Be sure to answer all parts. A freshly isolated sample of 90Y was found to have an activity of 2.2 × 105 disintegrations per minute at 1:00 p.m. on December 3, 2006. At 2:15 p.m. on December 17, 2006, its activity was measured again and found to be 5.8 × 103 disintegrations per minute. Calculate the half-life of 90Y. Enter your answer in scientific notation.

Question options:

a) 2.05

b) 0.963

c) 0.955

d) 1.00

Answer:

b) 0.963

Explanation:

H2SO4→ HSO4- + H3O+

HSO4- + H2O ⇌ SO42- + H3O+

Construct ICE table:

        HSO4- (aq)    +    H2O        ⇌      SO42- (aq)     +     H3O+ (aq)

I          0.1                  solid &                   0                          0.1

C         -x                     liquid                 + x                            + x

E         0.1 - x          are ignored              x                          0.1 + x

Calculate x

Ka = products/reactants

  = [tex]\frac{[SO42-] [H3O+]}{[HSO4-]}[/tex]

0.011 = [tex]\frac{x (0.1 + x)}{0.1 - x}[/tex]

0.011 x (0.1 -x) = o.1x + x^2

0.0011 - 0.011 x - o.1x - x^2 = 0

0.0011 - 0.011 x - x^2 = 0

Use formula to solve for quadratic equation

x = [tex]{ -b +,-\sqrt{b^2 - 4ac[/tex] / 2a

a = -1, b = -0.111, c = 0.001

Solve for x

x = [tex]\sqrt[-(-o.111)]{(-0.111)^2 - 4(-1) (0.0011) }[/tex]  / 2(-1)

x = 0.111 +,- [tex]\sqrt{0.012321 + 0.0044}[/tex] / -2

x = 0.111 +,- [tex]\sqrt{0.016721}[/tex] / -2

x = [tex]\frac{0.111 +, - 0.1293}{-2}[/tex]

x = [tex]\frac{0.111 + 0.1293}{-2}[/tex]   , x = [tex]\frac{0.111 - 0.1293}{-2}[/tex]

x = [tex]\frac{0.2403}{-2}[/tex]    , x = [tex]\frac{0.0183}{-2}[/tex]

x = - 0.12015  , x = 0.00915

x cannot be negative, so

x = 0.00915 M

Calculate [H3O+]

[H3O+] = 0.1 M + x

[H3O+] = 0.1 M + 0.00915 M

[H3O+] = 0.10915 M

Clculate pH

pH = - log [ H3O+]

pH = - log [ 0.10915]

pH = 0.963

Final answer:

The pH of a 0.100 M H2SO4 solution is approximately 1.00, considering the complete ionization of the first proton and the partial ionization of the second proton, which is less significant due to its lower Ka value.

Explanation:

The question asks about the pH of a 0.100 M H2SO4 solution, taking into account the ionization of both protons. Sulfuric acid (H2SO4) is a strong diprotic acid that dissociates completely for the first proton, yielding a concentration of 0.100 M H+ and 0.100 M HSO4-. The second proton dissociation is less extensive, with a given Ka of 1.1x10-2, which we need to include in our calculation of pH.

First step ionization (complete dissociation):
H2SO4 → H+ + HSO4-

Second step ionization (partial dissociation):
HSO4- ↔ H+ + SO42- (Ka = 1.2 x 10-2)

To calculate the pH, we first consider the complete ionization of the first proton, which directly gives us 0.100 M of H+. The pH contribution from this ionization is pH = -log(0.100) = 1.00. Then we consider the second ionization of HSO4-. Given the Ka and the initial HSO4- concentration of 0.100 M, we can set up an equilibrium expression to find the additional contribution of H+ from the second ionization. However, because the ionization is low, the change in concentration of H+ due to the second ionization can be negligible for this approximate calculation. Therefore, we can assume the pH of the solution largely results from the first dissociation.

Therefore, the answer is that the pH of the 0.100 M H2SO4 solution is approximately 1.00.

Answer:

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

Explanation:

Step 1: Data given

gaseous methane = CH4(g)

Combustion reaction is adding O2. The products will be carbondioxide (CO2) and water vapor (H2O)

Step 2: The unbalanced equation

CH4(g) + O2(g) → CO2(g) + H2O(g)

Step 3: Balancing the equation

CH4(g) + O2(g) → CO2(g) + H2O(g)

On the left side we have 4x H (in CH4), on the right side we have 2x H (in H2O). To balance the amount H on both sides, we have to multiply H2O by 2.

CH4(g) + O2(g) → CO2(g) + 2H2O(g)

On the left side we have 2x O (in O2), on the right side we have 4x O (2x in CO2 and 2x in 2H2O). To balance the amount of O on both sides, we have to multiply O2 on the left side, by 2. Now the equation is balanced.

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

The balanced chemical equation for the combustion of gaseous methane (CH₄) with gaseous oxygen (O₂) to form gaseous carbon dioxide (CO₂) and gaseous water (H₂O) is:

CH₄ + 2O₂ → CO₂ + 2H₂O

The combustion of gaseous methane (CH₄) with gaseous oxygen (O₂) to form gaseous carbon dioxide (CO₂) and gaseous water (H₂O) is a fundamental chemical reaction that occurs in natural gas combustion and many other combustion processes. To write a balanced chemical equation for this reaction, we must ensure that the number of atoms of each element on both sides of the equation is the same.

The unbalanced equation for the combustion of methane is:

CH₄ + O₂ → CO₂ + H₂O

Now, let's balance the equation:

Balance the carbon (C) atoms:

There is one carbon atom on the left and one on the right, so carbon is already balanced.

Balance the hydrogen (H) atoms:

There are four hydrogen atoms on the left (in CH₄) and two on the right (in H₂O). To balance hydrogen, we need to place a coefficient of 2 in front of H₂O on the right side.

CH₄ + O₂ → CO₂ + 2H₂O

Balance the oxygen (O) atoms:

On the left side, there are two oxygen atoms in CH₄ and two in O₂, making a total of four oxygen atoms. On the right side, there are two oxygen atoms in CO₂ and four in 2H₂O, making a total of six oxygen atoms. To balance the oxygen atoms, we need to adjust the coefficient of O₂ on the left side.

CH₄ + 2O₂ → CO₂ + 2H₂O

Now, the equation is balanced with an equal number of atoms of each element on both sides:

CH₄ + 2O₂ → CO₂ + 2H₂O

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Answer:

31.5mL

Explanation:

The following were obtained from the question:

C1 (concentration of stock solution) = 2M

V1 (volume of stock solution) =.?

C2 (concentration of diluted solution) = 0.630M

V2 (volume of diluted solution) = 100mL

Using the dilution formula C1V1 = C2V2, the volume of the stock solution needed can be obtained as follow:

C1V1 = C2V2

2 x V1 = 0.630 x 100

Divide both side by 2

V1 = (0.630 x 100) /2

V1 = 31.5mL

Therefore, 31.5mL of 2M solution of FeCl2 required

Answer:

We need 31.5 mL of the 2.0 M FeCl2 solution

Explanation:

Step 1: Data given

Molarity of a FeCl2 solution = 2.0 M

Initial volume of FeCl2 = 100 mL

Initial molarity of FeCl2 = 0.630 M

Step 2: Calculate volume of the stock solution

C1V1 = C2V2

⇒with C1 = the initial molarity FeCl2 = 0.630 M

⇒with V1 = the initial volume = 100 mL = 0.100 L

⇒with C2 = the new molarity FeCl2 = 2.0 M

⇒with V2 = the new volume = TO BE DETERMINED

0.630M * 0.100 L = 2.0 M * V2

V2 = (0.630 * 0.100) / 2.0

V2 = 0.0315 L = 31.5 mL

We need 31.5 mL of the 2.0 M FeCl2 solution

Answer:

The mole fraction of [tex]KCl[/tex] is [tex]N_{KCl}=0.099[/tex]

Explanation:

Generally number of mole is mathematically represented as

                   [tex]n = \frac{mass}{Molar mass }[/tex]

 The number of mole of  [tex]KCl[/tex] is

               [tex]n_{KCl} = \frac{mass \ of \ KCl}{Molar\ mass \ of \ KCl }[/tex]

                   [tex]n_{KCl} = \frac{125}{74.6}[/tex]

                            [tex]=1.676 \ moles[/tex]

 The number of mole of  [tex]H_2O[/tex] is

         [tex]n_{H_2O} = \frac{mass \ of \ H_2O}{Molar\ mass \ of \ H_2O }[/tex]

         [tex]n_{H_2O} = \frac{275}{18}[/tex]

                   [tex]= 15.28 \ moles[/tex]

Mole fraction of     [tex]N_{KCl}= \frac{n_{KCl}}{n_{KCl} + n_{H_2O}}[/tex]

                                        [tex]= \frac{1.676}{15.28 +1.676}[/tex]

                                        [tex]N_{KCl}=0.099[/tex]

Answer:

The mole fraction of KCl is 0.13

Explanation:

no of moles of KCl (n KCl)    = W/G.F.Wt

                                                = 135/74.6  

                                                = 1.81moles

no of moles of H2O (nH2O) = W/G.F.Wt

                                              = 225/18   = 12.5 moles

mole fraction of KCl ( XKCl)   = nKCl/nKCl + nH2O

                                                = 1.81/(1.81+12.5)

                                                 = 1.81/14.31  

      The mole fraction of KCl is   = 0.13

Answer:

pH → 1.13

Explanation:

Our solution is pure HCl

HCl(aq) + H₂O(l)  →  H₃O⁺(aq) + Cl⁻(aq)

As a strong acid, it is completely dissociated.

1 mol of HCl, can give 1 mol of H⁺ to the medium. Water does not participate. Let's find out M for the acid.

1st step: We convert the mass from mg to g → 327 mg . 1g /1000mg = 0.327 g

2nd step: We convert the mass(g) to moles: 0.327 g / 36.45 g/mol = 8.97×10⁻³ moles

3rd step: We convert the volume from mL to L → 120mL . 1L /1000 mL = 0.120L

Molarity (mol/L) = 8.97×10⁻³ mol / 0.120L = 0.075M

We propose: HCl(aq) + H₂O(l)  →  H₃O⁺(aq) + Cl⁻(aq)

                     0.075M                    0.075M

pH = - log [H₃O⁺] → - log 0.075 = 1.13 → pH

Answer : The molarity of KF solution is, 1 M

Explanation : Given,

Mass of [tex]KF[/tex] = 116 g

Volume of solution = 2 L

Molar mass of [tex]KF[/tex] = 58 g/mole

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

[tex]\text{Molarity}=\frac{\text{Mass of }KF}{\text{Molar mass of }KF\times \text{Volume of solution (in L)}}[/tex]

Now put all the given values in this formula, we get:

[tex]\text{Molarity}=\frac{116g}{58g/mole\times 2L}=1mole/L=1M[/tex]

Therefore, the molarity of KF solution is, 1 M

Answer:

The time required for the coating is 105 s

Explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode [tex](m_{ch})[/tex] is given as :

[tex]\frac{m_{ch}}{M} ZF = It[/tex]

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also; [tex](m_{ch})[/tex] = [tex](Ad) \rho[/tex] ; replacing that into above equation; we have:

[tex]\frac{(Ad) \rho}{M} ZF = It[/tex]  ---- equation (1)

where;

A = area

d = thickness

[tex]\rho[/tex] = density

From the above equation (1); The time required for coating can be calculated as;

[tex][ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t[/tex]

[tex]t = \frac{2100}{20}[/tex]

= 105 s

Answer:

B) 1-propanol has more hydrogen bonding than ethyl methyl ether.

Explanation:

1-propanol and ethyl methyl ether look very similar but have very different boiling points. They both have three carbon atoms but ethyl methyl ether has an oxygen atom.

Ethyl methyl ether has both London dispersion forces and dipole-dipole interactions.

1-Propanol has London dispersion forces, dipole-dipole interactions and hydrogen bonding.

1-propanol has more hydrogen bonding than ethyl methyl ether which explains why they both have different boiling points.

Answer:

First, Second, Second-to-last, and last choice

Explanation:

Chemistry student. The other options are incorrect. If you would like a more thorough explanation, please reply to this comment.

pH according to Arrhenius definition is the measure of hydrogen ion concentration in solution:

[tex]pH=-log[H^{+}][/tex] Acids release H+ ions into solution, while bases release OH- ions into solution. This explains why second-to-last choice is correct.

Litmus paper are thin strips of paper that have been manufactured with indicators, examples being red cabbage or phenolphthalein. Indicators react to changes in pH with an according color change. This explains why the last choice is also correct.  

Acid strength is better the lower the number it is, hence why pH 2 is stronger acid than 5, but in turn is a weaker base. This explains why second choice is correct.

The first option can be explained by the pH diagram. HCl is acidic, and will turn blue (basic) litmus paper more acidic, and move towards an acidic pH, hence more "red."

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thanks,

Answer:

I dont know if im correct number 1 is 2

Explanation:

ps im not good at this subject

Answer:

9.12x10¹³ Hz

Explanation:

The vibrational frequency (ω) of a molecule is given by:

[tex] \omega = \sqrt{\frac{k}{\mu}} [/tex]

Where:

k: is the spring constant

μ: is the reduced mass

The reduced mass of a diatomic molecule is:

[tex] \frac{1}{\mu} = \frac{1}{m_{a}} + \frac{1}{m_{b}} [/tex]

Where ma and mb are the atomic masses of the atoms a and b, respectively, of the diatomic molecule.

Hence, the vibrational frequency of the hydrogen molecule is:

[tex]\omega_{H_{2}} = \sqrt{\frac{k}{\mu_{H_{2}}}}[/tex]   (1)

From equation (1) we can find k:

[tex] k = \omega_{H_{2}}^{2}*\mu_{H_{2}} [/tex]    (2)

The vibrational frequency of the deuterium molecule is:

[tex] \omega_{D_{2}} = \sqrt{\frac{k}{\mu_{D_{2}}}} [/tex]    (3)

By entering equation (2) into equation (3) we can calculate the vibrational frequency of the deuterium molecule:

[tex] \omega_{D_{2}} = \sqrt{\frac{\omega_{H_{2}}^{2}*\mu_{H_{2}}}{\mu_{D_{2}}}} [/tex]

[tex] \omega_{D_{2}} = \sqrt{\frac{\omega_{H_{2}}^{2}*\mu_{H_{2}}}{2*\mu_{H_{2}}}} [/tex]

[tex] \omega_{D_{2}} = \frac{\omega_{H_{2}}}{\sqrt{2}} = \frac{1.29 \cdot 10^{14} Hz}{\sqrt{2}} = 9.12 \cdot 10^{13} Hz [/tex]

Therefore, the vibrational frequency of the deuterium molecule is 9.12x10¹³ Hz.

I hope it helps you!

