Which of the following should have the largest Henry's law constant (kH) in water?
A) Ar B) CO C) Xe D) CH3CH3 E) CO2

Answer:

the mass of the impure reagent required to prepare the solution is approximately 0.41875 g.

Explanation:

A) To calculate the mass of the impure reagent required to prepare the solution, we can use the formula:

mass = volume x concentration x molar mass

First, let's calculate the moles of OCl- required:

moles = volume x concentration

Given that the volume is 50.0 mL and the concentration is 55.0 ppm (parts per million), we convert the concentration to a decimal by dividing it by 1,000,000:

55.0 ppm = 55.0 / 1,000,000 = 0.000055

moles = 50.0 mL x 0.000055 = 0.00275 mol

Now, let's calculate the mass of Ca(OCl)2 needed:

mass = moles x molar mass

Given that the molar mass of Ca(OCl)2 is 142.983 g/mol, we have:

mass = 0.00275 mol x 142.983 g/mol = 0.39395 g

However, the Ca(OCl)2 is impure, with a purity of 94.0%. To find the mass of the impure reagent, we divide the mass by the purity percentage and multiply by 100:

mass of impure reagent = (0.39395 g / 94.0%) x 100 = 0.41875 g

Therefore, the mass of the impure reagent required to prepare the solution is approximately 0.41875 g.

B) The best method to accurately prepare 50.0 mL of the 55.0 ppm OCl- solution is:

- Use an analytical balance to weigh out the amount of reagent determined in part A. Transfer the reagent to a 50.0 mL volumetric flask, add water to the line, and mix thoroughly.

This method ensures that the desired concentration is achieved by precisely measuring the required mass of the impure reagent and diluting it to the desired volume in a volumetric flask. The use of an analytical balance and a volumetric flask helps to ensure accuracy and precision in the preparation of the solution.

The other methods mentioned (using a pipet or graduated cylinder) may not provide the same level of accuracy and precision as using a volumetric flask, which is specifically designed for precise volume measurements.

Final answer:

Water boiling is endothermic, gasoline burning is exothermic, and ice forming is exothermic.

Explanation:

a. Water boiling is an endothermic process because heat is required to convert water from the liquid to the gaseous phase. The reaction absorbs energy from the surroundings, resulting in a decrease in temperature.

b. Gasoline burning is an exothermic process because it releases heat into the surroundings. The combustion of gasoline produces energy in the form of heat and light.

c. Ice forming on a pond is an exothermic process. When liquid water freezes, it releases heat into the surroundings, resulting in a decrease in temperature.

The answer is as follows: (a) Endothermic, H > 0

(b) Endothermic, H > 0

(c) Exothermic, H < 0

Explanation and logic of the

 (a) When an ice cube melts, it absorbs heat from its surroundings to break the hydrogen bonds between water molecules, which requires energy. This process is endothermic, meaning it absorbs heat from the surroundings, and the enthalpy change (H) is positive because the system is gaining energy.

(b) Nail polish remover evaporating quickly after being spilled also involves an endothermic process. The liquid absorbs heat from the skin, causing it to change state from liquid to gas. This phase change requires energy, which is why the skin feels cooler as the nail polish remover evaporates. The enthalpy change (H) is positive because the system is gaining energy from the surroundings.

(c) Gasoline burning within the cylinder of an automobile engine is an exothermic reaction. When gasoline combusts, it releases a significant amount of energy in the form of heat and light. This energy is transferred to the surroundings, and the enthalpy change (H) is negative because the system is losing energy. This is characteristic of exothermic reactions, where the energy released is greater than the energy absorbed.

Answer:

The answer to your question is pH = 2.28

Explanation:

Chemical reaction

                    HCOOH(ac)  +  H₂O  ⇔   H₃O⁺   +  HCOO⁻

I                        0.15                 --              0               0

C                       - x                   --             +x              +x

F                     0.15 - x             --               x                x

Write the equation of equilibrium

                             [tex]ka = \frac{[H3O][HCOO]}{[HCOOH]}[/tex]

Substitution

                             [tex]1.8 x 10^{-4} = \frac{[x][x]}{0.15 - x}[/tex]

But     0.15 - x ≈   0.15

                             [tex]1.8 x 10^{-4} = \frac{x^{2} }{0.15}[/tex]

Solve for x

                             x² = (0.15)(1.8 x 10⁻⁴)

Simplification

                             x² = 0.000027

Result

                             x = 0.0052

                          pH = -log [H₃O⁺]

Substitution

                          pH = - log [0.0052]

Simplification and result

                         pH = 2.28

The pH of a 0.15M solution of HCOOH with a Ka of 1.8×10⁻´ is calculated using an ICE table, which leads to an equilibrium pH of approximately 2.78.

To calculate the pH of a 0.15M solution of HCOOH with a Ka of 1.8×10⁻´, we can set up an ICE (Initial, Change, Equilibrium) table to find the equilibrium concentrations of the species in solution:

Applying the expression for Ka, we have:

Ka = 1.8×10⁻´ = (x)(x) / (0.15 - x)

Assuming x is small and can be ignored in the denominator, we simplify to:

Ka = x² / 0.15

Solving for x (which represents [H⁺]), we find that x is approximately equal to the square root of (Ka × [HCOOH]), thus:

[H⁺] = √(1.8×10⁻´ × 0.15) ≈ 1.65×10⁻²

To find the pH, we take the negative logarithm of [H⁺]:

pH = -log(1.65×10⁻²) ≈ 2.78

The pH of the solution at equilibrium is approximately 2.78.

Answer:

a. The balanced chemical equation for the reaction

[tex]NH_3(g)+HCl(g)\rightarrow NH_4Cl(g)[/tex]

b. HCl is the limiting reagent.

c. 7.3295 grams of ammonium chloride could form from the reaction mixture in part (b).

d. 0.6715 grams of ammonia is left over in the reaction mixture in part b.

Explanation:

a. The balanced chemical equation for the reaction

[tex]NH_3(g)+HCl(g)\rightarrow NH_4Cl(g)[/tex]

b.

Moles of ammonia =[tex]\frac{3.0 g}{17 g/mol}=0.1765 mol[/tex]

Moles of HCl = [tex]\frac{5.0 g}{36.5 g/mol}=0.1370 mol[/tex]

According to reaction, 1 mole of HCl reacts with 1 mole of ammonia . Then 0.1370 moles of HCl will react with :

[tex]\frac{1}{1}\times 0.1370 mol=0.1370 mol[/tex] of ammonia

Hence, HCl is the limiting reagent.

c.

Since, HCl is a limiting reagent amount of ammonium chloride will depend upon moles of HCl.

According to reaction, 1 mole of HCl gives with 1 mole of ammonium chloride . Then 0.1370 moles of HCl will give :

[tex]\frac{1}{1}\times 0.1370 mol=0.1370 mol[/tex] of ammonium chloride

Mass of 0.1370 moles of ammonium chloride :

53.5 g/mol × 0.1370 mol =  7.3295 g

7.3295 grams of ammonium chloride could form from the reaction mixture in part (b).

d.

Moles of ammonia =[tex]\frac{3.0 g}{17 g/mol}=0.1765 mol[/tex]

HCl is a limiting reagent and ammonia is an excessive reagent.

According to reaction, 1 mole of HCl reacts with 1 mole of ammonia . Then 0.1370 moles of HCl will react with :

[tex]\frac{1}{1}\times 0.1370 mol=0.1370 mol[/tex] of ammonia

Moles of Ammonia reacted = 0.1370 mol

Moles of ammonia left unreacted = 0.1765 mol - 0.1370 mol = 0.0395 mol

Mass of 0.0395 moles of ammonia :

0.0395 mol × 17 g/mol = 0.6715 g

0.6715 grams of ammonia is left over in the reaction mixture in part b.

Answer:

pHe = 261 torr

pAr = 472 torr

P = 733 torr

Explanation:

The final volume for both gases is the same: V₂ = 255 mL + 475 mL = 730 mL

We can find the final partial pressure of each gas using Boyle's law.

He

P₁ × V₁ = P₂ × V₂

P₂ = P₁ × V₁ / V₂

P₂ = 746 torr × 255 mL / 730 mL = 261 torr

Ar

P₁ × V₁ = P₂ × V₂

P₂ = P₁ × V₁ / V₂

P₂ = 726 torr × 475 mL / 730 mL = 472 torr

The total pressure is the sum of the partial pressures.

P = 261 torr + 472 torr = 733 torr

The mass of MgCO₃ is 1.9g.

The balanced chemical reaction is shown below

Na₂CO₃   +   Mg(NO₃)₂     ⇒   2 NaNO₃   + MgCO₃

0.200 M   0.0450 M                                        ?

10.0           5.00 mL                                          ?

Since the volume and concentration of Mg(NO₃)₂ and Na₂CO₃  is given , we can calculate the number of moles for each of them and then determine the limiting reagent.

Convert the volume of  Mg(NO₃)₂and Na₂CO₃ to liters:

5.00 mL x ( 1 L/1000 mL ) =   5.00 x 10⁻³ L

10.00 mL x ( 1L/ 1000 mL ) = 1.000 x 10 ⁻² L

Number of  mol Mg(NO₃)₂ = ( 0.0450 mol /L  ) x 5.00 x 10⁻³ L

                                           = 2.25 x 10⁻⁴ mol Mg(NO₃)₂

Number of mol Na₂CO₃ = ( 0.200 mol / L ) x 1 x 10⁻² L  

                                        = 2.000 x 10⁻³  mol Na₂CO₃

Limiting reagent

    = 2.25 x 10⁻⁴ mol Mg(NO₃)₂ x ( 1 mol Na₂CO₃ / mol  Mg(NO₃)₂ )

      = 2.25 x 10⁻⁴ mol  Na₂CO₃ required .

