8.50g of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molecular molar mass of 176./gmol, is burned completely in excess oxygen, and the mass of the products carefully measured:

Product mass
Carbon dioxide 12.75g
Water 3.48g

Use this information to find the molecular formula of X.

Answer:

1.05 V

Explanation:

Now recall Nernst equation;

Ecell= E°cell - 0.0592/n log [Red]/[Ox]

Now we look at the values of E°cathode and E°anode

E°cathode= 0.34 V

E°anode = -0.74 V

E°cell= 0.34-(-0.74)

E°cell= 1.08 V

[Red] = 1.453 M

[Ox] = 0.00176 M

n= 6

Ecell= E°cell - 0.0592/n log [Red]/[Ox]

Ecell= 1.08 - 0.0592/6 × log[1.453]/[0.00176]

Ecell= 1.08 - 0.0592/6 × 2.917

Ecell= 1.08 - 0.02878

Ecell= 1.05 V

Answer:

These are the chemical names and molecular formula of the compounds formed from these elements:

Answer:

The correct answer will be " RbF > RbCl > RbBr > Rbl".

Explanation:

The size of the given ions will be:

RbCl:

⇒  689kJ/mol

RbBr:

⇒  660kJ/mol

Rbl:

⇒  630kJ/mol

RbF:

⇒  785kJ/mol

Now according to the size, the arrangement will be:

⇒  (785kJ/mol) > (689kJ/mol) > (660kJ/mol) >(630kJ/mol)

⇒  RbF > RbCl > RbBr > Rbl

The bond among all opposite charging ions seems to be strongest whenever the ions were indeed small.

Answer:

Explanation:

The rate of reaction will not depend upon concentration of reactant . It will be always constant and equal to .0089M s⁻¹.

Initial moles of reactant = 400 x 10⁻³ mole in 5 L

molarity = 400 x 10⁻³ /5 M

= 80 x 10⁻³ M .

= .08M

no of moles reacted in 2 s  = .0089 x 2

= .0178 M

concentration left = .08 - .0178 M

= .0622 M .

No of moles left in 5 L

= 5 x .0622 = .31 moles .

Answer:

The wavelength of the monochromatic light is 486.2 nm.

Explanation:

The illumination of the hydrogen atom by the monochromatic light causes an absorption of energy by its electrons which causes an excitation. After a period, the particle de-excites (decays) losing the absorbed energy and falls back to its initial state releasing the energy in the form of a photon. This photon can be observed as a colored light of the Balmer series.

From Rydberg's expression,

     1/λ=−R([tex]\frac{1}{n_{2} ^{2} }[/tex] − [tex]\frac{1}{n_{1} ^{2} }[/tex])

The transition of the electron is from n = 2 to 4, so that;

1/λ = R ([tex]\frac{1}{2^{2} }[/tex] - [tex]\frac{1}{4^{2} }[/tex])

    = 1.097 x [tex]10^{7}[/tex] ([tex]\frac{1}{2^{2} }[/tex] - [tex]\frac{1}{4^{2} }[/tex])

1/λ  = 2056875

So that,

λ = [tex]\frac{1}{2056875}[/tex]

  = 4.8617 x [tex]10^{-7}[/tex] m

The wavelength of the monochromatic light is 486.2 nm.

Answer:

See explanation below

Explanation:

In this case, let's see both molecules per separate:

In the case of SeO₂ the central atom would be the Se. The Se has oxidation states of 2+, and 4+. In this molecule it's working with the 4+, while oxygen is working with the 2- state. Now, how do we know that Se is working with that state?, simply, let's do an equation for it. We know that this molecule has a formal charge of 0, so:

Se = x

O = -2

x + (-2)*2 = 0

x - 4 = 0

x = +4.

Therefore, Selenium is working with +4 state, the only way to bond this molecule is with a covalent bond, and in the case of the oxygen will be with double bond. See picture below.

In the case of CO₂ happens something similar. Carbon is working with +4 state, so in order to stabilize the charges, it has to be bonded with double bonds with both oxygens. The picture below shows.

