Determine the freezing point of a 0.51 molal
solution of benzoic acid in chloroform. Chloroform
has a freezing point of -63.5°C and a freezing
point depression constant of 4.70°C.kg/mol.
What is the freezing point of this solution?
°C

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.

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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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:

Thus, 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.

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.

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]

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.

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.

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:

Final answer:

Approximately 9.32 liters of radon gas would be in 3.43 moles at standard temperature and pressure (273K and 100 kPa).

Explanation:

To find the number of liters of radon gas in 3.43 moles at standard temperature and pressure (STP), we can use the ideal gas law equation: PV = nRT.

Substituting the given values into the equation:

Pressure (P) = 100 kPa

Temperature (T) = 273 K

Number of moles (n) = 3.43 mol

Ideal gas constant (R) = 8.31 L·kPa/mol·K

Volume (V) is what we need to find.

Using the equation PV = nRT, we can rearrange it to solve for the volume:

V = (nRT) / P

Plugging in the values:

V = (3.43 mol)(8.31 L·kPa/mol·K)(273 K) / 100 kPa

V ≈ 9.32 L

Therefore, there would be approximately 9.32 liters of radon gas in 3.43 moles at standard temperature and pressure.

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.

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,

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.

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

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

Answer:

B. is the correct answer

A chemical bond holds atoms together,is the statement that description of a chemical bond.

A chemical bond holds atoms together,is the statement that description of a chemical bond.

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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.

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.

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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The equilibrium expression for the given reaction 2SO3(g) <=> O2(g) + 2SO2(g) is Ke = [SO₃]² / ([SO₂]² [O₂]).

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)).

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

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

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

Answer:

the answer is letter B. it is  a gas containing nuclei and electrons.

B. It is a gas containing nuclei and electrons.

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.

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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

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.

Answer:

Answer choice A

Explanation:

When an electron is transferred to another atom, both atoms involved become ions.

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.

Answer:

No.

Explanation:

Mercury is not a solution​. It is a detonator.

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.

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.

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.

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

Answer:

Soil

Explanation:

Plants(a.k.a. Producers) obtain nitrogen(N) from the soil by absorption through their roots.

Answer:

D

Explanation: