The electron configuration for Helium (He) is shown below.
152
Which diagram shows the correct distribution of electrons in the electron shells of a helium atom?
1P
ON
2 electrons in the atomic shell
Further explanationHelium belongs to the noble gas group (group 18), s block and period 1
Electron configuration: 1s²
Symbol: ₂He⁴
With atomic number 2 and mass number 4, the composition of the subatomic particles is:
2 protons, 2 electrons, and 2 neutrons
2 protons and 2 neutrons make up the atomic nucleus while 2 electrons are in the atomic shell
An aqueous solution contains dissolved and . The concentration of is 0.50 M and pH is 4.20. Calculate the concentration of in this buffer solution.
Here is the correct format for the question.
An aqueous solution contains dissolved [tex]\mathbf{C_6H_5NH_3Cl}}[/tex] and [tex]\mathbf{C_6H_5NH_2}[/tex]. The concentration of [tex]\mathbf{C_6H_5NH_2}[/tex] is 0.50 M and pH is 4.20. Calculate the concentration of [tex]\mathbf{C_6H_5NH_3^+}[/tex] in this buffer solution. [tex]\mathbf{K_b = 3.8 \times 10^{-10}}[/tex]
Answer:
[tex]\mathbf{C_6H_5NH_3^+ = 1.1995 M }[/tex]
Explanation:
From the above information:
[tex]pKb \ of \ C _6H_5NH_2 = -log(3.8 \times 10^{-10})[/tex]
[tex]pKb \ of \ C _6H_5NH_2 = 9.42[/tex]
pH = 4.20
pOH = 14 - pH
pOH = 14 - 4.20 = 9.8
According to Henderson Hasselbalch equation
[tex]pOH = pKb + log \dfrac{[C_6H_5NH_3^+]}{[C_6H_5NH_2]}[/tex]
[tex]9.8 = 9.42 + log \dfrac{[C_6H_5NH_3^+]}{(0.50)}[/tex]
[tex]9.8-9.42 = log \dfrac{[C_6H_5NH_3^+]}{(0.50)}[/tex]
[tex]0.38 = log \dfrac{[C_6H_5NH_3^+]}{(0.50)}[/tex]
[tex]10^{0.38} = \dfrac{[C_6H_5NH_3^+]}{(0.50)}[/tex]
[tex]2.399 = \dfrac{[C_6H_5NH_3^+]}{(0.50)}[/tex]
[tex]C_6H_5NH_3^+ = 2.399 \times(0.50)[/tex]
[tex]\mathbf{C_6H_5NH_3^+ = 1.1995 M }[/tex]
What kind of reaction is this? C5H8 + 7O2 --> 5CO2 + 4H2O
A. Decomposition
B. Combustion
C. Single replacement
D. Combination
Answer:
B. Combustion .
Explanation:
Hello.
In this case, since this reaction is started by pentyne and oxygen which are converted to carbon dioxide and water, we can infer this is a combustion reaction because it involves the burnt of a fuel, in this case the pentyne, by using oxygen in order to yield carbon dioxide and water, which are smaller molecules than the original pentyne.
It is important to notice that these reactions are very exothermic because they go to break the C-H bonds in the fuel which release a considerably high amount of energy.
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4.60 g of 3-hexanol were obtained from 5.33 g of hex-3-ene. Determine the percentage yield of 3-hexanol. a Determine the moles of hex-3-ene, , used in the experiment. (To avoid introducing rounding errors on intermediate calculations, enter your answer to four significant figures.)
Answer:
Explanation:
C₆H₁₂ + H₂O = C₆H₁₃OH
hexene hexanol
1 mole 1 mole
Mol weight of hexene = 84
Mol weight of hexanol = 102
5.33g of hexene = .06345 moles
4.6 g of hexenol = .0451 moles
percentage yield of hexanol
= .0451 x 100 / .06345
= 71.07 %
Moles of hexene used = .0451 moles
A chemist must prepare 650.0mL of sodium hydroxide solution with a pH of 13.90 at 25°C. He will do this in three steps:
Answer:
1. Weigh 3.27 ×10⁻⁴ ng of NaOH in a special balance for weighing in nanograms
2. Measure a volume of 650 mL in a test tube
3. Make the solution by mixture
Explanation:
NaOH is a strong base. As every strong base, can be completely dissociated:
NaOH → Na⁺ + OH⁻
If pH is 13.90, we can calculate the [OH⁻], so we would know the molarity of NaOH.
1 mol of NaOH can generate 1 mol of OH⁻
[OH⁻] = 10⁻¹³'⁹ = 1.26×10⁻¹⁴ M
In conclussion, molarity of NaOH is 1.26×10⁻¹⁴ M
M = moles of NaOH / volume of solution
We convert the volume from mL to L
650 mL . 1 L /1000mL = 0.650 L
Moles of NaOH = 0.650 L . 1.26×10⁻¹⁴ M = 8.18×10⁻¹⁵ moles
We convert the moles to mass, to determine the grams:
8.18×10⁻¹⁵ moles . 40 g/mol = 3.27 ×10⁻¹³ g
We can convert the grams to ng = 3.27 ×10⁻⁴ ng
When temperature drops, particle speed decreases.
True?
False?
yes they decrease when the temperature drops so it's true
An iron ore sample contains plus other impurities. A 896-g sample of impure iron ore is heated with excess carbon, producing 182 g of pure iron by the following reaction: What is the mass percent of FeO2 in the impure iron ore sample
Answer:
20.3%
Explanation:
Given mass of impure ore = 896g and mass of pure iron to be 182g after purification,
[tex]\frac{(896-182)g}{896}[/tex] × 100
= 79.7%
in subtracting the weight of impure mass from that of the pure sample, we are left with the mass of the impurities alone.
This means the mass percent of pure iron in this iron ore sample is 20.3%.
Let me know if this was helpful.
Explain what is wrong with the following structure.
HH—0:
Answer:
for the Lewis diagram of water, hydrogens should go on the outside with oxygen in the center
Explanation:
hydrogens always go on the outside
What is the wavelength (in nanometers) of a photon emitted during a transition from ni = 7 to nf = 3 state in the H atom?
Answer:
[tex]\mathbf{\lambda = 1.01 \times 10^{3} \ nm}[/tex]
Explanation:
To determine the wavelength; let's first calculate the energy (E) change of the transition by using the Rydberg constant [tex](R_H)[/tex]
[tex]\Delta E = R_H ( \dfrac{1}{n_i^2}- \dfrac{1}{n_f^2})[/tex]
[tex]\Delta E = 2. 18 \times 10^{-18} \ J ( \dfrac{1}{7^2}- \dfrac{1}{3^2})[/tex]
[tex]\Delta E = 1.977 \times 10^{-19 } \ J[/tex]
Now; to calculate the wavelength by using the formula:
[tex]\lambda = \dfrac{c*h}{\Delta E}[/tex]
[tex]\lambda = \dfrac{(3.00 \times 10^8 \ m/s) *(6.63 \times 10^{-34} \ J.s)}{1.977 \times 10^{-19 } \ J}[/tex]
[tex]\lambda = 1.01 \times 10^{-6} \ m[/tex]
To nanometers; we have:
[tex]\lambda = 1.01 \times 10^{-6} \ m \times \dfrac{1 \ nm}{ 1 \times 10^{-9} \ m}[/tex]
[tex]\mathbf{\lambda = 1.01 \times 10^{3} \ nm}[/tex]
How many degrees along its orbit does the Moon travel between new moons?
Answer:
The moon orbits quite fast: it moves about 0.5 degrees per hour in the sky. In 24hrs it moves 13 degrees. the moons observed motion eastward results from its physical motion of the moon along its orbit around the earth
Plz mark brainliest
If an acyclic alkane hydrocarbon contains n carbon atoms, how many hydrogen atoms must it also contain
Answer: The answer is 2n+2
Explanation:
the general formula for defining an Alkane is [tex]CnH2n+2[/tex]
Hence for each n carbon there will be 2n+2 hydrogens present in the hydrocarbon.
1. What surface would reflect light the best?
Answer:
Glass mirror
Explanation:
The chemical formula for a molecule that contains two chlorine (Cl) atoms is
Chlorine is a halogen gas element which has atomic number 17 which is in group 17, p block and period 3
The electron configuration of Cl : [Ne] 3s² 3p⁵ ⇒ 2, 8, 7
So the valence electron is 7, so to achieve stability you will need 1 more electron so it is stable like Argon
Cl will be covalently bonded (using shared electron pairs) with other Cl atoms to form a non-polar molecule, namely Cl₂
what is listed on the right side of a chemical equation
Explanation:
The substances that "go in" to a chemical reaction are called the reactants (by convention these are usually listed on the left side of a chemical equation), and the substances found that "come out" of the reaction are known as the products (by convention these are usually found on the right side of a chemical equation
Answer: The reactants that go into the chemical reaction are on the left of the equation. The substances that come out of the chemical reaction are usually on the right side of the equation.
Hope it helps!
Where are metals found on the periodic table?
O Metals are on the far left side of the periodic table
Metals are found on the left side/middle
O Metals are on the bottom two rows of the periodic table
Metals are found on the stairstep line
1. How is a covalent bond formed?
When electrons between atoms are transferred
When electrons between atoms are shared.
When electrons are subtracted from atoms.
When electrons are added to atoms.
Plz help ASAP I will give brainliest to the first answer!!
An element that is usually a gas or brittle solid at room temperature, that is not ductile or malleable. Also it doesn’t conduct heat or electricity well.
A. Lithium
B. Arsenic
C. Nitrogen
D. Cobalt
What are two important characteristics of the silica gel and alumina that are used for column chromatography
Answer:
Two important characteristics of the silica gel and alumina that are used for column chromatography-:
Uniform particle sizeHigh specific areaExplanation:
The adsorbent must be thinly split in column chromatography to provide a well packed column that serves as a stationary step.
The silica gel and alumina qualities that render them appropriate as column chromatography adsorbents are-:
Have a uniform particle size that guarantees uniform column packaging. A highly specific area in which a rapid balance is formed between the mobile phase and the stationary phase.Explain how cells are the basic unit of all living things
Answer:A cell is the smallest unit of a living thing. A living thing, whether made of one cell (like bacteria) or many cells (like a human), is called an organism. Thus, cells are the basic building blocks of all organisms. ... Several systems that function together form an organism (like a human being).
Hope this helped! If it did leave a brainliest.
Have an amazing night/day!
Which scientist determined that electrons had predicted zones orbiting the nucleus?
Rutherford
Bohr
Dalton
Schrödinger
Marthie
Answer:
Bohr
Explanation:
Neils Bohr was the scientist that suggested that electrons follow predictable orbits round the nucleus.
In 1913, he put forward his own model of the atom based on the quantum mechanics originally developed by Planck. He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus. The orbits/energy levels are designated as K, L, M, N.....Answer:
schrodinger
Explanation:
jelly benee
Calculate the mass of sodium acetate that must be added to 500.0 mL of 0.300 M acetic acid to form a pH
Answer:
22.4 g
Explanation:
Calculate the mass of sodium acetate that must be added to 500.0 mL of 0.300 M acetic acid to form a pH = 5.00 buffered solution.
Step 1: Given data
Volume of solution: 500.0 mL
[acetic acid]: 0.300 M
pH = 5.00
pKa of acetic acid: 4.74
Step 2: Calculate the concentration of sodium acetate
We will use the Henderson-Hasselbach equation.
pH = pKa + log [sodium acetate]/[acetic acid]
5.00 = 4.74 + log [sodium acetate]/0.300 M
[sodium acetate] = 0.546 M
Step 3: Calculate the moles of sodium acetate
We have 500.0 mL of a 0.546 M sodium acetate solution
0.5000 L × 0.546 mol/L = 0.273 mol
Step 4: Calculate the mass of sodium acetate
The molar mass of sodium acetate is 82.03 g/mol.
0.273 mol × 82.03 g/mol = 22.4 g
Iodine – 125 emits gamma rays when it decays to Tellerium-125 and has a half-life of 60 days. If a 0.020 g pellet of iodine – 125 is implanted into a prostate gland, how much iodine – 125 remains there after one year
Answer:
0.0003125 g
Explanation:
Given data:
Half life of iodine-125 = 60 days
Mass of iodine pellet = 0.020 g
Mass of iodine remain after one year = ?
Solution:
one year = 365 days
Number of half lives = Time elapsed/ half life
Number of half lives = 365 days/ 60 days
Number of half lives = 6
At time zero = 0.020 g
At 1st half life = 0.020 g/2 = 0.01 g
At 2nd half life = 0.01 g / 2 = 0.005 g
At 3rd half life = 0.005 g/2 = 0.0025 g
At 4th half life = 0.0025 g / 2 = 0.00125 g
At 5tht half life = 0.00125 g / 2 = 0.000625 g
At 6th half life = 0.000625 g/ 2 = 0.0003125 g
If 18.2 of 0.800 solution are needed to neutralize 5.00 of a household ammonia solution, what is the molar concentration of the ammonia
Answer:
2.91M is the concentration of the household ammonia solution
Explanation:
18.2mL of a 0.800M HCl solution to neutralize 5.00mL
The reaction of HCl with NH3 is:
HCl + NH3 → NH4Cl
Thus, the moles of HCl needed to neutralize the household are equal to moles of NH3. That is:
18.2mL = 0.0182L * (0.800mol / L) = 0.01456 moles HCl = Moles NH3.