The vibrational frequency of D₂ is :   9.12 * 10¹³ Hz

Given that:

Vibrational frequency ( w ) = [tex]\sqrt{\frac{k}{u} }[/tex]

u = reduced mass

The reduced mass of a diatomic molecule is expressed as

[tex]\frac{1}{u} = \frac{1}{m_{a} } + \frac{1}{m_{b} }[/tex]

Where : Ma and Mb are the atomic masses of mass A and mass B

First step : expressing the vibrational frequency of the hydrogen molecule

wH₂ = [tex]\sqrt{\frac{k}{uH_{2} } }[/tex]   ----- ( i )

from the equation

k = ( wH₂ )² * uH₂ ---- ( ii )

Next step : expressing the vibrational frequency of the deuterium molecule.

wD₂ = [tex]\sqrt{\frac{k}{uD_{2} } }[/tex]  ---- ( iii )

Insert equation ( ii ) into equation ( iii )

wD₂ = [tex]\frac{wH_{2} }{\sqrt{2} }[/tex]  = ( 1.29 * 10¹⁴ ) / ( √2 ) = 9.12 * 10¹³ Hz

Hence we can conclude that The vibrational frequency of D₂ is :   9.12 * 10¹³ Hz.

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Answer:

992.302 K

Explanation:

V(rms) = 750 m/s

V(rms) = √(3RT / M)

V = velocity of the gas

R = ideal gas constant = 8.314 J/mol.K

T = temperature of the gas

M = molar mass of the gas

Molar mass of CO₂ = [12 + (16*2)] = 12+32 = 44g/mol

Molar mass = 0.044kg/mol

From

½ M*V² = 3 / 2 RT

MV² = 3RT

K = constant

V² = 3RT / M

V = √(3RT / M)

So, from V = √(3RT / M)

V² = 3RT / M

V² * M = 3RT

T = (V² * M) / 3R

T = (750² * 0.044) / 3 * 8.314

T = 24750000 / 24.942

T = 992.302K

The temperature of the gas is 992.302K

Note : molar mass of the gas was converted from g/mol to kg/mol so the value can change depending on whichever one you use.

The temperature of a gas can be calculated from the root-mean-square speed of its molecules using the kinetic theory of gases. For CO2 gas with the rms speed of 750 m/s, the derived temperature is approximately 485.4 K.

The temperature of a gas can be calculated from the root-mean-square (rms) speed of its molecules using the kinetic theory of gases. This theory develops a relationship between the average kinetic energy of the gas molecules and the temperature of the gas through the equation K = 3/2kBT = mv²/2, where kB is Boltzmann’s constant, T is the temperature, m is the mass of a gas molecule, and v is the rms speed. Thus, temperature can be derived as T = mv² / (3kB).

For CO2, the molar mass is 0.044 kg/mol. Knowing that the number of molecules (n) is the number of moles times Avogadro's number (6.022 × 10²³), we derive the molecular mass m = 0.044 kg/mol / (6.022 × 10²³) = 7.3 × 10^-26 kg. Plugging in the values for v (750 m/s), m, and kB (1.38 × 10^-23 J/K), we get an approximate temperature of 485.4 K.

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The given question is incomplete. The complete question is :

Predict the products of the reaction below. That is, complete the right-hand side of the chemical equation. Be sure your equation is balanced and contains state symbols after every reactant and product

[tex]HNO_3(aq)+H_2O(l)\rightarrow[/tex]

Answer: The complete equation is [tex]HNO_3(aq)+H_2O(l)\rightarrow NO_3^-(aq)+H_3O^+(aq)[/tex]

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

[tex]HNO_3[/tex] being a strong acid dissociates to give [tex]H^+[/tex] ions an [tex]H_2O[/tex] will act as base and accept [tex]H^+[/tex] to form [tex]H_3O^+[/tex]

Thus the complete equation is [tex]HNO_3(aq)+H_2O(l)\rightarrow NO_3^-(aq)+H_3O^+(aq)[/tex]

Answer:

Mole Fraction of O2 --> 0.42

Mole Fraction of Ar --> 0.037

Explanation:

Answer:

Mole Fraction of O2 --> 0.42

Mole Fraction of Ar --> 0.037

Explanation:

In chemical reactions, a change in volume affects the position of equilibrium based on stoichiometry. Increasing volume results in a shift towards the side with more gaseous molecules for reactions with Δn not equal to zero, while there is no shift if Δn equals zero. The direction of the shift is to decrease the reaction quotient (Q) in order to re-establish equilibrium with the equilibrium constant (K).

Explanation:

The effect of volume change on the position of equilibrium in chemical reactions is dependent on the stoichiometry and the reaction in question. For a reaction where Δn = -1, increasing the volume would result in a decrease in pressure and a shift towards the side with more moles of gas to re-establish equilibrium, typically the side with more molecules. However, if Δn = 0, an increase in volume has no effect on the equilibrium as there is no change in moles of gaseous substances on either side of the reaction. When Δn = +1, increasing the volume leads the equilibrium to shift towards the products, as this increases the total number of gaseous molecules which tends to lower the pressure.

When volume is increased and the reaction quotient Q becomes greater than the equilibrium constant K (Q > K), the reaction tends to shift towards the reactants to re-establish equilibrium. Conversely, when volume is decreased, and the pressure is increased, the reaction tends to shift towards the side of the reaction with fewer moles of gas.