Limiting reagent is Mg(NO₃)₂ since 2.25 x 10⁻⁴ mol  Na₂CO₃ is required to

react completely with  2.25 x 10⁻⁴Mg(NO₃)₂, and there's an excess.

Number of  mole  of MgCO₃ produced

= 2.25 x 10⁻⁴ mol  Mg(NO₃)₂ x ( 1 mol MgCO₃ / 1 mol Mg(NO₃)₂ )

= 2.25 x 10⁻⁴ mol  MgCO₃

Mole = mass/molar mass

Mass= Mole × molar mass

2.25 x 10⁻⁴ mol  MgCO₃ x   84.31 g/mol  = 1.90 g

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To calculate the mass of MgCO3 precipitated, determine the limiting reactant and use stoichiometry to find the moles and mass of MgCO3.

To calculate the mass of MgCO3 precipitated, we need to determine the limiting reactant in the reaction between Na2CO3 and Mg(NO3)2. First, calculate the moles of Na2CO3 and Mg(NO3)2 using their respective concentrations and volumes. Then, compare the moles of each reactant to determine which is limiting. Use the stoichiometry of the balanced equation to find the moles of MgCO3 produced. Finally, calculate the mass of MgCO3 using its molar mass.

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This question requires the mass of sulfuric acid and a balance equation. The complete question is given below

Question:

According to the following reaction, how many grams of water are produced in the complete reaction of 24.1 grams of sulfuric acid?

H₂SO₄(aq) + Zn(OH)₂(s) ---------> ZnSO₄(aq) + 2H₂O(l)

Answer:

8.85 grams of water is obtained from 24.1 grams of sulfuric acid according to the given reaction

Explanation:

In this problem, the mass of water can be determined by using the balanced chemical equation.

Step 1: Write all data

Molar mass of water = 18 g

Molar mass of sulfuric acid = 98 g

Given mass of sulfuric acid = 24.1 g

Mass of water from reaction = ?

Step 2: Write statement for conversion

Given equation shows that

1 mole of H₂SO₄ gives 2 moles of water

Step 3: Convert moles into molar mass

Convert the moles into molar mass so, the statement becomes,

98 g of H₂SO₄ gives (2)(18) g of water

1 g of H₂SO₄ gives (2)(18)/98 g of water

Step 4: Use given data

24.1 g of H₂SO₄ gives (2)(18)(24.1)/98 g of water

amount of water = 8.85 g

Answer: 40731.8 grams of this gasoline would fill a 14.6gal tank

Explanation:

Density is defined as the mass contained per unit volume.

[tex]Density=\frac{mass}{Volume}[/tex]

Given : Mass of gasoline = ?

Density of the gasoline = [tex]0.737g/ml[/tex]

Volume of the gasoline = 14.6gal = 55267.01 ml           (1gal=3785.41ml)

Putting in the values we get:

[tex]0.737g/ml=\frac{mass}{55267.01ml}[/tex]

[tex]{\text {mass of gasoline}}=40731.8g[/tex]

Thus 40731.8 grams of this gasoline would fill a 14.6gal tank

Explanation:

It is known that acidic strength of hydrides of same group tends to increase when we move from top to bottom in a group. On the other hand, acidic strength of hydrides of same period elements increases when we move from left to right in a period.

As both bromine and iodine belongs to the same group. Also, selenium and oxygen are same group elements. Therefore, their acidic strength increases on moving down the group.

Therefore, we can conclude that acidic strength of given compounds from strongest to weakest is as follows.

                HI > HBr > [tex]H_{2}Se[/tex] > [tex]H_{2}O[/tex]

To rank the acids in decreasing acid strength using periodic trends, consider the size, electronegativity, and presence of lone pairs of electrons. HI is the strongest acid, followed by HBr, H2O, and H2Se.

To rank the acids in order of decreasing acid strength using periodic trends, we need to consider the size and electronegativity of the atoms. The larger the atom, the weaker the acid, and the more electronegative the atom, the stronger the acid. Additionally, we can consider the presence of lone pairs of electrons, as they increase the acidity.

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Answer:

The diameter of Mercury would be 0.735 times smaller than the actual diameter i.e., it would become 3590 km from 4879 km

Explanation:

For the sake of simplicity, let us consider Mercury spherical and uniform. The provided data shows that if the Mercury planet is purely composed of mercury then it will require less space as compared to the actual planet, due to the higher density of the mercury. The ratio of the two densities shows that the volume of Mercury would reduce 2.52 times. From the change in volume we can determine the change in diameter by taking the ratio of initial and final states, shown in the following derivation:

[tex]V=(\frac{4}{3})(\pi )(r^{3})[/tex],

Here, V is the volume and r is the radius of the Mercury.