Answer:

1. 2.3

2. 4.5

3. 10.5

4. 5.6

5. 3.5

6. 3.9

7. 1.6

Explanation:

pH = - log [H+]

1. Lemon juice

[H+] = 0.005

pH = - log [H+]

pH = - log 0.005

pH = 2.3

2. Beer

[H+] = 3.16x10^-5

pH = - log [H+]

pH = - log 3.16x10^-5

pH = 4.5

3. Milk of Magnesia

[H+] = 3.16x10^-11

pH = - log [H+]

pH = - log 3.16x10^-11

pH = 10.5

4. Rain water

[H+] = 2.51x10^-6

pH = - log [H+]

pH = - log 2.51x10^-6

pH = 5.6

5. Soda

[H+] = 3.16x10^-4

pH = - log [H+]

pH = - log 3.16x10^-4

pH = 3.5

6. Tomatoes

[H+] = 1.23x10^-4M

pH = - log [H+]

pH = - log 1.23x10^-4

pH = 3.9

7. Bleach

[OH-] = 2.3x10^-2M

pOH = - log [OH-]

pOH = - log 2.3x10^-2

pOH = 1.6

Answer:

answer = -0.95

Explanation:

Answer:

The wavelength is [tex]\lambda =97.3 nm[/tex]

Explanation:

Generally the series whose emission  line show on the visible spectrum is the

Balmar series so this two emission line seen on the visible spectrum  could either be due to the move of electron from

[tex]n=3 \to \ n=2[/tex]

OR

[tex]n=4 \to n=2[/tex]

This implies that the first excitement is from [tex]n_i=1 \to \ n_f=4[/tex]

So the energy change due to the excitement is mathematically represented as

     [tex]\Delta E = R_H [\frac{1}{n_i^2} -\frac{1}{n_f^2} ][/tex]

substituting values

       [tex]\Delta E= R_H [\frac{1}{1^2} -\frac{1}{4^2} ][/tex]

       [tex]\Delta E= \frac{15}{16} R_H[/tex]

This energy change can also be represented as

       [tex]\Delta E = \frac{hc}{\lambda}[/tex]      

So   [tex]\frac{15}{16} R_H = \frac{hc}{\lambda}[/tex]

=>    [tex]\lambda = \frac{16hc}{15 R_H}[/tex]

Where  [tex]R_H[/tex] is the Rydberg constant with a value of  [tex]R_H = 2.18 * 10^{-18} J.[/tex]

              h is the Planck's constant with values   [tex]h = 6.626 * 10^{-34} m^2 kg / s[/tex]

                c is the speed of light with value  [tex]c = 3.0*10^{8} \ m/s[/tex]

So

       [tex]\lambda = \frac{16(6.626 *10^{-34})(3*10^{8})}{15 * (2.18*10^{-18})}[/tex]

        [tex]\lambda = 9.73 *10^{-8} \ m[/tex]

       [tex]\lambda =97.3 nm[/tex]

Answer:

The correct answer is 0.15 × 10⁻³ M.

Explanation:

C₆H₈O₇ is the molecular formula of citric acid. The mass of the one mole of the substance that comprise Avogadro's no of molecules is termed as the molar mass of the substance.  

The molar mass of the citric acid (C₆H₈O₇) will be,  

6 × atomic mass of carbon + 8 × atomic mass of hydrogen + 7 × atomic mass of oxygen = 6×12 + 8×1 + 7×16 = 192. Thus, the molar mass of citric acid is 192 g/mol.  

The value of the solution given in the question is 8 L.  

The mass of citric acid given is 0.24 g or 240 mg, which can also be written as 240/1000 g or 240 × 10⁻³ g.  

The number of moles can be calculated by using the formula = mass / molar mass. Thus, by putting the values we get,  

= 240 × 10⁻³ g / 192 g/mol

= 1.25 × 10⁻³ mol

The number of moles of the solute present in the 1 liter of the solution is termed as the molarity of the solution. The formula of molarity or M is,  

= no of moles of solute / volume of solution in L

Now putting the values we get,  

= 1.25 × 10⁻³ mol / 8 L

= 0.156 × 10⁻³ M

Hence, the molarity of citric acid in the given solution is 0.15 × 10⁻³ M

Answer:

[tex]3.06mol~C_6H_14[/tex]

Explanation:

We have to start with the reaction:

[tex]2C_6H_1_4 + 19O_2->12CO_2 + 14H_2O[/tex]

We have 2 carbons, 6 hydrogens and 38 oxygens on both sides.

Now the molar ratio between [tex]C_6H_14[/tex] and [tex]CO_2[/tex] is 2:12 or [tex]2~mol~C_6H_14=~12~mol~CO_2[/tex]. With this  in mind we can calculate the moles of [tex]C_6H_14[/tex], so:

[tex]18.4~mol~CO_2\frac{2~mol~C_6H_14}{12~mol~CO_2}=3.06mol~C_6H_14[/tex]

I hope it helps!

Answer:

B)    3.07 mol

Explanation:

Answer:

II. The orbitals have different shapes.  

IV. The orbitals have different energies.  

Explanation:

1. Shapes

Below are pictures of a 3s and a 3p orbital.

The 3s orbital has a spherical shape, and the 3p orbital has a dumbbell shape.

2. Energies

For every element except H, the order of energies is

3s < 3p

For a hydrogen atom,

3s = 3p

Answer:

K=CHANGE IN CONCENTRATION/TIME TAKEN

Explanation:

Answer:

Lactate dehydrogenase (LDH)

Explanation:

LDH is tetrameric enzyme found in the muscles (M-type) and the heart (H-type) of living cells, responsible for the conversion of pyruvate to lactate and back, to promote generation of nicotinamide adenine dinucleotide (NAD).

Answer:

See explanation below

Explanation:

In this case, we can explain this in a very basic way.

We know that heavier objects will go always at the bottom when we are carrying two objects, one heavier than the other right?

In the same manner works the density of two liquids. In this case, we have a mix of water and bromoethane. Bromoethane is an organic compound and it's less polar than water which is extremely polar. When we mix these two liquids, we can see that both of them are insoluble, so no matter how much we shake the funnel, the liquids will not mix to form a solution.

Instead of that, both of them will be in the funnel, and they'll be gradually separating into two layers. The bromoethane has a higher density than water, this means that in the bottom layer we will have the bromoethane and in the top layer we will have the water.

In case you are wondering what happens if we added water first and then, the bromoethane?, it will happen the same, it does not matter the order you add the liquid, because density here is a very important factor, so when the water is added no matter which position, it will go to the top layer after the bromoethane is added.

Now when the hexane is added, it will form now three layers, and again, density plays an important factor. The higher density will go to the bottom, and the lowest to the top.

In this case, the order of layer will be:

Top layer: hexane (d = 0.66 g/mL)

Middle layer: water (d = 1 g/mL)

Bottom layer: bromoethane (d = 1.46 g/mL)

Hope this helps

Answer:

58.702

Explanation:

Data obtained from the question include:

Mass number of isotope 1 (M1) = 57.93

Abundance of isotope 1 (M1%) = 67.76%

Mass number of isotope 2 (M2) = 59.93

Abundance of isotope 2 (M2%) = 26.16%

Mass number of isotope 3 (M3) = 60.93

Abundance of isotope 3 (M3%) = 1.25%

Mass number of isotope 4 (M4) = 61.93

Abundance of isotope 4 (M4%) = 3.66%

Mass number of isotope 5 (M5) = 63.93

Abundance of isotope 5 (M5%) = 1.16%

Relative atomic mass =...?

The relative atomic mass(RAM) of the element can be obtained by doing the following:

RAM = [(M1×M1%) /100] +[(M2×M2%) /100] + [(M3×M3%) /100] + [(M4×M4%) /100] + [(M5×M5%) /100]

RAM = [(57.93×67.76)/100] + [(59.93×26.16)/100] + [(60.93×1.25) /100] + [(61.93×3.66)/100] + [(63.93×1.16)/100]

RAM = 39.253 + 15.678 + 0.762 + 2.267 + 0.742

RAM = 58.702

Therefore, the relative atomic mass (RAM) of the element is 58.702

Answer:

A. CH2.

B. CH.

Explanation:

A. Determination of the empirical formula of polyethylene.

Data obtained from the question include:

Carbon (C) = 86%

Hydrogen (H) = 14%

The empirical formula of the polyethylene can be obtained as follow:

C = 86%

H = 14%

Divide by their molar mass

C = 86/12 = 7.17

H = 14/1 = 14

Divide by the smallest

C = 7.17/7.17 = 1

H = 14/7.17 = 2

Therefore, the empirical formula of the polyethylene is CH2.

B. Determination of the empirical formula of polystyrene

Data obtained from the question include:

Carbon (C) = 92.3%

Hydrogen (H) = 7.7%

The empirical formula of the polystyrene can be obtained as follow:

C = 92.3%

H = 7.7%

Divide by their molar mass

C = 92.3/12 = 7.69

H = 7.7/1 = 7.7

Divide by the smallest

C = 7.69/7.69 = 1

H = 7.7/7.69 =

Therefore, the empirical formula of the polystyrene is CH.

Answer:  The correct answer is:  " endothermic . "

______________________________________

Note:  Heat flows into  [heat may be absorbed within] an "endothermic" reaction or system

          To the contrary, heat flows out  [heat   may exit from or may be released from] an "exothermic" reaction or process.

Hint:  Think of the "prefixes" of:  "endothermic"  and "exothermic" :

_____________________________________

  1)  endo- = "within" (as in "endothermic" —heat tends to be absorbed/"within"/"released within"/released within"/into" ;

  2) exo-   = " outwards"/"exit" (as in "exothermic") —heat tends to '"exit"/leave/escape from/"be released out of/form".

