Magnesium oxide is an ionic compound ( because it consists of a metal and a non-metal)
In ionic compounds, electrons from the outer shell exchange between the atoms so that they each get a full outer shell. Once these electrons are exchange, the atoms will become ions. One ion will have a positive charge, and the other ion will have a negative charge. The positive and negative ions then bond strongly together in a lattice structure, due to the electrostatic forces of attraction.
These electrostatic forces of attraction are very strong and require a lot of energy to break, as such the compound will have a high melting point.
__________________________________________
Now lets look at the ionic bonding between magnesium and oxygen:
In the outer shell of Magnesium, there are 2 electrons.
In the outer shell Oxygen, there are 6 electrons.
Magnesium gives it's two electrons to Oxygen, so that the Oxygen now has a full outer shell of 8 electrons. However, since Oxygen gained two electrons, it will form a negatively charged ion with a charge of -2.
Since Magnesium lost the two electrons, it's second shell (which has 8 eletrons) now becomes the outer shell. So Magnesium also now has a full outer shell. But since it has lost two electrons, it becomes a positively charged ion with a charge of + 2.
The positive Magnesium ion and negative Oxygen ion and now strongly attracted to each other, and form a strong ionic compound (magnesium oxide) with a lattice structure.
The electrostatic forces of attraction between the positive Magnesium and negative Oxygen are so strong that a lot of heat and energy are needed to break them.
Therefore magnesium oxide has a high melting point.
Which statement is the best description of a chemical bond?
A. A chemical bond connects 2 different molecules.
B. A chemical bond holds atoms together.
c. A chemical bond turns molecules into atoms.
D. A chemical bond identifies atoms in a molecule.
Answer:
B. is the correct answer
A chemical bond holds atoms together,is the statement that description of a chemical bond.
What is meant by chemical bond?A chemical bond is what holds atoms together in molecules. Bonds arise from the electrostatic forces between positively charged atomic nuclei and negatively charged electrons (the positions of which in space are determined by quantum mechanics).A chemical bond holds atoms together,is the statement that description of a chemical bond.
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Which element has an atomic number of 16?
Answer:
Sulfur
Explanation:
the atomic number is the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table
Sulfur has 16 protons in its nucleus
The element with an atomic number of 16 is sulfur.
How do we explain?Sulfur is a chemical element that has an atomic number of 16. It is represented by the symbol "S" on the periodic table.
Sulfur is a nonmetal and belongs to Group 16, also known as the chalcogens, on the periodic table. It is located in the third period. It is classified as a multivalent element, meaning it can form compounds with various oxidation states.
In its pure form, sulfur is a yellow, brittle solid. It is known for its distinctive odor, often described as being similar to rotten eggs. Sulfur is found in various minerals and is also a component of many natural resources such as coal, petroleum, and natural gas.
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why is concentrated sulphuric acid is weak acid
Answer:
Sulfuric acid is a strong acid in any state
Explanation:
You may be thinking if the definition that a weak acid produces relatively few ions in aqueous solution,
If you have 100 % sulfuric acid, there is no water, so the definition does not apply.
Commercial sulfuric acid contains about 2 % water. The sulfuric acid in that small amount of water consists of about 99 % HSO₄⁻ and 1 % SO₄²⁻. The acid is almost completely ionized.
Sulfuric acid is a strong acid.
is when two atoms combine to form a larger atom,
The process of _
releasing energy.
Nuclear fusion is a process where light atomic nuclei merge to form a heavier nucleus, releasing energy due to the mass difference being converted into energy. This reaction powers stars and has potential applications in generating clean energy on Earth.
The process being described is known as nuclear fusion. It occurs when two light atomic nuclei combine to form a larger, heavier nucleus, typically releasing a significant amount of energy. This process explains why fusion is considered a potential source of almost inexhaustible clean energy. In stars, such as our Sun, fusion is the energy-producing process, where hydrogen nuclei fuse under intense pressure and temperature to form helium, outputting immense energy in the process.
In terms of mass, the total mass of the resulting heavier nucleus is slightly less than the sum of the original nuclei. This difference in mass, according to Einstein's equation E = mc2, is converted into energy, which is radiated away. The ability to control nuclear fusion on Earth is a goal of many research programs, as it promises a less hazardous and more abundant alternative to current nuclear fission power plants.
how much does 12 liters of ammonia weighs at room temperature and pressure (293K and 100 kPa)?
Answer:
8.38g
Explanation:
Given parameters:
Volume of the gas = 12L or 12dm³
Temperature = 293k
Pressure = 100kPa
Unknown: mass of the ammonia gas = ?
_____ Now let us take the unit of pressure to atm:
Pressure = 100 kPa
1kPa = 0.00986923atm
100kPa = 100 x 0.00986923 = 0.987atm
Solution:
From the ideal gas law, we can find the number of moles of the ammonia gas. Using the number of moles, it would be possible to find the mass of the ammonia.
PV = nRT
n = [tex]\frac{PV}{RT}[/tex]
Where R is the gas constant and its value is 0.082atmdm³mol⁻¹K⁻¹
n = [tex]\frac{0.987atm x 12dm³}{0.082atmdm³mol⁻¹K⁻¹ x 293K}[/tex]
n = 0.493mol
We know that, mass = number of moles x molar mass
Molar mass of NH₃ = 14 + (3x1) = 17gmol⁻¹
mass of NH₃ = 0.493 x 17 = 8.38g
what is the equilibrium expression for the reatcion bellow
2SO3(g)<=>O2(g)+2SO2(g)
The equilibrium expression for the given reaction 2SO3(g) <=> O2(g) + 2SO2(g) is Ke = [SO₃]² / ([SO₂]² [O₂]).
Explanation:The equilibrium expression for the given reaction is Ke = [SO₃]² / ([SO₂]² [O₂]).
Ke represents the equilibrium constant, which is a measure of the extent to which a reaction reaches equilibrium. In this case, the equilibrium constant is calculated by taking the square of the concentration of SO₃ and dividing it by the product of the squares of the concentrations of SO₂ and O₂.
For example, if the concentrations at equilibrium are [SO₂] = 0.90 M, [O₂] = 0.35 M, and [SO₃] = 1.1 M, the value of the equilibrium constant, Ke, can be calculated as Ke = (1.1)² / ((0.90)² (0.35)).
A person suspects that an unknown liquid is water. he adds 110.0 J of heat to 55.0 g of liquid. The temperature of the liquid increases by 2.1 Celsius. I s the liquid water?The specific heat of water is 4.18 J/ g-Celsius.Please explain answer
Explanation:
First thing first, you mistyped the specific heat of water, which should be
c
water
=
4.18
J
g
∘
C
Now, a substance's specific heat tells you how much heat is required to increase the temperature of
1 g
of that substance by
1
∘
C
.
In the case of water, you would need
4.18 J
to increase the temperature of
1 g
of water by
1
∘
C
.
Notice that your sample of water has a mass of
1 g
as well, which means that the only factor that will determine the amount of heat needed will be the difference in temperature.
The equation that establishes a relationshop between heat and change in temperature looks like this
q
=
m
⋅
c
⋅
Δ
T
, where
q
- heat absorbed
c
- the specific heat of the substance, in your case of water
Δ
T
- the change in temperature, defined as the difference between the final temperature and the initial temperature
Plug in your values and solve for
q
to get
q
=
1.00
g
⋅
4.18
J
g
⋅
∘
C
⋅
(
83.7
−
26.5
)
∘
C
q
=
239.096 J
Rounded to three sig figs, the answer will be
q
=
239 J
Which describes the fourth state of matter known as plasma?
A It is a liquid containing nuclei and electrons.
B It is a gas containing nuclei and electrons.
C It is a liquid containing electrons created by fusion.
D It is a gas containing nuclei created by fusion.
Answer:
the answer is letter B. it is a gas containing nuclei and electrons.
B. It is a gas containing nuclei and electrons.
What is the fourth state of matter?Plasma is called the fourth state of matter. It is a state of matter in which an ionized substance turns into distinctly electrically conductive to the point that long-range electric and magnetic fields dominate its behavior.
A plasma is an ionized gas.a gas into which sufficient energy is provided to free electrons from atoms or molecules to allow both species, ions, and electrons, to coexist. Plasma is the fourth state of matter.Learn more about Plasma here
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Which is a fossil fuel?
A.nuclear
B.Biomass
C.geothermal
D.coal
Answer:
Coal
Explanation:
Coal is composed of the remains of dead animals and plants, being pressed down over the course of thousands of years.
(Also can I please have Brainliest? I need it to level up)
Answer:
coal
Explanation:
a fossil fuel is a general term for buried combustible geologic deposits of organic materials formed from decayed plants and animals. hope this helps i took physical science.
Consider the proportionality below.
PV ont
What does this best represent?
Dalton's law
Charles's law
ideal gas law
combined gas law
Answer:
Ideal gas law
Explanation:
The expression is the ideal gas law when properly written;
PV = nRT
where P is the pressure of the gas
V is the volume of the gas
n is the number of moles of the gas
R is the gas constant
T is the temperature
The ideal gas law is derieved from the three major gas laws;
--- Boyle's law, Charles's law and Avogadro's law
Determine the number of moles. 2.4x10^24 atoms of Fe
Imagine you are a detective examining a crime scene. You are trying to
identify the person who committed the crime, so you collect many samples at
the crime scene. Which sample would be most useful in identifying the
person who committed the crime?
O
A. A newspaper left at the crime scene
O
B. An ant found crawling across the crime scene
O
C. Pieces of hair found at the crime scene
O
D. Gravel and dirt on the ground at the crime scene
SUBMIT
Answer:
C. pieces of hair found at the crime scene.
Explanation:
using the pieces of hair, you can get the DNA of the person. This will give u a better lead in solving the crime.
Hope it helps u ....
Answer:
C. Pieces of hair found at the crime scene.
Explanation:
Pieces of hair found at the crime scene is more useful to find the criminal who committed the crime, because it helps in indetifying criminal's DNA through the process of DNA fingerprinting. The hair is analyzed by the chemical makeup of the hair and extracting DNA from the hair follicle, pieces of hair must have hair follicle attached to find DNA of the criminal.
Nuclear DNA can be successfully extracted from the hair root. Cut hair samples are useless without hair follicle attached. Its DNA will be useful only few months for testing. The DNA last in hairs about 1,000 to 10,000 years.
Rate or Reaction Past Exam Questions 2
10 Fatimah investigates the reaction between sodium hydrogencar
acid.
reaction between sodium hydrogencarbonate and dilute hydrocrc
She always adds 0.5g of sodium hydrogencarbonate to 20 cm of dilute hydrochia
She measures the time it takes for the reaction mixture to stop bubbling.
This is called the reaction time.
She does five different experiments.
She keeps the temperature the same.
Each experiment uses a different concentration of acid.
Look at a graph of her results.
1004
60F
reaction time
in seconds
0.5
1.5
2
.0
2.5
1.0
concentration in mol/dms
Fatimah concludes that as the concentration of acid increases, the rate of reaction increases.
Explain, with a reason, whether the results support Fatimah's conclusion.
Use the reacting particle model to explain Fatimah's results.
The quality of written communication will be assessed in your answer to this question.
The experiment results support Fatimah's conclusion that higher acid concentration increases the reaction rate, based on the reacting particle model and the kinetic molecular theory.
Explanation:Based on the description of the experiment, Fatimah observed that as the concentration of acid increased, the reaction time decreased, indicating that the rate of reaction increased. This can be explained by the reacting particle model, which suggests that with a higher concentration of acid, there are more acid particles in a given volume. This increases the likelihood of effective collisions between acid particles and sodium hydrogencarbonate particles, thereby increasing the rate of reaction.
The relationship between the concentration of reactants and the rate of reaction is explained in kinetic molecular theory. In the case of sodium hydrogencarbonate reacting with hydrochloric acid, producing bubbles of carbon dioxide, we would see a shorter reaction time with higher concentrations of acid. This is due to more frequent and effective collisions, which is consistent with the results as shown in Fatimah's graph. Calculating reaction rate involves the change in concentration of reactants or products over time, which can be reflected in the dynamics of the experiment she conducted.
How many grams of PbBr2 will precipitate when excess CrBr; solution is added to 60.0 mL of 0.551 M Pb(NO3)2 solution?
