An aqueous solution contains 0.397 M ammonia. Calculate the pH of the solution after the addition of 4.63 x 10-2 moles of perchloric acid (HClO4) to 250 mL of this solution. (Assume the volume does not change upon adding perchloric acid). Ka = 5.7 x 10-10, Kb = 1.80 x 10-5

Answer:

The total photons required = 5.19 × 10²⁸ photons

Explanation:

Given that:

the radiation wavelength λ= 12.5 cm = 0.125 m

Volume of the container = 0.250 L = 250 mL

The density of water = 1 g/mL

Density = mass /volume

Mass =  Volume ×  Density

Thus; the mass of the water =  250 mL ×  1 g/mL

the mass of the water = 250 g

the specific heat of water s = 4.18 J/g° C

the initial temperature [tex]T_1[/tex] = 20.0° C

the final temperature [tex]T_2[/tex] = 99° C

Change in temperature [tex]\Delta T[/tex] = (99-20)° C = 79 ° C

The heat q absorbed during the process = ms [tex]\Delta T[/tex]

The heat q absorbed during the process = 250 g × 4.18 J/g° C × 79° C

The heat q absorbed during the process = 82555 J

The energy of a photon can be represented by the equation :

= hc/λ

where;

h = planck's constant = [tex]6.626 \times 10^{-34} \ J.s[/tex]

c = velocity of light = [tex]3.0 \times 10^8 \ m/s[/tex]

=  [tex]\dfrac{6.626 \times 10^{-34} \times 3.0 \times 10^8}{0.125}[/tex]

= [tex]1.59024 \times 10^{-24}[/tex] J

The total photons required = Total heat energy/ Energy of a photon

The total photons required = [tex]\dfrac{82555 J}{1.59024 \times 10^{-24}J}[/tex]

The total photons required = 5.19 × 10²⁸ photons

Answer:

See explanation below

Explanation:

IUPAC came up with the idea of an unambiguous system of nomenclature for organic compounds. This unambiguous system relates the structure of a compound with its name. Thus, IUPAC has established a worldwide standard for the unambiguous naming of organic compounds. Scientists all over the world can now have a uniform system of nomenclature for compounds in order to facilitate easy communication of scientific information.

The systematic names of the following compounds listed in the question are shown below;

(R)-2- butyl bromide has the systematic name (R)-2-bromobutane

(S)-2-butyl bromide has the systematic name (S)-2-bromobutane

This unified system of nomenclature avoids the confusion created by the use of different trivial names in deferent localities and by various scientific academies. This is a major advantage of the systematic nomenclature.

Answer:

1. It dissolves much more ice faster than sodium chloride

2. Calcium chloride is more effective in melting ice at lower temperatures.

Explanation:

Salts are used to melt ice on roadways and sidewalks because they help to lower the freezing point of water.

Sodium chloride and calcium chloride are both salts used for this purpose but calcium chloride is usually preferred for the following two reasons:

1. It dissolves much more ice faster than sodium chloride: Calcium chloride dissolves much more ice faster than sodium chloride because when it dissociates, it produces three ions instead of the two produced when sodium chloride. Therefore, the heat of hydration of its ions is greater than that of sodium chloride.

2. Calcium chloride is more effective in melting ice at lower temperatures. It lowers the freezing point of water more than sodium chloride. Calcium chloride is able to lower the freezing point of water to about -52°C while sodium chloride only lowers it to about -6°C.

Answer:

3.01 × 10²³ molecules

Explanation:

Step 1: Given data

Moles of water (n): 0.500 mol

Step 2: Calculate the molecules of water present in 0.500 moles of water

In order to perform this calculation, we will use the Avogadro's number: in 1 mole of water there are 6.02 × 10²³ molecules of water.

0.500 mol × (6.02 × 10²³ molecules/1 mol) = 3.01 × 10²³ molecules

Answer:

[tex]0.688M[/tex]

Explanation:

Hello,

In this case, it is widely acknowledged that strong bases usually correspond to those formed with metals in groups IA and IIA which have relatively high activity and reactivity, therefore, when they are dissolved in water the following dissociation reaction occurs (for calcium hydroxide):

[tex]Ca(OH)_2\rightarrow Ca^{2+}+2OH^-[/tex]

In such a way, for the same volume, we can compute the concentration of hydroxyl ions by simple stoichiometry (1:2 molar ratio):

[tex]0.344\frac{molCa(OH)_2}{L}*\frac{2molOH^-}{1molCa(OH)_2} \\\\0.688\frac{mol OH^-}{L}[/tex]

Or simply:

[tex]0.688M[/tex]

Regards.

Answer:

#1: 0.00144 mmolHCl/mg Sample

#2: 0.00155 mmolHCl/mg Sample

#3: 0.00153 mmolHCl/mg Sample

Explanation:

A antiacid (weak base) will react with the HCl thus:

Antiacid + HCl → Water + Salt.

In the titration of antiacid, the strong acid (HCl)  is added in excess, and you're titrating with NaOH moles of HCl that doesn't react.

Moles that react are the difference between mmoles of HCl - mmoles NaOH added (mmoles are Molarity×mL added). Thus:

Trial 1: 0.391M×14.00mL - 0.0962M×34.26mL = 2.178 mmoles HCl

Trial 2: 0.391M×14.00mL - 0.0962M×33.48mL = 2.253 mmoles HCl

Trial 3: 0.391M×14.00mL - 0.0962M×33.84mL = 2.219 mmoles HCl

The mass of tablet in mg in the 3 experiments is 1515mg, 1452mg and 1443mg.

Thus, mmoles HCl /mg OF SAMPLE for each trial is:

#1: 2.178mmol / 1515mg

#2: 2.253mmol / 1452mg

#3: 2.219mmol / 1443mg

Answer:

[tex]m_{CO_2}=46.6gCO_2[/tex]

Explanation:

Hello,

In this case, considering the combustion of propane:

[tex]C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(g)\ \ \ \Delta _CH=-2220.0 kJ/mol[/tex]

We can compute the burnt moles of propane as shown below:

[tex]n=\frac{-784kJ}{-2220.0 kJ/mol} =0.353molC_3H_8[/tex]

Then, by noticing propane and carbon dioxide are in a 1:3 molar ratio, we can compute the grams carbon dioxide by using the shown below stoichiometric procedure:

[tex]m_{CO_2}=0.353molC_3H_8*\frac{3molCO_2}{1molC_3H_8} *\frac{44gCO_2}{1molCO_2} \\\\m_{CO_2}=46.6gCO_2[/tex]

Best regards.

Answer:

CH4

Explanation:

In solving this problem, we must remember that one mole of a compound contains Avogadro's number of elementary entities. These elementary entities include atoms, molecules, ions etc. Recall that one mole of a substance is the amount of substance that contains the same number of elementary entities as 12g of carbon-12. The Avogadro's number is 6.02 × 10^23.

Hence we can now say;

If 163 g of the compound contains 6.13 ×10^24 molecules

x g will contain 6.02 × 10^23 molecules

x= 163 × 6.02 × 10^23 / 6.13 × 10^24

x= 981.26 × 10^23/ 6.13 ×10^24

x= 160.1 × 10^-1 g

x= 16.01 g

x= 16 g(approximately)

16 g is the molecular mass of methane hence x must be methane (CH4)

Answer:

Option B. 2096.1 K

Explanation:

Data obtained from the question include the following:

Enthalpy (H) = +1287 kJmol¯¹ = +1287000 Jmol¯¹

Entropy (S) = +614 JK¯¹mol¯¹

Temperature (T) =.?

