Why is it important that the primary standard chemical be non-hygroscopic and pure? Why is it important to dry the primary standard to a constant weight?

Answers

Answer 1

Answer:

It is extremely important for the primary standard chemical to be non – hygroscopic and pure and to also have a constant weight because you don't want any moisture or any impurities to alter the stoichiometric point in the reaction

Answer 2

It is important that the primary standard chemical be non-hygroscopic and pure to calculate the exact calculation of the reaction.

What is non hygroscopic chemicals?

Non hygroscopic chemicals are those compounds which will not absorb water or mositure from the outside.

If we take any substance which are hygroscopic in nature and during the chemical reaction if they absorb water content or moisture then the mass of that substance will alter and changes all the calculation of the reaction.

So, to maintain the stability of calculation we use non hygroscopic materials.

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Related Questions

Why is phosphorus unusual compared to other group 15 elements? Select the correct answer below: A. There are compounds that contain phosphorus-phosphorus bonds with uncommon oxidation states. B. Phosphorus is relatively unreactive. C. Phosphorus only forms compounds where the oxidation number of phosphorus is 5+. D. Phosphorus is the most electronegative of the group 15 elements.

Answers

Answer:

There are compounds that contain phosphorus-phosphorus bonds with uncommon oxidation states.

Explanation:

Phosphorus is a member of group 15 in the periodic table. Its common oxidation States are -3 and +5. Phosphorus is believed to firm some of its compounds by the participation of hybridized d-orbitals in bonding although this is also disputed by some scientists owing to the high energy of d - orbitals.

Phosphorus form compounds having phosphorus-phosphorus bonds in unusual oxidation states such as diphosphorus tetrahydride, H2P-PH2, and tetraphosphorus trisulfide, P4S hence the answer.

The heat of vaporization of 1-pentanol is 55.5 kJ/mol, and its entropy of vaporization is 148 J/K.mol. What is the approximate boiling point of 1-pentanol? 100 oC 375 oC 0 oC 25 oC

Answers

Answer:

Approximately 100 °C.

Explanation:

Hello,

In this case, since the entropy of vaporization is computed in terms of the heat of vaporization and the temperature as:

[tex]\Delta S_{vap}=\frac{\Delta H_{vap}}{T}[/tex]

We can solve for the temperature as follows:

[tex]T=\frac{\Delta H_{vap}}{\Delta S_{vap}}[/tex]

Thus, with the proper units, we obtain:

[tex]T=\frac{55500J/mol}{148J/(mol*K)} =375K\\\\T=102 \°C[/tex]

Hence, answer is approximately 100 °C.

Best regards.

HELPPP PLZ !
Which one of the following is an example of a difficulty caused by thermal
expansion?
A. butter melting too fast
B. falling through the ice while skating
C. sagging power lines on a cold day
D. cracking in the walls of a house

Answers

The answer is D. Because thermal expansion makes the wall expand and crack

A pressure cooker contains 5.68 liters of air at a temperature of 394 K. If the absolute pressure of the air in the pressure cooker is 205 pascals, how many moles of air are in the cooker? The cooker contains _______ moles of air. 1 SEE ANSWER

Answers

Answer:

Explanation:

We shall find out volume of air at NTP or at 273 K and 10⁵ Pa ( 1 atm )

Let it be V₂

[tex]\frac{P_1V_1}{T_1} =\frac{P_2V_2}{T_2}[/tex]

[tex]\frac{2\times 10^5\times 5.68}{394} =\frac{10^5\times V_2}{273}[/tex]

V₂ = 7.87 litres

22.4 litres of any gas is equivalent to 1 mole

7.87 litres of air will be equivalent to

7.87 / 22.4 moles

= .35 moles .

odine atoms will combine to form I2 in liquid hexane solvent with a rate constant of 1.5×1010L/mol⋅s. The reaction is second order in I . Since the reaction occurs so quickly, the only way to study the reaction is to create iodine atoms almost instantaneously, usually by photochemical decomposition of I2. Suppose a flash of light creates an initial [I] concentration of 2.00×10−2 M .
How long will it take for 94% of the newly created iodine atoms to recombine to form I2? Express your answer using two significant figures.

