An element is a pure substance. Which of the following is used to represent an element?

Answer:

a. The rate of the reaction is not proportional to the concentration of the reactant.

Explanation:

The rate expression for a zero order reaction is given as;

A → Product

Rate = k[A]⁰

[A]⁰ = 1

Rate = K

GGoing through the options;

a) This is correct because in the final form of the rate expression, the rate is independent of the concentration.

b) This option is wrong

c) This option is also wrong

d) Like options b and c this is also wrong becaus ethere is no relationship between either the concentration or t.

Answer:

The answer is option c.

I hope this helps you.

Answer:

B. None of these

Explanation:

Sulfur has less ionization energy than phosphorus because sulfur has a pair of electron in its 3p subshell that increases electron repulsion in sulfur and sulfur electrons can easily remove from its sub-level.

While, there are no electron pairs in 3p subshell of phosphorus, therefore it requires more energy to remove an electron from 3p subshell.

Hence, the reason is electron repulsion and the correct answer is B.

Answer:

Q = 81.59kJ

Explanation:

Hello,

The heat of condensation is the energy required to to convert the steam into water.

Mass = 195g

Specific heat capacity of water = 4.184J/g°C

Initial temperature(T1) = 100°C

Final temperature(T2) = 0°C

Heat energy (Q) = ?

Heat energy (Q) = mc∇T

M = mass of the substance

C = specific heat capacity of the substance

∇T = T2 - T1 = change in temperature of the substance

Q = 195 × 4.184 × (0 - 100)

Q = -81588J

Q = -81.588kJ

The heat required for the condensation of 195g of steam is 81.59kJ

Answer: 9.53 *2= 19.06

Explanation:

The law of multiple proportions states that if two elements combines to form more than one compound the ratio of masses of the second element which combines to the fixed mass of the first element will always be the ratios of the small whole numbers.

in case of carbon monoxide, mass of carbon will be the same of mass of oxygen.

But in case of carbon dioxide, if carbon is 9.53 units then oxygen will be twice as that of carbon.

CO2, so 9.53*2= 19.06 grams of oxygen will combine with 9.53 grams of carbon to form carbon dioxide.

Answer:

d) is an activator and an ortho/para- director

Explanation:

We options for this question are:

a) is a deactivator and an ortho/para- director

b) is a deactivator and a meta-director

c) is an activator and a meta-director

d) is an activator and an ortho/para- director

e) is an activator and an ortho/meta/para director

f) none of the above

We have to remember that Cl is a halogen, therefore a lone pair of electrons will be involved in the resonance (see figure 1). So, we will have activation in the ortho and para positions.  We have to take into account that the halogens have a high electronegativity. This means that inductively they are electron-withdrawing. So, we will have opposite phenomenons that will result in very weak activation

Answer:

In the attachment you can find all the possible chemical reactions.

Some reaction can not be obtained by using alkyl halides because halides are weak leaving group which can leave compound during reaction easily but hydroxyl groups is a strong nucleophile which can not leave compound easily. So we can obtain alcohol from ethyl bromide, but we can not obtain hydroxyl ion from ethyl bromide.  

Explanation:

The methyl of ethyl halides as the organic starting materials are using the needed solvents or the inorganic reagents. These can be not repeated in steps that arrive out in earlier parts.

Learn more about the methyl or the cyclopentyl.

brainly.com/question/12621202

Answer:

Here's what I get  

Explanation:

1. POCl₃

(a) Lewis structure

Set P as the central atom, with O and Cl atoms directly attached to it.

Electrons available = P + O + 3Cl = 5 + 6 + 3×7 = 11 + 21 = 32

Arrange these electrons to give every atom an octet. Put a double bond between P and O.

You get the structure shown below.

(b) Geometry

There are four bond pairs and no lone pairs about the P atom.

Electron pair geometry — tetrahedral

    Molecular geometry — tetrahedral

(c) Ideal bond angles

Tetrahedral bond angle = 109.5°

2. AlCl₆³⁻

(a) Lewis structure

Set Al as the central atom, with the Cl atoms directly attached to it.

Electrons available = Al + 6Cl + 3(-) = 3 + 6×6 +3 = 6 + 36 = 42

Arrange these electrons to give every atom an octet. Assign formal charges.

You get the structure shown below.

(b) Geometry

There are six bond pairs and no lone pairs about the Al.

Electron pair geometry — octahedral

    Molecular geometry — octahedral

(c) Ideal bond angles

        Axial-equatorial =  90°

Equatorial-equatorial = 120°

                 Axial-axial = 180°

Answer:

The answer is A

Explanation:

Answer:

K₂SO₄(aq)  + 2AgNO₃ (aq) →  2KNO₃(aq) + Ag₂SO₄ (s) ↓

2Ag⁺ (aq) + SO₄⁻²(aq) ⇄ Ag₂SO₄ (s) ↓

Explanation:

Our reactants are: K₂SO₄ and AgNO₃

By the solubility rules, we know that sulfates are insoluble when they react to Ag⁺, Pb²⁺, Ca²⁺, Ba²⁺, Sr²⁺, Hg⁺

We also determine, that salts from nitrate are all soluble.

The reaction is:

K₂SO₄(aq)  + 2AgNO₃ (aq) →  2KNO₃(aq) + Ag₂SO₄ (s) ↓

2Ag⁺ (aq) + SO₄⁻²(aq) ⇄ Ag₂SO₄ (s) ↓

Answer:

Explanation:

C₉H₇O₄⁻ = weakest base

C₆H₅COO⁻ = strongest base

HCOO⁻ = intermediate base

HCOOH = not a Bronsted-Lowry base

HC₉H₇O₄ = not a Bronsted-Lowry base

C₆H₅COOH = not a Bronsted-Lowry base

Answer:

combustion

Explanation:

The enthalpy change for the complete burning of one mole of a substance

is the enthalpy of __combustion_____ .

Answer:

2.92 mol

Explanation:

Step 1: Write the balanced equation

2 B(s) + 6 HCI(aq) ⇒ 2 BCl₃(aq) + 3 H₂(g)

Step 2: Establish the appropriate molar ratio

The molar ratio of hydrochloric acid to boron chloride is 6:2.

Step 3: Calculate the moles of boron chloride produced from 8.752 moles of hydrochloric acid

[tex]8.752molHCl \times \frac{2molBCl_3}{6molHCl} = 2.92molBCl_3[/tex]

Answer:

c

Explanation:

The correct answer would be that the bond angles in the methane molecule and in the perchlorate ion are approximately equal.

A tetrahedral shape or geometry means both molecules are sp3 hybridized with the hydrogen atoms and the oxygen ions surrounding the central carbon and chlorine atoms respectively being as far away from one another as possible. This results in an approximate angle of 109.5 degrees in both molecules.

The correct option is c.

Answer: 3390

Explanation:

Since this problem already gives is the equilibrium values, all we have to do is to plug them into the formula for [tex]K_{p}[/tex].

[tex]K_{p} =\frac{[ICl]^2}{[I_{2}][Cl_{2}] }[/tex]

[tex]K_{p} =\frac{(9.81)^2}{(0.171)(0.166)} =3390[/tex]

Answer:

it's a two step elimination reaction

Explanation:

it follows a carbocationic pathway. When carbocation is stable, the equation is favourable, that is, double bond is formed by expelling hydrogen atom.

Answer:

The molar mass of the unknown compound is 153.3 g/mol

Explanation:

Step 1: Data given

Mass of an unknown molecular compound = 27.6 grams

Mass of benzene =  0.250 kg

Kf of benzene = 5.12 °C/m

freezing point depression of 3.69 °C

Step 2:  Calculate molality

ΔT = i*Kf*m

⇒with ΔT = reezing point depression of 3.69 °C

⇒with i = the van't Hoff factor of Benzene = 1

⇒with Kf = 5.12 °C/m

⇒ with m = molality = moles unknown compound / mass of benzene

3.69 = 1 * 5.12 * m

m = 0.72 molal

Step 3: Calculate moles of the unknown compound

molality = moles / mass benzene

0.72 molal = moles / 0.250 kg

Moles = 0.72 m * 0.250 kg

Moles = 0.18 moles

Step 4: Calculate molar mass of the unknown compound

molar mass = mass / moles

Molar mass = 27.6 grams / 0.18 moles

Molar mass = 153.3 g/mol

The molar mass of the unknown compound is 153.3 g/mol

Molar mass is the mass of the one mole of substance. The molar mass of the given unknown compound is 153.3 g/mol.

