Coloumb's Law shows that opposite charges (positive and negative) attractwhereas charges that are both positive or both negative repel and a greater
distance decreases the force between objects. TRUE or FLASE​

Answer:

d. Ar, because of its higher effective nuclear charge

For the secon part see explanation below.

Explanation:

The first ionization energy is the energy required to remove an electron from the atom from its outermost shell. It depends on the nuclear charge, distance from the nucleus and the screening of other electrons in the inner shells of the atom.

Comparing Cl and Ar we see that being both elements of the third period, the Ar atom has one more proton than Cl and therefore the electron feels more nuclear charge making the first ionization of Ar greater than Cl.

a) False, electronegativity relates to attraction for an electron and not to the first ionization.

b) False, again electron affinity is not first ionization, it is defined as the energy released when the atom captures an added electron.

c) False,athough it is true that Ar has  a complete octet, the higher first ionization is affected by nuclear charge. The screening of electrons in the n= 1 and 2 shells is almost the same so what is important is that the electrons in the n= 3 shell feel more nuclear charge.

d) True for all the reasons given previously : the higher effective nuclear charge in Ar.

For the second part, we have to make an inventory of the bonds being broken and formed:

ΔHºrxn = H broken - H formed, where H is the bond energy

H2 C = CH_2  +   H-Br    ⇒   CH_3CH_2Br

ΔHºrxn  = ( 1 C=C + 4 C-H + 1 H-Br)   -   ( 1 C-C + 5 C-H + 1 C-Br)

ΔHºrxn (kJ) =  (614 + 4(413) + 363) - ( 347 + 5 (413) + 276)

ΔHºrxn (kJ) = 2629 -  2688 =  -59 kJ

This value is not in the choices due to mistaken bond energy values from the tables.

Answer:

1. Ar, because of its higher effective nuclear charge.

2. ∆Hrxn = -200 KJ/mol

Explanation:

The size of the atoms of chemical elements can be measured from their atomic radius which is also affected by the effective nuclear charge.

Recall that elements in a particular period have the same number of electron shells. Also, along a given period, atomic radius decreases due to an increase in the effective (positive) nuclear charge. This is because as the atomic (proton) number increases along that period, the charge on the nucleus also increases. With more protons in the nucleus the overall attraction between the positively charged nucleus and the negatively charged surrounding electrons increases, so the electrons are pulled closer to the nucleus thereby leading to a decrease in the atomic size.

So, along a given period atomic size decreases due to an increase in the effective nuclear charge.

The first ionization energy is the minimum energy (in kilojoules) needed to strip one mole of electrons from one mole of a gaseous atom of an element to form one mole of a gaseous unipositive ion.

Along a particular period, ionization energy increases due to an increase in the effective nuclear charge and a decrease in atomic radius. This is because, the smaller the atom the more stable it is and the more difficult it will be to remove an electron.

For the second question,

The enthalpy change of a reaction is the difference in the bond dissociation energies of the reactants and products. Bonds are broken in reactant molecules and formed in product molecules. Bond breaking energies are usually intrinsic ( endothermic, +be ∆H ) while bond forming energies are usually extrinsic ( exothermic, -ve ∆H ).

So,

∆Hrxn = n∆H(reactants/bonds broken) - m∆H(products/bonds formed)

Where n and m = stoichiometric coefficients of the products and reactants respectively from the balanced chemical equation.

First, draw the correct Lewis structures of the compounds.

Next, identify all the bonds broken and formed.

Then, from the bond dissociation energies ( usually given or looked up in texts ), sum up the bond breaking energies and the bond forming energies and subtract the bond forming energies from the bond breaking energies.

Considering this equation:

H_2C = CH_2 + H-Br rightarrow CH_3CH_2Br

The equation is balanced.

Bonds broken (number of bonds ):

I. C=C (1)

II. H-Br (1)

III. C-H (4)

Bonds formed:

I. C-C (1)

II. C-H (5)

III. C-Br (1)

∆Hrxn = [ ( 1 x C=C ) + ( 4 x C-H ) + ( 1 x H-Br ) ] – [ ( 1 x C-C ) + ( 5 x C-H ) + ( 1 x C-Br ) ]

∆Hrxn = [ ( 1 x 614 ) + ( 4 x 413 ) + ( 1 x 141 ) ] – [ ( 1 x 348 ) + ( 5x 413 ) + ( 1 x 194 ) ]

∆Hrxn = [ ( 614+1652+141) ] – [ ( 348 + 2065 + 194 ) ]

∆Hrxn = 2407 – 2607

∆Hrxn = -200KJ/mol

question no 1 answer is compounds

Final answer:

Elements combine to form millions of compounds. The force holding atoms together in these combinations are chemical bonds. Each electron has a negative charge, electrons are always moving, and have more energy the farther they are from the nucleus.

