Answer:
D. 2:5
Explanation:
It has 5 valency electrons
[tex].[/tex]
In the given question, the electronic configuration of nitrogen is 2,5. The correct answer is option D.
The electronic configuration of an atom describes the arrangement of its electrons in different energy levels or orbitals.
Nitrogen has an atomic number of 7, which means it has 7 electrons.
The first energy level or shell can hold up to 2 electrons, and the second can hold up to 8 electrons. Nitrogen has 2 electrons in its first energy level and 5 electrons in its second energy level.Therefore, the electronic configuration of nitrogen is 2,5, which means it has 2 electrons in its first energy level and 5 electrons in its second energy level. Option D is the correct answer.
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us
Which of the following is a chemical property?
A. Hardness
B. Flammability
C. Malleability
D. Melting point
Reset Selection
the carbon tetrachloride molecule CCI 4 is
Answer:
is a nonpolar molecule with polar bonds
When 4.41g of phosphoric acid (H3PO4) react with 9.25g of barium hydroxide, water and insoluble barium phosphate form. [T/I-7] a. Write and balance the chemical equation.
Answer:
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)
Explanation:
Let's consider the unbalanced equation that occurs when phosphoric acid reacts with barium hydroxide to form water and barium phosphate. This is a neutralization reaction.
H₃PO₄(aq) + Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)
We will balance it using the trial and error method.
First, we will balance Ba atoms by multiplying Ba(OH)₂ by 3 and P atoms by multiplying H₃PO₄ by 2.
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)
Finally, we will get the balanced equation by multiplying H₂O by 6.
2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)
Write the symbol for every chemical element that has atomic number greater than 70 and atomic mass less than 185.2
Answer:
HF...Ta... W....Lu...
0.50 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric acid solution
Explanation:
Given the mass of HCl is ---- 0.50 g
The volume of solution is --- 4.0 L
To determine the pH of the resulting solution, follow the below-shown procedure:
1. Calculate the number of moles of HCl given by using the formula:
[tex]number of moles of a substance=\frac{given mass of the substance}{its molecular mass}[/tex]
2. Calculate the molarity of HCl.
3. Calculate pH of the solution using the formula:
[tex]pH=-log[H^+][/tex]
Since HCl is a strong acid, it undergoes complete ionization when dissolved in water.
[tex]HCl(aq)->H^+(aq)+Cl^-(aq)[/tex]
Thus, [tex][HCl]=[H^+][/tex]
Calculation:
1. Number of moles of HCl given:
[tex]number of moles of a substance=\frac{given mass of the substance}{its molecular mass}\\=0.50g/36.5g/mol\\=0.0137mol[/tex]
2. Concentration of HCl:
[tex]Molarity of HCl=\frac{number of moles of HCl}{its molar mass}\\=\frac{0.0137 mol}{4.0 L} \\= 0.003425 M[/tex]
3. pH of the solution:
[tex]pH=-log[H^+]\\=-log(0.003425)\\=2.47[/tex]
Hence, pH of the given solution is 2.47.
In the process of preparing liquid air for fractional distillation, one fraction will be separated as a solid. What is the chemical name of this fraction?
Answer:
carbon dioxide CO₂
Explanation:
Each gas has a characteristic boiling point. You can separate a random sample of gases by gradually cooling the sample until each component gas liquifies. Some compounds, such as CO₂ never liquify. Instead, they turn directly into solids.
The fraction that will be separated as a solid in the process of liquefaction of air is carbon dioxide.
What is sublimation?
Sublimation is the process of changing the material from its solid to gaseous form without it being liquid, according to physics. An illustration is the evaporation of dry ice, which is frozen carbon dioxide, at typical atmospheric pressure and temperature. Vapour pressure and temperature correlations cause the phenomena.
Food is freeze-dried to preserve it by sublimating water from it while it is frozen under a strong vacuum. Phase is a term used in thermodynamics to describe an amount of matter that is chemically and physically uniform or homogeneous, can be mechanically isolated from a nonhomogeneous mixture, and may consist of a single material or a combination of substances.
The three basic phases of matter are solid, liquid, and gas (vapor), however additional phases, including crystalline, colloid, glassy, amorphous, and plasma, are thought to exist.
Therefore, during the liquefaction of air, the gas that will be separated as a solid is carbon dioxide.
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Identify the oxidation half-reaction for this reaction:
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
A. Fe2+ + 2e → Fe(s)
O B. H2(g) → 2H+ + 2e
O C. Fe(s) → Fe2+ + 2e
O D. 2H+ + 2e → H2(9)
Answer:
Fe(s)->Fe2+2e-
Explanation:
A.p.e.x
The oxidation half-reaction for the given reaction is Fe(s) → Fe²⁺ + 2e⁻ Hence, Option (C) is correct
What is Oxidation reaction ?Oxidation reaction is a chemical reaction which can be described as follows ;
Addition of oxygen Removal of hydrogen Loss of ElectronAddition of electronegative atomRemoval of Electropositive elementIn the given reaction ;
Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)
Fe at RHS got converted to Fe²⁺ state at LHS which shows the gain of electron by Fe with in the reaction.
Therefore,
The oxidation half-reaction for the given reaction is Fe(s) → Fe²⁺ + 2e⁻ Hence, Option (C) is correct
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Does water mess up carbon dating?
Answer:
THE hard-water effect is a recognized source of error in radiocarbon dating. It causes ages to be over-assessed and arises when the material to be dated, such as mollusc shell or plant, synthesizes its skeleton under water and so uses bicarbonate derived in part from old, inert sources.
https://www.nature.com/articles/240460a0#:~:text=THE%20hard%2Dwater%20effect%20is,part%20from%20old%2C%20inert%20sources.
Answer:
In radiocarbon dating, the hard-water effect has been identified as a cause of inaccuracy. It occurs when the item to be dated, such as a mollusk shell or a plant, synthesizes its skeleton underwater and therefore utilizes bicarbonate obtained in part from ancient, inert sources, resulting in the overestimation of ages.
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In a aqueous solution of 4-chlorobutanoic acid , what is the percentage of -chlorobutanoic acid that is dissociated
Answer:
Explanation:
Let assume that the missing aqueous solution of 4-chlorobutanoic acid = 0.76 M
Then, the dissociation of 4-chlorobutanoic acid can be expressed as:
[tex]\mathsf{C_3H_6ClCO_2H }[/tex] ⇄ [tex]\mathsf{C_3H_6ClCO_2^-}[/tex] + [tex]\mathsf{H^+}[/tex]
The ICE table can be computed as:
[tex]\mathsf{C_3H_6ClCO_2H }[/tex] ⇄ [tex]\mathsf{C_3H_6ClCO_2^-}[/tex] + [tex]\mathsf{H^+}[/tex]
Initial 0.76 - -
Change -x +x +x
Equilibrium 0.76 - x x x
[tex]K_a = \dfrac{[\mathsf{C_3H_6ClCO_2^-}] [\mathsf{H^+}]}{\mathsf{[C_3H_6ClCO_2H ]}}[/tex]
[tex]K_a = \dfrac{[x] [x]}{ [0.76-x]}[/tex]
where:
[tex]K_a = 3.02*10^{-5}[/tex]
[tex]3.02*10^{-5} = \dfrac{x^2}{ [0.76-x]}[/tex]
however, the value of x is so negligible:
0.76 -x = 0.76
Then:
[tex]3.02*10^{-5}*0.76 = x^2[/tex]
[tex]x=\sqrt{3.02*10^{-5}*0.76 }[/tex]
x = 0.00479 M
∴
[tex]x = \mathsf{[C_3H_6ClCO_2^-] = [H^+]=}[/tex] 0.00479 M
[tex]\mathsf{C_3H_6ClCO_2H }[/tex] = (0.76 - 0.00479) M
= 0.75521 M
Finally, the percentage of the acid dissociated is;
= ( 0.00479 / 0.76) × 100
= 0.630 M
5. A beam of photons with a minimum energy of 222 kJ/mol can eject electrons from a potassium surface. Estimate the range of wavelengths of light that can be used to cause this phenomenon. Show your calculations with units of measure (dimensional analysis) and briefly explain your reasoning.
Answer: The range of wavelengths of light that can be used to cause given phenomenon is [tex]8.953 \times 10^{21} m[/tex].
Explanation:
Given: 222 kJ/mol (1 kJ = 1000 J) = 222000 J
Formula used is as follows.
[tex]E = \frac{hc}{\lambda}[/tex]
where,
E = energy
h = Planck's constant = [tex]6.625 \times 10^{-25} Js[/tex]
c = speed of light = [tex]3 \times 10^{8} m/s[/tex]
Substitute the values into above formula as follows.
[tex]E = \frac{hc}{\lambda}\\222000 J = \frac{6.625 \times 10^{-34}Js \times 3 \times 10^{8} m/s}{\lambda}\\\lambda = 8.953 \times 10^{21} m[/tex]
Thus, we can conclude that the range of wavelengths of light that can be used to cause given phenomenon is [tex]8.953 \times 10^{21} m[/tex].
what will the time for half life of the first order reaction?
Answer:
The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t1/2 = 0.693/k. Radioactive decay reactions are first-order reactions.
Explanation:
The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t1/2 = 0.693/k. Radioactive decay reactions are first-order reactions.
Calculate percent yield when you start with 0.78 grams of camphor and end with 0.23 grams of iso/borneol. The molecular weight of camphor is 152.23 g/mol, and the molecular weight of iso/borneol is 154.25 g/mol.
Answer:
29.1%
Explanation:
First we convert 0.78 g of camphor to moles, using its molar mass:
0.78 g ÷ 152.23 g/mol = 0.00512 mol camphorThen we convert 0.23 g of isoborneol to moles, using its molar mass:
0.23 g ÷ 154.25 g/mol = 0.00149 mol isoborneolFinally we calculate the percent yield:
0.00149 mol / 0.00512 mol * 100% = 29.1%Liquid nitrogen boils at –195.8°C. Express the boiling point of liquid nitrogen in kelvin
Answer:
[tex]\boxed {\boxed {\sf 77.35 \ K}}[/tex]
Explanation:
The Celsius and Kelvin scales are used to measure the temperature of matter. Their scales and unit differences are the same (1 K increase = 1 °C increase), but they have different starting points.
So, the conversion is quite simple and only requires addition because of the different starting points. The formula is:
[tex]T_K = T_C+ 273.15[/tex]
The boiling point of liquid nitrogen is -195.8 °C. We can substitute this value into the formula.
[tex]T_K= -195.8 + 273.15[/tex]
[tex]T_K= 77.35 K[/tex]
The boiling point of liquid nitrogen is 77.35 Kelvin.
A molecule of acetone and a molecule of propyl aldehyde are both made from 3 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom. The molecules differ in their arrangement of atoms. How do formulas for the two compounds compare? Both compounds have the same molecular formula, but have unique structural formulas. Both compounds have unique molecular formulas and structural formulas. Both compounds have the same structural formula, but have unique molecular formulas.
Explanation:
The structures of both acetone and propanal are shown below:
In the formula of propanal there is -CHO functional group at the end.
In acetone -CO- group is present in the middle that is on the second carbon.
The molecular formula is C3H6O.
Both have same molecular formula but different structural formulas.
give reason why mendeleev's definition of transition elements is no longer acceptable
Alkanes are chains of carbon atoms surrounded by hydrogen atoms.
a. True
b. False
Answer:
a. True
Explanation:
Alkanes are chains of carbon atoms surrounded by hydrogen atoms. TRUE.
Alkanes are hydrocarbons, that is, they are organic compounds formed only by carbon and hydrogen. In alkanes, carbon atoms are bonded to each other through single covalent bonds and they are also bonded to hydrogen atoms through the same type of bonds. Alkanes have the general formula CnH2n+2.
Hydrogen is manufactured on an industrial scale by this sequence of reactions: Write an equation that gives the overall equilibrium constant in terms of the equilibrium constants and . If you need to include any physical constants, be sure you use their standard symbols, which you'll find in the ALEKS Calculator.
The question is incomplete. The complete question is :
Hydrogen is manufactured on an industrial scale by this sequence of reactions:
[tex]$CH_3(g) + H_2O(g) \rightleftharpoons CO(g) + 3H_2(g ) \ \ \ \ \ \ \ \ \ \ K_1$[/tex]
[tex]$CO(g) + H_2O(g) \rightleftharpoons CO_2(g) + H_2(g) \ \ \ \ \ \ \ \ \ \ \ \ K_2$[/tex]
The net reaction is :
[tex]$CH_4(g) + 2H_2O(g) \rightleftharpoons CO_2(g) + 4H_2(g) \ \ \ \ \ \ \ \ \ K$[/tex]
Write an equation that gives the overall equilibrium constant [tex]K[/tex] in terms of the equilibrium constants [tex]K_1[/tex] and [tex]K_2[/tex]. If you need to include any physical constants, be sure you use their standard symbols, which you'll find in the ALEKS Calculator.
Solution :
[tex]$CH_3(g) + H_2O(g) \rightleftharpoons CO(g) + 3H_2(g ) \ \ \ \ \ \ \ \ \ \ K_1$[/tex]
[tex]$K_1 = \frac{[CO][H_2]^3}{[CH_4][H_2O]}$[/tex] ...............(1)
[tex]$CO(g) + H_2O(g) \rightleftharpoons CO_2(g) + H_2(g) \ \ \ \ \ \ \ \ \ \ \ \ K_2$[/tex]
[tex]$K_2 = \frac{[CO_2][H_2]}{[CO][H_2O]}$[/tex] ...................(2)
[tex]$CH_4(g) + 2H_2O(g) \rightleftharpoons CO_2(g) + 4H_2(g) \ \ \ \ \ \ \ \ \ K$[/tex]
[tex]$K=\frac{[CO_2][H_2]^4}{[CH_4][H_2O]^2}$[/tex]
On multiplication of equation (1) and (2), we get
[tex]$K_1 \times K_2=\frac{[CO][H_2]^3}{[CH_4][H_2O]} \times \frac{[CO_2][H_2]}{[CO][H_2O]}$[/tex]
[tex]$K_1K_2=\frac{[CO_2][H_2]^4}{[CH_4][H_2O]^2}$[/tex] .................(4)
Comparing equation (3) and equation (4), we get
[tex]$K=K_1K_2$[/tex]
Which of state of matter has no definite shape but does have a definite volume?
A. Liquid
O B. Element
C. Solid
D. Gas
Answer:
A. Liquid .
Explanation:
Hello there!
In this case, according to the given information, it turns possible for us to to infer that the answer is A. Liquid because solids have both definite shape and volume and gases have no definite neither volume nor shape because they depend on the container.
This is this way because the molecules in the liquid are able to vibrate and slowly move around unlike gases and solids whereas molecules readily move and merely vibrate respectively.
Regards!
Calculate the percent dissociation of crotonic acid (C,H,CO,H) in a 0.63 mM aqueous solution of the stuff.
Answer:
16%
Explanation:
Crotonic acid : C₃H₅CO₂H
C₃H₅CO₂H ⇄ C₃H₅CO₂⁻ + H⁺
C O O
where : C = C ( 1 - ∝ ) , O = C∝
also: Ka = C∝² / ( 1 - ∝ ) ---- ( 1 )
From Alexa data resource :
Pka = 4.69 , [ Ka = 2.04 * 10^-5 = C∝² / ( 1 - ∝ ) ]
back to equation 1
2.04 * 10^-5 = [ ( 0.63 * 10^-3 ) * ∝² / ( 1 - ∝ ) ] ----- ( 2 )
∴ ∝² / ( 1 - ∝ ) = 3.24 * 10⁻²
Resolving equation above
∝ = 0.1645 = 16.45%
An electrolysis reaction is
A)
exothermic.
B)
hydrophobic.
C)
spontaneous.
D)
non-spontaneous.
Answer:
the electrolysis reaction is a non- spontaneous reaction
Explanation:
Since electrons flow from it, the anode in an electrolytic cell is positive, while the cathode is negative when electrons flow into it. The device functions like a galvanic cell in that direction. In an electrolytic cell, an external voltage is applied and that is what causes a non spontaneous reaction
Calculate the mass percent of KCl in a 0.35 m solution of KCl in water. Assume that the density of water is 1.00 g/mL.
Answer:
Mass percent of KCl is 2.61 %
Explanation:
Our solute is KCl
Our solvent is water
m means molality (moles of solute in 1kg of solvent)
1 kg = 1000 g
0.35 m means that 0.35 moles of KCl are contained in 1000g of solvent
We determine mass of solute: 0.35 mol . 74.55 g/mol = 26.09 g
Total mass of solution is: mass of solute + mass of solvent
26.09 g + 1000 g = 1026.09 g
Mass percent of KCl = (mass of KCl/ mass of solution) . 100
(26.09 / 1026.09) . 100 = 2.61 %
Classify the following as either solutions or colloids. If a colloid, name the type of colloid and identify both the dispersed and the dispersing phases.
a. glucose in water
b. smoke in air
c. carbon dioxide in air
d. milk
Answer:
a. glucose in water( solution)
b. smoke in air (colloids)
c. carbon dioxide in air (solution)
d. milk( colloids)
Explanation:
A solution is said to be formed when a solute dissolves in a solvent to form a homogeneous mixture. The solute particles are less than 10^-9m in size. Familiar solutions are those where the solute are dissolved in a liquid solvent. When the liquid water, the solution is known as an aqueous solution. A typical example is (glucose in water). In some other cases, the apparent solution of a solute in a solvent is accompanied by a chemical reaction and this is often known as a chemical reaction. A typical example is (carbon dioxide in air).
Colloids are also known as false solutions. Here, the individual solute particles are larger than the particles of the true solution, but not large enough to be seen by the naked eye. When a light beam is placed beside a beaker containing a colloid, the light rays of the beam can be clearly seen. This shows that it exhibits the Tyndall effect while a solution dosent exhibit such.
In a colloid, the liquid solvent is more appropriately know as the DISPERSION medium while the solid solute particles constitute the DISPERSED substance. This can either be solid, liquid or gas.
For example:
--> smoke in air : Dispersion medium is gas while the dispersed substance is solid.
--> milk: Dispersion medium is liquid while the dispersed substance is liquid.
Determine whether the reaction will be spontaneous at high temperatures only, at low temperatures only, at all temperatures, or no temperatures. (HINT: Use your chemical sense and your real-world knowledge to predict the signs of delta Hrxn & delta Srxn)
4Fe(s) + 3O2(g) ----> 2Fe2O3(s) [rust]
Circle one:High T, Low T, All T, No T
Answer:
The rusting of iron is spontaneous at low temperatures.
Explanation:
The given chemical reaction is:
4Fe(s) + 3O2(g) ----> 2Fe2O3(s) [rust]
The rusting of iron is a chemical reaction in which iron reacts with oxygen in presence of moisture and forms iron oxide.
This reaction takes place in a faster rate when there is low temperatures in the atmosphere.
When temperature is low, the moisture in the atmosphere is more and hence, rate of rusting is more.
explain in brief how some bacteria cause tooth cavities
Answer:
because some bacteria change the ph of the teeth and leads to tooth cavitiew
If you were to perform a recrystallization experiment and wanted to form very large crystals of pure substance, what would be the most UNfavorable conditions
The question is incomplete, the complete question is;
If you were to perform a recrystallization experiment and wanted to form very large crystals of pure substance, what would be the most UNfavorable conditions?
A. Fast cooling solution, use of an anti-solvent, rapidly evaporating solution
B. Slowly cooling solution, slowly evaporating solvent
Answer:
Fast cooling solution, use of an anti-solvent, rapidly evaporating solution
Explanation:
Recrystallization is a process of obtaining pure crystals from solution. The procedure involves dissolving the crystals in a solution in which they are soluble at high temperature but insoluble at low temperature.
As the solution cools, the pure crystals are obtained from the solution.
The solvent to be used must be a slow cooling, slow evaporating solvent so that the crystals can be efficiently recovered from solution.
Write the equation for the neutralization reaction in which barium chloride is the salt formed. Show the reaction in which the fully protonated acid reacts with the base to form the salt indicated. Use the smallest integer coefficients possible. (Use the lowest possible coefficients. Omit states of matter.)
Answer:
2 HCl + Ba(OH)₂ ⇒ BaCl₂ + 2 H₂O
Explanation:
In a complete neutralization reaction, an acid reacts with a base to form neutral salt and water. To form barium chloride, hydrochloric acid (acid) reacts with barium hydroxide (base). The balanced chemical equation is:
2 HCl + Ba(OH)₂ ⇒ BaCl₂ + 2 H₂O
At 298 K, ∆H = -314 kJ/mol and ∆S = -0.372 kJ/(K•mol). What is the Gibbs free energy of the reaction?
Answer:
-203 kJ/mol
Explanation:
Step 1: Given data
Standard enthalpy of the reaction (ΔH°): -314 kJ/molStandard entropy of the reaction (ΔS°): -0.372 kJ/K.molAbsolute temperature (T): 298 KStep 2: Calculate the standard Gibbs free energy of the reaction (ΔG°)
We will use the following expression.
ΔG° = ΔH° - T × ΔS°
ΔG° = (-314 kJ/mol) - 298 K × (-0.372 kJ/K.mol) = -203 kJ/mol
By convention, when ΔG° < 0, the reaction is spontaneous.
For a gas sample containing equimolar amounts of carbon monoxideand heliumat 300 K, heliumhas _____________average speed and _____________ average kinetic energy compared tocarbon monoxidegas.a.a lower; the same b. the same; the same c. a higher; the same d. a higher; higher
Answer:
Option C (a higher; the same) is the appropriate response.
Explanation:
Given:
Temperature,
T = 300 K (both [tex]N_2[/tex] and [tex]H_2[/tex])
As we know,
Average speed of a molecule,
⇒ [tex]\bar v=\sqrt{\frac{8RT}{\pi M} }[/tex]
Thus, the average speed of [tex]N_2[/tex] will be lower as its molar mass is greater than [tex]H_2[/tex].
Now,
⇒ [tex]Average \ kinetic \ energy = \frac{3}{2} \ KT[/tex] (not depend on molar mass)
Hence, it will be the same.
The other three alternatives aren't connected to the scenario given. So the above is the correct answer.
4. A salvage operator recovered coins believed to be gold. A sample weighed 385.000g and has a volume of 20.0mL. Were the coins gold (Density= 19.3g/mL) or yellow brass (Density =8.47g/mL)? Show your calculation and explain your answer.
Answer:
Gold
Explanation:
We are given that
Mass of sample ,m=385 g
Volume ,V=20mL
We have to find the coin is gold or yellow brass.
We know that
Density=[tex]\frac{Mass}{volume}[/tex]
Using the formula
[tex]Density=\frac{385}{20}g/mL[/tex]
[tex]Density=19.25g/mL[/tex]
[tex]Density\approx 19.3g/mL[/tex]
Density of coin=19.3g/mL
Density of gold=19.3g/mL
Hence, the coin is gold.
it takes 513 kj to remove a mole of electrons from the atoms at the surface of a piece of metal. how much energy does it take to remove a single electron from n atom at the surface of the metal
Answer:
The right solution is "[tex]8.5\times 10^{-19} \ joule[/tex]".
Explanation:
As we know,
1 mole electron = [tex]6.023\times 10^{23} \ no. \ of \ electrons[/tex]
Total energy = [tex]513 \ KJ[/tex]
= [tex]513\times 1000 \ joule[/tex]
For single electron,
The amount of energy will be:
= [tex]\frac{513\times 1000}{(6.023\times 10^{23})}[/tex]
= [tex]8.5\times 10^{-19} \ joule[/tex]
