O2)

On the left, its oxidation state is 0 (O2)

On the right, it is -2 (H2O)

Step 3

The half-reaction is written as:

6 O + 12 e- => 6 O2-

Therefore, O2 is being reduced

Answer: O2

The best  way for her to accomplish the task of evaluating a hair strip is DNA testing. Hence, option A is correct.

The DNA testing in forensic laboratories include extract the DNA strands from the sample and strictly evaluate it some reagents and color indicators.

Hair analysis involves examining the DNA of cells linked to the hair's root as well as the hair's structure. It can be used to determine a person's family relationship. It is possible to use forensic hair analysis to identify a person who may have been at a crime scene. Hair samples are examined under a microscope and evaluated using particular chemicals.

Additionally, metal poisoning from lead or mercury can be detected through hair analysis. However, this form of testing often does not involve hair analysis alone.

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The pressure of the refrigerant using the ideal-gas equation is 1.861 MPa, the generalized compressibility chart is 1.583 MPa and the refrigerant tables is 1.6 MPa.

Ideal gas equation is defined as the state equation for a fictitious perfect gas. Although it has significant drawbacks, it is a decent approximation of the behavior of many gases under various conditions.

Ideal gas equation is expressed as

PV = nRT

By using Ideal gas equation

P x 0.016773 = 1 x 81.49 x 483

P = 1.861 MPa

By using generalized compressibility chart

For r134a

Temperature = 374.2 K

Pressure = 4.06 MPa

vR = V / R x Tc / Pc

    = 0.016773 / 81.49 x ( 374.2 / 4.06 x 10⁶ )

    = 2.2332

Tr = T/Tc = 383 / 374.2 = 1.024

Therefore from the chart Z = 0.85

So, P = Z mRT / V

      P = 0.85 x 1 x 81.49 x 383 / 0.016773

         = 1.582 MPa

By using refrigerant tables

T = 110 C and v = 0.0167763

So, P = 1.6 MPa

Thus, the pressure of the refrigerant using the ideal-gas equation is 1.861 MPa, the generalized compressibility chart is 1.583 MPa and the refrigerant tables is 1.6 MPa.

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Explanation:

A 13.68 g sample of iron is reacted in presence of excess fluorine and an iron fluoride with a mass of 27.64 g is formed.

We have to find the empirical formula of our compound. This compound has two elements: Fe and F. We can express it like:

metal fluoride = FeₐFₓ

Where a is the subscript of Fe and x is the subscript for F.

First we have to find the mass of F present in the compound. We know that our compound has a total mass of 27.64 g and the mass of Fe present is 13.68 g. Since it only has two elements we can find the mass of F.

mass of sample = mass of Fe + mass of F

mass of F = mass of sample - mass of Fe

mass of F = 27.64 g - 13.68 g

mass of F = 13.96 g

So we found that our sample has 13.96 g of F and 13.68 g of Fe. Now we can determine the number of moles of each element that are present in the sample by using their molar masses.

molar mass of Fe = 55.85 g/mol

molar mass of F = 19.00 g/mol

moles of Fe = 13.68 g * 1 mol/(55.85 g)

moles of Fe = 0.245 moles

moles of F = 13.96 g * 1 mol/(19 g/mol)

moles of F = 0.735 moles

By definition the empirical formula is "simplest whole number ratio of atoms present in a compound". So if we want to find the ratio between them we have to divide both of them by the smallest number.

a = subscript of Fe = 0.245/0.245 = 1

x = subscript of F = 0.735/0.245 = 3

So the empirical formula of our compound is:

empirical formula = FeₐFₓ

empirical formula = FeF₃

Answer: empirical formula = FeF₃

ANSWER

8 moles of water

EXPLANATION

The major products formed when an organic compound undergo combustion reaction are water and carbon dioxide

Below is the combustion formula

In the question above, 4 moles of methane reacts with oxygen

Therefore, 4 moles of methane will give 8 moles of water

Explanation:

As an example, Let's writte some ionic compounds:

Answer

The weight/weight % of solute = 5.3%

Explanation

Given

Mass of solute (potassium nitrate) = 4.87 g

Volume of solvent (water) = 86.4 mL

Density of water = 1.00 g/mL

Required: Weight/weight% of the solute

Solution

Step 1: Covert the volume of water to mass

mass = density x volume

mass = 1.00 g/mL x 86.4 mL

mass = 86.4 g

Step 2: Calculate the weight/weight % of the solute

Mass % solute = [mass of solute/(mass of solute + mass of solvent)] x 100

Mass % solute = 4.87g/(4.87 + 86.4)

Mass % solute = 5.3%

Answer: They serve as proof that an established and documented work can be verified, repeated, and reproduced.

