Allene (1,2-propadiene) has point group D2d, itself is achiral because it has two planes of symmetry. ... An allene with substituents on one terminal carbon atom are unlike and substituent on other terminal carbon atoms are same, allene will be achiral. It will have one symmetry plane.
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A sample of serum of mass 25 g is cooled from 290 K to 275 K at constant pressure by the extraction of 1.2 kJ of energy as heat. Calcuate q and ∆H and estimate the heat capacity of the sample.
5.195 kg + 10.95 kg + 73.2 kg
Answer: 89.345
Explanation:
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Which answer choices correctly describe why the number of known elements more then doubled by 1861
Answer:
Communication between scientists increased.
Technological advancements were made.
Explanation:
The options:
Metalworkers began using new metals.
Communication between scientists increased.
The American Civil War started.
Technological advancements were made.
The reasons the number of known elements more than double by 1861 would be because technological advancements have been made and communication between scientists increased.
With the advancement in technology, more equipment become available and research became more sophisticated leading to new discoveries. The new discoveries would not have made much difference if they are not adequately communicated to other scientists.
The compound on the right contains two functional groups. It is:________
A) an aldehyde and an ether
B) an aldehyde and an alcohol
C) a ketone and an ether
D) a ketone and an ester
E) a carboxylic acid and an ether
Answer : Option C is correct -- a ketone and an ether
Explanation:
It should be noted that Ketone and ether are the compound on the right that contain two functional groups. an aldehyde and an ether, an aldehyde and an alcohol, a ketone and an ester, and also a carboxylic acid and an ether don't contain two functional groups on the right.
The standard cell potential for a reaction in an electrolytic cell is always:_____
a. Positive
b. Negative
c. Zero
d. Impossible to determine
Answer:
The correct answer is b. Negative
Explanation:
An electrolytic cell is based on a reduction- oxidation reaction which is non spontaneous. That means that the standard cell potencial (Eº) is negative. For this reason, an electrical potential must be applied in order to force the reaction. Conversely, a galvanic cell is based on a spontaneous redox reaction, so the galvanic cell produces electrical energy.
Energy from radiation can cause chemical bonds to break. To break a nitrogen-nitrogen bond in N2 gas, 941kJ/mole is required.
a. Calculate the wavelength of radiation that could break the bond.
b. In what spectral range does this radiation occur?
Answer:
a) 1.269 × 10^-7 m
b) This wavelength occurs in the ultraviolet region of the electromagnetic spectrum
Explanation:
The energy required to break the bond= energy of the incident photon
E= 941 × 10^3/6.02 × 10^23 = 1.56 ×10^ -18 J
From
E= hc/λ
h= Plank's constant
c= speed of light
λ= wavelength of incident photon
λ= hc/E
λ= 6.6 ×10^-34 × 3 ×10^8/1.56 ×10^ -18 J
λ= 1.269 × 10^-7 m
b) This wavelength occurs in the ultraviolet region of the electromagnetic spectrum
A sample of gas occupies a volume of 61.5 mL . As it expands, it does 130.1 J of work on its surroundings at a constant pressure of 783 Torr . What is the final volume of the gas? g
Answer:
the final volume of the gas is [tex]V_2[/tex] = 1311.5 mL
Explanation:
Given that:
a sample gas has an initial volume of 61.5 mL
The workdone = 130.1 J
Pressure = 783 torr
The objective is to determine the final volume of the gas.
Since the process does 130.1 J of work on its surroundings at a constant pressure of 783 Torr. Then, the pressure is external.
Converting the external pressure to atm ; we have
External Pressure [tex]P_{ext}[/tex]:
[tex]P_{ext} = 783 \ torr \times \dfrac{1 \ atm}{760 \ torr}[/tex]
[tex]P_{ext} = 1.03 \ atm[/tex]
The workdone W = [tex]P_{ext}[/tex]V
The change in volume ΔV= [tex]\dfrac{W}{P_{ext}}[/tex]
ΔV = [tex]\dfrac{130.1 \ J \times \dfrac{1 \ L \ atm}{ 101.325 \ J} }{1.03 \ atm }[/tex]
ΔV = [tex]\dfrac{1.28398717 }{1.03 }[/tex]
ΔV = 1.25 L
ΔV = 1250 mL
Recall that the initial volume = 61.5 mL
The change in volume V is [tex]\Delta V = V_2 -V_1[/tex]
[tex]- V_2= - \Delta V -V_1[/tex]
multiply through by (-), we have:
[tex]V_2= \Delta V+V_1[/tex]
[tex]V_2[/tex] = 1250 mL + 61.5 mL
[tex]V_2[/tex] = 1311.5 mL
∴ the final volume of the gas is [tex]V_2[/tex] = 1311.5 mL
The final volume of the gas when the volume of 61.5 mL should be 1311.5 mL.