Molality of the compound can be calculated using

ΔT = i Kf m

Where,

ΔT = freezing point depression = 3.69 °C

i =  Van't Hoff factor of Benzene = 1

Kf =  constant of freezing = 5.12 °C/m

m = molality = ?

Put the values in the equation,

3.69 = 1 x 5.12 x m

m = 0.72 molal

Number of moles of the compound,

[tex]\bold {molality =\dfrac { moles} { mass\ benzene}}\\\\\bold {0.72\ molal = \dfrac {moles }{0.250\ kg}}\\\\\bold {Moles = 0.72\ m \times 0.250\ kg}\\\\\bold {Moles = 0.18}[/tex]

So, molar mass of the unknown compound,

[tex]\bold {Molar\ mass =\dfrac { mass}{ moles}}\\\\\bold {Molar\ mass = \dfrac {27.6\ grams }{0.18\ moles}}\\\\\bold {Molar\ mass = 153.3 g/mol}[/tex]

The molar mass of the given unknown compound is 153.3 g/mol.

To know more about molar mass,

https://brainly.com/question/12127540

Answer:

The correct answer is i) 50.2 % ii) 13440.906 kW and iii) 71.986 kg/s.

Explanation:

In order to find the mass flow rate of the combustion of gases, there is a need to use the energy balance equation:  

Mass of water × specific heat of water (T2 -T1)w = mass of gas × specific heat of gas (T2-T1)g

100 × 4.18 × [(240 + 273) - (150 + 273)] = mass of gas × 1.005 × [(1067+273) - (547+273)]

Mass of gas = 71.986 kg/s

The entropy generation of water can be determined by using the formula,  

(ΔS)w = mass of water × specific heat of water ln(T2/T1)w

= 100 × 4.18 ln(513/423)

= 80.6337 kW/K

Similarly the entropy generation of water will be,

(ΔS)g = mass of gas × specific heat of gas ln(T2/T1)g

= 71.986 × 1.005 ln (820/1340)

= -35.53 kW/K

The rate of energy destruction will be,  

Rate of energy destruction = To (ΔS)gen

= T₀ [(ΔS)w + (ΔS)g]

= (25+273) [80.6337-53.53)

Rate of energy destruction = 13440.906 kW

The availability of water will be calculated as,  

= mass of water (specific heat of water) [(T₁-T₂) -T₀ ln T₁/T₂]

= 100 × 4.8 [(513-423) - 298 ln 513/423]

= 13591.1477 kW

The availability of gas will be calculated as,  

= mass of gas (specific heat of gas) [(T₁-T₂) - T₀ ln T₁/T₂]

= 71.986 × 1.005 × [(1340-820) - 298 ln 1340/820]

= 27031.7728 kW

The exergetic efficiency can be calculated as,  

= Gain of availability / loss of availability  

= 13591.1477/27031.7728

= 0.502

The exergetic efficiency is 50.2%.  

Answer:

Molarity = 0.0428 M = 42.8 mM

Explanation:

Step 1: Data given

Mass of nickel(II) bromide = 1.87 grams

Molar mass of nickel(II) bromide = 218.53 g/mol

Volume = 200 mL = 0.200 L

Step 2: Calculate moles of nickel(II) bromide

Moles nickel (II) bromide = mass / molar mass

Moles nickel (II) bromide = 1.87 grams / 218.53 g/mol

Moles nickel (II) bromide = 0.00856 moles

Step 3: Calculate moles nickel (II) cation

For 1 mol NiBr2 we have 1 mol Ni^2+

For 0.00856 moles NiBr2 we have 0.00856 moles Ni^2+

Step 4: Calculate final molarity of Ni^2+

Molarity = moles / volume

Molarity = 0.00856 moles / 0.200 L

Molarity = 0.0428 M = 42.8 mM

Answer:

ΔGreaction < 0

ΔSuniverse > 0

ΔHreaction < 0

Explanation:

A spontaneous process is one which can proceed without additional input of energy releasing free energy in the process and then moves to a lower more stable thermodynamical state.