Answers

Answer:

The time taken is  [tex]t = 1.11 *10^{-9} \ s[/tex]

Explanation:

From the question we are told that

    The  rate constant is  [tex]k = 1.50 *10^{10} \ L /mol \cdot s[/tex]

    The initial concentration of iodine atom  is  [tex][I] = 2.0*10^{-2} \ M[/tex]

Generally the integrated  rate law for a second order reaction is  mathematically represented as

        [tex]\frac{1 }{[I_r]} = \frac{1}{[I]} * k * t[/tex]

Where [tex][I_r][/tex] is the concentration of the remaining iodine atom  after the recombination which is mathematically evaluated as

      [tex][I_r ] = [I_o ] *[/tex][100%  - 94%]

The reason for the 94%  is that we are told from the question that only 94% of the iodine atom recombined

=>  [tex][I_r ] = [I_o ] *[/tex][6%]

=>  [tex][I_r ] = [I_o ] *0.06[/tex]

substituting values

    [tex][I_r ] = 2.0 *10^{-2}*0.06[/tex]

    [tex][I_r ] = 1.2 *10^{-3}[/tex]

So

    [tex]\frac{1 }{1.2 *10^{-3}} = \frac{1}{2.0 *10^{-2}} * 1.50*10^{10} * t[/tex]

  [tex]t = 1.11 *10^{-9} \ s[/tex]

         

It will take "1.11 × 10⁻⁹ s".

Chemical reaction:

A process wherein the two or even more compounds collide with both the proper orientation as well as enough effort to generate a new substance or the outcomes, is considered as Chemical reaction. This process involves the breaking as well as formation of atom connections.

According to the question,

Rate constant, k = 1.5 × 10¹⁰ L/mol.s

Initial concentration, [I] = 2.0 × 10⁻² M

By using the integrated rate law,

→ [tex]\frac{1}{[I]_r} = \frac{1}{[I]}[/tex] × k × t ...(Equation 1)

Now,

The concentration of remaining Iodine atom,

[[tex]I_r[/tex]] = [[tex]I_o[/tex]] × [100% - 94%]  

     = [[tex]I_o[/tex]] × 6%

     =  [[tex]I_o[/tex]] × 0.06

By substituting the values is above equation,

[[tex]I_r[/tex]] = 2.0 × 10⁻² × 0.06

     = 1.2 × 10⁻³

hence,

The time taken will be:

[tex]\frac{1}{[I]_r} = \frac{1}{[I]}[/tex] × k × t

By substituting the values,

[tex]\frac{1}{1.2\times 10^{-3}} = \frac{1}{2.0\times 10^{-2}}[/tex] × 1.50 × 10 × t

           t = 1.11 × 10⁻⁹ s

Thus the above answer is correct.

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True or False: Adding 4.18 joules to water will increase the temperature more than adding 1 calorie to water.

Answers

Answer:

Because one calorie is equal to 4.18 J, it takes 4.18 J to raise the temperature of one gram of water by 1°C. In joules, water's specific heat is 4.18 J per gram per °C. If you look at the specific heat graph shown below, you will see that 4.18 is an unusually large value.

The Haber Process is the main industrial procedure to produce ammonia. The reaction combines nitrogen from air with hydrogen mainly from natural gas (methane) and is reversible and exothermic. The enthalpy change for this reaction is - 92 kJ mol-1. In an experiment, 1.5 moles of N2 and 4.0 moles of H2 is mixed in a 1.50 dm3 reaction vessel at 450 °C. After reaching equilibrium, the mixture contained 0.9 mole of NH3.
A) With the above information, write the reaction equilibrium equation in the Haber process. t.
B) Calculate Kc for this reaction.
C) What is the equilibrium yield of ammonia in this reaction?
D) Referring to Le Chatelier's principle and above information, suggest two ways to increase the yield of ammonia in this reaction and explain.

Answers

Answer:

A) [tex]N_2(g)+3H_2(g)\rightleftharpoons 2NH_3(g)[/tex].

B) [tex]Kc=0.0933[/tex].

C) 0.9 mol.

D) Increasing both temperature and pressure.