3Pb(NO3)2(aq) + 2CrBr3(aq) –>3PbBrz(s) + 2Cr(NO3)(aq)
Answer:
5.48 g
Explanation:
M: 367.01
3Pb(NO3)2(aq) + 2CrBr3(aq) → 3PbBr2(s) + 2Cr(NO3)3(aq)
1. Moles of Pb(NO3)2
n = 30.0 mL × (0.551 mmol/1 mL) = 16.53 mmol Pb(NO3)2
2. Moles of PbBr2
n = 16.53 mmol Pb(NO3)2 × (3 mmol PbBr/3 mol Pb(NO3)2)
= 16.53 mmol PbBr2
(3) Mass of PbBr2 formed
m = 16.53 mmol × (367.01 mg/1 mol) = 6067 mg
(4) Mass of PbBr2 in solution
PbBr2 is slightly soluble, so a significant amount will remain in solution.
Its solubility is 973 mg/100 mL.
Mass of dissolved PbBr2 = 60.0 mL × 973 mg/100 mL = 584 mg
(5) Mass of precipitate
Mass of precipitate = mass of PbBr2 formed - mass of PbBr2 in solution
m = 6067 mg - 584 mg = 5480 mg = 5.48 g
The mass of precipitate is 5.48 g.
The mass of PbBr2 precipitate produced is 12.1 g.
The equation of the reaction is;
3Pb(NO3)2(aq) + 2CrBr3(aq) –>3PbBr2(s) + 2Cr(NO3)3(aq)
Number of moles of Pb(NO3)2 = 60.0/1000 L × 0.551 M = 0.0331 moles
From the information in the question, we already know that Pb(NO3)2 is the limiting reactant and CrBr3 is the reactant in excess.
From the equation of the reaction;
3 moles of Pb(NO3) yields 3 moles of PbBr2
0.0331 moles of Pb(NO3) yields 0.0331 moles × 3 moles/3 moles
= 0.0331 moles of PbBr2
Mass of PbBr2 = number of moles × molar mass
Mass of PbBr2 = 0.0331 moles × 367 g/mol= 12.1 g
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Which cohesive forces are the strongest in water?
A.) London dispersion forces
B.) dipole interactions
C.) hydrogen bonding interactions.
D.) All intermolecular forces in water are equally strong.
is mercury a solution
Answer:
No.
Explanation:
Mercury is not a solution. It is a detonator.
An atom of boron has an atomic number of 5 and an atomic mass of 11. The atom contains
5 protons, 6 electrons, and 5 neutrons.
11 protons, 11 electrons, and 5 neutrons.
5 protons, 5 electrons, and 6 neutrons.
11 protons, 6 electrons, and 6 neutrons.
Answer:
5 protons, 5 electrons, and 6 neutrons
An atom of boron has 5 protons, 5 electrons, and 6 neutrons. This composition aligns with its atomic number of 5 and an atomic mass of 11. Therefore, the correct option is the one with 5 protons, 5 electrons, and 6 neutrons.
To determine the composition of a boron atom, we need to understand the concepts of atomic number and atomic mass. Boron has an atomic number of 5, which means it has 5 protons. The atomic mass of boron is approximately 11, which is the sum of the number of protons and neutrons.
Given these details, the correct configuration of a boron atom with an atomic number of 5 and an atomic mass of 11 is:
5 protons5 electrons6 neutronsThus, an atom of boron has 5 protons, 5 electrons, and 6 neutrons. This corresponds to the configuration that meets both the atomic number and atomic mass criteria as mentioned earlier.
A 50°C solution has a pH of 3.30. At this temperature, Kw = 5.48 x 10 9. What is the pOH of the solution?
Answer:
9.93
Explanation:
Your value for Kw is incorrect. The correct value is 5.48 × 10^-14.
pH + pOH = pKw
3.30 + pOH = -log(5.84 × 10^-14) = 13.23
pOH = 13.23 - 3.30 = 9.93
The pOH of the solution is 9.93.
The pOH of the solution is 10 .
Given that, the pH of the solution is 3.30, we also know that;
pH = - log[H^+]
Hence;
[H^+] = Antilog (-3.3)
[H^+] = 5.0 × 10^-4 M
But;
Kw = [H^+] [OH^-]
[OH^-] = Kw/[H^+]
The accurate value of Kw is 5.48 × 10^-14 not 5.48 x 10 9
[OH^-] = 5.48 x 10^-14/ 5.0 × 10^-4
[OH^-] = 1.1 x 10^-10 M
pOH = - log[1.1 x 10^-10 M]
pOH = 10
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Consider the chemical reaction below.
Zn(s)+ 2H*(aq) → Zn2+ (aq) + H2(g)
Which half reaction correctly represents reduction for this equation?