Calculation of the final volume:Since
a sample gas has an initial volume of 61.5 mL
The workdone = 130.1 J
Pressure = 783 torr
So, here the external pressure should be
= 783 * 1 / 760
= 1.03 atm
Now the change in volume is
= 130.1 J * 1 / 101.325 J / 1.03
= 1250 mL
Now the change in volume should be
= 1250 + 61.5
= 1311.5 mL
hence, The final volume of the gas when the volume of 61.5 mL should be 1311.5 mL.
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Atomic radius generally increases as we move
A) down a group and from right to left across a period
B) up a group and from left to right across a period
C) down a group and from left to right across a period
D) up a group and from right to left across a period
E) down a group; the period position has no effect
Answer:
C
Explanation:
Atomic radius generally increases as we move down a group and from left to right across a period
Cell notation will list each half-reaction:
A.) starting with the reaction at the cathode
B.) with coefficients to balance the species
C.) on each side of the salt bridge, which is represented by a double vertical line
D.) none of the above
Answer:
on each side of the salt bridge, which is represented by a double vertical line
Explanation:
While writing a cell notation, the general convention is; anode || cathode. The anode and the cathode are separated by a double line. The anode is written on the lefthand side while the cathode is written on the righthand side.
The cell notation is a shorthand representation of a cell, hence any electrochemical cell can easily be produced based on its cell diagram.
Of the following, which is the dominant (strongest) type of intermolecular force present in RbCl(s)?
A. lon-dipole
B. lonic
C. Dispersion
D. Dipole-dipole
E. Hydrogen bonding
Answer:
B. Ionic
Explanation:
RbCl is ionic compound formed from the combination of rubidium (a strongly electropositive element) and chlorine (a strongly electronegative element).
The transfer of an electron from rubidium to chlorine leads to the formation of two oppositely charged ions Rb⁺ and Cl⁻.
In a solid crystal of RbCl, the major intermolecular forces of attraction are electrostatic forces of attraction between oppositely charged ions in the molecules of the crystalline solid.
Ion-dipole attraction only occur when the solid is dissolved in a polar molecule like water. Dispersion forces as well as dipole-dipole forces, though present are weak forces and contribute very little to intermolecular attraction. Hydrogen bonding is not present as there are no hydrogen atoms in solid RbCl.
The dominant (strongest) type of intermolecular force present in RbCl(s) is ionic force (Option B).
An ion-dipole attraction refers to a type of attraction between ions and neutral dipole molecules. Ionic forces are commonly observed in different types of chemical solutions. An ion-dipole force consists of a positive/negative ion that exerts an attractive force to the negative/positive end present in a polar molecule.In conclusion, the dominant (strongest) type of intermolecular force present in RbCl(s) is ionic force (Option B).
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2. (2 points) Calculate the Effective Nuclear Charge for each atom. Show all of your work for full credit. Se: Br: (1 point) Which atom is larger? (This is your claim.)
Answer:
Bromine.
Explanation:
There is more nuclear charge on bromine because in bromine, there are 35 number of protons and 46 number of neutrons while in selenium, there are 34 number of protons and 45 number of neutrons. The atomic size of selenium is larger because they have lower nuclear charge as compared to bromine and we know that when we go to the left of periodic table atomic size increases which attract the electrons towards itself so the shell comes close to the nucleus and decrease occurs in atomic radius.
i need to know the measurements of this to the appropriate amount of significant figures
Answer:
[See Below]
Explanation:
13 cm.
Answer the following questions in brief.
Why does silver get tarnished on exposure to air?
Answer: When silver is exposed to sulfur-containing gases in the air, it discolours and then darkens as it reacts with the gas to form a surface layer of tarnish. This process is called tarnishing.
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Which is an example of the practical pursuit of alchemy
Answer:
A practical pursuit of alchemy was the development of metallurgy practices.
Explanation:
As alchemists always tried to turn various metals into other things, metalworking techniques were developed even though their experiments were often unsuccessful.
Answer: developing metalworking techniques
Explanation:
trust it!!
) Why is the Lewis structure for CO2 usually written as O = C = O rather than
O ≡ C - O ?
Answer:
The Lewis structure for CO2 is O = C = O rather than O ≡ C - O because of the covalent nature of the bonds that makes CO2 a polar molecule and to become stable it is important to fill valence shell of both atoms equally.
CO2 can not be written as O ≡ C - O because then there will be one non-paired electron in the oxygen atom that can disturb the stability of CO2.
Which process is an example of a chemical change?
Answer:
burning of paper
melting of lead
Answer:
d- activating a glow stick
Explanation:
Glow sticks produce light through a chemical reaction.
Relative to the energy stored in chemical bonds, nuclear binding energies are:_________.
a. much greater
b. much smaller
c. approximately equal
d. depends on the substance
Answer:
much greater
Explanation:
Binding energy of a nucleus is the energy evolved in the formation of a nucleus from free protons and neutrons. It is also defined as the energy that binds nucleons together in the nucleus of an atom.
The nuclear binding energy is far greater than the chemical energy stored in chemical bonds. Nuclear energy is the greatest source of energy which could be exploited to achieve various ends.
The public is not yet able to ourchase cars powered by hydrogen fuel cells because engineers have to determine how the cars perform based on which scenario
Answer:
in real-world conditions
Explanation:
What is the partial pressure of nitrogen in a container that contains 3.96mol of oxygen, 7.49 mol of nitrogen and 1.19 mol of carbon dioxide when the total pressure is 563 mmHg?
Answer:
333.6 atm
Explanation:
The following data were obtained from the question:
Mole of O2 (nO2) = 3.96 moles
Mole of N2 (nN2) = 7.49 moles
Mole of CO2 (nCO2) = 1.19 moles
Total pressure = 563 mmHg
Partial pressure of N2 =..?
Next, we shall determine the total number of mole in the container.
This can be obtained as follow:
Mole of O2 (nO2) = 3.96 moles
Mole of N2 (nN2) = 7.49 moles
Mole of CO2 (nCO2) = 1.19 moles
Total mole =?
Total mole = nO2 + nN2 + nCO2
Total mole = 3.96 + 7.49 + 1.19
Total mole = 12.64 moles
Next, we shall determine the mole fraction of N2.
This can be obtained as follow:
Mole fraction = mole of substance/total mole
Mole of N2 (nN2) = 7.49 moles
Total mole = 12.64 moles
Mole fraction of N2 =?
Mole fraction of N2 = 7.49/12.64
Finally, we shall determine the partial pressure of N2.
This can be obtained as follow:
Mole fraction of N2 = 7.49/12.64
Total pressure = 563 mmHg
Partial pressure of N2 =..?
Partial pressure = mole fraction x total pressure
Partial pressure of N2 = 7.49/12.64 x 563
Partial pressure of N2 = 333.6 atm
The, the partial pressure of nitrogen, N2 is 333.6 atm
Which of the following is not a technique that could be used to separate a mixture into its components?
a) stirring.
b) decanting.
c) filtration.
d) distillation.
e) none of the above.
Answer:
Mixtures can be physically separated by using methods that use differences in physical properties to separate the components of the mixture, such as evaporation, distillation, filtration and chromatography.
Explanation:
You are very much welcom
Answer:
stirring. because it will mixup together
A force of 26.4lb is applied to an area of 1.71 in2. What is the pressure?
A) 15.4 lb/in2
B) 0.0648 lb/in2
C) 45.1 lb/in2
D) 22.8 lb/in2
Answer:
Pressure, P = 15.4 lb/in²
Explanation:
Given that,
Force applied, F = 26.4 lb
Area of cross section, A = 1.71 in²
To find,
Pressure.
Solution,
Pressure is equal to force per unit area of cross section.
[tex]P=\dfrac{F}{A}\\\\P=\dfrac{26.4\ lb}{1.71\ in^2}\\\\P=15.43\ lb/in^2\\\\P=15.43\ Pa[/tex]
Hence, the correct option is (a) "15.4 lb/in²".