_____________________________________

Hope this is helpful to you!

Best wishes to you in your academic pursuits

     —and within the "Brainly" community"!

_____________________________________

Answer:

K = 1.79x10⁻³³

Explanation:

Using Hess's law, it is possible to fin K of a reaction by the algebraic sum of another related reactions.

In the reactions:

1. N2(g)+O2(g) ⇌ 2NO(g), K1 = 4.10×10−31 2.

2. N2(g)+2H2(g) ⇌ N2H4(g), K2 = 7.40×10−26

3. 2H2O(g)⇌2H2(g)+O2(g), K3 = 1.06×10−10

The sum of 1/2 (1) + 1/2 (2) produce:

N2(g) + 1/2O2(g) + H2(g) ⇌ 1/2N2H4(g) + NO(g)

And K' = √4.1x10⁻³¹×√7.4x10⁻²⁶ = 1.74x10⁻²⁸

Now, this reaction + 1/2 (3):

N2(g) + H2O(g) ⇌ NO(g) + 1/2N2H4(g)

And K of reaction is:

1.74x10⁻²⁸×√1.06x10⁻¹⁰ = 1.79x10⁻³³

Answer:

Gravitational Energy: The energy of an object due to its movement

Mechanical Energy: The potential energy of position

Nuclear Energy: internal energy caused by vibrations of atoms and molecules

Thermal Energy: Energy stored in the nucleus of an atom

Answer:

radiant

nuclear

thermal

potential

Explanation:

Answer:

The level is  [tex]n_1 = 5[/tex]

Explanation:

From the question we are told that

  The level of the hydrogen atom is   [tex]n_2 = 8[/tex]

  The wavelength of the photon is  [tex]\lambda = 3745 nm = 3745 *10^{-9} \ m[/tex]

Generally the wave number is mathematically represented as

        [tex]k = \frac{1}{\lambda }[/tex]

Now this wave number can also be mathematically represented as

       [tex]k = R_{\infty} [\frac{1}{n_1^2} + \frac{1}{n_2^2} ][/tex]  

This implies that

 So  

   Here [tex]R_{\infty}[/tex] is the Rydberg constant, with a value  [tex]1.097 * 10^7[/tex]

and  [tex]n_1 \ and \ n_2[/tex]  are the principal quantum levels

 substituting values

               [tex]0.0243= [\frac{1}{n_1^2} - \frac{1}{8^2} ][/tex]  

               [tex]0.0243= \frac{1}{n_1^2} - 0.015625[/tex]  

              [tex]0.0243 + 0.015625= \frac{1}{n_1^2}[/tex]

              [tex]n_1 = 5[/tex]  

Answer:

THE STANDARD ENTHALPY OF FORMATION OF AMMONIA GAS IS 293.75kJ OF HEAT.

Explanation:

To solve this question, you must first write out the equation for the reaction.

Equation:

N2 (g) + 3H2(g) <-------> 2NH3(g)

So therefore, when 50 g of N2 reacts, 164.5 kJ of Heat was liberated.

First equate the number of moles of Nitrogen and ammonia gas

1 mole of N2 produces 2 moles of ammonia

Calculate the molar mass of each variables:

Molar mass of N2 = 14*2 = 28 g/mol

Molar mass of ammonia = ( 14 + 1*3) = 17 g/mol

So, 1 mole of N2 = 2 moles of NH3

28 g/mol of N2 = 17 * 2 g/mol of NH3

If 50 g of nitrogen was used to react with excess hydrogen, the mass of ammonia formed is;

28 g of N2 = 34 g/mol of NH3

50 g of N2 = ( 50 * 34 / 28 ) g of NH3

= 1700 / 28

= 60 .71 g of ammonia.

At standard conditions, 34 g of ammonia will liberate 164.5 kJ of heat. What amonut would be generated by 60.71 g of ammonia?

34 g of ammonia = 164.5 kJ of heat

60.71 g of ammonia = ( 60.71 * 164.5  / 34) kJ of heat

= 9987.5 / 34

= 293.75 kJ of heat.

In other words, the standard enthalpy of formulation for ammonia gas is 293.75 kJ of heat.