From the ratio of initial and final states, we obtain the following relation

[tex]\frac{V_{2} }{V_{1} } = \frac{r_{2} ^{3}}{r_{1} ^{3}}[/tex]

as,

[tex]V_{2}=\frac{V_{1}}{2.52}[/tex]

so,

[tex]\frac{1}{2.52} = \frac{r_{2} ^{3}}{r_{1} ^{3}}[/tex]

[tex]r_{2}^{3}=\frac{r_{1}^{3}}{2.52}[/tex]

[tex]r_{2}= 0.735.r_{1}[/tex]

The factor will remain same for the diameter i.e.,

[tex]D_{2}= 0.735 D_{1}[/tex]

For absolute diameter of Mercury:

Actual diameter of Mercury = 4879.4 km

Hence, the diameter of Mercury, if it was made of mercury would become 3590 km.

P.S.: The element mercury first letter is kept small while the other is capped

The concentration of the pesticide DDT in the 3.7 L solution is approximately 113.51 ppm.

The mass of the solute (DDT) must be determined to calculate the concentration in parts per million (ppm).

So, the given quantities are:

Volume of solution (V) = 3.7 L

Density of solution (d) = 1.00 g/mL

Mass of DDT (m) = 4.21 × 10^-7 kg

Let's start by using the volume and density provided to determine the mass of the solution:

Mass of solution = Volume × Density

Mass of solution = 3.7 L × 1.00 g/mL = 3.7 kg

Now, we'll convert the mass of DDT to grams:

1 kg = 1000 g

Mass of DDT in grams = 4.21 × [tex]10^-^7[/tex] kg × 1000 g/kg = 4.21 × [tex]10^-^4[/tex] g

Now we can calculate the concentration in ppm:

Concentration (ppm) = (Mass of solute / Mass of solution) × 10^6

Concentration (ppm) = (4.21 × [tex]10^-^4[/tex] g / 3.7 kg) × [tex]10^-^6[/tex] ≈ 113.51 ppm

Therefore, the concentration of the pesticide DDT in the 3.7 L solution is approximately 113.51 ppm.

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The concentration of DDT in the solution is 0.1137 ppm. This calculation involved converting mass to grams, understanding the density to find out the total mass of the solution, and then using the formula for concentration in ppm.

To calculate the concentration of DDT in ppm (parts per million), you firstly need to convert the given mass of DDT into grams as ppm is typically expressed in terms of mass (g). We know that 1kg is equal to 1000g, so 4.21 x 10^-7 kg corresponding to 4.21 x 10^-4 g. We also know that the density of the solution is given to be 1g/mL, a 3.7L solution is therefore 3700 mL. So, the total mass of the solution will be 1.00 g/mL x 3700 mL = 3700 g.

Now, to get the concentration in ppm, we use the formula:

Concentration (ppm) = (mass of solute/mass of solution) x 10^6

Plugging in the values, we have:

Concentration (ppm) =

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Answer:

47.5 g of water can be formed

Explanation:

This is the reaction:

CH₄  +  2O₂  →  CO₂ + 2H₂O

Methane combustion.

In this process 1 mol of methane react with 2 moles of oxygen to produce 2 moles of water and 1 mol of carbon dioxide.

As ratio is 1:2, I will produce the double of moles of water, with the moles of methane I have.

1.320 mol  .2 = 2.64 moles

Now, we can convert the moles to mass (mol . molar mass)

2.64 mol . 18g/mol = 47.5 g

Answer:

mass H2O = 47.56 g

Explanation:

balanced reation:

∴ moles CH4 = 1.320 mol

⇒ moles H2O = (1.320 mol CH4)×(2 mol H2O/mol CH4)

⇒ moles H2O = 2.64 mol H2O

∴ molar mass (mm) H2O = 18.015 g/mol

⇒ mass H2O = (2.64 mol H2O)×(18.015 g/mol)

⇒ mass H2O = 47.56 g

This is an incomplete question. The complete question is :

Calculate the change in internal energy (ΔE) for a system that is giving off 25.000 kJ of heat and is changing from 18.00 L to 15.00 L in volume at 1.50 atm pressure.

Answer: The change in internal energy for a system is -24544 Joules

Explanation:

According to first law of thermodynamics:

[tex]\Delta E=q+w[/tex]

[tex]\Delta E[/tex]=Change in internal energy

q = heat absorbed or released

w = work done or by the system

w = work done by the system=[tex]-P\Delta V[/tex]  {Work done on the system as the final volume is lesser than initial volume and is positive}

w =[tex]-1.50atm\times (15.00-18.00)L=4.50Latm=456Joules[/tex]  {1Latm=101.3J}

q = -25.000 kJ =[tex]-25.000\times 10^3J[/tex] {Heat released by the system is negative}

[tex]\Delta E=456J+(-25000)=-24544J[/tex]

Thus change in internal energy for a system is -24544 Joules

Answer:

C

Explanation:

Pb + H2O + O2 => Pb(OH)2

Number of oxygen atom on left = 3

Number of oxygen atom on the right = 2

To balance number of oxygen

Change the coefficient of Pb and H2O to two each

2Pb + 2H2O + O2 => 2Pb(OH)2

The coefficient of Pb and H2O is 2,2

The correct coefficients for Pb and H₂O when balancing the equation Pb + H₂O + O₂ ⇒ Pb(OH)₂ are 1 and 2, respectively; therefore, the answer is A. 1,2. This ensures that the chemical equation is fully balanced with the correct number of atoms for each element on both sides.

