Answer:
Electron pair geometry - tetrahedral
molecular geometry- trigonal pyramidal
Explanation:
According to Valence Shell Electron Pair Repulsion Theory, the shape of a molecule is determined by the number of electron pairs around the central atom in the molecule. Lone pairs distort a molecule away from its expected geometry based on VSEPR. This is why the electron pair geometry differs from the actual molecular geometry.
PCl3 has four regions of electron density, three substituents and one lone pair hence its electron pair geometry is tetrahedral. However, the three substituents are arranged in a trigonal pyramidal geometry(its molecular geometry).
A molecule has a molar mass of 22.45 g/mol. What is the mass of 4.12*10^24 of the molecules?
Answer:
153.56g
Explanation:
Number of moles = mass/molar mass
To get the number of moles of the molecule, we divide the number of molecules contained by Avagadro's number, which is 6.02 × 10^23 molecules.
moles = 4.12 × 10^24 ÷ 6.02 × 10^23
number of moles = 0.684 × 10^(24-23)
number of moles = 0.684 × 10^(1)
number of moles = 6.84mol
If the molar mass of the molecule is 22.45 g/mol, the mass of the molecule can be calculated thus:
mass = moles × molar mass (MM)
mass = 6.84 × 22.45
mass = 153.558
mass = 153.56g
The combustion of ethyne, shown below unbalance, produces heat which can be used to weld metals:
C2H2 (g) +502 (g) →2CO: (g) +H20 (g) AH reaction= -1544kJ
How much ethyne gas (in g) would you need to react with excess oxygen according to this reaction in order to raise the temperature of 325 g of high carbon steel from 165'C to its melting point, 1540 C? The heat capacity of high carbon steel is 0.490 J/g'C. (Assume a complete reaction and that all heat is transferred from the reaction to the metal with no loss.)
a. 7.37g
b. 1.84 g
c. 4.13 g
d 3.69 g
Answer:
3.69 g
Explanation:
Given that:
The mass m = 325 g
The change in temperature ΔT = ( 1540 - 165)° C
= 1375 ° C
Heat capacity [tex]c_p[/tex] = 0.490 J/g°C
The amount of heat required:
q = mcΔT
q = 325 × 0.490 × 1375
q = 218968.75 J
q = 218.97 kJ
The equation for the reaction is expressed as:
[tex]C_2H_{2(g)} + 5O_{2(g)} \to 2CO_{2(g)} + H_2O_{(g)} \ \ \ \ \ \Delta H^o_{reaction} = -1544 \ kJ[/tex]
Then,
1 mole of the ethyne is equal to 26 g of ethyne required for 1544 kJ heat.
Thus, for 218.97 kJ, the amount of ethyne gas required will be:
[tex]= \dfrac{26 \ g}{1544 \ kJ} \times 218.97 \ kJ[/tex]
= 3.69 g
A student makes observations of a tree in a nearby forest. Which of the following observations of the
tree's characteristics would be useful in determining its identity with a dichotomous key?
A
It contains the nests of several birds.
B
Its leaves are long and narrow.
с
Its branches were recently cut.
D
It provides shade for ground brush.
The observations of the tree's characteristics would be useful in determining its identity with a dichotomous key is its leaves are long and narrow. The correct option is B.
What is an observation?Observation is a process of recognizing and recording an event or fact that frequently involves measuring it with tools. Recognizing and recording an event, or fact frequently involves measuring with tools. Field notes are written observations made while participating in field observations or immediately afterward.
They are crucial for understanding phenomena that have been seen in the field. Field notes frequently take the form of scratch notes, diaries, and notebooks. In the scientific field, observation is a crucial step.
Therefore, the correct option is B. Its leaves are long and narrow.
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PLUS 30 PT
Why does DNA dissolve in water?
Why is salt added to solution of DNA and water?
How does ethanol help the precipitate form?
After a pellet is formed, is the DNA in the pellet or the supernate?
Explanation:
Because of this, DNA and RNA can easily dissolve in water. ... Adding ethanol helps the Na+ and PO3- ions come together, because ions travel easier in ethanol than water. The supernate is removed and new ethanol is added in the second washing. This removes any residual salt that remained on the pelleted DNA.
Answer:
DNA is polar due to its highly charged phosphate backbone. Its polarity makes it water-soluble (water is polar) according to the principle "like dissolves like". ... This fact makes water a very good solvent for charged compounds like salts.
Your DNA's sugar phosphate backbone is charged. By adding salt, we help neutralize the DNA charge and make the molecule less hydrophilic, meaning it becomes less soluble in water. The salt also helps to remove proteins that are bound to the DNA and to keep the proteins dissolved in the water.
It is well known that Ethanol has a lower dielectric constant than water, making it to promote ionic bond formations between the Na+ (from the salt) and the PO3- (from the DNA backbone), further, causing the DNA to precipitate.
Explanation:
Ideally DNA needs to be precipitated with pellet and should not remain in supernatant. DNA is acidic in nature and therefore, needs optimum salt concentration in the buffer to be pelleted from a solution. At very low salt concentration or without salt DNA would remain in supernatant.
You want to calculate the average atomic mass of a sample of Nickle. There are 32 atoms of Nickle-60 and 89 atoms of Nickle-57.
What is the percent distribution of Nickle-60?
What is the percent distribution of Nickle-57?
What is the average atomic mass of the sample? Round to the correct number of decimals and include units?
Answer:
Average atomic mass = 57.79 amu
Percent contribution of Ni-60 = 26.45%
Percent contribution of Ni-5 = 73.55%
Explanation:
Given data:
Number of atoms of Ni-60 = 32
Number of atoms of Ni-57 = 89
Percent distribution of both isotopes = ?
Average atomic mass of sample = ?
Solution:
Percent contribution:
Total number of atoms = Ni-60 + Ni-57
Total number of atoms = 32 +89 = 121
Percent contribution of Ni-60 = 32/121×100
= 26.45%
Percent contribution of Ni-57 = 89/121×100
= 73.55%
Average atomic mass:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass = (26.45×60)+(73.55×57) /100
Average atomic mass = 1587 + 4192.35 / 100
Average atomic mass = 5779.35 / 100
Average atomic mass = 57.79 amu.
During homogeneous catalysis, if a catalyst is present in the liquid phase, which phase must the reactants be in?
Answer:
The reactants must be in the liquid phase.
Explanation:
Homogeneous means that something is of the same nature.
In the context of catalysis, it means that the catalyst and the reactants are in the same phase.
If the catalyst is in the solid phase, the reactants are solids are well.
If the catalyst is in the liquid phase, then the reactants are also in the liquid phase.
And so on.
At what temperature is water a gas
Answer:
212 degrees Fahrenheit
Explanation:
When liquid water reaches a low enough temperature, it freezes and becomes a solid—ice. When solid water is exposed to enough heat, it will melt and return to a liquid. As that liquid water is further heated, it evaporates and becomes a gas—water vapor.
A metal is found that has a mass of 27g and will displace 6mL of water. Calculate its density and identify the metal.
The density of metal = 4.5 g/ml, and the metal = Titanium
Further explanationDensity is a quantity derived from the mass and volume
Density is the ratio of mass per unit volume
Density formula:
[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]
ρ = density
m = mass
v = volume
mass of metal=27 g
volume = 6 ml
The density :
[tex]\tt \rho=\dfrac{27}{6}\\\\\rho=4.5~g/ml[/tex]
The metal with a density of 4.5 g/ml is Titanium
Based on the activity series provided, which reactants will form products? F > Cl > Br > I CuI2 + Br2 Right arrow. Cl2 + AlF3 Right arrow. Br2 + NaCl Right arrow. CuF2 + I2 Right arrow.
Answer: Cul2 + Br2 ->
Explanation:
Answer:
i believe the answer is a
Explanation:
g Which statement concerning the structure of the atom is correct? Protons and neutrons have most of the mass and occupy most of the volume of the atom. Electrons have most of the mass but occupy very little of the volume of the atom. Electrons have most of the mass and occupy most of the volume of the atom. Protons and neutrons have most of the mass but occupy very little of the volume of the atom.
Protons and neutrons have most of the mass but occupy very little of the volume of the atom.
The statement concerning the structure of the atom is correct is Protons and neutrons have most of the mass but occupy very little of the volume of the atom. Therefore, option D is correct.
What is an atom ?Each atom is made up of a nucleus and one or more electrons that are linked to it. One or more protons and a significant number of neutrons make up the nucleus. Only the most prevalent type of hydrogen is neutron-free. Atoms that are neutral or ionized make up every solid, liquid, gas, and form of plasma.
But when it comes to the name atom, we must travel back to 400 B.C. ancient Greece. The Greek word atomos, which meaning "uncuttable," was proposed by Democritus, a renowned philosopher. In the end, all matter could be reduced to distinct, tiny particles, or atomos, he said.
The smallest unit of matter that may be divided without producing electrically charged particles is the atom.
Thus, option D is correct.
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The only sure evidence for a chemical reaction is
Answer:
that one or more new substances are produced. Temperature Changes Chemical reactions can release energy or absorb energy.
Explanation: .
Percent yield is very important in terms of money. The higher the percent yield, the more of a product you can make. If you are working for a drug company and your theoretical yield is 120 kg, but you actually made 105 kg, what is your percent yield?
A. 8.75%
B. 114%
C. 87.50%
D. 15.00%
Answer:
87.5 %
Explanation:
Step 1: Given data
Theoretical yield: 120 kgReal yield: 105 kgStep 2: Calculate the percent yield
When working with chemical reactions, we can determine the efficience in obtaining a product measuring the percent yield. The theoretical yield is the maximum amount of product that we could obtain according to the stoichiometry, whereas the real yield is the amount of product that we actually obtain when we carry out the process. We can calculate the percent yield usign the following expression.
%yield = real yield / theoretical yield × 100%
%yield = 105 kg / 120 kg × 100%
%yield = 87.5 %
How high of a Frequency would a photon have to be for it to have an energy of 4 joules
The frequency of photon=6.03 x 10³³ /s
Further explanationRadiation energy is absorbed by photons
The energy in one photon can be formulated as
[tex]\large{\boxed{\bold{E\:=\:h\:.\:f}}}[/tex]
Where
h = Planck's constant (6,626.10⁻³⁴ Js)
f = Frequency of electromagnetic waves
Energy of photon = 4 J
So the frequency :
[tex]\tt f=\dfrac{E}{h}\\\\f=\dfrac{4}{6.626.10^{-34}}\\\\f=6.03.10^{33}/s[/tex]
Decide which element probably has a boiling point most and least similar to the boiling point of aluminum.
Comparing boiling point:
gallium rubidium magnesium oxygen
most similar to aluminum
least similar to aluminum
Answer:
The boiling point of gallium would be most similar to aluminum, and the boiling point of oxygen would be least similar to aluminum.
Explanation:
The atomic number of aluminum is 13, in the periodic table, magnesium lies in a similar period as Aluminum and Gallium is also present in a similar group. Thus, it can be expected that both magnesium and gallium exhibits similar boiling points with aluminum. However, gallium is a poor non-metal just like aluminum, while magnesium is a metal. Thus, it can be said that the boiling point of aluminum is more similar to gallium.
Now of the given elements, oxygen is a gas, thus, the boiling point of oxygen would be least similar to aluminum.
Calculate the molar mass of Ga(NO3)3
255.732 g/mol
159.738 g/mol
227.718 g/mol
131.727 g/mol
Answer:
255.732 g/mol
Explanation:
Molar mass of Ga(NO3)3 = 255.7322 g/mol. This compound is also known as Gallium(III) Nitrate.
What is electron affinity?
Answer:
The ability of an atom to accept an electron.
Explanation:
Electron affinity is measured by observing the energy change of a substance when an electron is added to it in its neutral gas form. For example, elements that are on the far right of the periodic table (excluding noble gases) are more likely to accept electrons rather than give them up. This is why Fluorine has the highest electron affinity of all atoms on the periodic table.
Which model of the solar system is shown here?
Answer: C
Explanation: hope this helps
The model of the solar system that is shown here is:
C. Geometric model
Model for description of earth and other entites
Geometric model:In astronomy, the geocentric model is a superseded description of the Universe with Earth at the center. Under the geocentric model, the Sun, Moon, stars, and planets all orbit Earth.
Characteristics:
the Earth is the focal point of the universe and it is fixed,the planets, the Sun, and the stars spin around the Earth,the circle and the circle are "awesome" shapes, so all movements overhead ought to follow roundabout ways, which can be credited to objects being appended to circular shells.Thus, option C is correct.
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Which is stronger, the strong force (SF) or the electromagnetic force (EMF)? Describe how they battle each other in the nucleus. What would happen if their strengths were reversed?
Answer:uclear Force that holds together the nucleus of an atom. electromagnetic force. ... They are unstable because the Strong Force that would hold them together if the protons and neutrons were closer is weakened because the protons and neutrons get too far apart.
Explanation:
When chemists work with solid materials, we simply weigh out amounts of solid reagents and calculate mole amounts when thinking about stoichiometry. However, when we dissolve a solid (also known as a solute) in a solvent to form a solution, the solute becomes evenly distributed throughout the solution and we need to know how many moles of solute are present in a particular volume of solution.a) A solution is created by dissolving 13.5 grams of ammonium chloride in enough water to make 315 mL of solution. How many moles of ammonium chloride are present in the resulting solution?b) What is the molarity of the solution described above?c) To carry out a particular reaction, you determine that you need 0.0500 moles of ammonium chloride. What volume (mL) of the solution described above will you need to complete the reaction without any leftover NH4Cl?