For an isolated system, a spontaneous process proceeds with an increase in entropy.

The conditions for a spontaneous process at constant temperature and pressure, can be determined using the change in Gibbs free energy, which is given by: ∆G = ∆H - T∆S

Where ∆G is change in free energy; ∆H is change in enthalpy or Heat content; ∆S is change in entropy, T is temperature.

For a process to be spontaneous, the following conditions are necessary:

1. ∆G < 0; must be negative

2. ∆S > 0; there must be an increase in entropy

3. ∆H < 0; enthalpy change must be negative such that heat is lost to the surroundings

The above conditions ensures that ∆G is negative and the process is spontaneous.

Answer:

T = 48.39%

Explanation:

In this case we need to apply the Beer law which is the following:

A = CεL  (1)

Where:

A: Absorbance of solution

C: Concentration of solution

ε: Molar Absortivity (Constant)

L: Length of the cell

Now according to the given data, we have transmittance of 93% or 0.93. We can calculate absorbance using the following expression:

A = -logT (2)

Applying this expression, let's calculate the Absorbance:

A = -log(0.93)

A = 0.03152

Now that we have the absorbance, let's calculate the concentration of the solution, using expression (1).

A = CεL

C = A / εL

Replacing:

C = 0.03152 / 1 *ε   (3)

Now, we want to know the transmittance of the solution with a length of 10 cm. so:

A = CεL

Concentration and ε are constant, so:

A = (0.03152 / ε) * ε * 10

A = 0.3152

Now that we have the new absorbance, we can calculate the new transmittace:

T = 10^(-A)

T = 0.4839 ----> 48.39%

Answer:

heat capacity of the sample = 37.8 J/K

Explanation:

Step 1: Data given

Temperature of the sample = 275 K

The mass of liquid nitrogen = 2kg

temperature of liquid nitrogen = 70 K

The final temperature of the nitrogen is 75 K

Step 2: Calculate heat

Q = m*c*ΔT

⇒with m = the mass of liquid nitrogen = 2 kg = 2000 grams

⇒with c= the specific heat of the liquid nitrogen = 1.04 J/g*K

⇒with ΔT = the change of temperature of liquid nitrogen = T2 - T1 = 75 - 70 = 5K

Q = 2000 grams * 1.04 J/g*K * 5K

Q = 10400 J

Step 3: Calculate the heat capacity of the sample

heat capacity of the sample = 10400 J / 275 K

heat capacity of the sample = 37.8 J/K

Answer:

[tex]0.0102~mol~CaCl_2*2H_2O[/tex]

[tex]0.0102~mol~CaCl_2[/tex]

Explanation:

For this question, we have to start with the molar mass calculation of [tex]CaCl_2*2H_2O[/tex]. For this, we have to know the atomic mass of each atom:

O: 16 g/mol

Cl: 35.45 g/mol

H: 1 g/mol

Ca: 40 g/mol

If we take into account the amount of each atom in the formula we will have:

[tex](40*1)+(35.45*2)+(1*4)+(16*2)=~147.01~g/mol[/tex]

So, in 1 mol of [tex]CaCl_2*2H_2O[/tex] we will have 147.01 g. Now we can do the conversion:

[tex]1.50~g~CaCl_2*2H_2O\frac{1~mol~CaCl_2*2H_2O}{147.01~g~CaCl_2*2H_2O}=0.0102~mol~CaCl_2*2H_2O[/tex]

Additionally, in 1 mol of [tex]CaCl_2*2H_2O[/tex] we will have 1 mol of [tex]CaCl_2[/tex]. Therefore, we have a 1:1 mol ratio . With this in mind, we will have the same number of moles for [tex]CaCl_2[/tex]

[tex]0.0102~mol~CaCl_2*2H_2O=0.0102~mol~CaCl_2[/tex]

I hope it helps!

Answer:

Option C. Keq = [SO2]² [O2] /[SO3]²

Explanation:

The equilibrium constant keq for a reaction is simply the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient.

Now, let us determine the equilibrium constant for the reaction given in the question.

