Answer:
False
Explanation:
Boron is an exception to the octet rule because it possesses less than eight electrons. Boron has five electrons with three of them being valence electrons and therefore has an incomplete octet. It readily forms compounds in which it has six valence electrons, rather than the usual eight.
Hope that helps.
Considering the exception to the octet rule, the statement is false because Boron is an exception to the octet rule and can take up to 6 electrons in its valence shell.
An exception to the octet rule is when there are too few valence electrons resulting in an incomplete octet. That is, the default exceptions imply that there can be covalently bonded atoms that surround themselves with fewer than eight electrons.
This exception occurs with boron. Boron has an incomplete octet because it only has six electrons around it. That is, boron has three valence electrons and can only form electron pair bonds in two locations, gaining stability only with 6 valence electrons.
In summary, the statement is false because Boron is an exception to the octet rule and can take up to 6 electrons in its valence shell.
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https://brainly.com/question/21922467?referrer=searchResultshttps://brainly.com/question/12089726?referrer=searchResultshttps://brainly.com/question/20347349?referrer=searchResultsHow does the solubility of atmospheric carbon dioxide change with variations in pH and salinity?
Answer:
Decreasing pH decreases the solubility; increasing salinity increases the salinity.
Explanation:
Atmospheric carbon dioxide in seawater is involved in the following equilibria:
(i) CO₂(g) ⇌ CO₂(aq)
(ii) CO₂(aq) + H₂O ⇌ H₂CO₃(aq)
(iii) H₂CO₃(aq) + H₂O(l) ⇌ H₃O⁺(aq) + HCO₃⁻(aq)
(iv) HCO₃⁻(aq)+ H₂O(l) ⇌ H₃O⁺(aq) + CO₃²⁻(aq)
1. Effect of pH
Decreasing pH increases [H₃O⁺].
According to Le Châtelier's Principle, the position of equilibrium of (iv) will be pushed to the left.
This, in turn, pushes the positions of equilibrium of (iii), (ii), and (i) to the left.
The net effect is that CO₂ is pushed out of the solution and back into the atmosphere.
Thus, decreasing the pH decreases the solubility of atmospheric CO₂.
2. Effect of salinity
Salinity includes the measurement of all ions in seawater, not just Na⁺ and Cl⁻.
An important ion that contributes to salinity is Ca²⁺.
Ca²⁺ ions are involved in the equilibrium
Ca²⁺(aq) + CO₃²⁻(aq) ⇌ CaCO₃(s).
Thus, increasing the salinity ([Ca²⁺]) removes CO₃²⁻ from the solution and pulls the position of equilibrium of (iv) to the right.
The effect goes back through the chain of equilibria.
The net result is that more atmospheric CO₂(g) dissolves in the seawater to replace the CO₃²⁻ that has been removed.
Increasing the salinity increases the solubility of atmospheric CO₂.
How many grams (of mass m) of glucose are in 255 mL of a 5.50% (m/v) glucose solution?
Answer:
14.0 g
Explanation:
Step 1: Given data
Volume of solution (%w/v): 255 mL
Weight/volume % of glucose (solute): 5.50% (m/v)
Step 2: Calculate the mass of glucose
We can calculate the mass of glucose using the following expression.
%w/v = mass of glucose / milliters of solution × 100%
mass of glucose = %w/v × milliters of solution / 100%
mass of glucose = 5.50% (m/v) × 255 mL / 100%
mass of glucose = 14.0 g
Light energy from the sun is converted by plants into
A electricity
B mechanical energy
C leaves
D chemical energy
How many atom are in 5fes2, 6c2h4o2 and 2cah2po42
Answer:
83 atoms
Explanation:
5*(1 fe + 2 S) + 6(2 C + 4H + 2O) + 2*2(1 Ca + 2 H + 1 P + 4 O) = 15 + 36 + 32 = 83 atoms
The carbon atoms in saturated hydrocarbons ________. Group of answer choices contain a benzene ring contain at least one double bond contain both a double and a triple bond have only single bonds contain at least one double bond
Answer:
Have only single bonds.
Explanation:
Hello,
In this case, we need to remember that saturation is a state at which a carbon chain contains no insaturations, that is neither double nor triple bonds such case are alkenes and alkynes, but saturations only which are characterized by the presence of single bonds between adjacent carbon atoms. Such is the case of ethane (CH₃-CH₃), propane (CH₃-CH₂-CH₃), butane (CH₃-CH₂-CH₂-CH₃) and so on.
Best regards.
Which of the following is a characteristic of a good roasting pan?
Answer:
i can't understand the question
The 488 nm laser is shine on a lithium metal whose work function is 2.9 eV will you be able to see any photoelectrons? if yes what is the kinetic energy of the electrons if no what wavelength of light should be used to see the photoelectrons
Answer:
There will not be any ejection of photoelectrons
Explanation:
Energy of the photon= hc/λ
Where;
h= Plank's constant
c= speed of light
λ= wavelength of the incident photon
E= 6.6×10^-34 × 3 ×10^8/488 × 10^-9
E= 4.1 ×10^-19 J
Work function of the metal (Wo)= 2.9 eV × 1.6 × 10^-19 = 4.64 × 10^-19 J
There can only be ejected photoelectrons when E>Wo but in this case, E<Wo hence there will not be any ejection of photoelectrons.
A solution is made by dissolving
3.60g of sodium chloride to a final
volume of 115mL solution.
What is the weight/volume % of the
solute?
Answer:
3.13%
Explanation:
Step 1: Given data
Mass of sodium chloride (solute): 3.60 g
Volume of solution: 115 mL
Step 2: Calculate the weight/volume % of the solute
We will use the following expression.
%w/v = mass of solute / milliliters of solution × 100%
%w/v = 3.60 g / 115 mL × 100%
%w/v = 3.13%
The weight/volume % of the solute is 3.13%
Answer:
3.13
Explanation:
correct
A) For the following reaction, K > 1. Classify each of the reactants and products based on their strength as Bronsted-Lowry acids or bases.
C9H7N + HNO2Doublearrow.GIFC9H7NH+ + NO2-
a) HNO2 1) stronger acid
b) NO2- 2) weaker acid
c) C9H7NH+ 3) stronger base
d) C9H7N 4) weaker base
B)
For the following reaction, K < 1. Classify each of the reactants and products based on their strength as Bronsted-Lowry acids or bases.
C5H11NH+ + C6H5COO-Doublearrow.GIFC5H11N + C6H5COOH
a) C5H11NH+ 1) strongest acid
b) C6H5COO- 2) stongest base
c) C5H11N 3) weakest acid
d) C6H5COOH 4) weakest base
Answer:
Explanation:
According to Bronsted-Lowry acids or base theory , the reagent capable of giving hydrogen ion or proton will be acid and that which accepts hydrogen ion or proton will be base .
C₉H₇N + HNO₂ ⇄ C₉H₇NH⁺ + NO₂⁻
If K > 1 , reaction is proceeding from left to right .
Hence HNO₂ is giving H⁺ or proton and C₉H₇N is accepting proton to form
C₉H₇NH⁺ .
Hence HNO₂ is bronsted acid and C₉H₇N is bronsted base .
B )
when K < 1 , reaction above proceeds from right to left . That means
C₉H₇NH⁺ is giving H⁺ so it is a bronsted acid and NO₂⁻ is accepting H⁺ so it is a bronsted base .
Hence , NO₂⁻ is a bronsted base and C₉H₇NH⁺ is a bronsted acid .
Which of the following solutions will have the lowest freezing point?
a. 0.010 m Li2SO4
b. 0.015 m MgCl2
c. 0.035 m CH3CH2CH2OH
d. 0.010 m NaCl
Answer:
0.035 m CH3CH2CH2OH
Explanation:
We know that freezing point is a coligative property hence it depends on the number of solute particles present.
Covalent substances do not break up into ions, hence they do not produce many particles in solution unlike ionic substances. Hence, ionic substances have a far higher freezing point than covalent molecules.
For this reason, 0.035 m CH3CH2CH2OH has the lowest freezing point.
For a concentration cell, the standard cell potential is always:________.
a. positive
b. negative
c. zero
d. need more information
Answer:
C. Zero
Explanation:
A concentration cell is defined as a type of galvanic cell which has two equivalent half-cells of the same constituent in the electrodes but different concentration in the electrolytes.
For a concentration cell, the standard cell potential is always Zero and the cell potential is usually measured with the use of the Nernst equation.
Identify the major factor affecting reaction rates that accounts for the following observations:
a. Tadpoles grow more rapidly near the cooling water discharged from a power plant. 尤mpeca
b. Enzymes facilitate certain biochemical reactions but are not onsumed
c. Hydrogen peroxide antiseptic rapidly decomposes when applied to an open wound.
Answer:
a. Tadpoles possess the tendency to grow more rapidly close to the cooling water released from the power plant as the temperature is greater in these waters, permitting them to acquire more nutrients. Thus, in the given case, the factor is the temperature of the system.
b. In the given case, the factor is the catalyst, and in the given case enzymes are the biological catalyst. An enzyme increases the rate of the reaction as they lower the activation energy.
c. In the given case, the factor is the enzyme, as the blood comprises an enzyme, peroxidase, which catalyzes the decomposition of hydrogen peroxide.
How does a scientist use observations to help create the
hypothesis in a scientific investigation?
Answer:
They use hypotheses to guess a result based on what they already know. Observations are used to record the results of an experiment. Predictions are used to have an expected outcome of a test, thinking the hypothesis is correct. Experiments are used to test the hypothesis.
If you spill a chemical on a balance and continue to weigh, do you think it will affect your reading
Answer:
It shouldn't, but it might there is a chance. Liquid doesn't really weigh that much but it still can add slight weight.
Explanation:
The chemical could maybe make the balancer move a bit. But not a lot.
calculate the specific heat of copper if it takes 23 cal to heat a 5.0 g sample from 25 C to 75 C
Answer:
0.384928 J/g°C
Explanation:
The formula for Specific Heat (C)
= q/m × ∆t
Where q = Heat energy required to heat the compound (in joules)
m = mass of the compound (sample)
∆t = Change in temperature
In the question, we are given the following values.
m = 5.0g
∆t = Change in temperature = 75°C - 25°C
= 50°C
q = Heat energy = 23 cal
We have to convert to joules
One calorie is equal to 4.184 joules.
1 Cal = 4.184 joules
23 Cal =
23 × 4.184 joules
= 96.232 joules
Specific Heat (C) of copper
= 96.232 J /(5g × 50°C)
= 96.232J / 250
= 0.384928 J/g°C
Therefore, the Specific Heat of Copper is 0.384928 J/g°C
The term electron capture best fits which of the following descriptions?
A. Electron capture is a phenomenon exhibited by an unstable nucleon that spontaneously converts into a more stable nuclei.
B. Electron capture is the combination of a core electron with a proton to yield a neutron within the nucleus.
C. Electron capture is the addition of an electron to a neutral atom to form an anion.
D. None of the above.
Answer:
Option B:
Electron capture is the combination of a core electron with a proton to yield a neutron within the nucleus.
Explanation:
The electron capture is a nuclear process whereby a neutral atom absorbs an electron from its closest shell (which is usually the K shell of the atom).
This capture phenomenon, causes one of the protons within the nucleus of the atom to convert into a neutron because of the merging of the positive and negative charges. Once they merge, a light particle called the electron neutrino is emitted from the nucleus of the atom.
This phenomenon occurs mostly in atoms that have a proton-rich nucleus. This provides the positive charge that pulls the electron from its shell into the nucleus of the atom.
are any substance made up of matter and can be natural or man-made.
Answer:
Yes.
Explanation:
Substances are made up of matter or matter are made up of tiny molecules or atoms that occur naturally or some are synthetic or man made.
All matter are made up of substances called elements and each elements have its own physical and chemical properties and cannot be broken easily by ordinary chemical reactions.
Of all the 118 elements only 92 occur naturally and 26 are man made or synthetic which are made in the laboratories.
In general, which of the following gases would you expect to behave the most ideally even under extreme conditions? View Available Hint(s) In general, which of the following gases would you expect to behave the most ideally even under extreme conditions? N2 CO H2
Answer:
The correct option is H₂
Explanation:
An ideal gas is the gas that obeys the gas laws perfectly. There molecules occupy little/negligible space with no interaction. Since they occupy negligible space, it can be said that the smaller the molecule of a gas, the more it behaves like an ideal gas. There size also accounts for there weak intermolecular force between it's molecules.
From the explanation above, H₂ has the smallest molecule and hence will behave the most like an ideal gas.
The gases that one would expect to behave the most ideally even under extreme conditions is H2.
An ideal gas is commonly described to as gases that are present i gas molecules that do not encounter any kind of interaction with the neighboring molecules.H2 is simply known as a molecule of hydrogen that has two hydrogen atoms which are bonded to each other by covalent bond.
Due to the fact that the hydrogen atom has a smaller size and lesser electronegativity the hydrogen molecule is thus regarded to be the least polar.
N2 is known to have greater polarizability than hydrogen molecule and thus cannot be the answer.
Note that for a gas to behave ideally, the attractive and repulsive intermolecular forces need to be negligible. When looking at the three molecules
H2,N2,CO, the molecule which is most polar will behave least ideally.
Therefore, hydrogen molecule will have the least intermolecular forces and will be most ideal.
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If 12.8 g lead(II) sulfate (303.3 g/mol) precipitates when excess potassium chloride is added to 1.65 L of a water sample, what is molar concentration of Pb2+ in the sample?
Answer:
[tex]M=0.0256M[/tex]
Explanation:
Hello,
In this case, the undergoing chemical reaction is:
[tex]PbSO_4(aq)+2KCl(aq)\rightarrow PbCl_2(s)+K_2SO_4(aq)[/tex]
In such a way, since all the lead (II) is converted due to the excess of potassium chloride, the moles of lead (II) in the sample are computed from the mass of lead (II) sulfate:
[tex]n_{Pb^{2+}}=12.8gPbSO_4*\frac{1molPbSO_4}{303.3gPbSO_4} *\frac{1molPb^{2+}}{1molPbSO_4} \\\\n_{Pb^{2+}}=0.0422molPb^{2+}[/tex]
Thus, since volume of the solution is 1.65 due to the fact that the addition of the reactants is not enough to significantly modify the reaction's volume, the resulting molar concentration of the lead (II) ions is:
[tex]M=\frac{n_{Pb^{2+}}}{V}=\frac{0.0422molPb^{2+}}{1.65L}\\ \\M=0.0256M[/tex]
Regards.
A compound has an M-/M-2 ratio of 75:25. Which of the following could be the molecular formula of this compound? a) CH2Br2 b) CH2Cl2 c) CHCI d) CH:Bre) CHF
Answer:
c) CH₃Cl
Explanation:
Due the relative abundance of chlorine and bromine. It is possible to determine which of the halogens is present in a mass spectrum of a organic compound:
The Cl-35, Cl-37 have a relative abundance of 75/25; Br-79 and Br-81 of 50/50.
For that reason, if a compound has a M/M+2 ratio of 75:25 you can be sure the compound has 1 Cl in its structure. Thus, the only possible structure is:
c) CH₃ClWhen a 235 92U 92235U nucleus is bombarded by neutrons (10n01n) it undergoes a fission reaction, resulting in the formation of two new nuclei and neutrons. The following equation is an example of one such fission process: 235 92U+10n→AZBa+9436Kr+310n 92235U+01n→ZABa+3694Kr+301n Enter the isotope symbol for the barium (BaBa) nucleus in this reaction. Express your answer as an isotope.
Answer:
139/56 Ba
Explanation:
In writing nuclear equations, there must be a balance of the mass and charge on both sides of the reaction equation. That is, the sum of masses on the lefthand side of the nuclear reaction equation must equal the sum of masses on the righthand side of the nuclear reaction equation. Similarly, the charges on the lefthand side of the nuclear reaction equation must equal the sum of the charges on the right hand side of the nuclear reaction equation.
Hence, the isotope of barium formed in the equation mentioned in the question is 139/56 Ba.
On the basis of intermolecular forces of attraction, rank the following three compounds in terms of increasing boiling point.