Zn(s) → Zn2+ (aq)+2e
2H* (aq)+2e → H2(g)
Zn(s) → Zn?- (aq)+e"
2H* (aq)+e™ → H2(g)
Answer: [tex]2H^++2e^-\rightarrow H_2(g)[/tex]
Explanation:
Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously.
Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.
Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.
For the given reactio:
[tex]Zn(s)+2H^+\rightarrow Zn^{2+}+H_2[/tex]
On reactant side:
Oxidation state of zinc= 0
Oxidation state of hydrogen = +21
On product side:
Oxidation state of zinc = +2
Oxidation state of hydrogen = 0
The oxidation state of hydrogen reduces from +1 to 0, it is getting reduced. Thus, it is getting reduced and it undergoes reduction reaction
Hence, the correct answer is [tex]2H^++2e^-\rightarrow H_2(g)[/tex]
Answer:
2H+(aq) + 2e– → H2(g) or B.)
on edge 2023
What does this equation, 2 C(s) + O 2(g) ® 2 CO(g), tell us?
A) the number of atoms of each kind in reactants and products is the same
B) carbon monoxide (CO) is a product
C) two atoms of carbon undergo reaction
D) all of these
Answer:
D. All of these.
Explanation:
For an equation to be balanced the number of atoms of each kind in the reactants and the products should be the same.
Then from this equation, CO is a product.
Last, two carbon atoms undergo reaction with the oxygen molecule for complete reaction to occur. Each atom combines with one oxygen atom.
Answer:
D) All of these
Explanation:
[tex]2 C(s) + O_2 (g) > 2 CO(g)[/tex]
Reactant side (Left side) Element Product side (Right side)
2 C 2
2 O 2
Balanced!!!
Balancing is making the number of atoms of each element same on both the sides (reactant and product side).
To find the number of atoms of each element we multiply coefficient × subscript
For example [tex]5 Ca_1 Cl_2[/tex] contains
5 × 1 = 5 ,Ca atoms and
5 × 2 = 10, Cl atoms
If there is a bracket in the chemical formula
For example [tex]3Ca_3 (P_1 O_4 )_2[/tex] we multiply coefficient × subscript × number outside the bracket.......... to find the number of atoms (Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )
So
3 × 3 = 9 , Ca atoms
3 × 1 × 2 = 6, P atoms
3 × 4 × 2 = 24, O atoms are present.
Which molecular solid would have the highest melting point?
O
A. One with induced dipole attractions
O
B. One that has hydrogen bonding
O
C. One made of nonpolar molecules
O
D. One with dipole-dipole attractions
Answer:
Choice B. The solid with hydrogen bonding.
Assumption: the molecules in the four choices are of similar sizes.
Explanation:
Molecules in a molecular solid are held intact with intermolecular forces. To melt the solid, it is necessary to overcome these forces. The stronger the intermolecular forces, the more energy will be required to overcome these attractions and melt the solid. That corresponds to a high melting point.
For molecules of similar sizes,
The strength of hydrogen bonding will be stronger than the strength of dipole-dipole attractions.The strength of dipole-dipole attractions (also known as permanent dipole) will be stronger than the strength of the induced dipole attractions (also known as London Dispersion Forces.)That is:
Strength of Hydrogen bond > Strength of Dipole-dipole attractions > Strength of Induced dipole attractions.
Accordingly,
Melting point due to Hydrogen bond > Melting point due to Dipole-dipole attractions > Melting point due to Induced Dipole attractions.
Induced dipole is possible between all molecules.Dipole-dipole force is possible only between polar molecules.Hydrogen bonds are possible only in molecules that contain [tex]\rm H[/tex] atoms that are bonded directly to atoms of [tex]\rm F[/tex], [tex]\rm O[/tex], or [tex]\rm N[/tex].As a result, induced dipoles are the only force possible between molecules of the solid in choice C. Assume that the molecules are of similar sizes, such that the strengths of induced dipole are similar for these molecules.
Melting point in choice B > Melting point in choice D > Melting point in choice A and C.
Answer:
B. One that has hydrogen bonding
Give the location of the elements found in the periodic table which have the same number valence electrons.