When balancing the chemical equation Pb + H₂O + O₂ ⇒ Pb(OH)₂, the correct coefficients for Pb and H₂O, respectively, are 1 and 2. Balancing chemical equations requires that the same number of atoms for each element be present on both sides of the equation. Starting with lead (Pb), we see that one Pb atom is needed on both sides, so we keep the coefficient for Pb as 1.

Next, we balance the hydrogen atoms. There are two hydrogens in each hydroxide ion, and since there are two hydroxide ions in Pb(OH)₂, this means there are a total of four hydrogen atoms in the product. To balance this, we need 2 molecules of H₂O (since each molecule of water contains two hydrogen atoms, giving us the four we need), making the coefficient for H₂O equal to 2.

Lastly, the oxygen atoms will balance themselves once H and Pb are balanced. With 2 H₂O molecules, we have 2 oxygen atoms, and the Pb(OH)₂ molecule has 2 oxygen atoms as well, which means we don't need any additional O₂ for balance. The balanced equation is 1 Pb + 2 H₂O + O₂ ⇒ 1 Pb(OH)₂. Therefore, the correct answer is A. 1,2.

Answer: voltage-gated channels

Explanation:

voltage-gated Ion channels: They are proteins of multi-subunit complexes that reacts with confrontations changes that occurs in the members potential which results in the opening and closing of the pore. They mainly help to generate electrical signals within the cell membrane. The locations of the voltage-gated ion channels includes in the cell body of the neurons, on the dendrites, on the axon hillock, on the node of Ranvier, etc. Majorly, when ion channels open, it is a form of response to stimuli.

Voltage-gated channels are the membrane ion channels that open in response to changes in membrane potential, cycling through closed, open, or inactivated states depending on the cell's electrical charge.

The membrane ion channels that open and close in response to changes in the membrane potential are known as voltage-gated channels. These channels can exist in one of three states - closed, open, or inactivated. Initially, voltage-gated ion channels are closed, but they open in response to a change in the electrical potential of the cell membrane. Specifically, when the inner membrane voltage becomes less negative in comparison to the outside, the channels sense the change through amino acids in their structure that are sensitive to charge, prompting the pore to open and allow ions to move across the membrane. Once activated, these channels will then become inactivated for a brief period, during which time they cannot open in response to a signal even if the membrane potential changes.

Answer:

5.0x10⁻⁵ M

Explanation:

It seems the question is incomplete, however this is the data that has been found in a web search:

" One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silver nitrate solution. Any chloride anions in solution will combine with the silver cations to produce bright white silver chloride precipitate. Suppose a EPA chemist tests a 250 mL sample of groundwater known to be contaminated with nickel(II) chloride, which would react with silver nitrate solution like this:

NiCl₂ + 2AgNO₃ →  2AgCl + Ni(NO₃)₂

The chemist adds 50 mM silver nitrate solution to the sample until silver chloride stops forming. She then washes, dries, and weighs the precipitate. She finds she has collected 3.6 mg of silver chloride. Calculate the concentration of nickel(II) chloride contaminant in the original groundwater sample. Round your answer to 2 significant digits. "

Keep in mind that while the process is the same, if the values in your question are different, then your answer will be different as well.

First we calculate the moles of nickel chloride found in the 250 mL sample:

Now we divide the moles by the volume to calculate the molarity:

Answer:  459 nm

Explanation:

The relation between energy and wavelength of light is given by Planck's equation, which is:

[tex]E=\frac{Nhc}{\lambda}[/tex]

where,

E = energy of the light  = [tex]261 kJ=261000J[/tex]   (1kJ=1000J)

N= avogadro's number  = [tex]6.023\times 10^{23}[/tex]

h = Planck's constant  = [tex]6.626\times 10^{-34}Js[/tex]

c = speed of light  = [tex]3\times 10^8m/s[/tex]

[tex]\lambda[/tex] = wavelength of light  = ?

Putting the values in the  equation:

[tex]261000J=\frac{6.023\times 10^{23}\times 6.626\times 10^{-34}Js\times 3\times 10^8m/s}{\lambda}[/tex]

[tex]\lambda=4.587\times 10^{-7}m=459nm[/tex]       [tex]1nm=10^{-9}m[/tex]

Thus the longest wavelength of light that can be used to eject electrons from the surface of this metal via the photoelectric effect is 459 nm

The question is incomplete, complete question is:

For each trial, enter the amount of heat lost by the chemical system, qrxn.

Hints: The specific heat of water is 4.184 J/g°C.   Be careful of your algebraic sign here and remember that the change in temperature is equal to the final temperature minus the initial temperature.

qrxn = - (qwater + qcalorimeter).

The heat gained by the calorimeter water, qwater, depends on the mass of water, the specific heat of water, Cpand ΔT, while the heat gained by the calorimeter, qcalorimeter, depends on the heat capacity, C and ΔT.    

DATA :        1,      2,      3

[tex]T_i(^oC)[/tex]       24.2, 24.0 ,  23.2

[tex]T_f(^oC)[/tex]        38.2, 37.8   , 36.6

Mass (g)          70.001 , 70.008 , 70.271

Explanation:

[tex]Q=mc\Delta T[/tex]

Where:

Q = heat absorbed or heat lost

c = specific heat of substance

m = Mass of the substance  

ΔT = change in temperature of the substance

Trail 1

Heat absorbed by the water = [tex]Q_1[/tex]

Mass of water ,m,= 70.001 g

Specific heat water = c = 4.184 J/g°C

ΔT = [tex]T_f-T_i=38.2 ^oC - 24.2^oC = 14^oC[/tex]

[tex]Q_2=70.001 g\times 4.184 J/g^oC\times 14^oC=4,100.38 J[/tex]

Heat absorbed by the water is 4,100.38 J.

Trail 2

Heat absorbed by the water = [tex]Q_2[/tex]

Mass of water ,m,= 70.008 g

Specific heat water = c = 4.184 J/g°C

ΔT = [tex]T_f-T_i=37.8 ^oC - 24.0^oC = 14.2^oC[/tex]

[tex]Q_2=70.008 g\times 4.184 J/g^oC\times 14.2^oC=4,042.21 J[/tex]

Heat absorbed by the water is 4,042.21 J.

Trail 3

Heat absorbed by the water = [tex]Q_3[/tex]

Mass of water ,m,= 70.271 g

Specific heat water = c = 4.184 J/g°C

ΔT = [tex]T_f-T_i=36.6^oC - 23.2^oC = 13.4^oC[/tex]

[tex]Q_3=70.271 g\times 4.184 J/g^oC\times 13.18^oC=3939.78 J[/tex]

Heat absorbed by the water is 3,939.78 J.

Answer:

E Indium =     4.407 x 10⁻¹⁹ J

E Thallium =  3.716 x 10⁻¹⁹ J

Explanation:

From Planck´s equation for a given wavelength, the energy is given by.

E = h ( c/ λ )

h: Planck´s constant, 6.626 x 10⁻³⁴ J·s

c: light speed, 3 x 10⁸ m/s

λ: wavelength in m

We will need first to convert the given wavelengths to m:

451.1  nm x ( 1 m/10⁹  nm ) = 4.511 x 10⁻⁷  m

535.0 nm x ( 1 m/10⁹ nm ) = 5.350 x 10⁻⁷ m

E Indium =    6.626 x 10⁻³⁴  J·s x 3x 10 ⁸ m/s/ 4.511 x 10⁻⁷  m = 4.407 x 10⁻¹⁹ J

E Thallium =  6.626 x 10⁻³⁴ J·s x 3x 10 ⁸ m/s/ 5.350 x 10⁻⁷ m = 3.716 x 10⁻¹⁹ J

The question is incomplete, here is the complete question:

A chemist adds 370.0 mL of a 2.25 M iron(III) bromide solution to a reaction flask. Calculate the mass in grams of iron(III) bromide the chemist has added to the flask. Round your answer to 3 significant digits

Answer: The mass of iron (III) bromide is 246. grams

Explanation:

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

[tex]\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}[/tex]

We are given:

Molarity of solution = 2.25 M

Molar mass of iron (III) bromide = 295.6 g/mol

Volume of solution = 370.0 mL

Putting values in above equation, we get:

[tex]2.25M=\frac{\text{Mass of solute}\times 1000}{295.6\times 370.0}\\\\\text{Mass of solute}=\frac{2.25\times 295.6\times 370.0}{1000}=246.1g[/tex]

Hence, the mass of iron (III) bromide is 246. grams

Answer:

1. Hydrogen bond

2. Ion-ion

3. Hydrogen bond

4. London force

5. Hydrogen bond

Explanation:

Intermolecular forces are the ones that keep the molecules, or ions, together in the substance. If the substance is metal then, metallic forces are involved in it; if it's an ionic compound, then ion-ion forces are involved in it, and, if the compound is a molecule, it may have 3 different types of forces.

The force depends on the polarity of the molecule, which is given by the measure of the dipole moment. If the dipole moment is 0, the molecule is nonpolar, and if it's different from 0, it's polar. The polarity is given by the dipole moment, which is the vector sum of the dipoles of the bonds. The dipole is the difference of electronegativity between the elements of the bond.

The nonpolar molecules have a London force, which is the weakest force. The polar molecules have dipole-dipole forces, and, if the dipole is formed by hydrogen and a high electronegative element (N, O, or F), the dipole-dipole is extremely strong and it's called a hydrogen bond.

1. The water is a polar molecule because it has angular geometry, so, the dipole of the O-H bond is not canceled. Because it has the bond between H and O, the force is hydrogen bond.