CH3CH2OH
CH3OCH3
CH3CH2CH3
a. (lowest bp) CH3CH2CH3 < CH3OCH3 < CH3CH2OH (highest bp)
b. (lowest bp) CH3CH2OH < CH3OCH3 < CH3CH2CH3 (highest bp)
c. (lowest bp) CH3OCH3 < CH3CH2OH < CH3CH2CH3 (highest bp)
d. (lowest bp) CH3CH2OH < CH3CH2CH3 < CH3OCH3 (highest bp)
e. (lowest bp) CH3CH2CH3 < CH3CH2OH < CH3OCH3 (highest bp)
Answer:
a. (lowest bp) CH3CH2CH3 < CH3OCH3 < CH3CH2OH (highest bp
Explanation:
CH3CH2OH is an alkanol. The intermolecular forces present within the molecules include dispersion forces, dipole-dipole attraction as well as hydrogen bonding which is the major intermolecular force of attraction present.
CH3OCH3 is an ether. The intermolecular forces present within the molecules are dispersion forces and dipole-dipole attraction.
CH3CH2CH3 is an alkane. The only intermolecular forces present is dispersion forces.
The order of increasing strength of these intermolecular forces is dispersion forces ,dipole-dipole forces<hydrogen bonding, the alkanol has the highest bioling point, followed by the ether and then the alkane with the lowest boiling point.
The ranking of the compounds in terms of increasing the boiling point is option a.
What is ethanol?Ethanol i.e. (CH3-CH2-O-H) has three types of intermolecular interactions i.e. weak van der Waals interaction, dipole-dipole interaction, and strong intermolecular H-bonding interaction.
While on the other hand, in dimethyl ether (CH3-O-CH3) have two types of interactions - weak van der Waals interaction, and dipole-dipole interaction.
In propane (CH3-CH2-CH3) has only weak van der Waals interaction.
So ethanol needed more energy to overcome this these interactions for the conversion to a liquid state to the gaseous state.
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Determine the pH of a buffer which is a 0.20 M solution of trimethylamine (N(CH3)3) and a 0.40 M solution of trimethylammonium chloride (NH(CH3)3Cl). The Kb of trimethylamine at 25°C is 6.3x10-5.
Answer:
pH of the buffer is 10.10
Explanation:
trimethylamine is a weak base that, in presence with its conjugate base, trimethylammonium ion, produce a buffer.
To determine the pH of the buffer we use H-H equation for weak bases:
pOH = pKb + log [Conjugate acid] / [Weak base]
pKb is -log Kb = 4.20
pOH = 4.20 + log [N(CH₃)₃] / [NH(CH₃)₃]
Replacing the concentrations of the problem:
pOH = 4.20 + log [0.20M] / [0.40M]
pOH = 3.90
As pH = 14 -pOH
pH of the buffer is 10.10
limitations of bohr
Answer:
Bohr's Atomic model
Explanation:
The limitations of Bohr’s model are Bohr’s model of an atom that could not explain the line spectra of atoms containing more than one electron called multi-electron atoms.
Radioactive manganese-52 decays with a half-life of 5.6 days. A chemist obtains a fresh sample of manganese-52 and measures its radioactivity. She then determines that to do an experiment, the radioactivity cannot fall below 25% of the initial measured value. How long does she have to perform the experiment?
Answer: 11.2 days
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
[tex]t_{\frac{1}{2}}=\frac{0.693}{k}[/tex]
[tex]k=\frac{0.693}{5.6days}=0.124days^{-1}[/tex]
b) for completion of 75% of reaction
[tex]t=\frac{2.303}{0.124}\log\frac{100}{100-75}[/tex]
[tex]t=\frac{2.303}{0.124}\log\frac{100}{25}[/tex]
[tex]t=11.2days[/tex]
The time for which she has to perform the experiment is 11.2 days
Which compound is more soluble in an acidic solution than in a neutral solution? a) PbBr2 b) CuCl c) AgI d) BaF2
Answer:
d) BaF2
Explanation:
The compound which is more soluble in an acidic solution than in a neutral solution is shown below:-
First we will compare acidic with Neutral
[tex]acidic \rightarrow H+ ions[/tex]
So,
[tex]PbBr2 \rightarrow Pb+2 + 2Br-[/tex]
[tex]BaF2 \rightarrow Ba+2 + 2F-[/tex]
[tex]AgI \rightarrow Ag+ + I-[/tex]
[tex]CuCl \rightarrow Cu+ + Cl-[/tex]
Now, when we add H+ ions, so it will be
[tex]BaF2 \rightarrow Ba+2 + 2F-[/tex]
[tex]F- + H2O <-> HF + OH-[/tex]
Then it will reduces F-, as BaF2 begin to form more aqueous ions, so, it will rises the solubility
In the following net ionic equation, identify each reactant as either a Bronsted-Lowry acid or a Bronsted-Lowry base. HCN(aq) H2O(l) CN-(aq) H3O (aq) B-L _____ B-L _____
The formula of the reactant that acts as a proton donor is_______
The formula of the reactant that acts as a proton acceptor is________
Answer:
Explanation:
The definition of acids and bases by Arrhenius Theory was modified and extended by Bronsted-Lowry.
Bronsted-Lowry defined acid as a molecule or ion which donates a proton while a base is a molecule or ions that accepts the proton. This definition can be extended to include acid -base titrations in non-aqueous solutions.
In this theory, the reaction of an acid with a base constitutes a transfer of a proton from the acid to the base.
From the given information:
[tex]\mathsf{HCN _{(aq)} + H_2O_{(l)} \to CN^{-}_{(aq)} + H_3O_{(aq)}}[/tex]
From above:
We will see that HCN releases an H⁺ ion, thus it is a Bronsted-Lowry acid
[tex]H_2O[/tex] accepts the H⁺ ion ,thus it is a Bronsted-Lowry base.
The formula of the reactant that acts as a proton donor is HCN
The formula of the reactant that acts as a proton acceptor is H2O
What are scientific models used for? Give an example of each of the follwoing types of models: idea, physical, computer
Answer:
Scientific models are used to explain phenomena that can not be experience directly and it is also used for prediction.
Explanation:
An example of idea model is the Eistein equation. An idea model shows how things interact together to produce a particular result.
An example of physical model is the solar system.
Computer model is used to predict long term events and an example of this is computer simulations.
Which species functions as the oxidizing agent in the following reduction-oxidation reaction?
Which one the reducing agent?
Which one is oxidized?
Which one is reduced?
Which one loses electrons?
Which one gains electrons?
Zn(s) + Cu2+(aq) ? Cu(s) + Zn2+(aq).
Answer:
See explanation
Explanation:
In this case, we can start with the half-reactions. If the total reaction is:
[tex]Zn_(_s_)~+~Cu^2^+~_(_a_q_)~->~Cu_(_s_)~+~Zn^2^+_(_a_q_)[/tex]
If we split the reaction we will have:
Half-reaction 1:
[tex]Zn_(_s_)~->~Zn^2^+_(_a_q_)[/tex]
Half-reaction 2:
[tex]Cu^2^+~_(_a_q_)~->~Cu_(_s_)[/tex]
Now we can add the electrons, keeping in mind that we have to obtain zero charge in both sides of each half-reaction:
Half-reaction 1:
[tex]Zn_(_s_)~->~Zn^2^+_(_a_q_)~+~2e^-[/tex]
Half-reaction 2:
[tex]Cu^2^+~_(_a_q_)~+~2e^-~->~Cu_(_s_)[/tex]
With this in mind, we can solve the questions:
Which one loses electrons?
In half-reaction number 1 we have the electrons in the products side, therefore this half-reaction is the one that loses electrons.
Which one gains electrons
In half-reaction number 2 we have the electrons in the reagent side, therefore this half-reaction is the one that gains electrons.
Which one is oxidized?
If half-reaction number 1 loses electrons will be the oxidation reaction.
Which one is reduced?
If half-reaction number 2 gains electrons will be the reduction reaction.
Which species functions as the oxidizing agent in the following reduction-oxidation reaction?
If half-reaction number 2 is the reduction will be a oxidizing agent.
Which one the reducing agent?
If half-reaction number 1 is the oxidation will be a reducing agent.
I hope it helps!
If 28.0% of a sample of gallium-66 decays in 4.46 hours, what is the half-life of this isotope (in hours)?
Answer:
I hope it will work dear,
Explanation:
by simple mathematical rule,
if 28%=4.46 hrthen we know at half life 50% decay occur hence we get
2. 50% = T 1/2
solving the 2 equations by cross multiplication we will get,
T 1/2= 7.96 hr
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