Entropy is related to enthalphy and temperature by the following equation:

Change in entropy (ΔS) = change in enthalphy (ΔH) / Temperature (T)

ΔS = ΔH / T

With the above formula, we can obtain the temperature at which the reaction will be feasible as follow:

ΔS = ΔH / T

614 = 1287000/ T

Cross multiply

614 x T = 1287000

Divide both side by 614

T = 1287000/614

T = 2096.1 K

Therefore, the temperature at which the reaction will be feasible is 2096.1 K

Answer:

THE HEAT CAPACITY OF THE CALORIMETER IS 3666.67 J/C

Explanation:

Mass = 2 g

Temperature difference = 32 C - 29 C = 3 C

Heat of combustion = 11 kJ/g

Heat capacity of the calorimeter = unknown

It is important to note that the heat of combustion of the reaction is the heat absorbed by the calorimeter in raising the mixture by 3 C

So therefore,

Heat = heat capacity * temperature difference

Heat capacity = Heat / temperature difference

Heat capacoty = 11 000 J / 3 C

Heat capacity = 3666.67 J/ C

Answer:

B. Valence Electron Pairs

Explanation:

Valence-shell electron-pair repulsion, or VSEPR, describes the shape of molecules by determining the repulsion of valence electrons. Therefore, our answer is B.

Answer:

95.7 g CO to the nearest tenth.

Explanation:

2C + O2 ---> 2CO

Using relative atomic masses:

24 g C produces  2*12 + 2*16 g CO.

So 41 g produces  ( (2*12 + 2*16) * 41  ) / 24

= 95.7 g CO,

Answer:

B

Explanation:

All the elements in a period have valence electrons in the same shell. The number of valence electrons increases from left to right in the period. When the shell is full, a new row is started and the process repeats.

A new period starts when a new neutron cycle starts. Hence, option B is correct.

A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells.

All the elements in a period have valence electrons in the same shell.

The number of valence electrons increases from left to right in the period.

When the shell is full, a new row is started and the process repeats.

Hence, option B is correct.

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Answer:

3,4,1 and 6,5,2

Explanation:

In the electromagnetic spectrum the arrangement of the waves in increasing frequencies and decreasing wavelengths are as follows;

Radio waves

Microwaves

Infrared waves

Visible light rays

Ultraviolet rays

X-rays

Gamma rays

(a simple mnemonic is RMIVUXG)

Answer:

none of these statements is true

according to the question E) None of these statements is true.

The concentration of a chemical substance expresses the amount of a substance present in a mixture. There are many different ways to express concentration. Chemists use the term solute to describe the substance of interest and the term solvent to describe the material in which the solute is dissolved

Quantitative units of concentration include molarity, molality, mass percentage, parts per thousand, parts per million, and parts per billion.

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Answer:

E 1: cyclohexene

Explanation:

This reaction is an example of the dehydration of cyclic alcohols. The reaction proceeds in the following steps;

1) The first step of the process is the protonation of the cyclohexanol by the acid. This now yields H2O^+ attached to the cyclohexane ring.

2) the water molecule, which a good leaving group now leaves yielding a carbocation. This now leaves a cyclohexane carbocation which is highly reactive.

3) A water molecule now abstracts a proton from the carbon adjacent to the carbocation leading to the formation of cyclohexene and the regeneration of the acid catalyst. This is an E1 mechanism because it proceeds via a carbocation intermediate and not a concerted transition state, hence the answer.

Answer:

198.56g of GaCl3

Explanation:

We'll begin by calculating the number of mole HCl in 2.25 L of a 1.50 M solution of HCl. This is illustrated below:

Molarity of HCl = 1.50 M

Volume = 2.25 L

Mole of HCl =..?

Molarity = mole /Volume

1.5 = mole /2.25

Cross multiply

Mole = 1.5 x 2.25

Mole of HCl = 3.375 mole

Next, we shall determine the number of mole Gallium chloride, GaCl3 produced from the reaction. This is shown below:

2Ga + 6HCl —> 2GaCl3 + 3H2

From the balanced equation above,

6 moles of HCl reacted to produce 2 moles of GaCl3.

Therefore, 3.375 mole of HCl will react to produce = (3.375 x 2)/6 = 1.125 mole of GaCl3.

Therefore, 1.125 moles of GaCl3 were produced from the reaction.

Next, we shall convert 1.125 mole of GaCl3 to grams. This is illustrated below:

Molar mass of GaCl3 = 70 + (35.5x3) = 176.5g/mol

Mole of GaCl3 = 1.125 mole

Mass of GaCl3 =..?

Mole = mass /Molar mass

1.125 = mass of GaCl3 /176.5

Cross multiply

Mass of GaCl3 = 1.125 x 176.5

Mass of GaCl3 = 198.56g

Therefore, 198.56g of GaCl3 were produced from the reaction.

Answer:

THE MASS OF 7.68 *10^24 MOLECULES OF PHOSPHORUS TRICHLORIDE IS 1746.25 g.

Explanation:

Molar mass of PCl3 = ( 31 + 35.5 *3) = 137.5 g/mol

At 7.68 * 10^24 molecules, how many number of mole is present?

6.03 * 10^23 molecules = 1 mole

7.68*10^24 molecules = x mole

x mole = 7.68 *10^24 molecules/ 6.03 *10^23

x mole = 1.27 *10 moles

x mole = 12.7 moles

Using mole = mass / molar mass

mass = mole * molar mass

mass = 12.7 moles * 137.5 g/mol

mass = 1746.25 g

Hence, the mass of 7.68 *10^24 molecules is 1746.25 g

Answer:

1 mole of CaC₂ will produce 26g of C₂H₂ or 64.1g of CaC₂ will produce 26g of C₂H₂

Explanation:

Hello,

To solve this question, we'll require a balanced chemical equation of reaction between calcium carbide and water.

Equation of reaction

CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂

Molar mass of calcium carbide (CaC₂) = 64.1g/mol

Molar mass of water (H₂O) = 18g/mol

Molar mass of calcium hydroxide (Ca(OH)₂) = 74g/mol

Molar mass of ethyne (C₂H₂) = 26g/mol

From the equation of reaction, 1 mole of CaC₂ will produce 1 mole of C₂H₂

1 mole of CaC₂ = mass / molar mass

Mass = 1 × 64.1

Mass = 64.1g

1 mole of C₂H₂ = mass / molar mass

Mass = 1 × 26

Mass = 26g

Therefore, 1 mole of CaC₂ will produce 26g of C₂H₂

Note: this is a hypothetical calculation since we were not given the initial mass of CaC₂ that starts the reaction

Answer:

351.1g/mol

Explanation:

you can find the answer using The ideal gas equation

n= PV/RT

n=(1.21*1.9/0.082*301)mol

n=0.092 mol

molar mass=Mass/mole

m=32.3g/0.092mol

m=351.1g/mol

Answer:

Equilibrium constant Kc = [x]² / [A - x] [B - x]

Explanation:

The equilibrium constant is defined as the ratio of the concentration of the products to that of the reactants at equilibrium

ie Kc = [products] / [reactants].

The balanced equation of the reaction is given as : A + B ⇄ AB

At the beginning of the reaction,

Initial concentration I = A = 1M

                                       B = 1M

                                      AB = 0M

After a period of time and assuming 'x' to be the concentration of product AB formed, the concentrations become

                                         C = reactant A = [A - x] M

                                                 rectant B =   [B - x] M

                                              Product AB =  [x] [x] M

At equilibrium, the concentrations are,

                                            E  = rectant A = [A - x] M

                                                   reactant B = [B - x] M

                                                   product AB = [x]² M

therefore , the equilibrium constant, Kc  = [products]/[reactants]

                                                                   = [x]² / [A - x] [B - x]

Answer: 0.150 m [tex]Na_2SO_4(aq)[/tex] will have highest boiling point.

Explanation:

Formula used for Elevation in boiling point :

[tex]\Delta T_b=i\times k_b\times m[/tex]

where

[tex]\Delta T_b=T_b-T^o_b[/tex]= elevation in boiling point

[tex[k_b[/tex]  = boiling point constant  

m = molality

i = Van't Hoff factor

A) 0.100 m [tex]NiBr_2[/tex]

i = 3 as [tex]NiBr_2\rightarrrow Ni^{2+}+2Br^-[/tex]

concentration will be [tex]3\times 0.100=0.300[/tex]

B) 0.250 m [tex]CH_3OH[/tex]

i = 1 as [tex]CH_3OH[/tex] is a non electrolyte

concentration will be [tex]1\times 0.250=0.250[/tex]

C) 0.100 molal [tex]MgSO_4(aq)[/tex]

i = 2 as [tex]MgSO_4\rightarrrow Mg^{2+}+SO_4^{2-}[/tex]

concentration will be [tex]2\times 0.100=0.200[/tex]

D. 0.150 molal [tex]Na_2SO_4(aq)[/tex]

i = 3 as [tex]Na_2SO_4\rightarrrow 2Na^{+}+SO_4^{2-}[/tex]

concentration will be [tex]3\times 0.150=0.450[/tex]

E. 0.150 molal [tex]NH_4NO_3(aq)[/tex]

i = 2 as [tex]NH_4NO_3\rightarrrow NH_4^{+}+NO_3^{-}[/tex]

concentration will be [tex]2\times 0.150=0.300[/tex]

The solution having the highest concentration of ions will have the highest boiling point and thus 0.150 m [tex]Na_2SO_4(aq)[/tex] will have highest boiling point.

The aqueous solution that would have the highest temperature at boiling point would be:

D). 0.150 molal Na2SO4(aq)

The boiling point is described as the temperature at which the solution starts boiling or the vapor pressure becomes equivalent to the provided external/outer pressure.

To determine the elevation in boiling point, we will use:

Δ[tex]T_{b}[/tex] [tex]= i[/tex] × [tex]k_{b}[/tex] × [tex]m[/tex]

with

[tex]T_{b}[/tex] [tex]= T_{b} - T^{0}_{b}[/tex]

[tex]k_b[/tex] [tex]=[/tex] constant of boiling point

Using this formula,

0.150 molal Na2SO4(aq)

Given,

[tex]i = 3[/tex]

[tex]Na2So4[/tex] will have

[tex]2Na^{+}[/tex] [tex]+[/tex] [tex]SO^{2-}_{4}[/tex]

So,

Concentration [tex]= 3[/tex] × [tex]0.15[/tex][tex]0[/tex]

[tex]= 0.45[/tex][tex]0[/tex]

∵ 0.150 molal [tex]Na2SO4[/tex]Na2SO4(aq) has the maximum concentration.

Thus, option D is the correct answer.

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Answer:

Oxygen present in food items makes then rancid due to the presence of oils and fats. If the food is flushed with nitrogen, it prevents it from being oxidised (the nitrogen acts as an antioxidant).

Hope it helps ! :)

Answer:

A. Partial pressure of krypton, Kr is 346.97 mmHg

B. Partial pressure of nitrogen, N2 is 364.03 mmHg.

Explanation:

Step 1:

Data obtained from the question. This include the following:

Total pressure (Pt) = 711 mmHg

Mass of Kr = 11.7 g

Mass of N2 = 4.10 g

Partial pressure of Kr =..?

Partial pressure of N2 =...?

Step 2:

Determination of the number of mole of krypton, Kr and nitrogen, N2. This is illustrated below:

Molar mass of Kr = 84g/mol

Mass of Kr = 11.7g

Mole of Kr =?

Mole = mass /Molar mass

Mole of Kr = 11.7/84 = 0.139 mole

Molar mass of N2 = 2x14 = 28g/mol

Mass of N2 = 4.10g

Mole of N2 =?

