Calculate the moles of Fe in 4.95x 1022 atoms of Fe .

Answer:

pH = 8.75

Explanation:

100.0mL of a 0.8108M of a butanoic acid (HC₃H₇CO₂, pKa 4.82) solution is titrated with 0.0520M KOH.

The reaction is:

HC₃H₇CO₂ + KOH → H₂O + KC₃H₇CO

Moles of butanoic acid are:

0.1000L × (0.8108mol / L) = 0.08108 moles of butanoic

For a complete reaction, volume of KOH must be added is the volume in which 0.08108 moles of KOH are added, that is:

0.08108 mol × (L / 0.0520mol) = 1.56L of KOH.

Total volume in equilibrium is 1.56L + 0.10L = 1.66L

That means concentration of butanoic acid is:

0.08108 mol / 1.66L = 0.04884M HC₃H₇CO₂

At equivalence point, there is just C₃H₇CO⁻ in solution

Kb of butanoic acid is:

C₃H₇CO⁻ + H₂O ⇄ HC₃H₇CO₂ + OH⁻

Kb = Kw / Ka

Ka = 10^-pKa

Ka = 1.51x10⁻⁵

Kb = 1x10⁻¹⁴ / 1.51x10⁻⁵ = 6.61x10⁻¹⁰

The equilibrium of Kb is:

Kb = 6.61x10⁻¹⁰ =  [HC₃H₇CO₂] [OH⁻] / [C₃H₇CO⁻]

As at equivalence point there is just C₃H₇CO⁻, the equilibrium concentrations are:

[C₃H₇CO⁻] = 0.04884M - X

[HC₃H₇CO₂] = X

[OH⁻] = X

Replacing in Kb:

6.61x10⁻¹⁰ =  X² / [0.04884M - X]

0 =  X² + 6.61x10⁻¹⁰X - 3.23x10⁻¹¹

Solving for X:

X = -5.68x10⁻⁶ → False solution. There is no negative concentrations

X = 5.683x10⁻⁶ → Right solution.

As [OH⁻] = X, [OH⁻] = 5.683x10⁻⁶.

pOH = - log [OH⁻]

pOH = 5.245

pH = 14 - pOH

the possible quantum numbers (ordered n, ℓ, mℓ ) are:Option B.5, 3, -3 and Option C. 4, 3, -2

The quantum numbers n, ℓ, mℓ represent respectively the principal quantum number, the orbital angular momentum quantum number and the magnetic quantum number.

These are the three most important quantum numbers. T

here is another quantum number called the spin quantum number, denoted by ms.

Let's see which of the given quantum number sets is possible.2, 1, 3 is not possible because for ℓ = 1, mℓ can only be -1, 0, or 1. 5, 3, -3 is possible.4, 3, -2 is possible. -4, 3, 1 is not possible.

For any value of ℓ, mℓ must be between -ℓ and +ℓ. e. 2, 1, -2 is not possible because for ℓ = 1, mℓ can only be -1, 0, or 1. f. 3, 2, 2 is not possible because for ℓ = 2, mℓ can only be -2, -1, 0, +1, or +2. g. 3, 3, 1 is not possible because for any value of ℓ, mℓ must be between -ℓ and +ℓ.

Therefore, the possible quantum numbers (ordered n, ℓ, mℓ ) are:5, 3, -34, 3, -2

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Answer:

43 protons

36 electrons

56 neutron

Explanation:

neutron is mass number minus proton number.

in a non neutral atom the electron is determined after minusing the charges or electron lost.

the number of proton obviously is 43

When a chemical reaction releases energy it is called Exothermic Reaction.

hope it helps!

When a chemical reaction energy releases then this type of reaction is called exothermic reaction. In this reaction energy is release to the atmosphere.

In chemistry there are various type of reaction out of which the two main types are the exothermic reaction and endothermic reaction.

Exothermic reaction is the one in which energy releases in form of heat respiration reaction is an example of exothermic reaction. In respiration food that we eat are broken down in glucose with release of energy.