A. All members in group VIII only
B. All numbers within any group
C. All numbers within any period
D. All the nonmetals
Answer:
B - all numbers within any group (vertical column)
Explanation:
https://en.wikipedia.org/wiki/Valence_electron
Answer:
B - all numbers within any group
Explanation:
what name did wegener give to the single large landmass composed of all continents
Answer:
The large landmass was named Pangea
Answer:
The names of all continents is Pangaea given by Alfred Wegener in 1912
Explanation:
The name Pangaea or Pangea is derived from the Greek pan that in english means Whole and Gaia that in english means Land. The idea was not new because before Wegener, other scientist have proposed the idea of a huge landmass and then the separation by continents. but Wegener was the first to use the term continental drift.
The continental drift means that the continents are moving form each other since millions of years due to the mantle convection. This theory has been replaced by tectonic plate theory.
How many grams of CaCl2
are needed to make 344.9
g of a solution that is 32.0
% (m/m) CaCl2
in water? Note that mass is not technically the same thing as weight, but % (m/m) has the same meaning as % (w/w).
grams CaCl2=
g
How many grams of water are needed to make this solution?
grams H2O=
Answer:
[tex]\boxed{\text{110.4 g of CaCl$_{2 }$ and 234.5 g of water}}[/tex]
Explanation:
1. Mass of CaCl₂
[tex]\text{Let m = mass of CaCl}_{2}\\\\\begin{array}{rcl}\text{Mass percent} & = & \dfrac{\text{Mass of CaCl}_{2}}{\text{Total mass}} \times 100 \%\\\\32.0 \% & = & \dfrac{m}{\text{344.9 g}} \times 100 \% \\\\\text{32.0 $\times$ 344.9 g} & = & 100 m\\\\m & = &\dfrac{\text{32.0 $\times$ 344.9 g}}{100}\\\\ & = &\textbf{110.4 g}\\\end{array}\\\text{You need $\boxed{\textbf{110.4 g}}$ of calcium chloride}[/tex]
2. Mass of water
[tex]\text{Let m = mass of water}\\\begin{array}{rcl}\\\text{Mass of water + mass of CaCl}_{2} & = & \text{Mass of solution}\\m + 110.4 & = & 344.9\\m & = &\mathbf{234.5}\\\end{array}\\\text{The mass of water needed is $\boxed{\textbf{234.5 g}}$}[/tex]
Which of the following types of energy does an object have because of its motion?
Chemical energy
Gravitational energy
Kinetic energy
Potential energy
Answer: Kinetic energy
Explanation:
Chemical energy is the energy stored in the bonds of molecules.
Gravitational energy is the potential energy held by an object because of its higher position compared to a lower position.
Kinetic energy is the energy possessed by a body by virtue of its motion.
Potential energy is the energy possessed by a body by virtue of its position.
Thus kinetic energy is the energy associated with an object because of its motion.
What is the pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I? (Kb of CH₃NH₂ is 4.4 × 10⁻⁴)
Answer:
[tex]\boxed{\text{10.84}}[/tex]
Explanation:
A solution of a weak base and its conjugate acid is a buffer.
The equation for the equilibrium is
[tex]\rm CH$_3$NH$_2$ + H$_2$O $\, \rightleftharpoons \,$ CH$_3$NH$_2$+ H$_{3}$O$^{+}$\\\text{For ease of typing, let's rewrite this equation as}\\\rm B + H$_2$O $\longrightarrow \,$ BH$^{+}$ + OH$^{-}$; $K_{\text{b}}$ = 4.4 \times 10^{-4}$[/tex]
The Henderson-Hasselbalch equation for a basic buffer is
[tex]\text{pOH} = \text{p}K_{\text{b}} + \log\dfrac{[\text{BH}^{+}]}{\text{[B]}}[/tex]
Data:
[B] = 0.400 mol·L⁻¹
[BH⁺] = 0.250 mol·L⁻¹
Kb = 4.4 × 10⁻⁴
Calculations:
(a) Calculate pKb
pKb = -log(4.4× 10⁻⁴) = 3.36
(b) Calculate the pH
[tex]\text{pOH} = 3.36 + \log \dfrac{0.250}{0.400} = 3.36 + \log 0.625 = 3.36 - 0.204 = 3.16\\\\\text{pH} =14.00 -3.16 = \mathbf{10.84}\\\\\text{The pH of the solution is }\boxed{\textbf{10.84}}[/tex]
The pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I = 10.84
This given solution contains a weak base (CH₃NH₂) and the conjugate acid of that weak base (CH₃NH₃I) which makes a Buffer.