This is illustrated below:

2SO3(g) <==> 2SO2(g) + O2(g)

Reactant => SO3

Product => SO2, O2

Keq = concentration of products /concentration of reactants

Keq = [SO2]² [O2] /[SO3]²

Answer:

Leptón

Explanation:

Lepton son partículas elementales de espín de medio entero (espín 1⁄2), y se sabe que no experimentan interacciones fuertes. Los leptones se clasifican en leptones cargados (los leptones similares a los electrones) y leptones neutros (conocidos como neutrinos). Un electrón es un leptón. Los leptones cargados pueden combinarse con otras partículas para formar átomos compuestos de partículas y positronio, mientras que los neutrinos rara vez interactúan con algo, lo que los hace raros de observar.

Dado que la electricidad es el resultado del movimiento o flujo de electrones, la única partícula representativa de esta fuerza es el leptón.

Answer:

44.1°C

Explanation:

Step 1:

Data obtained from the question include:

Initial volume (V1) = 9.87 L

Initial temperature (T1) = 51°C = 51°C + 273 = 324K

Initial pressure (P1) = 0.565 atm

Final volume (V2) = 8.05 L

Final pressure (P2) = 0.678 atm

Final temperature (T2) =..?

Step 2:

Determination of the new temperature of the gas.

The new temperature of the gas can be obtained by using the general gas equation as shown below:

P1V1 /T1 = P2V2 /T2

0.565 x 9.87/324 = 0.678 x 8.05/T2

Cross multiply

0.565 x 9.87 x T2 = 324 x 0.678 x 8.05

Divide both side by 0.565 x 9.87

T2 = (324 x 0.678 x 8.05)/(0.565 x 9.87)

T2 = 317.1K

Step 3:

Conversion of 317.1K to decree celsius.

This is illustrated below:

T (°C) = T(K) – 273

T (K) = 317.1K

T (°C) = 317.1 – 273

T (°C) = 44.1°C

Therefore, the new temperature of the gas is 44.1°C

Answer:Mass of Potassium chloride =1.762g

Explanation:

Mass of empty beaker = 23.100 g

Mass of beaker with Potassium chloride = 24.862g

Mass of Potassium chloride = Final weight - initial weight = Mass of beaker with Potassium chloride  - Mass of empty beaker = 24.862-23.100 = 1.762g

Answer:

Explanation:

17. it goes from solid copper to aqueous copper:

Cu(s) --> Cu₂(aq) + 2e⁻

18. complete ionic:

Cu(s) --> Cu₂(aq) + 2e⁻

19. net ionic, must include only reacting species, so

Cu(s) --> Cu₂(aq) + 2e⁻

20. this type of reaction is dissolution reaction(redox reaction)

copper reduced from Cu²⁺ to Cu.

Answer:

315mL

Explanation:

Data obtained from the question include the following:

Molarity of stock solution (M1) = 0.135 M

Volume of stock solution needed (V1) =?

Molarity of diluted solution (M2) = 0.0851 M

Volume of diluted solution (V2) = 500mL

The volume of the stock solution needed can be obtain as follow:

M1V1 = M2V2

0.135 x V1 = 0.0851 x 500

Divide both side by 0.135

V1 = (0.0851 x 500) / 0.135

V1 = 315mL

Therefore, the volume of the stock solution needed is 315mL

Answer:

5x10⁻⁶ = [HTeH₄O₆⁺]

Explanation:

The first dissociation equilibrium of the telluric acid in water is:

H₂TeH₄O₆ + H₂O ⇄ HTeH₄O₆⁺ + H₃O⁺

Using H-H equation for telluric acid:

pH = pKa + log₁₀ [HTeH₄O₆⁺] / [H₂TeH₄O₆]

pKa of telluric acid is -logKa1

pKa = -log 2.0x10⁻⁸

pKa = 7.699

As concentration of [H₂TeH₄O₆] is 0.25M, replacing in H-H equation:

3.00 = 7.699+ log₁₀ [HTeH₄O₆⁺] / [0.25M]

-4.699 = log₁₀ [HTeH₄O₆⁺] / [0.25M]

2x10⁻⁵ = [HTeH₄O₆⁺] / [0.25M]