Endothermic reaction is the one in which energy is taken out during the reaction. Photosynthesis is an example of endothermic reaction where sunlight energy is taken by the plants to make food.

Thus when a chemical reaction releases energy these reactions are called exothermic reaction.

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The volume of the platinum solid is determined as 8.16 cm³.

The volume of the  platinum solid is calculated from its density and mass as shown below.

V = m/ρ

where;

Volume of the platinum solid is calculated as follows;

V = 175 g / 21.45 g/cm³

V = 8.16 cm³

Thus, the volume of the platinum solid is determined as 8.16 cm³.

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Answer:

Explanation:

he pH of the water will determine the toxic effects, if any, of these substances.

Pure water is neutral with the pH of 7. But when water combines with other substance the pH varies as per the acidity of the combining substance.

pH is the measure of acidity of a solution and mathematically it is the negative logarithm of hydrogen ion concentration. Acidic substance have a pH of less than 7 whereas, basic substance have higher pH value.

Water when combines with some acids, its acidity increases. For example acid rain resulting from the reaction of rain water with oxides of nitrogen and Sulphur forming nitric acid and sulphuric acid.

pH of water have a role in the toxic effects of components in water pH and alkalinity of water determines the coagulation of other substances in water.

Hence, the properties of other substance in water is pH dependent and might effect the alkalinity or acidity of water as well the properties of substances in water such as toxicity.

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Answer:

A. Mass

Explanation:

If it takes up space it has to have mass. Not everything that is matter has a color, certain length or width.

Answer:

Cu2+ (aq) + e- -------->Cu+ (aq)​E° = 0.15 V anode

Br2 (l) + 2e- -------------> 2Br- (aq) ​E° = 1.08 V cathode

Explanation:

The half equation having a more positive reduction potential indicates the reduction half equation while the half equation having the less positive reduction potential indicates the oxidation half equation.

The overall redox reaction equation is;

2Cu^+(aq) + Br2(g) ----> 2Cu^2+(aq) + 2Br^-(aq)

E°cell= E°cathode -E°anode

E°cathode= 1.08 V

E°anode= 0.15 V

E°cell= 1.08V-0.15V

E°cell= 0.93V

From;

∆G=-nFE°cell

n= 2

F=96500C

E°cell= 0.93V

∆G= -(2×96500×0.93)

∆G= - 179.49 J

From ∆G= -RTlnK

∆G= - 179.49 J

R=8.314Jmol-K-1

T= 25° +273= 298K

K= ???

lnK= ∆G/-RT

lnK=-( - 179.49/(8.314×298))

lnK= 0.0724

K= e^0.0724

Kc= 1.075

We can be able to determine the amount of toxic lead in the water by thee use of  atomic absorption spectrophotometry.

A toxic metal is known as any metal that is able to affect the health of people. We know that toxic metals are mostly the metals that are in the group of the heavy metals.

Now we know lead as a metal that is able to cause brain damage especially in children. This is why it is very important that there should be a thorough examination in order to know the amount of lead that is present in water.

There are several methods that could be applied in the determination of lead and one of the most common methods is by the use of atomic absorption spectrophotometry which is able to detect even the minutest amount of the led in solution.

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The volume of solution needed if I need to make 2.5 L of a 0.2 M fruit drink solution from the 0.7 M drink solution is 0.714L.

The concentration of a solution can be calculated using the following formula;

McVc = MdVd

According to this question, one needed to make 2.5 L of a 0.2 M fruit drink solution from the 0.7 M drink solution. The final volume needed is as follows:

2.5 × 0.2 = 0.7 × V

0.5 = 0.7V

V = 0.714L

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Xeriscaping is a landscaping approach that focuses on conserving water by using drought-tolerant plants and efficient irrigation techniques. The goal is to create a visually appealing and sustainable garden while minimizing water usage.

Successful xeriscaping projects involve several key elements. Firstly, careful plant selection is crucial, opting for species that can thrive in arid conditions without excessive watering. Mulching is used to reduce evaporation and retain soil moisture.

Proper soil preparation, such as improving drainage and adding organic matter, promotes healthier plant growth. Efficient irrigation systems, like drip irrigation or soaker hoses, deliver water directly to plant roots, minimizing wastage.

Additionally, controlling erosion through the use of retaining walls or terracing is important. Lastly, regular maintenance, including appropriate pruning and weed control, ensures the longevity and vitality of the xeriscape garden. Overall, a successful xeriscaping project harmonizes sustainable practices with a beautiful outdoor environment.

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The greatest electron affinity will be "Ar".

The quantity of energy produced when an electron must be coupled to a neutral atom as well as a molecule in the gaseous state to create an anion has been known as the electron affinity of an atom and molecule.

In the periodic table, electron affinity typically increases over a period although occasionally declines within a group. The generally increased nuclear charge up a group throughout a period provides the chemical explanation for differences in electron affinities across the periodic table.

Therefore, Ar will have a higher electron affinity.

So the correct answer will be option (D)

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Answer:

increasing the positive charge of the positively charged object and increasing the negative charge of the negatively charged object would make the oppositely charged objects attract each other more.

Answer:

5. higher

6. shifted down

7. closer together  

8. increase its wave length

Explanation:

There will be 0.4589 mL of ethyl acetate left in the space after evaporation.

The conversion of a liquid substance into a gas is known as evaporation. As a result of the liquid absorbing energy from its surroundings, molecules begin to travel faster and faster until they finally become a vapour and escape into the environment. Usually, the energy is absorbed as heat, but it can also be in the form of light or electricity.

No, the ethyl acetate won't all evaporate. The amount of ethyl acetate that will stay in the space after evaporation can be determined using the ideal gas law. As per the ideal gas law, PV = nRT

P is the overall system pressure, V is the room's volume, n is the amount of ethyl acetate in moles, R is the ideal gas constant, and T is the temperature.

To solve for n, the quantity of moles of ethyl acetate, we can rearrange the equation as follows: n = PV/RT

When the values are plugged in, we get:

n = (94.9 torr)(7.25 m x 2.75 m x 2.75 m)/(8.314 J/K mol)(298 K)

\(n = 4.666 \times 10^{-3} mol\)

The molar mass of ethyl acetate (88.11 g/mol) can then be used to compute the mass of ethyl acetate:

Mass = \(n \times M = (4.666 x 10^{-3} mol)(88.11 g/mol)\) = 0.4125 g

Using the density of ethyl acetate (0.901 g/mL), it is possible to determine the volume of the liquid that is still present:

Volume = mass/density = (0.4125 g)/(0.901 g/mL) = 0.4589 mL

As a result, there will be 0.4589 mL of ethyl acetate left in the space after evaporation.

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Answer:

a) CH2

b) C18H36

c) 80%

Explanation:

CO2 = 44.009 g/mol  --> 78.44 g = 1.782 mol of CO2

H2O - 18.015 g/mol --> 32.12 g = 1.782 mol of H2O

a) 1.782 mol of CO2 contain 1.782 mol of C, 1.782 mol of H2O contain 1.782 x 2 mol of H

Thus, Emperical formulae of Hydrocarbon = CH2

b) CH2 = 14.027 g

252.48g / 14.027 g = 18

Molecular formulae of Hydrocarbon = C18H36

c) 1.782 mol of CH2 was combusted

1.782 x (14.027 g) = 24.996 g

% of sample equaling HydroCarbon = 24.996 g/31.25 g = 79.98 % = 80 %

The answer of temperature change is mentioned below

The change in temperature is given by

 ΔT=Final Temperature −Initial Temperature  

Measurements of temperature

It is a measure of the degree of hotness or coldness of a body

To determine temperature changes,

the initial and final temperature of the iron and water is recorded.