Mole = mass /Molar mass

Mole of N2 = 4.1/28 = 0.146 mole

Step 3:

Determination of the mole fraction for each gas. This is illustrated below:

Mole of Kr = 0.139 mole

Mole of N2 = 0.146 mole

Total mole = 0.139 + 0.146 = 0.285 mole

Mole fraction of Kr = mol of Kr/total mol

Mole fraction of Kr = 0.139/0.285

Mole fraction of Kr = 0.488

Mole fraction of N2 = mol of N2/total mol

Mole fraction of N2 = 0.146/0.285

Mole fraction of N2 = 0.512

A. Determination of the partial pressure of krypton, Kr.

This is illustrated below:

Total pressure (Pt) = 711 mmHg

Mole fraction of Kr = 0.488

Partial pressure of Kr =..?

Partial pressure = mole fraction x total pressure

Partial pressure of Kr = 0.488 x 711

Partial pressure of Kr = 346.97 mmHg

B. Determination of the partial pressure of nitrogen, N2

This is illustrated below:

Total pressure (Pt) = 711 mmHg

Mole fraction of N2 = 0.512

Partial pressure of N2 =?

Partial pressure = mole fraction x total pressure

Partial pressure of N2 = 0.512 x 711

Partial pressure of N2 = 364.03 mmHg

Answer:

W= -11KJ

Explanation:

Given:

volume expands from 28 L to 51 L

pressure =4.9 atm.

We will need to Convert the pressure to Pascal SI

But 1 atm = 101,325 Pa.

Then,

Pressure= (4.9*101323)/1atm = 5*10^5 pa

Then we need to Convert the volumes to cubic meters

But we know that1 m³ = 1,000 L.

V1= 28L * 1m^3/1000L = 0.028m^3

V2=51L × 1m^3 /1000L =0.051m^3

The work done during the expansion of a gas can be calculated as

W= -P(V2-V1)

W= - 5*10^5(0.051m^3 - 0.028m^3)

W= -1.1× 10^4J

Then we can Convert the work to kiloJoule

But1 kJ = 1,000 J.

W= -1.1× 10^4J× 1kj/1000J

= -11KJ

Answer:

Alcl3 and Cl2

Explanation:

the product above will be formed

Answer:

silver (Ag) and aluminum chloride (AlCl₃)

Explanation:

The reaction between aluminum and silver chloride is a single replacement reaction. A single replacement reaction is when one element switches places with another.

Al + 3AgCl ➔︎ 3Ag + AlCl₃

In the reaction, the cations (positively charged ions) switch places. Aluminum (Al) switches places with Silver (Ag). So, the products of the reaction are silver and aluminum chloride.

Hope this helps.

Answer:

114 grams

Explanation:

3chlorines per compound*38grams=114

Answer:

The correct answer is - 0.570 grams

Explanation:

The balanced chemical reaction is given by

Cu(NO3)2(aq)     + 2NaOH(aq)    -------->    Cu(OH)2(s)      + 2NaNO3(aq)

        1.0 mole            2.0 mole                 1.0 mole          2.0 mole

number of mol of Cu(OH)2,

n = Molarity * Volume

= [tex]35.0*0.167 = 5.845[/tex] millimoles

As clear in the equation, 1 mole of Cu(NO3)2 gives 1 mole of Cu(OH)2 , So, 5.845 millimoles of Cu(NO3)2 will produce 5.845 millimoles of Cu(OH)2

Mass of Cu(OH)2 = number of mol * molar mass

= [tex]97.5*5.845*10^-3[/tex]

= 0.570 grams

Thus, the correct answer is - 0.570 grams

Answer:

Polarity in chemistry referred to physical properties of compounds related to solubility, melting and boiling properties.

Polarity of black pepper can be seen when black pepper is sprinkled on water. The balck pepper float on water and get displaced if touched.

It means black pepper is non-polar and have no difference in electronegativity between bonded atoms. Black pepper is so light in weight and non-polar, the surface tension of water keep it floating in the water.