Complete Question

The complete question is shown on the first and second uploaded image

Answer:

A

The percentage of water of hydration is   [tex]P_h= 11.01[/tex]%

Mass of [tex]Fe^{3+}[/tex] in 100mg is 10.60mg

Moles of  [tex]Fe^{3+}[/tex] in 100mg is [tex]n_i= 0.19[/tex]

mol / mol Fe (3 sig figs) is [tex]= 1.00[/tex]

mol / mol Fe (whole number) is = 1

B

Mass of [tex]K^{+}[/tex] in 100mg is 27.70mg

Moles of  [tex]K^{+}[/tex] in 100mg is [tex]n_i= 0.581 moles[/tex]

mol  of K / mol of Fe (3 sig figs) is [tex]= 3.05[/tex]

mol  of K / mol of Fe (whole number) is [tex]=3[/tex]

C

Mass of [tex]C_2O_4^{-2}[/tex] in 100mg is 55.69 mg

Moles of [tex]C_2O_4^{-2}[/tex]  in 100mg is [tex]n_i= 0.633 moles[/tex]

mol  of  [tex]C_2O_4^{-2}[/tex] / mol of Fe (3 sig figs) is [tex]= 3.33[/tex]

mol  of [tex]C_2O_4^{-2}[/tex] / mol of Fe (whole number) is [tex]=3[/tex]

D

Mass of water in 100mg is 11.01 mg

Moles of water  in 100mg is [tex]n_i= 0.611 moles[/tex]

mol  of  water / mol of Fe (3 sig figs) is [tex]= 3.21[/tex]

mol  of water / mol of Fe (whole number) is [tex]=3[/tex]

Explanation:

The percentage of water of hydration is mathematically represented as

        [tex]P_h = 100 - (Pi + P_p + P_o)[/tex]

Now substituting 10.60% for [tex]P_i[/tex] (percentage of iron ) , 22.70% for [tex]P_p[/tex](Percentage of potassium) , 55.69% for [tex]P_o[/tex] (percentage of Oxlate)

        [tex]P_h =100 - (10.60 + 22.70+55.69)[/tex]

             [tex]P_h= 11.01[/tex]%

For IRON

Since the percentage of [tex]Fe^{3+}[/tex] is 10.60% then in a 100 mg of the sample the amount of [tex]Fe^{3+}[/tex] would be 10.60 mg

  Now the no of moles is mathematically denoted as

            [tex]n = \frac{mass}{molar \ mass }[/tex]

The molar mass of [tex]Fe[/tex] is  55.485 g/mol

     So the number of moles of [tex]Fe^{3+}[/tex] in 100mg of he sample is

                  [tex]n_i = \frac{10.60}{55.485}[/tex]

                       [tex]n_i= 0.19[/tex]

mol / mol Fe (3 sig figs) is [tex]= \frac{0.19}{0.19} = 1.00[/tex]

FOR POTASSIUM

Since the percentage of [tex]K^{+}[/tex] is 22.70% then in a 100mg of the sample the amount of [tex]K^{+}[/tex] would be 22.70mg

The molar mass of [tex]K[/tex] is  39.1 g/mol

   So the number of moles of [tex]K^{+}[/tex] in 100mg of he sample is

                  [tex]n_i = \frac{22.70}{39.1}[/tex]

                      [tex]=0.581 moles[/tex]

mol  of K / mol of Fe (3 sig figs) is [tex]= \frac{0.581}{0.19} = 3.05[/tex]

FOR OXILATE [tex]C_2O_4^{-2}[/tex]

Since the percentage of [tex]C_2O_4^{-2}[/tex]  is 55.69% then in a 100mg of the sample the amount of [tex]C_2O_4^{-2}[/tex] would be 55.69 mg

The molar mass of [tex]C_2O_4^{-2}[/tex] is  88.02 g/mol

  So the number of moles of [tex]C_2O_4^{-2}[/tex]   in 100mg of he sample is

                  [tex]n_i = \frac{55.69}{88.02}[/tex]

                         [tex]=0.633 moles[/tex]

mol  of [tex]C_2O_4^{-2}[/tex] / mol of Fe (3 sig figs) is  [tex]= \frac{0.633}{0.19} = 3.33[/tex]

FOR WATER OF HYDRATION

        Since the percentage of water  is 11.01% then in a 100mg of the sample the amount of water would be 11.0 mg

   The molar mass of water  is  18.0 g/mol

  So the number of moles of water   in 100mg of he sample is

                  [tex]n_i = \frac{11.01}{18.0}[/tex]

                      [tex]=0.611 moles[/tex]

mol  of  water / mol of Fe (3 sig figs) is  [tex]= \frac{0.611}{0.19} = 3.21[/tex]

Answer:

[tex]\large \boxed{\text{a) HBr; b) K; c) 0.0503 g}}[/tex]

Explanation:

The limiting reactant is the reactant that gives the smaller amount of product.

Assemble all the data in one place, with molar masses above the formulas and masses below them.