Explanation: Reproducibility and research integrity are essential tenets of every scientific study and discovery. They serve as proof that an established and documented work can be verified, repeated, and reproduced. New knowledge in biomedical science is built on the shoulders of established and proven principles.

Answer:

Evidence of accuracy

Explanation:

it creates new opportunities for insights and facilitates innovation in terms of scientific knowledge.

Answer:

Rutherford's model of the atom included the nucleus, something lacking in Thomson's model. Rutherford's inclusion of the nucleus came about after his discovery of the nucleus of the atom in 1911. He was testing J.J. Thomson's Plum Pudding model by directing a beam of alpha particles toward a thin sheet of gold foil.

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2 brome butane

it has 4 C atoms therefor we know it is a butan-- and the brome is placed in the second carbone so that gives the answer 2 brome butane

The experiment mass of the product is 28.1g

What is mass ?
Mass is a physical body's total amount of matter. It also serves as a gauge for the body's inertia, or resistance to acceleration (change in velocity) in the presence of a net force. The strength of an object's gravitational pull to other bodies is also influenced by its mass.

The kilogramme is the primary mass unit in the SI (kg). Although weight is frequently measured using a spring scale rather than a balancing scale and compared directly with known masses, mass is not the same as weight in physics.

2K + Cl2 =====> 2KCl

70g Cl2 produces 2(39+35.5) = 149 g KCl

13.2g Cl2 produces 28.1g KCl

the experiment mass of the product is 28.1g

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Joules of heat are needed to raise the temperature of 100 g of iron from 23°C to 33°C, if the specific heat of iron is 0.45 J/g°C is 450 J.

Given that :

The specific heat capacity expression is given as :

Q = m cΔT

Q = heat energy

m = mass = 100 g

c = specific heat = 0.45 J/g °C

ΔT = change in temperature = 33  °C - 23  °C  =  10  °C

substituting the values in the formula:

Q = m cΔT

Q = 100 g × 0.45 J/g °C × 10 °C

Q = 450 J

Thus, Joules of heat are needed to raise the temperature of 100 g of iron from 23°C to 33°C, if the specific heat of iron is 0.45 J/g°C is 450 J.

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The body of avocado fruit can be compared with the cell structure. The skin of the avocado is relatable with the cell membrane. Thus option B is correct.

Cell is the basic unit of life. Cells connect together to forms  tissues and tissues forms organs and a group organs forms an organ system. These different organ systems buildup the whole body.

Cell contains the core called nucleus. Inside the nucleus genetic material DNA, ribosomes, Golgi apparatus, lysosomes etc are located. The function of cell membrane is to protect the cell from damages as the skin do for our body.

In plants unlike animals, their cell is protected by a cell wall apart from cell membrane and various other differences are there in the cell structure of plant cells.

The fluid filled portion of cell is called cytoplasm. The inner content of the avocado fruit is comparable with the cytoplasm and its seed can be considered as the model for nucleus.

Therefore, the avocado's skin represents the cell membrane. Hence, option B is correct.

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Answer:

Explanation:

Here, we want to get the class of lipids that the given substances belong to

These substances are formed from glycerol and fatty acids

From their make up,we know that they are simple lipids

Thus, the answer here is simple

The molecular equation of the reaction of sulfuric acid and aqueous potassium hydroxide:

H₂SO₄ (aq)  + 2 KOH (aq)  →   K₂SO₄ (aq)  +  2H₂O (l)  

The net ionic equation is:

2H⁺ (aq)  +  2OH⁻ (aq) [tex]\longrightarrow[/tex] 2H₂O (l)

The net ionic equation of a reaction can be described as an equation that expresses only those elements, compounds, or ions that directly contributed in that chemical reaction.

The balanced chemical equation reaction of sulfuric acid and aqueous potassium hydroxide:

H₂SO₄ (aq)  + 2 KOH (aq)  →   K₂SO₄ (aq)  +  2H₂O (l)  

The complete ionic equation for the above reaction can be written as follows:

2H⁺ (aq) + SO²₄⁻ (aq)  +  2K⁺(aq)  + 2OH⁻ →  2K⁺ (aq) + SO₄²⁻ (aq)  + 2H₂O (l)

In the ionic equation, the potassium and sulfate ions appear unchanged on both sides of the equation. When we mix the two solutions, the potassium and sulfate ions do not participate in the reaction. So potassium and sulfate ions can be eliminated from the ionic equation.

2H⁺ (aq)  +  2OH⁻ (aq) [tex]\longrightarrow[/tex] 2H₂O (l)

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The total number of electoral votes does Virginia have is 13. This addressed in congressional apportionment.

When people cast their vote, means they actually voting for the group of people called electors. Senator and representatives are equal to the number of voters in each state . According to the question , Virginia has 11 people in the house and 2 senate means 11 + 2 = 13 . the total number of electoral votes are 13. These votes are assigned by united states electoral college. In the constitution the congressional apportionment is addressed.

Thus, Virginia has 11 people in the House and 2 in the Senate. The total number of electoral votes does Virginia have is 13. This addressed in congressional apportionment.

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Unstable atoms usually are very large atoms with a big nucleus, this configuration sometimes gives the atoms this unstable characteristic, which is why they decay so fast (some will decay in a matter of milliseconds), and radioactive decay is a way that atoms can find to become more stable, in this type of process, particles (alpha and beta decay) and energy (gamma decay), can be emitted from an atom in order to reach stability, therefore the best option is the 3rd option

Answer:

1. 30 neutrons

2. 26 electrons

Explanation:

The number of neutron = mass - #protons = 56 - 26 = 30

The number of electrons = #protons = 26

- The numbers are called subscripts which is the total atoms of the elements present in a compound.

- The subsripts can change depending on the type of compound.

The subcripts in a chemical compounds allow us to us know or determine the total atoms of such element that is present in the compound. For instance, in H2O (water), the subscript 2 in H2O shows that there 2 atoms of hydrogen in the compound (H2O).

They numbers differs depending on the type of compound. For instance O2 is oxygen while O3 is ozone

The moles of electrons are needed to produce 53.5 mole of Zn is 107 moles.

Electrons are defined as a subatomic particle having a negative charge that makes up the nucleus of an atom together with protons and neutrons.

The electron has an intrinsic angular momentum of a half-integer number and has a mass that is around 1/1836th that of the proton. The quantum state of any two electrons cannot be identical.

The chemical reaction for solid zinc is

Zn²⁺  +  2e⁻  =  Zn (s)

When one mole of zinc ions receive two moles of electrons, one mole of zinc is created.

Electrons equal two moles to form one mole of solid zinc.

The electrons needed to create the 53.5 mole of zinc will provide 2 53.5 = 107 mol.

Thus, the moles of electrons are needed to produce 53.5 mole of Zn is 107 moles.

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Answer

Explanation

Given data:

Answer: Tetrachloroethylene is an nonpolar molecule.

The final temperature of the solution will be 29.5 °C.

The heat released when 21.5 g of LiCl is dissolved completely in water is determined from the enthalpy change, ∆H of the solution of LiCl as follows;

Moles of LiCl in 21.5 g = mass/ molar mass

molar mas of LiCl = 42.5 g/mol

Moles of LiCl in 21.5 g = 21.5/42.5

Moles of LiCl in 21.5 g = 0.506 moles

Heat released = 0.506 * -37.0 kJ/mol

Heat released = 18.722 kJ or 18722 J

Heat released = heat gained by solution

mass of solution = 450 + 21.5

mass of solution = 471.5 g

Temperature change of the solution = 18722 / (471.5 * 4.184)

Temperature change of the solution = 9.5 °C

Final temperature of the solution = 20 °C + 9.5 °C

Final temperature of the solution =29.5 °C

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Answer

Hydrogen bonding, dipole-dipole interaction, and dispersion forces.

Explanation

The chloramine (NH₂CI) molecule has N-H bonds, so there will be hydrogen bonding. Also, NH₂Cl is a polar molecule, so there will be dipole-dipole interaction. And as with molecules like O²⁻, there will be dispersion forces.

Therefore, the kind of intermolecular forces that act between a chloramine (NH₂CI) molecule and an oxide (O²⁻) anion are hydrogen bonding, dipole-dipole interaction, and dispersion forces.