For Iron

Iron at higher temperature is dipped in water

Water is at lower temperature so there will be change in temperature fo both

These data are recorded

Temperature change = Final temperature - Initial temperature.

a) Temperature change for metal =  200 -  100 = 100 0C

Temperature change for water = 22.5

Temperature change for both = 23.3

b)  For water 0.7

For iron Metal 76.6

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Answer: initial temp of metal: 100 C, initial temp of water 22.4, final temp of both 27.1

Explanation:

The concept VSEPR theory is mainly based on the arrangement of electron groups. This theory is generally used to predict the geometry of the molecules.

The Valence shell electron pair repulsion theory is based on the assumption that valence shell electron pairs repel each other and are oriented in space as far apart as possible to minimize mutual repulsion.

Each group around the central atom is designated as a bonding pair or non-bonding pair. For example BeF₂ is a two electron group in which the number of bond pairs on the central 'Be' atom is two.

Similarly the molecule BCl₃ is a three electron group, the number of electron pairs on the 'Be' atom is 3.

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A bond between 2 atoms as being covalent an electronegativity difference of greater than 1.7 between the atoms.

Bond is a debt instrument, which is issued by governments and corporations. These bonds are used to raise capital for various projects and investments. Bonds are a form of loan and investors are usually paid a fixed interest rate for lending their money. Bonds are typically issued for a fixed period of time, usually for a period of 5-30 years, and have a fixed maturity date. Investors receive interest payments at regular intervals and receive the principal amount of the bond at the end of the period.

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Explanation:

When calculating the equilibrium constant expression we don't include pure solids or liquids because their concentrations stay constant during the reaction. Since their concentrations don't change significantly throughout the reaction (if enough is present) they don't affect the equilibrium so we don't include them in the ksp formula.

Answer: because the concentration of a purid solid remains constant during the reaction.

Scientific theories explain why a phenomenon occurs and a scientific law explains what occurs. The correct option is A.

A scientific theory is an explanation for a phenomenon in the natural world or the universe that has undergone extensive testing and verification using approved procedures for observation, measurement, and result evaluation.

A scientific law often describes an observed phenomenon. It doesn't explain the phenomenon's existence or its origins.

A scientific theory is the explanation for a phenomenon. It is a myth that with enough study, theories can become laws.

Thus, the correct option is A.

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Answer:

The device shown is a calorimeter that used to measure the heat transfer by a reaction under constant volume.

Explanation:

The balanced molecular equation for the reaction between sodium hydroxide (NaOH) and aluminum chloride (\(AlCl_3\)) in aqueous solution can be written as follows: 2NaOH(aq) + 3\(AlCl_3\)(aq) → 3NaCl(aq) + \(Al(OH)_3\)(s)

In this reaction, sodium hydroxide (NaOH) reacts with aluminum chloride (\(AlCl_3\)) to form sodium chloride (NaCl) and aluminum hydroxide (\(Al(OH)_3\)). The coefficients in the balanced equation indicate the stoichiometric ratio between the reactants and products.

The physical states of the substances are indicated by the symbols (aq) for aqueous solutions and (s) for the solid precipitate.

The reaction is a double-displacement reaction, also known as a precipitation reaction. Double-displacement reactions involve the exchange of ions between two compounds, resulting in the formation of a precipitate.

In this case, sodium hydroxide and aluminum chloride react to form sodium chloride and aluminum hydroxide, with aluminum hydroxide being the white solid precipitate.

It's worth noting that the actual reaction might involve hydrated forms of the compounds, such as NaOH·x\(H_2O\) and \(AlCl_3\)·y\(H_2O\). However, for simplicity, these hydrated forms are not included in the balanced equation.

Overall, the balanced equation represents the chemical reaction between sodium hydroxide and aluminum chloride, showing the reactants, products, and their stoichiometric ratios.

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The half-life of Po-210 is 140 days. If the initial mass of the sample is 5 kg, 3.5g will remain after 280 days.

Chemical kinetics is a subfield of physical chemistry that studies the speeds of chemical processes. The rate of the reaction may be used to classify it as quick, moderate, or sluggish. Reaction mechanism also enables us to study the effects of temperature and catalyst on reaction rate and rate constant. It informs us about reaction processes and enables us to apply particular rate constants to certain mechanistic stages.