2. CaCl2 is an ionic compound formed by the ions Ca+2 and Cl-, so the force is ion-ion.

3. CH3CH(CH3)OH has a polarity at the O-H bond, so as the water it has hydrogen bond.

4. CH4 has a tetrahedral geometry, and the dipole of the C-H bonds are canceled, so it's a nonpolar molecule with the London force.

5. NH3 has a pyramid trigonal geometry, and so the dipole of N-H is not canceled, so it's polar and has the bond of H with N, so, it has hydrogen bond force.

The substances H2O, CaCl2, CH3CH(CH3)OH, CH4, NH3 predominantly have hydrogen bonding, ionic bonding, hydrogen bonding, London dispersion forces, and hydrogen bonding & dipole-dipole interaction as their intermolecular forces respectively.

The predominant intermolecular forces in these substances are as follows:

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Answer:

Volume of lithium atom is found to be 1.47 X 10⁻²⁹ m³

Explanation:

Let us consider the volume of atom as a sphere (but it is little complex than that). This volume is mathematically expressed as,

[tex]V=\frac{4}{3}\pi R^{3}[/tex]----------------------------------------------------------------------------------------(Eq. 1)

Here, R is the radius of lithium atom. The radius is given in picometers, so firstly let us convert it into meters

[tex]R=(152pm )(1X10^{-12}\frac{m}{pm})[/tex]

[tex]R = 1.52 X 10^{-10}m[/tex]

placing this value in Eq.1 the required result is achieved

[tex]V=\frac{4}{3}\pi  {1.52X10^{-10}}^{3}[/tex]

V= 1.47 X 10⁻²⁹ m³

The volume of the lithium atom is [tex]1.47 \times 10^{-29} \ m^3[/tex].

The given parameters:

The volume of the lithium atom is calculated from the volume of a sphere as follows;

[tex]V = \frac{4}{3} \pi r^3[/tex]

where;

[tex]\\\\V = \frac{4}{3} \times \pi \times (152 \times 10^{-12})^3\\\\V = 1.47 \times 10^{-29} \ m^3[/tex]

Thus, the volume of the lithium atom is [tex]1.47 \times 10^{-29} \ m^3[/tex]

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Answer: A & C

Explanation:

Hexokinase is also one of the enzymes.

(A) Fructose 6-phosphate -> fructose 1,6-bisphosphate; phosphofructokinase-2

(C) Phosphoenolpyruvate -> pyruvate; pyruvate kinase

In gluconeogenesis, bypass reactions circumvent irreversible steps in glycolysis. The correct matching of the glycolytic reaction and the gluconeogenic enzyme is glucose to glucose 6-phosphate via glucose 6-phosphatase.

The process known as gluconeogenesis uses what are known as bypass reactions to circumvent three different steps in the glycolytic reaction process that are essentially irreversible. These bypass reactions occur via the use of different enzymes.

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Answer: 0.14g

Explanation:

Mass conc. = n x molar Mass

Mass conc. = 0.070 x 2 = 0.14g

Answer:

The mass of hydrogen gas that participates is 0.14 grams

Explanation:

Step 1: Data given

Moles of H2 = 0.070 moles

Molar mass H2 = 2.02 g/mol

Step 2: Calculate the mass of hydrogen gas

Mass of H2 = moles H2 * molar mass H2

Mass of H2 = 0.070 moles * 2.02 g/mol

Mass of H2 = 0.14 grams

The mass of hydrogen gas that participates is 0.14 grams

Answer:

The longest wavelength observed in the Balmer series of the H atom spectrum is 656.3 nm.

The shortest wavelength observed in the Balmer series of the H atom spectrum is 364.6 nm.

Explanation:

Using Rydberg's Equation:

[tex]\frac{1}{\lambda}=R_H\left(\frac{1}{n_i^2}-\frac{1}{n_f^2} \right )[/tex]

Where,

[tex]\lambda[/tex] = Wavelength of radiation

[tex]R_H[/tex] = Rydberg's Constant

[tex]n_f[/tex] = Higher energy level

[tex]n_i[/tex]= Lower energy level

[tex]\frac{1}{\lambda}=R_H\left(\frac{1}{n_i^2}-\frac{1}{n_f^2} \right )[/tex]

For wavelength to be longest, energy would be minimum, i.e the electron  will jump from third level to second level  :

[tex]n_f[/tex] = Higher energy level = [tex]3[/tex]  

[tex]n_i[/tex]= Lower energy level = 2 (Balmer series)

Putting the values, in above equation, we get

[tex]\frac{1}{\lambda_{Balmer}}=R_H\left(\frac{1}{2^2}-\frac{1}{3^2} \right )[/tex]

[tex]\lambda_{Balmer}=\frac{36}{5R_H}[/tex]

[tex]\lambda_{Balmer}=\frac{36}{5\times 1.097\times 10^7 m^-1}}=6.563\times 10^{-7} m=656.3 nm[/tex]

[tex]1 m =10^9 nm[/tex]

The longest wavelength observed in the Balmer series of the H atom spectrum is 656.3 nm.

