(SK015) Naturally occurring argon consists of thre isotopes , argon-36, argon-38, argon-40 in the ratio of 4.86: 1 : 1423 i) Calculate the percentage composition of the three isotopes. ii) Calculate the relative atomic mass of argon to four significant figures.

Answer:

44.80

Explanation:

So to answer this question first let's decribe precision vs accuracy.

Precision in this case means exact and accurate; in this scenario all of the dots next to each other mean that it is highly precise.

Whereas Accuracy means aiming for the middle of the circle in this case. Thus   the accuracy is low, but the precision is high.

TLDR: It is highly precise but not accurate.

Look up "Accuracy vs. Precision: What’s the Difference?" for a better detailed example and solution.

Answer:

4Fe + 6H2O + 3O2 -------> 4Fe(OH)3

Explanation:

The chemical reaction involves the fewest oxygen atoms is 4Fe + 6H2O + 302 4Fe(OH)3. Therefore, option B is correct.

The chemical reaction, the transformation of one or more chemicals (the reactants) into one or more distinct compounds (the products). Chemical elements or chemical compounds make up substances.

When atoms establish or break chemical bonds, chemical processes take place. Reactants are the substances that begin a chemical reaction, while products are the compounds that are created as a result of the reaction.

We can learn about a substance's qualities by studying chemical reactions. We can learn about a substance's chemical characteristics by looking at how it interacts with other substances. These characteristics can be utilized to recognize an unidentified sample.

Thus, option B is correct.

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Answer: The concentration of Pb2+ in the anode compartment is [tex]1.74\times 10^{-6}M[/tex]

Explanation:

[tex]Sn^{2+}(aq)+Pb(s)\rightarrow Sn(s)+Pb^{2+}(aq)[/tex]

Here Pb undergoes oxidation by loss of electrons, thus act as anode. Sn undergoes reduction by gain of electrons and thus act as cathode.

[tex]E^0=E^0_{cathode}- E^0_{anode}[/tex]

Where both [tex]E^0[/tex] are standard reduction potentials.

[tex]E^0_{[Sn^{2+}/Sn]}=-0.14V[/tex]

[tex]E^0_{[Pb^{2+}/Pb]}=-0.13V[/tex]

[tex]E^0=E^0_{[Sn^{2+}/Sn]}- E^0_{[Pb^{2+}/Pb]}[/tex]

[tex]E^0=(-0.14-(-0.13)V=-0.01V[/tex]

Now using Nernst Eqn :

[tex]E=E^0-\frac{0.059}{n}\log\frac{[Pb^{2+}]}{[Sn^{2+}]}[/tex]

[tex]0.16=(-0.01)-\frac{0.059}{2}\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]0.17=-0.0295\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]-5.76=\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]1.74\times 10^{-6}=\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex][Pb^{2+}]=1.74\times 10^{-6}[/tex]

Answer:

90.4 mL

Explanation:

Step 1: Given data

Step 2: Calculate the final volume of the gas

According to Boyle's law, the volume of a gas is inversely proportional to the pressure. We can calculate the final volume of the gas using the following expression.

P₁ × V₁ = P₂ × V₂

V₂ = P₁ × V₁ / P₂

V₂ = 721 mmHg × 113 mL / 901 mmHg

V₂ = 90.4 mL

Answer:

D. 1.48atm

Explanation:

Van der waals equation is given as:

(P +an²/v²) (v - nb) = nRT

Where;

P = pressure (atm)

V = volume (L)

R = gas constant (0.0821 Latm/molK)

a and b = gas constant specific to each gas

T = temperature (K)

n = number of moles

According to the given information; V = 22.4L, T = 0.00°C (273.15K), R = 0.0821 Latm/molK, a = 6.49L^2-atm/mol^2, b = 0.0562 L/mol, n = 1.5mol

Hence;

(P + 6.49 × 1.5²/22.4²) (22.4 - 1.5×0.0562) = 1.5 × 0.0821 × 273.15

(P + 6.49 × 2.25/501.76) (22.4 - 0.0843) = 33.638

(P + 0.0291) (22.316) = 33.638

22.316P + 0.649 = 33.638

22.316P = 33.638 - 0.649

22.316P = 32.989

P = 32.989/22.316

P = 1.478

P = 1.48atm

The energy produced by burning : -32.92 kJ

Delta H reaction (ΔH) is the amount of heat change between the system and its environment

(ΔH) can be positive (endothermic = requires heat) or negative (exothermic = releasing heat)

The enthalpy and heat(energy) can be formulated :

[tex]\tt \Delta H=\dfrac{Q}{n}\rightarrow n=mol[/tex]

The enthalpy of combustion of naphthalene (MW = 128.17 g/mol) is -5139.6 kJ/mol.