Answer:
See the answers below
Explanation:
13.5 g of NH4Cl was dissolved in 315 mL of water.
Moles of NH4Cl present in the solution = mass/molar mass
Molar mass of NH4Cl = 54.49 g/mol
a) Moles of NH4Cl = 13.5/54.49
= 0.25 mole
b) Molarity of solution = moles of solute/volume of solution
moles of NH4Cl = 0.25
volume of solution = 315 mL = 0.315 L
molarity = 0.25/0.315
= 0.79 M
c) moles required = 0.0500 mole
molarity = 0.79 M
molarity = moles x volume
volume = molarity/moles
= 0.79/0.0500
= 15.8 L = 15,800 mL
What is the molarity of a NaOH solution if 28.2 mL of a 0.355 M H2SO4 solution is required to neutralize a 25.0-mL sample of the NaOH solution?A) 0.801B) 0.315C) 0.629D) 125E) 0.400
Answer:
A) 0.801
Explanation:
The reaction that takes place is:
2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂OFirst we calculate the H₂SO₄ moles that reacted:
0.355 M * 28.2 mL = 10.011 mmol H₂SO₄Now we convert H₂SO₄ moles to NaOH moles:
10.011 mmol H₂SO₄ * [tex]\frac{2mmolNaOH}{1mmolH_2SO_4}[/tex] = 20.022 mmol NaOHFinally we calculate the molarity of the NaOH solution:
20.022 mmol NaOH / 25.0 mL = 0.801 MSo the answer is option A.
The molarity of the NaOH solution used in the neutralization reaction has been 0.801 [tex]\rm \times\;10^-^3[/tex] M. Thus, option A is correct.
The neutralization reaction has resulted in the formation of the salt and water on reacting an acid with a base. In the neutralization reaction, the strength of acid and base can be given as:
[tex]\rm 2\;NaOH\;+\;H_2SO_4\;\rightarrow\;Na_2SO_4\;+\;H_2O[/tex]
For the neutralization of 1 mole of sulfuric acid, 2 moles of NaOH has been required.
The moles of sulfuric acid can be given as:
Moles = Molarity × Volume
Given, the molarity of acid ([tex]\rm H_2SO_4[/tex]) = 0.355 M
Volume of acid = 28.2 ml = 0.0282 L
Volume of base (NaOH) = 25 ml = 0.025 L
Moles of [tex]\rm H_2SO_4[/tex] = 0.355 × 0.0282 mol
Moles of [tex]\rm H_2SO_4[/tex] = 10.011 mol.
Since, 1 mole [tex]\rm H_2SO_4[/tex] = 2 moles NaOH
10.011 moles [tex]\rm H_2SO_4[/tex] = 10.011 × 2 moles NaOH
10.011 moles [tex]\rm H_2SO_4[/tex] = 20.022 moles NaOH.
The neutralization of 0.355 M [tex]\rm H_2SO_4[/tex] requires 20.022 moles NaOH. The strength of the NaOH solution will be:
Molarity = [tex]\rm \dfrac{Moles}{Volume\;(L)}[/tex]
Molarity of NaOH = [tex]\rm \dfrac{20.022}{0.025}[/tex]
Molarity of NaOH = 0.801 [tex]\rm \times\;10^-^3[/tex] M.
The molarity of the NaOH solution used in the neutralization reaction has been 0.801 [tex]\rm \times\;10^-^3[/tex] M. Thus, option A is correct.
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4. Look at the equation below and determine what fitsI in the empty box.
14 C --> 4 N+
?
re
c. en TH
What belongs in the empty box?
A.
В.
e
D.
Answer:
Beta particles
Explanation:
A beta emission is said to occur when a neutron is converted into a proton. When a beta emission takes place, the daughter nucleus increases it's atomic number by 1. A neutrino is also produced.
Since the mass number remain the same but the daughter nucleus has it's atomic number increased by 1, then the particle is a beta particle.
If 27.3% of a sample of silver-112 decays in 1.52 hours, what is the half-life (in hours to 3 decimal places)?
Answer: The half life of the sample of silver-112 is 3.303 hours.
Explanation:
All radioactive decay processes undergoes first order reaction.