M_r:   39.10    80.41               2.016  

            2K  +  2HBr ⟶ 2KBr + H₂

m/g:     5.5       4.04

a) Limiting reactant

(i) Calculate the moles of each reactant  

[tex]\text{Moles of K} = \text{5.5 g} \times \dfrac{\text{1 mol}}{\text{31.10 g}} = \text{0.141 mol K}\\\\\text{Moles of HBr} = \text{4.04 g} \times \dfrac{\text{1 mol}}{\text{80.91 g}} = \text{0.049 93 mol HBr}[/tex]

(ii) Calculate the moles of H₂ we can obtain from each reactant.

From K:  

The molar ratio of H₂:K is 1:2.

From HBr:  

The molar ratio of H₂:HBr is 3:2.  

[tex]\text{Moles of H}_{2} = \text{0.049 93 mol HBr } \times \dfrac{\text{1 mol H}_{2}}{\text{2 mol HBr}} = \text{0.024 97 mol H}_{2}[/tex]

(iii) Identify the limiting reactant

HBr is the limiting reactant because it gives the smaller amount of NH₃.

b) Excess reactant

The excess reactant is K.

c) Mass of H₂

[tex]\text{Mass of H}_{2} = \text{0.024 97 mol H}_{2} \times \dfrac{\text{2.016 g H}_{2}}{\text{1 mol H}_{2}} = \textbf{0.0503 g H}_{2}\\\text{The mass of hydrogen is $\large \boxed{\textbf{0.0503 g}}$}[/tex]

Answer:

3,5-dimethyl-2-octene

Explanation:

Please note that there is no H at carbon 3 less carbon becomes penta hydra.

The compound is:

CH3

I

C = CH2 - CH3

I

CH2

I

CH - CH3

I

CH2

I

CH2

I

CH3

To name the above compound, do the following:

1. Locate the longest continuous chain i.e octene

2. Start counting from the side that gives the double bond the lowest low count since the double bond is the functional group. In doing this, the double bond is at carbon 2.

3. Locate the substituent groups attached and their position in the parent chain. In doing so, you will see that there are two CH3 group attached and they are at carbon 3 and carbon 5. Since the substituents attached are the same, we'll name them as 'dimethyl' indicate that they are two methyl groups

Now, we'll combine the above findings in order to obtain the name. Therefore, the name of the compound is:

3,5-dimethyl-2-octene

Answer:

Option C. The concentration of base is higher than the concentration of the acid.

Explanation:

The reaction between a strong acid and a strong base follows the equation:

HA + OH⁻ ⇆  A⁻ + H₂O

The pH is:

[tex] pH = -log [H_3O^{+}] [/tex]

If we have 100 mL of a strong acid and 100 mL of a strong base, for the pH to be more than 7, that means that the concentration of the base is higher than the concentration of the acid. This is because, the number of moles that remains in the solution after the reaction between the acid and the base will be the moles of the base. The number of moles of the reaction above is:

[tex] n_{T} = n_{a} - n_{b} [/tex]    (1)

Where na: is the moles of acid, nb: the moles of the base, and nT is the total number of moles.

Case A) If the concentration of acid is the same as the concentration of the base since the volume of the acid and the base are the same, the number of moles of acid is the same as the number of moles of the base, hence, they neutralize, so the pH = 7. This is not the correct option.

Case B) If the concentration of acid is higher than the base since the volume of the acid and the base are the same, the number of moles of acid is also higher than the number of moles of the base and the total moles in equation (1) results in an excess of moles of the acid, so the pH is < 7. This is not the correct option.

Case C) If the concentration of base is higher than the concentration of the acid since the volume of the acid and the base are the same, the number of moles of the base is also higher than the number of moles of the acid and the total moles in equation (1) results in an excess of moles of the base, so the pH is > 7. This is the correct option.

Case D) The water autoionizes to give [OH-] ions. The autoionization of the water produces the same concentration of acid that the base, so this is not the correct option.

From all of the above, the correct option is C. For the pH to be more than 7, the concentration of the base is higher than the concentration of the acid.

I hope it helps you!

Answer:

Yes

Explanation:

It causes excess bromine to be given off as a gas. -It is used to absorb excess heat generated by the exothermic reaction.

Answer

The desired product should contain acidic group like -COOH group.

Explanation:

Saturated sodium bicarbonate solution will react with a acid compound which contain in reaction mixture and produce CO2 gas.

We have the reaction has;  

NaHCO3 (aq) + R-COOH (aq) ..............> R-COONa (aq) + H2O (l) + CO2 (g)

Therefore.

The desired product will contain acidic group like -COOH (carboxylic acid group).

Answer:

The stopper is not fitted on the flask quickly.

Explanation:

The reaction has to do with a gas. The predicted value of the slope is 1. The value of slope obtained from the experiment varies slightly from the predicted value of 1. This discrepancy may be caused by not fitting the stopper on the flask quickly enough. This means that some gas may still be left in the flask leading a discrepancy in the slope obtained.

Answer:

2) HClO3 is stronger because chlorine is more electronegative than iodine.

Explanation:

The more electronegative the element is the more strong or acidic it becomes.

Chlorine being more electronegative than Iodine makes it easier for it to pull the electron of hydrogen more strongly and hence has a higher tendency to release a H+ unit. Hence that makes it stronger.

HClO3 is stronger than HIO3 because chlorine is more electronegative than iodine.

Chloric acid (HClO3) is more stronger than Iodic acid (HIO3) because chlorine is more electronegative than iodine. As we go from top to bottom in the periodic table, the atomic size increases and electronegativity decreases.

Electronegativity is the ability of an atom to attract electron pair towards itself. Chlorine atom comes on the top whereas iodine is present lower than chlorine in the periodic table so the atomic size of chlorine is smaller and higher value of electronegativity as compared to iodine so we can conclude that Chloric acid (HClO3) is more stronger than Iodic acid (HIO3).

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Answer:

Water of crystallization, X = 4.

Explanation:

Molar mass of [tex]CuSO_{4}.XH_{2} O[/tex]

64 + 32 + (4x18) + x ( 1 × 2 + 16)

= 160 + 18x

Given: % water of crystallization (decrease in mass after heating) = 30%

⇒ [tex]\frac{18x}{160 + 18x} =\frac{31}{100}[/tex]

1800x = 31 (160 + 18x)

58.0645x = 160 + 18x

(58.0645 - 18)x = 160

x = [tex]\frac{160}{40.0645}[/tex] = 3.99 ≅ 4.

Water of crystallization, X = 4.

Answer:

Explanation:

The given overall reaction is as follows:

O 2 N N H ₂( a q ) k → N ₂O ( g ) + H ₂ O( l )

The reaction mechanism for this reaction is as follows:

O ₂ N N H ₂ ⇌ k 1 k − 1  O ₂N N H ⁻ + H ⁺ ( f a s t  e q u i l i b r i u m )

O ₂ N N H − k ₂→ N ₂ O + O H ⁻ ( s l ow )

H ⁺ + O H − k ₃→ H ₂ O ( f a s t )

The rate law of the reaction is given as follows:

k = [ O ₂ N N H ₂ ]  / [ H ⁺ ]

The rate law can be determined by the slow step of the mechanism.

r a t e = k ₂ [ O ₂ N N H ⁻ ] . . . ( 1 )

Since, from the equilibrium reaction

k e q = [ O ₂ N N H ⁻ ] [ H ⁺ ] /[ O ₂ N N H ₂ ] = k ₁ /k − 1

[ O ₂ N N H ⁻] = k ₁ /k − 1  × [ O ₂ N N H ₂ ] /[ H ⁺ ]. . . . ( 2 )

Substitituting the value of equation (2) in equation (1) we get.

r a t e = k ₂ k ₁/ k − 1  × [ O ₂ N N H ₂ ] /[ H ⁺ ]

Therefore, the overall rate constant is

k = k₂k₁/k-1

The observed rate constant k is related to the individual rate constants of the mechanism by the equation k = k2 (k1/k-1), where k2 is the rate constant of the rate-determining slow step and k1/k-1 is the equilibrium constant of the first fast equilibrium step.

The relationship between the observed rate constant k (in the rate law) and the rate constants for the individual steps (k1, k-1, k2, k3) in the proposed mechanism for the decomposition of nitramide can be determined by examining the rate-determining step (RDS). In a reaction mechanism, the slowest step controls the overall reaction rate. For the given mechanism:

the observed rate law is rate = k [O2NNH2] [H+]. Because the second step is slow, it is the RDS. The equilibrium of the first step means that the concentration of the intermediate O2NNH−(aq) can be expressed in terms of the concentrations of the reactants O2NNH2 and H+. Therefore, the observed rate constant k is a function of the rate constants of the individual steps, particularly k2 and the equilibrium constant (K = k1/k−1) from the first step. Hence, we can conclude that k is equal to k2 multiplied by the equilibrium constant of the first step, where k = k2 (k1/k−1)

Final answer:

Only statement b, which says that chlorine is reduced from +7 to -1 in both reactions, is correct. Statements a, c, and d cannot be confirmed as correct based on the given information.

Explanation:

The student has presented two chemical reaction equations involving the thermal decomposition of NH4ClO4 (ammonium perchlorate) and powdered aluminum. Let's address the statements provided:

a. All nitrogen atoms lose three electrons in both reactions. This statement is incorrect. In the provided reactions, nitrogen goes from an oxidation state of -3 in NH4+ to 0 in N2, which means each nitrogen atom gains three electrons.

b. Chlorine is reduced from +7 to -1 in both reactions. This statement is correct. In NH4ClO4, chlorine starts with an oxidation state of +7 and is reduced to -1 in HCl.

c. Reaction 2 produces more energy per gram of Al. Without details of the mass of aluminum involved in Reaction 2, we cannot determine which reaction produces more energy per gram of aluminum. However, if the reactions involve the same mass of aluminum, then Reaction 1 is more energetic since the absolute value of ΔH is greater.

d. The thrust produced by the formation of gaseous products is greater per mole of ammonium perchlorate in Reaction 2. This statement cannot be evaluated without more information about the moles of gaseous products formed in Reaction 2.

Therefore, based on the information provided, the correct statement is b. Chlorine is reduced from +7 to -1 in both reactions.

Answer: The volume of 0.684 mol of carbon dioxide at s.t.p. is 15.3 L

Explanation:

According to ideal gas equation:

[tex]PV=nRT[/tex]

P = pressure of gas = 1 atm (at STP)

V = Volume of gas = ?

n = number of moles = 0.684

R = gas constant = [tex]0.0821Latm/Kmol[/tex]

T =temperature =[tex]273K[/tex]   (at STP)

[tex]V=\frac{nRT}{P}[/tex]

[tex]V=\frac{0.684\times 0.0821L atm/K mol\times 273K}{1atm}[/tex]

[tex]V=15.3L[/tex]

Thus the volume of 0.684 mol of carbon dioxide at s.t.p. is 15.3 L

The solubility of CuX in a 0.200 M NaCN solution cannot be calculated solely based on the Ksp of CuX, because NaCN forms a complex with Cu2+, significantly affecting its solubility. Additional information on the stability constant of the copper-cyanide complex is needed

To calculate the solubility of CuX in a solution that is 0.200 M in NaCN, we must consider the common ion effect due to the presence of the cyanide ion, CN-. The equation for the solubility product (Ksp) is given by Ksp = [Cu2+][X2−]. Since cyanide ions form a complex with copper ions, the direct precipitation of CuX is suppressed, and we cannot simply take the square root of the Ksp to find its molar solubility.

Instead, we would write the reaction of copper with cyanide: CuX(s) + 4CN−
ightleftharpoons [Cu(CN)4]3− + X2−. This complexation reaction would vastly reduce the concentration of free Cu2+ ions in solution, thereby affecting the solubility of CuX. To find the actual solubility, we would need to know the stability constant (Kf) for the copper-cyanide complex, and then set up an equilibrium calculation that includes both the Ksp of CuX and the Kf of [Cu(CN)4]3−. Since the problem doesn't provide Kf, we would not be able to calculate the solubility without additional information

The presence of NaCN significantly decreases the solubility of CuX due to the common ion effect. Therefore, the solubility of CuX in a solution that is 0.200 M in NaCN remains extremely low, approximately 1.27×10 ⁻¹⁸ M.

To calculate the solubility of CuX in a solution that is 0.200 M in NaCN, we need to consider the common ion effect. When NaCN dissolves, it produces CN⁻ ions, which can interact with Cu²⁺ ions, reducing the solubility of CuX.

Given that the solution is 0.200 M in NaCN, we can assume that the concentration of CN⁻ ions ([CN⁻]) is 0.200 M.

Now, let's denote the solubility of CuX as x M. Since CuX dissociates into Cu²⁺ and X²⁻ ions, the concentration of Cu²⁺ ions ([Cu²⁺]) and X²⁻ ions ([X²⁻]) will both be equal to x M at equilibrium.

The solubility product constant (K sp​ ) expression for CuX is:

K sp​ =[Cu²⁺ ][X²⁻ ]

Given that K sp​ =1.27×10⁻³⁶ , we can substitute the concentrations into the expression:

1.27×10⁻³⁶ =(x)(x)

1.27×10⁻³⁶ =x²

Now, we'll solve this equation for x to find the solubility of CuX. Let's proceed with the calculations.

To solve for x, we take the square root of both sides of the equation:

x= 1.27×10⁻³⁶

x=1.127×10⁻¹⁸

So, the solubility of CuX in a solution that is 0.200 M in NaCN is

1.127×10⁻¹⁸  M.

Answer:

we are given the 3-methyl2 butanone and upon the reduction with LiAIH4 there is formed alcohol, there are two possible side attack,

therefore, whenever the front side attacks then the -CH3 moves back  the plain and the H will be above the plane. More so, when  attack from the back side the H moves below the plane and -CH3 moves above the plane. -OH is evident in the plane. see the attachment below to view the structure.

Explanation:

Answer:

p3=0.36atm (partial pressure of NOCl)

Explanation:

2 NO(g) + Cl2(g) ⇌ 2 NOCl(g)  Kp = 51

lets assume the partial pressure of NO,Cl2 , and NOCl at eequilibrium are P1 , P2,and P3 respectively

[tex]Kp=\frac{[NOCl]^{2} }{[NO]^{2} [Cl_2] }[/tex]

[tex]Kp=\frac{[p3]^{2} }{[p1]^{2} [p2] }[/tex]

p1=0.125atm;

p2=0.165atm;

p3=?

Kp=51;

On solving;

p3=0.36atm (partial pressure of NOCl)

The reaction,

Given values,

Pressure,

Value of Kp,

Now,

→ [tex]K_p = \frac{[NOCl]^2}{[NO]^2[Cl_2]^2}[/tex]

or,

→ [tex]K_p = \frac{[P_3]^2}{[P_1]^2[P_2]}[/tex]

By substituting the values,

   [tex]51 = \frac{[P_3]^2}{[0.125]^2[0.165]}[/tex]

   [tex]P_3 = 0.36 \ atm[/tex]

Thus the response above is appropriate.  

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Answer:

base and it's in solution

Explanation:

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