Explanation:

Hello,

In this case, given the information, we proceed as follows:

A)

[tex]N_2(g)+3H_2(g)\rightleftharpoons 2NH_3(g)[/tex]

B) For the calculation of Kc, we rate the equilibrium expression:

[tex]Kc=\frac{[NH_3]^2}{[N_2][H_2]^3}[/tex]

Next, since at equilibrium the concentration of ammonia is 0.6 M (0.9 mol in 1.5 dm³ or L), in terms of the reaction extent [tex]x[/tex], we have:

[tex][NH_3]=0.6M=2*x[/tex]

[tex]x=\frac{0.6M}{2}=0.3M[/tex]

Next, the concentrations of nitrogen and hydrogen at equilibrium are:

[tex][N_2]=\frac{1.5mol}{1.5L}-x=1M-0.3M=0.7M[/tex]

[tex][H_2]=\frac{4mol}{1.5L}-3*x=2.67M-0.9M=1.77M[/tex]

Therefore, the equilibrium constant is:

[tex]Kc=\frac{(0.6M)^2}{(0.7M)*(1.77M)^3}\\ \\Kc=0.0933[/tex]

C) In this case, the equilibrium yield of ammonia is clearly 0.9 mol since is the yielded amount once equilibrium is established.

D) Here, since the reaction is endothermic (positive enthalpy change), one way to increase the yield of ammonia is increasing the temperature since heat is reactant for endothermic reactions. Moreover, since this reaction has less moles at the products, another way to increase the yield is increasing the pressure since when pressure is increased the side with fewer moles is favored.

Best regards.

The equilibrium between carbon dioxide gas and carbonic acid is very important in biology and environmental science. CO2 ( aq) + H2O ( l) H2CO3 ( aq) Which one of the following is the correct equilibrium constant expression (K c) for this reaction?
a) K =[H2CO3]/ [CO2]
b) K=[CO2]/ [H2CO3]
c) K=[H2CO3]/ [CO2][H2O]
d) K=[CO2][H2O]/ [H2CO3]
e) K=1/[H2CO3]

Answers

Answer:

Kc = [H₂CO₃] / [CO₂]

Explanation:

Equilibrium constant expression (Kc) of any reaction is defined as the ratio between molar concentrations in equilibrium of products over reactants.

Pure solids and liquids don't affect the equilibrium and you don't have to take its concentrations in the equilibrium.

Also, each specie must be powered to its reactant coefficient.

For example, for the reaction:

aA(s) + bB(aq) ⇄ cC(l) + nD(g) + xE(aq)

The equilibrium constant, kc is:

Kc = [D]ⁿ / [B]ᵇ[E]ˣ

You don't take A nor C species because are pure solids and liquids. b, n and x are the reactant coefficients of each substance. Ratio of products over reactants

Thus, for the reaction:

CO₂(aq) + H₂O(l) ⇄ H₂CO₃(aq)

The Kc is:

Kc = [H₂CO₃] / [CO₂]

What is the magnetic quantum number value for an element with n = 1?

Answers

Answer:

ml= 0

Explanation:

The magnetic quantum number usually gives information regarding the directionality of an atomic orbital. The values of the magnetic quantum number ranges between integer values that lie between +l to -l.

However, the n=1 level contains only the 1s orbital which is spherically symmetrical. The s orbital having l=0 also has magnetic quantum number (ml) =0, hence the answer.

The titration of 78.5 mL of an unknown concentration H3PO4 solution requires 134 mL of 0.224 M KOH solution. What is the concentration of the H3PO4 solution

Answers

Answer:

0.127 M.

Explanation:

The balanced equation for the reaction is given below:

H3PO4 + 3KOH —› K3PO4 + 3H2O

From the balanced equation above, we obtained the following data:

Mole ratio of acid, H3PO4 (nA) = 1

Mole ratio of base, KOH (nB) = 3

Data obtained from the question include:

Volume of acid, H3PO4 (Va) = 78.5 mL

Molarity of acid, H3PO4 (Ma) =...?

Volume of base, KOH (Vb) = 134 mL

Molarity of base, KOH (Mb) = 0.224 M

The concentration of the acid, H3PO4 can be obtained as follow:

MaVa / MbVb = nA/nB

Ma x 78.5 / 0.224 x 134 = 1/3

Cross multiply

Ma x 78.5 x 3 = 0.224 x 134 x 1

Divide both side by 78.5 x 3

Ma = (0.224 x 134 x 1) /(78.5 x 3)

Ma = 0.127 M

Therefore, the concentration of the acid, H3PO4 is 0.127 M.

Calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. Round your answer to the nearest .