For wavelength to be shortest, energy would be maximum, i.e the electron  will from infinite level to second level. :

[tex]n_f[/tex] = Higher energy level = [tex]\infty[/tex]  

[tex]n_i[/tex]= Lower energy level = 2 (Balmer series)

Putting the values, in above equation, we get

[tex]\frac{1}{\lambda_{Balmer}}=R_H\left(\frac{1}{2^2}-\frac{1}{\infty^2} \right )[/tex]

[tex]\lambda_{Balmer}=\frac{4}{R_H}[/tex]

[tex]=\frac{4}{1.097\times 10^7 m^-1}=3.646\times 10^{-7} m=364.6 nm[/tex]

The shortest wavelength observed in the Balmer series of the H atom spectrum is 364.6 nm.

Answer:

The correct answer is option c. transfer of electrons from Mg to O.

Explanation:

Hello!

Let's solve this!

When Magnesium (Mg) reacts with oxygen (O), magnesium oxide is formed.

This reaction is spontaneous and occurs with oxidation number +2 of magnesium and oxidation number -2 of oxygen. It is an ionic union, so magnesium transfers its electrons to oxygen.

We conclude that the correct answer is option c. transfer of electrons from Mg to O.

Answer:The atomic mass of E is 51

Explanation:Please see attachment for explanation

The highest percent yield of N2 can be calculated by comparing the moles of N2 formed in the side reaction to the moles of N2 formed in the main reaction. In this case, the highest percent yield of N2 is 200%.

The highest percent yield of N2 that can be expected can be calculated by comparing the moles of N2 formed in the side reaction to the moles of N2 formed in the main reaction. Let's calculate:

In the side reaction, 2 moles of N2O4 produce 6 moles of NO. In this experiment, 112.4 g of N2O4 was used. So, the moles of N2O4 used is:

moles of N2O4 = mass of N2O4 / molar mass of N2O4

moles of N2O4 = 112.4 g / (92.01 g/mol) = 1.22 mol

According to the stoichiometry, 1 mole of N2 is produced for every 2 moles of N2O4 used. Therefore, the moles of N2 formed in the side reaction is:

moles of N2 = 1.22 mol / 2 = 0.61 mol

In the main reaction, 2 moles of N2H4 produce 3 moles of N2. Since the amount of N2H4 used is the same as the amount of N2O4 used (112.4 g), the moles of N2 formed in the main reaction is:

moles of N2 = 1.22 mol

Now we can calculate the highest percent yield of N2:

percent yield = (moles of N2 formed in the main reaction / moles of N2 formed in the side reaction) * 100

percent yield = (1.22 mol / 0.61 mol) * 100 = 200%

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Answer : The number of unpaired electrons in helium is, 0

Explanation :

As we are given that the element is helium. The symbol of helium element is, (He).

The atomic number of helium element is, 2 that means it has 2 number of electrons.

Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom are determined by the electronic configuration.

The electronic configuration of helium element is: [tex]1s^2[/tex]

There is no unpaired electrons in helium element.

Hence, the number of unpaired electrons in helium is, 0

The number of unpaired electrons in He is 0.

Helium (He) is an element with an atomic number of 2, which means it has 2 protons in its nucleus and, in its neutral state, 2 electrons in its electron configuration. The electron configuration of helium follows the principles of quantum mechanics, where electrons fill the lowest energy levels first according to the Pauli exclusion principle and Hund's rule.

The first energy level (n=1) can hold up to 2 electrons, and for helium, this energy level is filled with 2 electrons. These electrons occupy the 1s orbital, which is the only orbital available at this energy level. According to the Pauli exclusion principle, no two electrons can have the same set of quantum numbers, so one electron fills the 1s orbital with a spin of +1/2 (up), and the other fills it with a spin of -1/2 (down). This results in both electrons being paired with opposite spins, canceling each other out.

Since all electrons in helium are paired, there are no unpaired electrons. Therefore, the number of unpaired electrons in a helium atom is 0. This makes helium a noble gas, which is characterized by having a full valence shell and being chemically inert due to the lack of unpaired electrons available for chemical bonding.

Answer:

15.95

Explanation:

This question is a modification of the calculation of  the empirical formula of a compound given its percent composition and atomic weights of the elements in the compound.

Here we are given the formula and the percent composition, so we know that there are 4 atoms of E per 2 atoms of N so lets solve using the information given.

In 100 grams of the binary compound we have

30.46 g N

69.54 g E

The number of moles is the mass divided by atomic weight:

mol N = 30.46 g / A.W N = 30.46 g / 14.00 g/mol = 2.18 mol N

mol E = 65.54 g / A.W E

Thus,

4 mol E/ 2 mol N = ( 69.54 g/ A.W E ) / 2.18

2  A.E = 65.54 g / 2.18  ⇒ A.W E = 69.54 g / ( 2 x 2.18 ) = 15.94 g

So the A.W is 15.94 g/mol which is close  the atomic weight of O.