To calculate the rate constant for first order reaction, we use the integrated rate law equation for first order, which is:
[tex]k=\frac{2.303}{t}\log \frac{[A_o]}{[A]}[/tex]
where,
k = rate constant = ?
t = time taken = 1.52 hrs
[tex][A_o][/tex] = Initial concentration of reactant = 100 g
[A] = Concentration of reactant left after time 't' = [100 - 27.3] = 72.7 g
Putting values in above equation, we get:
[tex]k=\frac{2.303}{1.52hrs}\log \frac{100}{72.7}\\\\k= 0.2098hr^{-1}[/tex]
To calculate the half life period of first order reaction, we use the equation:
[tex]t_{1/2}=\frac{0.693}{k}[/tex]
where,
[tex]t_{1/2}[/tex] = half life period of first order reaction = ?
k = rate constant = [tex]0.2098hr^{-1}[/tex]
Putting values in above equation, we get:
[tex]t_{1/2}=\frac{0.693}{0.2098hr^{-1}}\\\\t_{1/2}=3.303hrs[/tex]
Hence, the half life of the sample of silver-112 is 3.303 hours.
Can someone answer 4 for me please?
The red outlined elements have what major characteristics in common?
1 point
Metals, Nonmetals, and Metalloids
One major characteristic they have in common is they are metals.
How many moles are in the 100,000g of CuSO4 • 5H2O ?
Answer:
try (107.87 amu)
Explanation:
What is the electron configuration for N (nitrogen)?
A. 1s22s23s23p1
B. 1s21p5
C. 1s22s22p3
D. 1s22s22p23s1
Explanation:
₇N = 1s² 2s² 2p³
Group = 15period = 2atomic mass = 14Hydride of Nitrogen = Ammoniavalency = 3Therefore,
Option C is correct ✔
The list identifies various properties of four elements:
Element 1 is a gas at room temperature.
Element 2 is a solid which conducts electricity.
Element 3 is a gas with an effective nuclear charge of +7.
Element 4 is malleable and can take the form of a shiny solid sheet.
Based on this list, which elements are metals?
A. Elements 1 and 3
B. Elements 1 and 4
C. Elements 2 and 3
D. Elements 2 and 4
Answer: D
Explanation: I guessed it and got it right
A fundamental object that is difficult to divide into smaller bits is known as an element. Therefore option D is correct.
What is element ?An element is a species of atoms, including the pure material made entirely of that species, that have a specific number of protons in their nuclei. Chemical elements, in contrast to chemical compounds, cannot be reduced by any chemical process into simpler molecules.
An element is a material that cannot be broken down by non-nuclear processes in chemistry and physics. A discrete component of a larger system or collection is referred to as an element in computers and mathematics.
Metals, nonmetals, and metalloids are the Periodic Table's three main groupings. Each group's constituent elements share comparable physical and chemical characteristics. Among the physical characteristics used to separate the three groups are, A substance's capacity to reflect light is referred to as luster.
Thus, option D is correct.
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Electron transfer between redox centers in proteins is controlled by quantum tunneling. We can model the region between two redox centers as an energy barrier which the electron must cross. If the distance between the redox centers is 0.681 nm and the energy of the electron is 0.5540.554eV lower than the height of the barrier, what is the probability that the electron will successfully cross to the next redox center
Answer:
5.61 e⁻³
Explanation:
Given that:
The barrier length = 0.681 nm = 6.81 × 10⁻¹⁰
The difference between the height of the barrier & the energy of the electron is;
[tex]V - E = 0.554 \ eV (1.6 \times 10^{-19} )[/tex]
= 8.864 × 10⁻²⁰ V
where;
m = 9.1 × 10⁻³¹ kg
The probability[tex]P = e^{-2 \ kd}[/tex]
[tex]k = 2 \pi \sqrt{\dfrac{2m (V-E)}{h^2} }[/tex]
[tex]k = 2 \pi \times \dfrac{\sqrt{2 \times 9.1 \times 10^{-31} \times 8.864 \times 10^{-20}}}{6.63 \times 10^{-34}}[/tex]
k = 3.806 × 10⁹
[tex]P = e^{-2 \ kd}[/tex]
[tex]P = e^{2 \times 3.806 \times 10^9 \times 6.81 \times 10^{-10}}[/tex]
P = 0.005606
P = 5.61 × 10⁻³
P = 5.61 e⁻³
Which scenario is likely to result in the most diverse offspring?
1 point
Sexual reproduction between two individuals from different continents
Sexual reproduction between two individuals in the same population
Asexual reproduction by binary fission
Asexual reproduction by budding
Answer: i think it is binary fission
Explanation:
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What is a main difference between a mixture and a pure substance?
OAmixture is only a liquid, but a pure substance can be in any state.
OAmixture looks the same throughout, but a pure substance does not.
OAmixture can vary in composition, but a pure substance has a set composition.
O Amixture can be made up of a single compound, but a pure substance cannot
Answer:
I think the answer is c!
Explanation:
Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. hope this helps you!