Answers

Answer:

-471 Kj/mole acrylic acid

Explanation:

THIS IS THE COMPLETE QUESTION BELOW;

There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. In the first step, calcium carbide and water react to form acetylene and calcium hydroxide: CaC (s) + 2 H2O(g) - CH (9) + Ca(OH),(s) AH -414. kJ In the second step, acetylene, carbon dioxide and water react to form acrylic acid: 6 C H (9) + 3 CO2(9) + 4H2O(g) - SCH,CHCO,H) AH-132. kJ Calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. Round your answer to the nearest kJ. x 5 ?

The two equations from the reaction can be written as;

a)CaC₂(s) + 2H₂O(l) ------->C₂H₂(g) + CaOH₂(s)

Δ H= -414Kj ........................ equation (a)

b)6C₂H₂(g) +3CO₂(g)+4H₂O(g) -------> 5CH₂CHCO₂H(g) Δ H= 132Kj ...................... equation (b)

In equation (b)acrylic acid was produced by the reaction between Acetylene carbon dioxide and water

Then we can multiply equation(a) by factor of 6 and the ΔH Then we have (6× -414Kj)= ΔH= -2484Kj.

6CaC₂(s) + 12H₂O(l) ------->6C₂H₂(g) + 6CaOH₂(s)

Δ H= -2484Kj.................. equation (c)

6C₂H₂(g) +3CO₂(g)+4H₂O(g) -------> 5CH₂CHCO₂H(g) Δ H= 132Kj

Then add equation (c) and equation(b) then we have

6CaC₂(s) + 16H₂O(l)+3CO₂(g)------> 5CH₂CHCO₂H(g) + 6CaOH₂(s) ΔH= -2352Kj

ΔH(net)= -2352Kj/5moles

=-471Kj/mole

therefore, net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. Round your answer to the nearest kJ. x 5 ? is -471Kj/mole acrylic acid

Suppose of copper(II) acetate is dissolved in of a aqueous solution of sodium chromate. Calculate the final molarity of copper(II) cation in the solution. You can assume the volume of the solution doesn't change when the copper(II) acetate is dissolved in it. Round your answer to significant digit.

Answers

Answer:

Molarity Cu²⁺ = 0.423M Cu²⁺

Explanation:

40.8g of copper (II) acetate into 200mL of a 0.700M sodium chromate

The reaction of copper acetate with sodium chromate occurs as follows:

Cu(CH₃COO)₂(aq) + Na₂CrO₄(aq) → CuCrO₄(s) + 2CH₃COONa

In water, the Copper(II) acetate dissociates in Cu²⁺ cation.

To know final molarity of Cu²⁺ we need to calculate the moles of Cu²⁺ that don't react with chromate ion, thus:

Moles of 40.8g of copper(II) acetate (Molar mass: 181.63g/mol) are:

40.8g × (1mol / 181.63g) = 0.2246 moles of Copper(II) acetate

Moles of sodium chromate are:

0.200L ₓ (0.700mol / L) = 0.140 moles of sodium chromate.

As 1 mole of Copper(II) acetate reacts per mole of sodium chromate, moles of Copper(II) acetate = Moles of Cu²⁺ that remains after the reaction are:

0.2246mol - 0.140moles = 0.0846 moles of Cu²⁺

Molarity is ratio between moles of solute (Moles Cu²⁺) and volume in liters of solution (200mL = 0.200L):

Molarity Cu²⁺ = 0.0846 moles / 0.200L

Molarity Cu²⁺ = 0.423M Cu²⁺

The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism:

Answers

Answer:

The two-step mechanism is a slow mechanism and a fast mechanism. When we combine them, the result is

2H₂O₂ (aq) ⇒2H₂O (l) + O₂ (g)

Explanation:

We know that the decomposition of hydrogen peroxide is catalyzed by iodide ion, which means that the iodide ion will react with the hydrogen peroxide. There is a slow mechanism and a fast one:

H₂O₂(aq) + I₋(aq) ⇒ H₂O(l) + IO₋(aq) this is the slow reaction

IO₋(aq) + H₂O₂(aq)⇒ H₂O(l) + O₂(g) + I₋ (aq) this is the fast reaction

If we cancel the same type of molecules and ions, the final result is:

2H₂O₂ (aq) ⇒2H₂O (l) + O₂ (g)

The two-step mechanism represents the slow mechanism and a fast mechanism. At the time of combining them, the result is 2H₂O₂ (aq) ⇒2H₂O (l) + O₂ (g)

Two-step mechanism:

The decomposition of hydrogen peroxide should be catalyzed by iodide ion, which represents the iodide ion will react with the hydrogen peroxide. There is a slow mechanism and a fast one

Now

H₂O₂(aq) + I₋(aq) ⇒ H₂O(l) + IO₋(aq) this is the slow reaction

IO₋(aq) + H₂O₂(aq)⇒ H₂O(l) + O₂(g) + I₋ (aq) this is the fast reaction

Now in case of cancelling, the same type of molecules and ions, the final result is 2H₂O₂ (aq) ⇒2H₂O (l) + O₂ (g)

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what is the IUPAC name of KNO3, Fe(OH)3, H2SO3 and Al2(SO4)3

Answers

Answer:

KNO₃ - Potassium nitrate

Fe(OH)₃ - Iron(III) hydroxide

H₂SO3 - Sulfurous acid

Al₂(SO₄)₃ - Aluminum sulfate

Hope that helps.

Answer: potassium nitrate

the equilibrium concentrations were found to be [H2O]=0.250 M , [H2]=0.600 M , and [O2]=0.800 M . What is the equilibrium constant for this reaction?

Answers

Answer:

Keq = 0.217

Explanation:

Let's determine the equilibrium reaction.

In gaseous state, water vapor can be decomposed to hydrogen and oxygen and this is a reversible reaction.

2H₂(g)  + O₂(g)  ⇄  2H₂O (g)         Keq

Let's make the expression for the equilibrium constant

Products / Reactants

We elevate the concentrations, to the stoichiometry coefficients.

Keq = [H₂O]² / [O₂] . [H₂]²

Keq = 0.250² / 0.8 . 0.6² =  0.217

The table below shows the electronegativity values of various elements on the periodic table. Electronegativities A partial periodic table. Which pair of atoms would form a covalent bond ? calcium (Ca) and bromine (Br) rubidium (Rb) and sulfur (S) cesium (Cs) and nitrogen (N) oxygen (O) and chlorine (Cl)

Answers

Answer:

Oxygen and Chlorine

Explanation:

Covalent bonds involve the sharing of electrons between nonmetals.

Answer:

oxygen (O) and chlorine (Cl)

Explanation:

cuz i said so

Match the symbol with the appropriate definition.

a. ΔG
b. ΔS
c. Keq
d. ΔH
e. ΔG°
f. J


1. Equation constant
2. Change in size
3. Change in entropy
4. Change in gas pressure
5. Change in stored energy
6. Equilibrium constant
7. Change in enthalpy
8. Joule
9. Standard free energy charge
10. Change in energy

Answers

Answer:

a. ΔG : It seems that the proper definition is not given, anyway, it is the free energy change.

b. ΔS : 3. Change in entropy.

c. Keq : 6. Equilibrium constant.

d. ΔH : 7. Change in enthalpy.

e. ΔG° : 9. Standard free energy change.

f. J : 8. Joule.

Explanation:

Hello,

In this case, we can match the symbol with the proper definition as shown below:

a. ΔG : It seems that the proper definition is not given, anyway, it is the free energy change and it uses G since it is better referred to the Gibbs free energy.

b. ΔS : 3. Change in entropy.

c. Keq : 6. Equilibrium constant.

d. ΔH : 7. Change in enthalpy.

e. ΔG° : 9. Standard free energy change.

f. J : 8. Joule.

Best regards.

For each row in the table below, decide whether the pair of elements will form a molecular compound held together by covalent chemical bonds

Answers

Answer:

1- yes

  HBr--hydrogen bromide

2- no

  BaBr₂----barium bromide  

3- yes

NCl----- nitrogen chlorine  

 

Hydrogen ,bromine and nitrogen , chlorine are the pair of elements which  will form a molecular compound by covalent bond as they have 1, 7,5, 7 valence electrons respectively.

What is a covalent bond?

Covalent bond is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.

Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.

Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.

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To format the electron configuration correctly make sure to superscript where needed, do not add spaces to your answer and italics are not possible in this module. Write the ground-state electron configuration for calcium, Ca. You may write either the full or condensed electron configuration.

Answers

Answer:

[tex]1s^{2}2s^{2} 2p^{6}3sx^{2}3p^{6} 4s^{2}[/tex]  [full configuration]

Explanation:

Calcium has 20 electrons in its nucleus, and by virtue of its position on the periodic table (fourth row, second column), it is an s-block element with its entire lower orbital filled. it has two valence electrons.

Therefore, its configuration is:

[tex]1s^{2}2s^{2} 2p^{6}3sx^{2}3p^{6} 4s^{2}[/tex]

To condense this, you can utilize Argon's stable configuration before [tex]4s^{2}[/tex] to show that all orbitals before 4s are filled.

I hope this was helpful.

33. Hydrocarbons that release pleasant odors are called_________
hydrocarbons. (1 point)

Answers

Answer:

Aromatic Hydrocarbons

Explanation:

Aromatic (Pleasant Odour) Hydrocarbons are those having pleasant odours.

Answer:

substituted hydrocarbons

Explanation:

i think

Which of the following statements about water is not true?

Answers

Answer:

Water has a low specific heat capacity and so large bodies of water moderate temperatures on Earth.

Explanation:

Water has a very high specific heat capacity, meaning that it has to absorb a lot of energy to raise the temperature by one degree. Because water has a high specific heat capacity, large bodies of water can moderate the temperature of nearby land.

Hope this helps.

g A spontaneous process is one in which: A. releases a large amount of heat B. may happen (is possible) C. will rapidly approach equilibrium D. will happen quickly

Answers

Answer:

A. releases a large amount of heat

Explanation:

A reaction is said to be spontaneous if it can proceed on its own without the addition of external energy. A spontaneous reaction is not determined by the length of time, because some spontaneous reactions are completed after a long period of time. They are exothermic in nature. An example is the conversion of graphite to carbon which takes a long period of time to complete. Spontaneous reactions are known to increase entropy in a system. Entropy is the rate of disorder in a system.

In the combustion of fire, energy is released to the surroundings as there is a decrease in energy. This is an example of a spontaneous reaction because it is an exothermic reaction, which causes an increase in entropy and a decrease in energy.

Which of the following best describes the interaction of the alkali metals with water? Select the correct answer below: A. They all dissolve easily in water. B. They do not react or dissolve in water. C. They react strongly with water to produce an alkaline solution and hydrogen. D. They react strongly with water to produce an alkaline solution and oxygen.

Answers

Answer:

C. They react strongly with water to produce an alkaline solution and hydrogen

Explanation:

All alkali metals react vigorously with cold water. In the reaction, hydrogen gas is given off and the metal hydroxide is produced.

Hope that helps.

Calculate the frequency (Hz) and wavelength (nm)

of the emitted photon when an electron drops from

the n = 4 to the n=2 level in a hydrogen atom

Answers

Answer:

wavelength, λ =  486.6 nm

frequency, f = 6.16 * 10¹⁴ Hz

Explanation:

a. Wavelength

Using the wavelength equation; 1/λ = (1/hc) * 2.18 * 10⁻¹⁸ J * (1/nf² - 1/ni²)

Where nf is the final energy level; ni is the initial energy level; h is Planck's constant = 6.63 * 10⁻³⁴ J.s; c is velocity of light = 3 * 10⁸ m/s

1/λ = 1/(6.63 * 10⁻³⁴ J.s * 3 * 10⁸ m/s) * 2.18 * 10⁻¹⁸ J * (1/2² - 1/4²)

1/λ = 2.055 * 10⁶ m

λ = 4.866 * 10⁻⁷ m

wavelength, λ =  486.6 nm

b.  Frequency

Using f = c/λ

f = (3 * 10⁸ m/s) / 4.866 * 10⁻⁷ m

frequency, f = 6.16 * 10¹⁴ Hz

Concentrated hydrochloric acid, HCl, comes with an approximate molar concentration of 12.1 M. If you are instructed to prepare 350.0 mL of a 0.975 M HCl solution, how many milliliters of the stock (concentrated) HCl solution will you use

Answers

Answer:

28.20 mL of the stock solution.

Explanation:

Data obtained from the question include the following:

Molarity of stock solution (M1) = 12.1 M

Volume of diluted solution (V2) = 350.0 mL

Molarity of diluted solution (M2) = 0.975 M

Volume of stock solution needed (V1) =..?

The volume of stock solution needed can be obtained by using the dilution formula as shown below:

M1V1 = M2V2

12.1 x V1 = 0.975 x 350

Divide both side by 12.1

V1 = (0.975 x 350)/12.1

V1 = 28.20 mL.

Therefore, 28.20 mL of the stock solution will be needed to prepare 350.0 mL of 0.975 M HCl solution.

Consider a triangle ABC like the one below. Suppose that C=83°, a = 43, and b = 44. Solve the triangle.
Carry your intermediate computations to at least four decimal places, and round your answers to the nearest tenth.
If there is more than one solution, use the button labeled "or".

Answers

Answer:

Explanation:

   In a triangle

a / sin A = b / sinB = c / sinC

Putting the values

43 / sin A = 44 / sinB

sinA / sinB = 43 / 44 = 1 / 1.023

A + B = 180 - 83 = 97

sinA / sin ( 97 - A ) = 1 / 1.023

sin 97 cos A - cos 97 sin A = 1.023 sin A

= .9925 cos A + .122 sin A = 1.023 sin A

.9925 cos A = .901 sin A

squaring

.985 cos²A = .8118 sin²A

.985 - .985 sin²A = .8118 sin²A

.985 = 1.7968 sin²A

sinA = .74

A = 47.73

B = 49.27

c / sin C = b / sin B

c = b sinC / sinB

= 44 x sin 83 / sin 49.27

= 44 x .9925 / .7578

= 57.62

Treatment of 1 mole of dimethyl sulfate with 2 moles of sodium acetylide results in the formation of propyne as the major product.
A) Draw a reasonable mechanism accounting for the formation of the byproduct 2-butyne.
B) 2-Butyne is observed as a minor product of this reaction. Draw a mechanism accounting for the formation of this minor product and explain how your proposed mechanism is consistent with the observation that acetylene is present among the reaction products.
C) Predict the major and minor products that are expected if diethyl sulfate is used in place of dimethyl sulfate.

Answers

Answer:

(a) appended underneath is the inorganic ion shaped in the reaction and the mechanism of its formation  

(b) 2-butyne framed as a minor product is appeared in the connection. It is shaped when the monosodium subordinate of dimethylsulphoxide gets a hydrogen from the propyne and reacts again with monosodium methylsulphoxide.  

(c) The major product framed when diethylsulphoxide is utilized, would be butyne and minor product would be 3-hexyne.

Explanation:

attached below is diagram

Rank the solutions in order of decreasing [H3O+]. Rank solutions from largest to smallest hydronium ion concentration.

a. 0.10 M HNO3HNO3
b. 0.10 M HClO2HClO2
c. 0.10 M HCNHCN
d. 0.10 M HC2H3O2

Answers

I think it’s goes B, A, D, then C

Calculate the ratio of moles of H2O to moles of anhydrous CuSO4 in CuSO4.
1H2O, CuSO4, 3H2O, CuSO4, 5H2O, CuSO4, 7H2O, and CuSO4, 9H2O.
(Mol wt. of H2O- 18.02g; Mol wt. of CuSO4 - 159.61g).

Answers

Answer:

CuSO₄.H₂O = 1

CuSO₄.3H₂O = 3

CuSO₄.5H₂O = 5

CuSO₄7.H₂O = 7

CuSO₄.9H₂O = 9

Explanation:

Some salts as CuSO₄ are presented in the hydratated form to give some stability in their uses.

Ratio of moles represents moles of H₂O / moles of CuSO₄.

In CuSO₄.H₂O you have 1 mole of water per mole of CuSO₄, Ratio is 1/1 = 1.

For CuSO₄.3H₂O are 3 moles of water per mole of CuSO₄. Ratio is 3/1 = 3

For CuSO₄.5H₂O are 5 moles of water per mole of CuSO₄. Ratio is 5/1 = 5

For CuSO₄.7H₂O are 7 moles of water per mole of CuSO₄. Ratio is 7/1 = 7

For CuSO₄.9H₂O are 9 moles of water per mole of CuSO₄. Ratio is 9/1 = 9

Determine which complex of the electron transport chain (respiratory chain) each phrase describes. (Coenzyme Q is also called ubiquinone or ubiquinol, depending on whether it is in oxidized or reduced form.)
Complex I:
Complex II:
Complex III:
Complex IV:
Here are the choices that need to be put in the correct complex:
1) NADH-ubiquinone(NADH-coenzyme Q oxidoreductase)
2) Coenzyme Q-cytochrome c oxidoreductase
3) Electron transfer from succinate to ubiquinone (coenzyme Q)
4) Electron transfer from cytochrome c to O2
5) Succinate-coenzyme Q Oxidoreductase (succinate dehydrogenase)
6) Cytochrome c oxidase
7) Electron transfer from ubiquinol (QH2) to cytochrom c
8) Electron transfer from NADH to ubiquinone (coenzyme Q)