The energy released for 0.8210 g of naphthalene :

[tex]\tt Q=\Delta H\times n\\\\Q=-5139.6~kJ/mol\times \dfrac{0.8210~g}{128.17~g/mol}~\\\\Q=-32.92~kJ[/tex]

Answer:

Explanation:

1) The ΔH shows the heat of reaction of the reaction illustrated in the question and the negative sign shows the reaction is an exothermic reaction, meaning heat is released in this reaction. The amount of heat released in this reaction is 851.5 kilojoules per mole of Al₂O₃ produced.

2) The thermal energy of this reaction is however very low when compared to the energy released when 2 moles of protons and 2 moles of neutrons combine to form 1 mole of alpha particles. This is because, the reaction illustrated in the (1) above is a normal chemical reaction while the one that involves the protons and neutrons (as described in this section 2) is a nuclear reaction which involves large amount of energy. Nuclear reactions usually involve way larger amount of energy than ordinary chemical reactions.

Answer:

none of these

Explanation:

The expression:

      P1/T1 = P2/T2 is a derivative of the combined gas law.

From the combination of the Boyle's and Charles's law, if the volume is taken to be constant, the pressure of the given mass of gas is directly proportional to the absolute temperature.

This is how the expression

      P1/T1 = P2/T2 was obtained.

Answer:

because cycle is a prosess that goes through multiple stages

Explanation:

.

Answer: equivalence point

When equal moles of an acid and a base are mixed, after reaction the two are compounds are said to be at the equivalence point.

The equivalence point is called the moment when the equivalents of the titrated substance and those of the titrant substance are equal.

When a strong acid is neutralized with a strong base, the pH undergoes a sharp change just at the equivalence point.

At the time of neutralization, it is true that the number of equivalents of acid that have reacted is equal to the number of equivalents of the base.

This equivalence point is very easily detected since a sharp pH jump is observed in its vicinity, which can be detected in a pH meter or with an indicator.

Therefore, we can conclude that the equivalence point of a reaction is the point at which an equivalent amount of acid and base has been added.

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Answer:

Mn

Explanation:

The cation in the chemical formula MnSe is the Mn specie.

Answer:

76.1%

Explanation:

The reaction that takes place is:

First we determine how many moles of each reactant were added:

Thus K₂SO₄ is the limiting reactant.

Using the moles of the limiting reactant we calculate how many moles of BaSO₄ would have been produced if the % yield was 100%:

Then we convert that theoretical amount into grams, using the molar mass of BaSO₄:

Finally we calculate the % yield:

Answer:

H=mc∆T

H=15×4.18×20

H=1254J

Answer:54.82%

Explanation:

Percentage of carbon = mass of carbon in that compound/ mass of the compund *100

216/394*100 = 54.82%

Answer:

Explanation:

The mass of the football can be found by using the formula

[tex]m = \frac{f}{a} \\ [/tex]

f is the force

a is the acceleration

From the question we have

[tex]m = \frac{600}{30} = \frac{60}{3} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

-It is considered the modern atomic model.

-It describes the probable locations of the electrons

Explanation:

edge 2020

The correct answer is:

The electron cloud model is another name used to describe the modern wave mechanical model of the atom.

It is the atomic model introduced by Erwin Schrodinger in 1927 based on the principles of quantum mechanics. It was an advancement over the Bohr model of the atom.

In this model, the atomic orbital is described as a region in space where there is a high probability of finding an electron. Hence, the electron is not found in specific orbits according to the Bohr model, rather, we describe the probability of finding the electron. This is the contemporary approach to the study of atomic structure.

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Answer:

Q8) True

Q9) First ionization energy

Q10) Metal oxides

Explanation:

A common property of group one elements (alkali metals) is their combination with water to form basic solutions. E.g 2K(s)+2H2O(l)→2KOH(aq)+H2​(g).