To find the pH of a basic buffer, we can use a modification of the Henderson Hasselbalch equation.We know that
[tex]pOH=pK_b+log\frac{[salt]}{[base]}[/tex]
or, [tex]pH=pK_a+log\frac{[base]}{[salt]}[/tex]
CH₃NH₂ is the base and CH₃NH₃I is the corresponding conjugate acid (salt).
Given:
[base] = 0.400 M
[salt] or [acid] = 0.250 M
= 4.4 * 10-4
So = 3.36
solution:
Putting in the equation,
[tex]pOH= 3.36 +log\frac{0.250\ M}{0.400\ M}[/tex]
pOH= 3.16
So pH = 14 - pOH
= 10.84
Thus, the pH of a solution of 0.400 M CH₃NH₂ containing 0.250 M CH₃NH₃I = 10.84
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Determine what is missing from this neutralization reaction: −−−−+KCl→AgCl+KNO3
A. Ag2KN
B. AgNO3
C. KN2O
D. NHO3
Answer:
B. AgNO₃
Explanation:
If the products contain Ag, Cl, K, and NO₃, then this means that these were also the reactants. Remember that matter cannot be created nor destroyed in a chemical reaction, so whatever elements in the reactants were used, would be found in the products. In other words, an element does not change into another.
AgNO₃ + KCl → AgCl + KNO₃
Please help me! I think the answer to this is C because gas produced from liquid has the greatest release in entropy, right? And C is the only option producing gas. Please help me out! Is C the right answer or which one is?
The systems that shows the greatest increase in entropy is -
a.2H2 + O2®2H2O
b.NaCl ®Na+1 + Cl-1
c.2H2O ®2H2 + O2
d.AgCl3®Ag+3 + 3Cl-1
Answer:
c. 2H₂O → 2H₂ + O₂
Explanation:
Entropy is the state of randomness or disorderliness of the particles of a system. The more random and disorderly a system is, the more its entropy. When the physical state of matter changes, there is a considerable change in the entropy of such a system.
The increasing order of entropy is as listed below:
Solid < liquid < gas
Gases have the highest randomness in all states of matter.
From the equation of the reaction in option C, we see that water is going into the gaseous phase. The products of the reaction are hydrogen and oxygen gases. This is an increase in entropy.
Reaction B and D produced ions which are in aqeous solutions. They move from originally solid sate to a liquid phase.
Reaction A takes gases and turns them into water. This is a decrease in entropy.
why does matter change from one phase to another
Answer:
the state of matter depends on its temperature and pressure. example, at constant pressure of 1atm (atmospheric pressure), water at 100 degrees Celsius is vapor, and at different phases at different temperature. Note that's at pressure other than 1atm, water will not boil (be vaporized) at 100 degrees Celsius, it could be lesser or higher(depending on whether pressure is increased or decreased).
Therefore, the state of mater changes with respect to temperature and pressure action on it.
The salt formed by the reaction of the weak acid hydrocyanic acid, HCN, with the strong base potassium hydroxide is
potassium cyanide, KCN. What is the hydroxide ion concentration of a 0.255 M solution of potassium cyanide at 25 °C
given that the value of for hydrocyanic acid is 4.9 X 10-102
Answer:
2.28 × 10^-3 mol/L
Explanation:
The equation for the equilibrium is
CN^- + H2O ⇌ HCN + OH^-
Ka = 4.9 × 10^-10
KaKb = Kw
4.9 × 10^-10 Kb = 1.00 × 10^-14
Kb = (1.00 × 10^-14)/(4.9 × 10^-10) = 2.05 × 10^-5
Now, we can set up an ICE table
CN^- + H2O ⇌ HCN + OH^-
I/(mol/L) 0.255 0 0
C/(mol/L) -x +x +x
E/(mol/L) 0.255 - x x x
Ka = x^2/(0.255 - x) = 2.05 × 10^-5
Check for negligibility
0.255/(2.05 × 10^-5) = 12 000 > 400. ∴ x ≪ 0.255
x^2 = 0.255(2.05 × 10^-5) = 5.20 × 10^-6
x = sqrt(5.20 × 10^-6) = 2.28 × 10^-3
[OH^-] = x mol/L = 2.28 × 10^-3 mol/L