The rate law for first order kinetics is

K=(2.303/T)×log(a/a-x)

half life=0.693/K

Where

k - rate constant

t - time passed by the sample

a - initial amount of the reactant

a-x - amount left after the decay process

K=0.693/half life

K=0.693/140

=0.086

0.086=(2.303/ 280)×log( 5 /a-x)

0.086=0.07×log( 136/a-x)

1.22=log( 136/a-x)

136/a-x=16.5

a-x=3.5g

Therefore, 3.5g will be left after 280 days.

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Dehydration of the process is linked to a decrease in entropy. correct option is (A).

Entropy is a measurement of a system's disorganization. It is an extended attribute of a thermodynamic system, which means that the amount of matter in the system affects its value. Entropy is frequently represented in equations by the letter S and is measured in joules per kelvin.

By combining several molecules into one, a dehydration reaction lowers the system's entropy. On the other hand, entropy is raised by catabolic, depolymerizing, and hydrolytic activities that break down molecules into smaller parts.

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Answer:

32.2 g of Na will produce 43.4 g of Na2O.

Explanation:

The balanced chemical equation for the reaction between sodium and oxygen shows that 4 moles of sodium react with 1 mole of oxygen to produce 2 moles of sodium oxide:

4Na(s) + O2(g) → 2Na2O(s)

To solve this problem, we can use the following steps:

Step 1: Convert the mass of Na given in the problem to moles using the molar mass of Na.

molar mass of Na = 23 g/mol

moles of Na = mass of Na / molar mass of Na

moles of Na = 32.2 g / 23 g/mol

moles of Na = 1.4 mol

Step 2: Use the mole ratio from the balanced chemical equation to determine the moles of Na2O produced.

From the balanced chemical equation, we can see that 4 moles of Na react to produce 2 moles of Na2O.

moles of Na2O = (moles of Na / 4) x 2

moles of Na2O = (1.4 mol / 4) x 2

moles of Na2O = 0.7 mol

Step 3: Convert the moles of Na2O to grams using the molar mass of Na2O.

molar mass of Na2O = 62 g/mol

mass of Na2O = moles of Na2O x molar mass of Na2O

mass of Na2O = 0.7 mol x 62 g/mol

mass of Na2O = 43.4 g

Therefore, 32.2 g of Na will produce 43.4 g of Na2O.

Answer:

Before we can sketch the Lewis structures of molecules, we must first understand the octet rule. The octet rule asserts that when atoms combine to create compounds, electrons are gained, lost, or shared among them, resulting in a stable electron configuration defined by eight valence electrons as a result. These rules are used in conjunction with the main-group components of the second period.

Explanation:

Hope it helps:)

Answer:

(C) It is favorable and is driven by ΔH° only.

Explanation:

Let's consider the following balanced equation.

2 Na₂O₂ + S + 2 H₂O → 4 NaOH + SO₂

To determine whether it will be favorable or not at 298 K, we need to calculate the standard Gibbs free energy (ΔG°).

We can calculate ΔG° using the following expression.

ΔG° = ΔH° - T.ΔS°

As we can see from the expression above, the favorability will be driven if ΔH° < 0 and if ΔS° < 0. Since ΔH° = -610 kJ/mol and ΔS° = -73 J/K.mol, the favorability will be driven by ΔH°. Now, let's calculate the overall favorability.

ΔG° = ΔH° - T.ΔS°

ΔG° = -610 kJ/mol - 298 K.(-0.073 kJ/K.mol) = -588 kJ/mol

The reaction is favorable and is driven by ΔH° only.

Answer:

2NaCN + CaCO3 --> Na2CO3 + Ca(CN)2

Explanation:

Knowing the names gets us: NaCN + CaCO3 --> Na2CO3 + Ca(CN)2

Balance: there are two sodiums and cyanides on the product side so add a 2 to the reactant side.