Answer:

A constant volume calorimeter (bomb calorimeter) was calibrated by performing in it a reaction in which 5.23 kJ of heat energy was released, causing the calorimeter to rise by 7.33 °C. What is the heat capacity Cy of the calorimeter

Explanation:

the heat capacity of the calorimeter is

[tex]C_v = \frac{q}{\Delta T} \\\\=\frac{5.23}{7.33} \\\\=0.714kJ /^\circ C[/tex]

Now that our  heat capacity of the calorimeter is 0.714kJ/°C

we can easily calculate  the change in internal energy ΔU of the neutralization reaction

[tex]\Delta U = C_v \ dt[/tex]

or

[tex]\Delta U = C_V \Delta T[/tex]

Δ T = 2.46 °C

[tex]C_v = 0.714 kJ/ ^\circ C[/tex]

[tex]\Delta U = 0.714*2.46\\\\=1.7564kJ[/tex]

Answer:

Option A. is correct

Explanation:

A reaction is at equilibrium when the amounts of the reactants and products are no longer changing.

Chemical equilibrium means that the rate of formation of products is equal to the rate at which the products re-form reactants.

Products are formed by the forward reaction and by the reverse reaction, the products re-form reactants.

Answer:

(3R,4R)-4-bromohexan-3-ol

Explanation:

In this case, we have  reaction called halohydrin formation. This is a markovnikov reaction with anti configuration. Therefore the halogen in this case "Br" and the "OH" must have different configurations. Additionally, in this molecule both carbons have the same substitution, so the "OH" can go in any carbon.

Finally, in the product we will have chiral carbons, so we have to find the absolute configuration for each carbon. On carbon 3 we will have an "R" configuration on carbon 4 we will have also an "R" configuration. (See figure 1)

I hope it helps!

Answer:

AT THE END OF 80% DISSOLUTION, THE PRESSURE OF NO2 HAS CHANGED FROM 99kPa TO 139.97kPa

Explanation:

P1 = 99 kPa

P2 = unknown

From the reaction,

2 mole of NO2 will produce 2 mole of NO

We can also say that 1 mole of NO2 will produce 1 mole of NO

At 56.6 % of NO2, 0.566 mole of NO2 will be consumed

At STP, 1 mole of  a substance will occupy 22.4 dm3 volume

0.566 mole will occupy ( 22.4 * 0.566 / 1) dm3 volume

= 39.58 dm3 volume

V1 = 39.56 dm3

At the new percent of 80%, 0.80 mole of NO2 will be consumed

Since, 1 mole = 22.4 dm3

0.80 mole = (22.4 / 0.80) dm3

= 28 dm3

V2 = 28 dm3

Using the equation of Boyle's law which shows the relationship between pressure and volume of a given mass of gas at constant temperature, we have:

P1 V1 = P2 V2

Re-arranging to make P2 the subject of formula:

P2 = P1V1 / V2

P2 = 99 kPa * 39.56 / 28

P2 = 3916.44 kPa / 28

P2 = 139.87 kPa

So at 80 % dissociation of NO2, the pressure has changed from 99 kPa to 139.97 kPa.

Answer:

56°

Explanation:

First calculate [tex]a:[/tex]

[tex]a=2 R \sqrt{2}=2(0.1246) \sqrt{2}=0.352 \mathrm{nm}[/tex]

The interplanar spacing can be calculated from:

[tex]d_{111}=\frac{a}{\sqrt{1^{2}+1^{2}+1^{2}}}=\frac{0.352}{\sqrt{3}}=0.203 \mathrm{nm}[/tex]

The diffraction angle is determined from:

[tex]\sin \theta=\frac{n \lambda}{2 d_{111}}=\frac{1(0.1927)}{2(0.2035)}=0.476[/tex]

Solve for [tex]\theta[/tex]

[tex]\theta=\sin ^{-1}(0.476)=28^{\circ}[/tex]

The diffraction angle is:

[tex]2 \theta=2\left(28^{\circ}\right)=56^{\circ}[/tex]

Answer:

340.000 ppm

Explanation:

Parts per million (ppm) is a unit of measure for concentration that measures the number of units of substance per million units of the set. It is a concept homologous to the percentage, only in this case it is not parts per percent but per million. The ppm calculation method is different for solids, liquids and gase. There are many formulas, however in this case, you can use this fact:

[tex]10000ppm=1\%[/tex]

Using Cross-multiplication:

[tex]\frac{10000ppm}{x} =\frac{1\%}{34\%}[/tex]

Solving for [tex]x[/tex] :

[tex]x=34*10000=340000ppm[/tex]

Therefore, the concentration of a 34% solution converted to parts per million is:

[tex]340000ppm[/tex]

Answer: Use the titration formula

Explanation:

Answer:

Sodium Chloride, Potassium Chloride

Explanation:

Sodium Chloride, Potassium Chloride, are the most common example of a strong electrolyte. Most salts are strong electrolytes, such as hydrochloric acid, nitric acid, perchloric acid and sulphuric acid. Strong bases, such as sodium hydroxide and calcium hydroxide, are also potent electrolytes.

hope this helped!