The distance of the outermost electron in the atom from the nucleus is inversely related to the first ionization energy. As the distance between the outermost electron and the nucleus in group 17 elements gets larger, the corresponding first ionization energies of elements in the group gets smaller.

Group 1 elements can combine with oxygen to give metal oxides. E.g  4K + O2 --> 2 K2O

The theoretical yield (in kilograms) of water produced from this reaction : 0.285 kg

Reaction

2C₁₂H₂₄O₁₁ + 25O₂ → 24CO₂ + 24H₂O

mass of C₁₂H₂₄O₁₁ - isomaltitol = 454 g

mol C₁₂H₂₄O₁₁(MW=344.31 g/mol) :

[tex]\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{454}{344.31 g/mol}\\\\mol=1.319[/tex]

mol H₂O based on C₁₂H₂₄O₁₁ as limiting reactant(O₂-oxygen as an excess)

From the equation above, mol ratio of C₁₂H₂₄O₁₁  : H₂O = 2 : 24, so mol H₂O:

[tex]\tt mol~H_2O=\dfrac{24}{2}\times 1.319=15.828[/tex]

then mass H₂O (MW=18 g/mol) :

[tex]\tt mass=mol\times MW\\\\mass=15.828\times 18=284.904~g=0.285~kg[/tex]

Answer:

a) 2.01 g

Explanation:

First we convert 0.0302 mol AgNO₃ to Na₂CO₃ moles, in order to calculate how many Na₂CO₃ moles reacted:

So the remaining Na₂CO₃ moles are:

Finally we convert Na₂CO₃ moles into grams, using its molar mass:

The closest answer is option a).

Answer:

C

Explanation:

I hope that helps!!! it kinda gave you the answer though

Answer:

a. 5.39 atm

Explanation:

Pressure = ?

Volume = 1 L

Temperature = 298 K

Mass = 9.70g

The formular relating these variables is the ideal gas equation;

PV = nRT

where R = gas constant = 0.082057 L.atm.K-1.mol-1

n can be obtained from the formular below;

n = mass / molar mass = 9.70 / 44

n = 0.2205 mol

P = nRT / V

P = 0.2205 * 0.082057 * 298 / 1

P = 5.392 atm

The correct option is option A.

Answer:

No because a straw is plastic look at it by this was, the energy used to create one metal straw is roughly equivalent to creating 90 plastic straws, and also produces carbon emissions equivalent to 150 plastic straws. This may not seem like a lot, but in order to offset the environmental impact of creating a metal straw, it must be used over 150 times

Explanation:

Answer:

530.835 g

Explanation:

First we convert 244 g of benzoic acid (C₇H₆O₂) to moles, using its molar mass:

Theoretically, one mol of ethyl benzene would produce one mol of benzoic acid. But the experimental yield tells us that one mol of ethyl benzene will produce only 0.4 moles of benzoic acid.

With the above information in mind we convert 2.00 moles of benzoic acid into moles of ethyl benzene:

Finally we convert moles of ethyl benzene (C₈H₁₀) into grams, using its molar mass:

Answer:

It should contain 32 hydrogen.

Answer:

Thermal energy

Explanation:

When gasoline, coal, batteries and logs are all burn they transform chemical energy to thermal energy.

The chemical energy is the energy held between chemical chains and bonds within an atom.

Answer: Two equatorial positions so as to minimize the repulsion.

Explanation:

Formula used for calculating number of electrons :

[tex]\frac{1}{2}[V+N-C+A][/tex]

where,

V = number of valence electrons present in central atom  = 8

N = number of monovalent atoms bonded to central atom = 4

C = charge of cation  = 0

A = charge of anion  = 0

Now we have to determine the hybridization of the [tex]XeF_4[/tex]   molecule.

[tex]\frac{1}{2}[8+4-0+0]=6[/tex]

Bond pair electrons = 4

Lone pair electrons = 2

The number of electrons are 6 that means the hybridization will be [tex]sp^3d^2[/tex] and the electronic geometry of the molecule will be octahedral.

The molecular geometry will be square planar as two alternate positio ns will be occupied by lone pair of electrons so as to minimize the repulsion.