Explanation:

The elements can combine in many ways to create compounds, which amount to millions. When atoms connect or adhere to each other to shape those compounds, it happens through chemical bonds. In an atom, each electron has a negative charge, a characteristic that's vital for the creation of chemical bonds. Electrons are in constant movement, which means we cannot exactly determine their positions. As for the energy level of these electrons, those farther away from the nucleus have, in general, more energy than the ones located closer to the nucleus.

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Answer:

0.113 M

Explanation:

Since B and D are on opposite sides of the reaction, the concentration of D increases when the concentration of B decreases. The amount by which D increases is determined by the coefficients of B and D in the balanced chemical equation:

[D]=(0.045 M)=0.113 M.

Answer:

Explanation:

Hello,

In this case, with the given by-volume percentage and considering the molarity as:

We assume the solution having 100 mL of volume in total, thus, the volume of ethanol is 27.0 mL, therefore, the moles:

Moreover, the volume of the solution in liters is:

Finally, the molarity is:

Best regards.

If the density of ethanol (c2h6o, molar mass 46.07 g/mol) is 0.790 g/ml, the molarity of the 27.0% (v/v) aqueous ethanol solution is 17.14 M.

Calculate the moles of ethanol contained in the solution, then divide that number by the volume of the solution in litres to determine the molarity of the ethanol solution.

To start, we must ascertain how much ethanol is included in each 100 millilitres of the solution. Given that ethanol has a density of 0.79 g/ml, the amount of ethanol in 100 millilitres is as follows:

Mass of ethanol = density × volume

Mass of ethanol = 0.790 g/ml × 100 ml = 79 g

Now,

Moles of ethanol = mass / molar mass

Moles of ethanol = 79 g / 46.07 g/mol = 1.714 mol

So,

Volume of solution = 100 ml / 1000 ml/L = 0.1 L

We know that:

Molarity = moles of solute / volume of solution

Molarity = 1.714 mol / 0.1 L = 17.14 M

Thus, the molarity is 17.14 M.

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Final answer:

The electron pair geometry of a phosphine, PH3, molecule is tetrahedral, though the molecule itself takes on a trigonal pyramidal shape due to the presence of a lone pair of electrons on the phosphorus atom.

Explanation:

The electron pair geometry for a phosphine molecule, PH3, is tetrahedral. In PH3, the phosphorus atom is the central atom surrounded by three hydrogen atoms. However, it is important to note that the phosphorus atom also has a lone pair of electrons. The lone pair occupies more space than bonding pairs, causing the molecule to take on a trigonal pyramidal molecular geometry. Despite the molecular geometry, the electron pair geometry is considered tetrahedral because it accounts for all regions of electron density, including lone pairs.

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Final answer:

The electron pair geometry for a phosphine molecule (PH3) is tetrahedral. This refers to the spatial arrangement of regions of electron density around the central atom, phosphorus, which is bonded to three hydrogen atoms and has one lone pair of electrons.

Explanation:

The electron pair geometry for a phosphine molecule, PH3, is best described as tetrahedral. Even though the PH3 molecule is not tetrahedral, the electron pair geometry refers to the spatial arrangement of regions of electron density around the central atom, in this case, phosphorus. Phosphorus in the PH3 molecule is bonded to three hydrogen atoms and has one lone pair of electrons. These four regions of electron density adopt a tetrahedral arrangement to minimize electron-electron repulsion. Please note that the molecular structure of PH3 is trigonal pyramidal as lone pairs are not included while determining the molecular geometry.

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The number of moles of iron needed to react with 16.0 moles of sulfur is 128.0 moles.

Calculation of number of moles of iron

Given equation, 8Fe + S8 = 8 FeS

Moles of sulfur = 16.0

To react 1 mole of sulfur, we need 8 moles of Fe

So, for 16.0 moles of sulfur we need

Thus, to react with 16.0 moles of Sulfur, 128.0 moles of Fe is needed.

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Answer:

To react with 16.0 moles of sulfur we need 128.0 moles of iron (Fe).

Explanation:

Step 1: Data given

Number of moles Sulfur = 16.0 moles

Step 2: The balanced equation

8 Fe + S8 → 8 FeS

Step 3: Calculate mole Fe

For 8 moles Fe we need 1 mol S8 to produce 8 moles FeS

For 16.0 moles of Sulfur we need 8*16.0 = 128.0 moles

To react with 16.0 moles of sulfur we need 128.0 moles of iron (Fe).