The total entropy that a pure material would accumulate upon warming from absolute zero (where S=0) to the specific temperature is the absolute entropy of that substance at that temperature.

What is entropy?

One of the key ideas that students studying physics and chemistry need to grasp with clarity is entropy. More importantly, entropy has multiple definitions and can be used in a variety of contexts, including the thermodynamic stage, cosmology, and even economics. Entropy is a notion that mostly discusses the spontaneous changes that take place in commonplace phenomena or the universe's propensity for chaos.

Determination in terms of heat capacity​

The third rule of thermodynamics has two significant ramifications: it establishes a constant reference point that enables us to measure the absolute entropy of any substance at any temperature, and it specifies the sign of the entropy of any substance at temperatures above absolute zero as positive. We look at two different approaches to calculating S for a reaction or a physical change in this section.

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To calculate the molar mass of a compound, we need to find at the periodic table the atomic mass of each element that belongs to the compound and then we multiply for the quantity of atoms of it.

So, for:

5. K2Cr2O7:

K = 39 g/mol

Cr = 52 g/mol

O = 16 g/mol

(2x39) + (2x52) + (7x16) = 78 + 104 + 112 = 294 g/mol

Molar mass of K2Cr2O7 = 294 g/mol

6. C12H22O11

C = 12 g/mol

H = 1 g/mol

O = 16 g/mol

(12x12) + (22x1) + (11x16) = 144 + 22 + 176 = 342 g/mol

Molar mass of C12H22O11 = 342 g/mol

The energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C is 2308.87 kJ.

The heat energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C is determined from the formulas below:

Heat change 1 = Heat capacity as gas * moles * temperature change

Heat change 2 = Heat of vaporization, ΔHvap * moles

Heat change 3 = Heat capacity as liquid, Cp (l) * moles * temperature change

moles of water = 950 kg * 1000 g/kg * 1 mol/ 18g = 52.78 mole

Heat change 1 = 33.6 * 52.78 * (103 - 100) = 5320.224 J

Heat change 2 = 40.67 * 1000 * 52.78 = 2146562.6 J

Heat change 3 = 75.3 * 52.78 * (100 - 60.5) = 156986.193 J

Total heat change = 5320.224 J + 2146562.6 J + 156986.193 J

Total heat change = 2308869.017 J = 2308.87 kJ

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To calculate the number of atoms of any compound it is necessary to use the Avogadro constant. This is a constant of proportion between the amount of matter and the number of entities that are linked to that amount. These entities can be atoms, molecules, ions, electrons, protons, neutrons. The value of the Avogrado constant is 6.022 x 10^23 mol^-1.

So to calculate the number of atoms in 275 grams of iron (III) hydroxide:

- First you need to transform grams into moles

- transform moles into atoms/molecule using Avogrado constant.

- To transform 275 grams of Fe(OH)₃ you need to use the molecular mass of Fe(OH)₃ and the following equation: mole = mass/molar mass

Molecular mass of Fe(OH)₃:

Fe - 55.85

O - 16

H - 1

(1x55.85) + (3x16) + (3x1) = 106.86 g/mol

Replace the value in the equation:

mole = 250/106.86

mole = 2.34 mole of Fe(OH)₃

- Now, let's solve the number of molecules of Fe(OH)₃ into 2.34 mole of Fe(OH)₃:

6.022 x 10^23 molecule --- 1 mol

x molecule ---- 2.34 mole

x = 1.41 x 10^24 molecules of Fe(OH)₃

Answer: There are 1.41 x 10^24 molecules of Fe(OH)₃

To calculate this, we will need to assume the gas behaves as an ideal gas.

So, we can use the Ideal Gas Law:

Where P is the pressure, V is the volume, n is the number of moles, is the absolut temperature and R is the gas law constant.

Since we have carbon dioxide, CO₂, we need to calculate its molar mass to convert the mass to number of moles:

So, the number of moles is:

Also, we need to convert the temperature to absolute temperature, so we can convert it to K by adding 273.15 to the degree celcius temperature:

Now, we need to use the constant R that has the unit we want. We have K for temperature, mol for number of moles and L for volume. Is we want the pressure in kPa, we need to use the R constant with units L*kPa/(K*mol), which have the value:

So, solving the equation for P and substituting the values, we have:

So, the pressure is approximately 15 kPa.