Answers

Answer:

Complex I:  (1) NADH-ubiquinone(NADH-coenzyme Q oxidoreductase), (8) Electron transfer from NADH to ubiquinone (coenzyme Q)

Complex II:  (3) Electron transfer from succinate to ubiquinone (coenzyme Q) (5) Succinate-coenzyme Q Oxidoreductase (succinate dehydrogenase)

Complex III:  (2) Coenzyme Q-cytochrome c oxidoreductase, (7) Electron transfer from ubiquinol (QH2) to cytochrome c

Complex IV: (4) Electron transfer from cytochrome c to O2, (6) Cytochrome c oxidase

Explanation:

The electron transport chain (ETC) in the mitochondria provides a pathway by which electrons are transferred from NADH and FADH₂ through a series of membrane-bound carriers to  molecular oxygen reducing it to water.

The electron transport chain electron carriers are organized into four complexes, Complexes I - IV.

Complex I : It is also called NADH:ubiquinone reductase. It transfers electrons from NADH to ubiquinone (also known as coenzyme Q)

Complex II : It is also called succinate dehydrogenase. It functions to tranfer electrons from succinate to FAD and then to ubiquinone.

Complex III : It is also called ubiquinone:cytochrome c oxidoreductase. It functions to transfer electrons from ubiquinol (reduced ubiquinone) to cytochrome c.

Complex IV : It is also called cytochrome oxidase. It functions to transfer electrons from cytochrome c to molecular oxygen reducing it to water.

The electron transporter chain is a series of enzymatic reactions to produce and store energy for the organism’s correct functioning. Complex I: 1 and 8. Complex II: 3 and 5. Complex III: 2 and 7. Complex IV: 4 and 6.

---------------------------------

Electron transporter chain

The electron transporter chain is located in the internal mitochondrial membrane. It constitutes a series of enzymatic reactions to release and save energy for the organism’s correct functioning.  

Along the chain, there are four proteinic complexes in the membrane, I, II, III, and IV, that contain the electrons transporters and the enzymes necessary to catalyze the electrons' transference from one complex to the other.  

Different redox reactions occur to pass electrons along the chain.  

Released energy creates a proton concentration gradient used to synthesize ATP.  

1)  NADH provides electrons to the first complex, Complex I (NADH-  

   ubiquinone or NADH-coenzyme Q oxidoreductase).

From there, electrons go to the coenzyme Q (Ubiquinone) that carries them to complex II and III. Meanwhile, complex I pomp four protons to the intermembrane space.  

2) Complex II (succinate-dehydrogenase) receives electrons from CoQ and also receives electrons from FADH2. Electrons are sent from complex II to ubiquinone Q that carries these electrons to complex III.

3) Complex III (Cytochrome C-reductase) receives electrons from ubiquinone Q and pomps protons to the intermembrane space.

Electrons are transferred to Cytochrome c.  

Electrons travel from cytochrome c to complex IV.

4) Complex IV (Cytochrome C-oxidase)  is the last complex that pomps protons to the intermembrane space. It takes electrons from cytochrome C and sends them to oxygen.

5) Electrons are sent to O₂ molecules, which also receive protons in the matrix to create water molecules.

Four electrons are needed to produce two water molecules from one O₂ molecule.  

The proton gradient is used to produce ATP molecules.

Now, we can join the complexes with the phrases.

Complex I:

1) NADH-ubiquinone (NADH-coenzyme Q oxidoreductase)

8) Electron transfer from NADH to ubiquinone (coenzyme Q)

Complex II:

3) Electron transfer from succinate to ubiquinone (coenzyme Q)

5) Succinate-coenzyme Q Oxidoreductase (succinate dehydrogenase)

Complex III:

2) Coenzyme Q - cytochrome c oxidoreductase

7) Electron transfer from ubiquinol (QH₂) to cytochrom c

Complex IV:

6) Cytochrome C oxidase

4) Electron transfer from cytochrome c to O₂

-----------------------------------

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