What are three ways that a solid, liquid, gas and plasma are different?
Answer:
like, plasmas have no fixed shape or volume, and are less dense then solid or liquids but unlike ordinary gases, plasma are made up of atoms in which some or all of the electrons have been stripped away and positively charged nuclei, called ions, roem freely
How much heat, in kJ, will be absorbed by a 25.0 g piece of aluminum (specific heat = 0.930 J/g･°C) as it changes temperature from 25.0°C to 76.0°C?
Answer:
quantity of heat=mc*theta
=25*0.930(76-25)
=25*0.930*51
=1185.75J
=11.9kJ
Answer:
1.19kJ
Explanation:
The heat can be calculated using the specific heat capacity, mass, and the change in temperature.
q=mxcxΔT=(25.0g)×(0.930Jg⋅∘C)×(76.0−25.0∘C)=1186J
Finally, the heat can be converted from J into kJ using the metric conversion factor.
1186J×1kJ1000J=1.19kJ
The numbers of nucleons required to generate complete shells in the nucleus are called:
A. nuclear numbers
B. shell numbers
C. special numbers
D. magic numbers
Answer:
The correct answer is option D, that is, magic numbers.
Explanation:
The magic number in nuclear physics refers to the number of nucleons, that is, either neutrons or protons, distinctly, such that their alignment results in the formation of complete shells within the nucleus of the atom. As a consequence, atomic nuclei comprising a magic number of neutrons or protons are much more stable in comparison to other nuclei.
The seven most broadly known magic numbers are 2,8,20,28,50,85 and 126.
What is the atom inventory for the following equation after it is properly balanced? ____K2S + ____CoCl2 Imported Asset ____KCl + ____CoS
Reactants: K = 2, S = 1, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2 Reactants: K = 2, S = 2, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 1 Reactants: K = 2, S = 2, Co = 1, Cl = 2; Products: K = 2, S = 2, Co = 1, Cl = 1 Reactants: K = 2, S = 1, Co = 2, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2
Answer:
Reactants: K = 2, S = 1, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2
Explanation:
The reaction is a double replacement reaction so the anions (Cl⁻ and S²⁻) switch places.
1 K₂S + 1 CoCl₂ ⇒ 2 KCl + 1 CoS (balanced chemical equation)
On the reactants and products side, K = 2, S = 1, Co = 1, and Cl = 2.
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The product of the reaction between Aluminium Oxide (Al2O3) and Carbon (C) is Aluminium (Al) and carbon monoxide (CO). The reaction of 60.0 g of Al2O3 with 30.0 g of C produced 22.5 g of Al. What is the percent yield for this reaction?
Answer:
Percent yield = 70.8%
Explanation:
Equation of the reaction:
Al2O3 + 3C ----> 2Al + 3CO
From the reaction equation, 1 mole of Aluminum oxide produces 2 moles of Aluminum when reacted with 3 moles of carbon.
Molar mass of Aluminum oxide = 102 g; molar mass of Aluminum = 27 g; molar mass of C = 12
3 moles of C = 36 g
2 moles Al = 54 g
102 g of Al2O3 reacts with 36 g of C
60 g of Al2O3 will react with (36/102) × 60 g of C = 21.2 g of C
Therefore, Al2O3 is the limiting reactant while C is in excess.
102 g of Al2O3 produces 54 g of Al
60 g of Al2O3 will produce (54/102) × 60 of Al = 31.8 g of Al
Percent yield = (actual yield/ theoretical yield) × 100%
Percent yield = (22.5 g / 31.8 g) × 100%
Percent yield = 70.8 %
Identify the following salts as neutral, acidic, or basic. Drag each item to the appropriate bin.
1. LiF
2. SrBr2
3. NH4CN
4. NH4Br
5. KCN
6. NH4ClO4
7. LiNO3
A. Neutral salts.
B. Acidic salts.
C. Basic salts.
Answer:
A. Neutral salts. (7, 2)
B. Acidic salts. (4, 6)
C. Basic salts. (1, 3, 5)
Explanation:
We must know where, do the ions come from. If they come from a weak acid or base, they can make hydrolysis in water, so OH⁻ and H⁺ are given to medium.
1. LiF → Li⁺ + F⁻
F⁻ + H₂O ⇄ HF + OH⁻
F⁻ can make the hydrolysis, and it gives OH⁻. Salt is basic.
2. SrBr₂ → Sr²⁺ + 2Br⁻
Both are weak and they can not hydrolyse. This salt is neutral.
3. NH₄CN → NH₄⁺ + CN⁻
Both ions are strong, so they can make the hydrolysis. The thing is, while the ammonium gives protons, the cyanide give hydroxides. To determine how's the salt, we need to compare the Ka and Kb.
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka = 5.7×10⁻¹⁰
CN⁻ + H₂O ⇄ HCN + OH⁻ Kb = 1.61×10⁻⁵
As Kb > Ka, pH is basic.
If Ka > Kb, pH would be acidic.
4. NH₄Br → NH₄ + Br⁻
Br⁻ does not hydrolize. The ammonium cation, reacts in water to give protons to medium that's why the salt will be acidic.
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka
5. KCN → K⁺ + CN⁻
K⁺ does not hydrolize. The cyanide anion, reacts in water to give hydroxides to medium that's why the salt will be basic.
CN⁻ + H₂O ⇄ HCN + OH⁻ Kb
6. NH₄ClO₄ → NH₄⁺ + ClO₄⁻
ClO₄⁻ comes from the perchlroric acid (a strong acid). It does not hydrolyze
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka
Ammonium gives H⁺ to medium so the salt is acidic.
7. LiNO₃ → Li⁺ + NO₃⁻
Both ions does not make hydrolysis. They come from a strong base and a strong acid, so they are the conjugate weak acid and base, respectively.
The salt in this case, will be neutral.
Determine the standard enthalpy of formation in kJ/mol for NO given the following information about the formation of NO2 under standard conditions, and (NO2) = + 33.2 kJ/mol. Keep one decimal point. 2 NO(g) + O2(g) → 2 NO2(g) ∆Hrxn = –114.2 kJ
Answer:
90.3 kJ/mol
Explanation:
Let's consider the following thermochemical equation.
2 NO(g) + O₂(g) → 2 NO₂(g) ∆H°rxn = –114.2 kJ
We can find the standard enthalpy of formation for NO using the following expression.
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g)) - 1 mol × ΔH°f(O₂(g))
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g)) - 1 mol × 0 kJ/mol
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g))
ΔH°f(NO(g)) = (2 mol × ΔH°f(NO₂(g)) - ∆H°rxn) / 2 mol
ΔH°f(NO(g)) = (2 mol × 33.2 kJ/mol + 114.2 kJ) / 2 mol
ΔH°f(NO(g)) = 90.3 kJ/mol
At a fixed volume, a four-fold increase in the temperature of a gas will lead to _______ in pressure.
Answer:
Increase in pressure
Explanation:
The rise in temperature will increase the pressure of the gas.
Answer:
increase is ur answer
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A 500.0-mL buffer solution is 0.10 M in benzoic acid and 0.10 M in sodium benzoate and has an initial pH of 4.19. What is the pH of the buffer upon addition of 0.010 mol of NaOH?
Answer:
pH after the addition of NaOH is 4.37
Explanation:
When the amount of the weak acid = Amount of the conjugate base (As in the problem) pH = pKa. That means pKa of benzoic buffer is 4.19.
Now, to solve the pH of the buffer we need to use H-H equation for benzoic buffer:
pH = pKa + log [Benzoate] / [Benzoic acid]
pH = 4.19+ log [Benzoate] / [Benzoic acid]
You can take [] concentrations as the moles of both species.
When you add NaOH to the buffer, it reacts with benzoic acid producing more sodium benzoate and water, thus:
NaOH + Benzoic Acid → Sodium benzoate + Water.
Before the reaction, moles of benzoic acid and sodium benzoate were:
500.0mL = 0.500L × (0.10mol / L) = 0.050 moles
After the reaction, 0.010 moles of Benzoic acid are consumed and the same 0.010 moles of sodium benzoate are produced. That means moles of both species after reaction are:
[Benzoate] = 0.050 moles + 0.010 moles = 0.060 moles
[Benzoic acid] = 0.050 moles - 0.010 moles = 0.040 moles
Replacing in H-H equation:
pH = 4.19+ log [Benzoate] / [Benzoic acid]
pH = 4.19+ log [0.060mol] / [0.040mol]
pH = 4.37
pH after the addition of NaOH is 4.37