In 5.00mL = 0.005L:
0.01456 moles NH3 / 0.005L =
2.91M is the concentration of the household ammonia solutionWhat does this image represent? (5 points)
-Formation of ionic bonds in water
-Formation of covalent bonds in water
-Transfer of valence electrons from oxygen to hydrogen
-Sharing of valence electrons between two hydrogen atoms
There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, the correct option is option B that is formation of covalent bonds in water.
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.
An ionic compound is a metal and nonmetal combined compound. Ionic compound are very hard. They have high melting and boiling point because of strong ion bond.
The given image represents the formation of covalent bonds in water. Water is a covalent compound having covalent bond between oxygen and hydrogen.
Therefore, the correct option is option B that is formation of covalent bonds in water.
To learn more about chemical compound, here:
brainly.com/question/26487468
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Imagine an element that has 15 protons, 16 neutrons, and 18 electrons. Which of the following would NOT be considered an isotope of this element? *
15 protons, 16 neutrons, and 15 electrons
15 protons, 17 neutrons, and 15 electrons
15 protons, 15 neutrons, and 18 electrons
Answer:
Explanation:
Option 1 15. Proton 16 neutron 15 electron
Isotopes have same atomic no but different atomic mass
Which reaction product (A or B) is more likely to form in the epoxide ring opening reaction? Consider resonance structures.
Answer:
Reaction product A is more likely to form in the epoxide ring-opening reaction
Explanation:
The diagram for the reaction can be seen in the image attached below.
An epoxide is any class of organic compound, cyclic ethers, having a three-membered ring; they are usually prepared by selective oxidation of alkenes or by ring-closure of halohydrins(any class of organic compound having a hydroxyl functional group and a halogen on neighboring carbon atom ) which are used in making plastic.
What is another way scientists find planets being blocked by the light of a star?
PLEASE ANSWER!
Answer:
The Short Answer: All of the planets in ... Planets that orbit around other stars are called exoplanets. All of the ... So, astronomers use other ways to detect and study these distant planets.
A gas occupies 1.00 L at 273 K. What is the volume at 606 °C?
Answer:
3.22 L
Explanation:
0.00 C = 273 K
k = C +273
606 K + 273 K = 879 K
879/273 = 3.219
V2 = 3.22 L
we want to prepare an acetate buffer of pH 6.420 from a 0.664 M acetic acid solution pKa =4.752 and a 2.50 M KOH solution. If we have 975 ml of the acetic acid solution, how many milliliters of the KOH solution do we need to add to make a buffer of pH 6.42?
Answer:
253.5mL must be added
Explanation:
To find pH of a buffer we need to use H-H equation:
pH = pKa + log [Acetate] / [Acetic acid]
Where pH is pH we want: 6.42; pKa is 4.752 and [] could be taken as moles of each species.
6.42 = 4.752 + log [Acetate] / [Acetic acid]
1.668 = log [Acetate] / [Acetic acid]
46.5586 = [Acetate] / [Acetic acid] (1)
And moles of acetate buffer = Initial moles of acetic acid are:
975mL = 0.975L * (0.664mol / L) = 0.6474 moles acetate buffer =
0.6474 = [Acetate] + [Acetic acid] (2)
Replacing (2) in (1):
46.5586 = 0.6474 - [Acetic Acid] / [Acetic acid]
46.5586 [Acetic acid] = 0.6474 - [Acetic Acid]
47.5586 [Acetic acid] = 0.6474
[Acetic acid] = 0.01361 moles
And [Acetate]: 0.6474 - 0.01361moles
[Acetate] = 0.63379moles
Now, in the beginning we have just Acetic acid that is converted in acetate with the use of KOH:
Acetic acid + KOH → Acetate
That means the moles of KOH added are the moles of acetate we need. That means we need to add 0.63379 moles of KOH that comes from a 2.50M. The volume is:
0.63379 moles KOH * (1L / 2.50 moles) = 0.2535L =
253.5mL must be addedSpecialist species can respond more easily to changing environmental conditions tan can generalist species OTrue O False
Answer:
false
Explanation:
