Final answer:
The Aufbau principle leads to the format of the periodic table by arranging elements based on their electron configurations and the number of valence electrons they have.
Explanation:
The Aufbau principle, in connection with the periodic law, leads to the format of the periodic table by arranging elements based on their electron configurations and the number of valence electrons they have. The periodic table is organized in a way that groups elements with similar properties in the same vertical columns, also known as groups. This arrangement follows the filling of subshells with electrons according to the Aufbau principle.
How many hours will it take for the concentration of methyl isonitrile to drop to 15.0 % of its initial value?
Answer:
The concentration of methyl isonitrile will become 15% of the initial value after 10.31 hrs.
Explanation:
As the data the rate constant is not given in this description, However from observing the complete question the rate constant is given as a rate constant of 5.11x10-5s-1 at 472k .
Now the ratio of two concentrations is given as
[tex]ln (\frac{C}{C_0})=-kt[/tex]
Here C/C_0 is the ratio of concentration which is given as 15% or 0.15.
k is the rate constant which is given as [tex]5.11 \times 10^{-5} \, s^{-1}[/tex]
So time t is given as
[tex]ln (\frac{C}{C_0})=-kt\\ln(0.15)=-5.11 \times 10^{-5} \times t\\t=\frac{ln(0.15)}{-5.11 \times 10^{-5} }\\t=37125.6 s\\t=37125.6/3600 \\t= 10.31 \, hrs[/tex]
So the concentration will become 15% of the initial value after 10.31 hrs.
Complete question:
The rearrangement of methyl isonitrile (CH3NC) to acetonitrile (CH3NC) is a first-order reaction and has a rate constant of 5.11x10-5s-1 at 472k . If the initial concentration of CH3NC is 3.00×10-2M. How many hours will it take for the concentration of methyl isonitrile to drop to 15.0 % of its initial value?
Answer:
The time taken for the concentration of methyl isonitrile to drop to 15.0 % of its initial value is 10.3 hours
Explanation:
The initial concentration of CH3NC is 3.00 X 10⁻²M =0.03M
The rate constant K= 5.11 X 10⁻⁵s⁻¹
If the concentration of methyl isonitrile to drop to 15.0 %;
The new concentration of methyl isonitrile becomes 0.15 X 0.03 = 0.0045 M
The time taken to drop to 0.0045 M, can be calculated as follows:
[tex]t = -ln[\frac{(CH_3NC)}{(CH_3NC)_0}]/K[/tex]
[tex]t = (-ln[\frac{0.0045}{0.03}]/5.11 X 10^{-5})X(\frac{1 min}{60 s}) = 618.8 mins[/tex]
→ 618.8 mins X 1hr/60mins = 10.3 hours
Therefore, the time taken for the concentration of methyl isonitrile to drop to 15.0 % of its initial value is 10.3 hours
How much glycerol ( is liquid supplied at 100%) would you need to make 200 mL of 20% v/v (volume/volume) glycerol solution?
Answer:
40mL of glycerol are needed to make a 20% v/v solution
Explanation:
This problem can be solved with a simple rule of three:
20% v/v is a sort of concentration. In this case, 20 mL of solute are contained in 100 mL of solution.
Therefore, in 100 mL of solution you have 20 mL of solvent (glycerol)
In 200 mL, you would have, (200 .20)/ 100 = 40 mL
Benzoyl peroxide, the substance most widely used against acne, has a half-life of 9.8 × 103 days when refrigerated. How long will it take to lose 5% of its potency (95% remaining)? Assume that this is a first-order reaction. Give your answer in scientific notation.
Answer:
[tex]7.3\times 10^2\ days[/tex]
Explanation:
Given that:
Half life = [tex]9.8\times 10^3[/tex] days
[tex]t_{1/2}=\frac{\ln2}{k}[/tex]
Where, k is rate constant
So,
[tex]k=\frac{\ln2}{t_{1/2}}[/tex]
[tex]k=\frac{\ln2}{9.8\times 10^3}\ days^{-1}[/tex]
The rate constant, k = 0.00007 days⁻¹
Using integrated rate law for first order kinetics as:
[tex][A_t]=[A_0]e^{-kt}[/tex]
Where,
[tex][A_t][/tex] is the concentration at time t
[tex][A_0][/tex] is the initial concentration
Given:
5 % is lost which means that 0.05 of [tex][A_0][/tex] is decomposed. So,
[tex]\frac {[A_t]}{[A_0]}[/tex] = 1 - 0.05 = 0.95
t = ?
[tex]\frac {[A_t]}{[A_0]}=e^{-k\times t}[/tex]
[tex]0.95=e^{-0.00007\times t}[/tex]
t = 732.76 days = [tex]7.3\times 10^2\ days[/tex]
It will take approximately [tex]\( 7.25 \times 10^2 \)[/tex] days for benzoyl peroxide to lose 5% of its potency when refrigerated.
To determine the time, it takes for benzoyl peroxide to lose 5% of its potency, we can use the first-order reaction kinetics formula:
[tex]\[ N(t) = N_0 \times e^{-kt} \][/tex]
where:
[tex]\( N(t) \)[/tex] is the amount of substance remaining after time [tex]\( t \)[/tex],
[tex]\( N_0 \)[/tex] is the initial amount of substance,
[tex]\( k \)[/tex] is the rate constant,
[tex]\( t \)[/tex] is the time.
The half-life [tex]\( t_{1/2} \)[/tex] is related to the rate constant [tex]\( k \)[/tex] by the equation:
[tex]\[ t_{1/2} = \frac{\ln(2)}{k} \][/tex]
Given the half-life [tex]\( t_{1/2} = 9.8 \times 10^3 \)[/tex] days, we can solve for [tex]\( k \)[/tex]:
[tex]\[ k = \frac{\ln(2)}{t_{1/2}} = \frac{\ln(2)}{9.8 \times 10^3} \][/tex]
Now, we want to find the time [tex]\( t \)[/tex] when 95% of the substance remains, so [tex]\( N(t) = 0.95N_0 \)[/tex]. Plugging this into the first-order reaction formula:
[tex]\[ 0.95N_0 = N_0 \times e^{-kt} \][/tex]
[tex]\[ 0.95 = e^{-kt} \][/tex]
Taking the natural logarithm of both sides:
[tex]\[ \ln(0.95) = -kt \][/tex]
Solving for [tex]\( t \)[/tex]:
[tex]\[ t = -\frac{\ln(0.95)}{k} \][/tex]
Substituting [tex]\( k \)[/tex] with the expression involving the half-life:
[tex]\[ t = -\frac{\ln(0.95)}{\ln(2)/t_{1/2}} \][/tex]
[tex]\[ t = -\frac{\ln(0.95) \cdot t_{1/2}}{\ln(2)} \][/tex]
[tex]\[ t = -\frac{\ln(0.95) \cdot 9.8 \times 10^3}{\ln(2)} \][/tex]
[tex]\[ t \approx -\frac{\ln(0.95) \cdot 9.8 \times 10^3}{0.693} \][/tex]
[tex]\[ t \approx -\frac{-0.051293 \cdot 9.8 \times 10^3}{0.693} \][/tex]
[tex]\[ t \approx \frac{0.5027 \times 10^3}{0.693} \][/tex]
[tex]\[ t \approx 7.25 \times 10^2 \][/tex]
At 1 atm, how much energy is required to heat 75.0 g H 2 O ( s ) at − 20.0 ∘ C to H 2 O ( g ) at 119.0 ∘ C?
Answer:
238,485 Joules
Explanation:
The amount of energy required is a summation of heat of fusion, capacity and vaporization.
Q = mLf + mC∆T + mLv = m(Lf + C∆T + Lv)
m (mass of water) = 75 g
Lf (specific latent heat of fusion of water) = 336 J/g
C (specific heat capacity of water) = 4.2 J/g°C
∆T = T2 - T1 = 119 - (-20) = 119+20 = 139°C
Lv (specific latent heat of vaporization of water) = 2,260 J/g
Q = 75(336 + 4.2×139 + 2260) = 75(336 + 583.8 + 2260) = 75(3179.8) = 238,485 J
Select the NMR spectrum that corresponds best to p-bromoaniline. (see Hint for the structure.) The selected tab will be highlighted in blue. Click the tab number to toggle among them. All spectra are taken in CDCl3 and the peak at 0.0 ppm is trimethylsilane, which is used as a standard to calibrate chemical shifts.
The best NMR spectrum that corresponds to p-bromoaniline can be determined by analyzing the chemical shift values and multiplicity of the peaks. Tab 2 is the correct spectrum that matches the expected chemical shifts for p-bromoaniline.
Explanation:The NMR spectrum that corresponds best to p-bromoaniline can be determined by analyzing the chemical shift values and multiplicity of the peaks. In the NMR spectrum of p-bromoaniline, we would expect to see a peak for the bromine atom at a lower chemical shift value and a peak for the amino group at a higher chemical shift value.
The chemical shift values for p-bromoaniline would be different from those of the other molecules given in the choices. By comparing the chemical shift values and multiplicity pattern, we can identify the correct spectrum that matches the expected chemical shifts for p-bromoaniline.
Based on the given information, the best NMR spectrum that corresponds to p-bromoaniline would be Tab 2. This tab shows the expected chemical shift values and multiplicity pattern for p-bromoaniline.
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A ground-state H atom absorbs a photon of wavelength 94.91 nm, and its electron attains a higher energy level. The atom then emits two photons: one of wavelength 1281 nm to reach an intermediate level, and a second to reach the ground state.
(a) What higher level did the electron reach?
(b) What intermediate level did the electron reach?
(c) What was the wavelength of the second photon emitted?
A) The higher level that the electron reached from ground state is; n = 5
B) The intermediate level that the electron reached from ground state is; n = 3
C) The wavelength of the second photon emitted is; λ = 103 nm
A) We are given;
Wavelength of photon absorbed by ground state H atoms; λ_g = 94.91 nm = 94.91 × 10⁻⁹ m
Formula to get the higher level is Rydberg's formula;
1/λ = R(1/n₁² - 1/n₂²)
where;
R is rydberg constant = 1.097 × 10⁷ m⁻¹
Thus;
1/(94.91 × 10⁻⁹) = 1.097 × 10⁷(1/1² - 1/n₂²)
0.9605 = 1 - 1/n₂²
1/n₂² = 1 - 0.9605
1/n₂² = 0.0395
n₂ = √(1/0.0395)
n₂ ≈ 5
B) We want to find the intermediate level where wavelength = 1281 nm = 1281 × 10⁻⁹ m
Thus;
1/(1281 × 10⁻⁹) = 1.097 × 10⁷(1/n₂² - 1/5²)
0.0712 = 1/n₂² - ¹/₂₅
1/n₂² = 0.0712 + ¹/₂₅
1/n₂² = 0.1112
n₂ = √(1/0.1112)
n₂ ≈ 3
C) Formula for energy of photon is;
E = hc/λ
where;
h is Planck's constant = 6.626 × 10⁻³⁴ m².kg/s
c is speed of light = 3 × 10⁸ m/s
Thus;
E = (6.626 × 10⁻³⁴ × 3 × 10⁸)/(1281 × 10⁻⁹)
E = 1.552 × 10⁻¹⁹ J
The energy at ground state is;
E = (6.626 × 10⁻³⁴ × 3 × 10⁸)/(94.91 × 10⁻⁹)
E = 20.944 × 10⁻¹⁹ J
Thus;
Energy of second photon = (20.944 × 10⁻¹⁹) - (1.552 × 10⁻¹⁹)
Energy of second photon = 19.352 × 10⁻¹⁹ J
Wavelength of second photon emitted is;
λ = hc/E
λ = (6.626 × 10⁻³⁴ × 3 × 10⁸)/19.352 × 10⁻¹⁹
λ = 103 nm
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The electron moves to the third energy level after the initial photon absorption, then drops to the fourth energy level releasing a photon of 1281 nm wavelength, and finally back to the ground state with a recorded emission of 97.08 nm wavelength.
Explanation:To solve this, we can use the Rydberg formula for hydrogen: 1/λ = R (1/n1^2 - 1/n2^2), where λ is the wavelength of the light, R is the Rydberg constant (1.096776 x 10^7 m^-1), n1 is the lower energy level, and n2 is the higher energy level.
(a) The photon absorbed takes the electron to a higher energy level, so we use the wavelength 94.91 nm, and n1 = 1 (ground state). This calculates to n2 = 2.32, meaning the electron moves to roughly the third energy level as energy levels are only in whole numbers.
(b) The first emitted photon has wavelength 1281 nm, which brings the electron to an intermediate level. By substituting the values, we calculate n1 = 3 and get n2 = 4. So, the intermediate energy level is 4.
(c) For the second photon emitted, we know the electron goes from n = 4 to the ground state n = 1. Rearranging the Rydberg formula, we find λ = 97.08 nm, which is the wavelength of the second photon emitted.
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Draw the structures of the 4 isomers of C8H18 that contain 2 methyl branches on separate carbons of the main chain.
Explanation:
1. 2,3-dimethylhexane
2. 2,4-dimethylhexane
3. 2,5-dimethylhexane
4. 3,4-dimethylhexane
Below are the structures of the isomers.
Rank the ions in each set in order of increasing size:
(a) CI⁻, Br⁻, F⁻
(b) Na⁺, Mg²⁺, F⁻
(c) Cr²⁺, Cr³⁺
Answer:
a) F⁻ < Cl⁻ < Br⁻
b) Mg²⁺ < Na⁺ < F⁻
c) Cr³⁺ < Cr²⁺
Explanation:
The ions in (a) part of the question belong to a halogen group. F, Cl, and Br are present in periods 2, 3, and 4 respectively. As we move down the group the size of atoms increases hence their ions will be in the same order. (ion from top to bottom of group 7)
The ions in (b) part of the question are isoelectronic. The relative size of such species can be estimated by the charge on their nucleus. Lower the nucleus charge greater will be the size of the ion.
Nuclear charge of Mg²⁺ = no. of protons = 12
Nuclear charge of Na⁺ = no. of protons = 11
Nuclear charge of F⁻ = no. of protons = 9
The ions in (c) part are the two oxidized states of chromium. In such cases, higher the number of nuclear charge smaller will be the ion.
What is the volume of a 0.5 mol/L NaOH solution required to completely react with 20 mL of a 2.0 mol/L HCl solution? What is the pH value of the produced solution? (Hint: Write and balance the chemical reaction between HCl and NaOH, and then use the stoichiometric relation (molar relation) between NaOH and HCl to calculate the minimum volume of NaOH solution.) Group of answer choices
Answer:
The volume of NaOH required is 80mL
pH of the resulting solution is 7 since reaction produces a normal salt
Explanation:
First, we generate a balanced equation for the reaction as shown below:
NaOH + HCl —> NaCl + H2O
From the equation,
nA = 1
nB = 1
From the question,
Ma = 2.0 mol/L
Va = 20 mL
Mb = 0.5 mol/L
Vb =?
MaVa / MbVb = nA /nB
2x20 / 0.5 x Vb = 1
0.5 x Vb = 2 x 20
Divide both side by 0.5
Vb = (2 x 20)/0.5
Vb = 80mL
The volume of NaOH required is 80mL
Since the reaction involves a strong acid and a strong base, a normal salt solution will be produced which is neutral to litmus paper. So since the salt solution is neutral to litmus paper then the pH of the resulting solution is 7
The pH of a solution prepared by mixing HCl and NaOH, we need to determine the concentration of the resulting solution. Since HCl and NaOH react in a 1:1 ratio to form water and salt (NaCl), we can use the concept of neutralization to find the resulting concentration.
Moles of HCl = volume (in L) × molarity = 0.020 L × 0.30 mol/L = 0.006 mol
Moles of NaOH = volume (in L) × molarity = 0.015 L × 0.60 mol/L = 0.009 mol
Since HCl and NaOH react in a 1:1 ratio, the limiting reagent is HCl. This means that all of the HCl will react with NaOH, and we will have an excess of NaOH. Therefore, the number of moles of HCl remaining will be zero.
Total volume = 20.0 mL + 15.0 mL = 35.0 mL = 0.035 L
Concentration of resulting solution = (Moles of HCl + Moles of NaOH) / Total volume
= (0.006 mol + 0.009 mol) / 0.035 L
= 0.429 mol/L
pH = -log[H+]
pH = -log(0.429)
≈ 0.366
Therefore, the pH of the solution prepared by mixing 20.0 mL of 0.30 M HCl with 15.0 mL of 0.60 M NaOH is approximately 0.366.
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(3) 1. HCl NaOH: In Part I: An aqueous solution of sodium hydroxide reacts with an aqueous solution of hydrochloric acid, yielding water. Write the balanced molecular, ionic, and net ionic equations
Answer:HCl(aq) + NaOH (aq) -> NaCl (aq) + H2O(l)
Explanation:
The reaction of HCl and NaOH is a neutralization reaction. When an acid and a base react salt and water is produced.
HCl(aq) + NaOH (aq) ----> NaCl (aq) + H2O(l)
Because the reactants and products are ionic compounds, they exist as ions in a solution.
H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) -------> Na+(aq) + Cl-(aq) + H2O(l)
The aim of a neutralization reaction is the formation of water. Na+(aq) + Cl-(aq) remain the same on both the reactants side and the products side, the net ionic reaction will be
H+(aq) + OH-(aq) -------> H2O(l)
The reaction of HCl and NaOH forms water in a neutralization reaction. The net ionic equation, H⁺ + OH⁻ → H₂O, emphasizes the essential combination of ions to produce water.
The reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) is a neutralization reaction, resulting in the formation of water and salt. In molecular form, the equation is written as:
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
Considering the ionic nature of these compounds in solution, they exist as ions. The complete ionic equation includes the dissociation of each compound into its constituent ions:
H⁺(aq) + Cl⁻(aq) + Na⁺(aq) + OH⁻(aq) → Na⁺(aq) + Cl⁻(aq) + H₂O(l)
Sodium cations (Na⁺) and chloride anions (Cl⁻) remain unchanged on both sides, acting as spectator ions. Eliminating these spectator ions yields the net ionic equation:
H⁺(aq) + OH⁻(aq) → H₂O(l)
This simplified representation emphasizes the essential components of the neutralization reaction, focusing on the combination of hydrogen ions (H⁺) from the acid and hydroxide ions (OH⁻) from the base to form water. The net ionic equation succinctly captures the core chemical transformation occurring in the neutralization process.
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When collecting your solid, why should the filter paper in the Buchner funnel be wetted with some of the cold recrystallization solvent before a recrystallization mixture is filtered?
Answer: It is important to wet the filter paper in the Buchner funnel first with cold re crystallization solvent before the re crystallization mixture being filtered to minimize gaps around the edges of the filter paper which can prevent mechanical impurities from passing through. This gives better filtration where most impurities can be filtered. Furthermore, it provides good vacuum.
If the density of water is 1.00 g/mL and the density of mercury is 13.6 g/mL, how high a column of water in meters can be supported by standard atmospheric pressure?
Answer:
The answer to this is
The column of water in meters that can be supported by standard atmospheric pressure is 10.336 meters
Explanation:
To solve this we first list out the variables thus
Density of the water = 1.00 g/mL =1000 kg/m³
density of mercury = 13.6 g/mL = 13600 kg/m³
Standard atmospheric pressure = 760 mmHg or 101.325 kilopascals
Therefore from the equation for denstity we have
Density = mass/volume
Pressure = Force/Area and for a column of water, pressure = Density × gravity×height
Therefore where standard atmospheric pressure = 760 mmHg we have for Standard tmospheric pressure= 13600 kg/m³ × 9.81 m/s² × 0.76 m = 101396.16 Pa
This value of pressure should be supported by the column of water as follows
Pressure = 101396.16 Pa = kg/m³×9.81 m/s² ×h
∴ [tex]h = \frac{101396.16}{(1000)(9.81)}[/tex] = 10.336 meters
The column of water in meters that can be supported by standard atmospheric pressure is 10.336 meters
Final answer:
A column of water about 10.33 meters high can be supported by standard atmospheric pressure, based on the relationship between pressure, fluid density, gravitational acceleration, and height of the fluid column.
Explanation:
To calculate the height of a column of water supported by standard atmospheric pressure, we can use the pressure exerted by a column of liquid formula, which is p = hρg where p is the pressure, h is the height of the liquid column, ρ (rho) is the density of the liquid, and g is the acceleration due to gravity. The standard atmospheric pressure is 101,325 Pa, and the density of water is 1.00 g/cm³ or 1000 kg/m³.
Since 1 atm is equivalent to the pressure exerted by a 760 mm column of mercury, and mercury is 13.6 times denser than water, a water column would need to be 13.6 times taller. Thus:
101325 Pa = (h)(1000 kg/m³)(9.81 m/s²)
h = 101325 Pa / (1000 kg/m³ × 9.81 m/s²) = 10.33 m
Therefore, a column of water about 10.33 meters high can be supported by standard atmospheric pressure.
There are exactly 60 seconds in a minute, exactly 60 minutes in an hour, exactly 24 hours in a mean solar day, and 365.24 solar days in a solar year. Part A How many seconds are in a solar year
Answer: The number of seconds in a solar year is [tex]3.2\times 10^7s[/tex]
Explanation:
We are given some conversion factors:
1 minute = 60 seconds
1 hour = 60 minutes
1 solar day = 24 hours
1 solar year = 365.24 solar days
Calculating the number of seconds in 1 solar year by using the conversion factors, we get:
[tex]\Rightarrow (\frac{60s}{1min})\times (\frac{60min}{1hr})\times (\frac{24hr}{1\text{solar day}})\times (\frac{365.24\text{solar days}}{1\text{ solar year}})\\\\\Rightarrow (\frac{31556736s}{1\text{ solar year}})[/tex]
There are 31556736 seconds in 1 solar year.
Hence, the number of seconds in a solar year is [tex]3.2\times 10^7s[/tex]
In what ways are microwave and ultraviolet radiation the same? In what ways are they different?
Answer:
Electromagnetic waves are usually defined as those waves that are generated due to the vibrations between an electric as well as a magnetic field. Here, the component comprising the electric field and the component comprising the magnetic field vibrates perpendicular to each other, and both are in phase. Some of the examples of this type of wave are microwaves, infrared, ultra-violet, visible light, X-rays and many more.
The microwave and ultraviolet radiations are two electromagnetic waves that have similar characteristics, travel at a similar speed of about 300,000 km per second.
They differ from one another in many ways. It is because the microwaves have a higher wavelength, low frequency, and low energy. On the other hand, ultraviolet radiations have a low wavelength, high frequency, and high energy.
Covalent bonds in a molecule absorb radiation in the IR region and vibrate at characteristic frequencies.
(a) The C—O bond absorbs radiation of wavelength 9.6 μm. What frequency (in s⁻¹) corresponds to that wavelength?
(b) The H—Cl bond has a frequency of vibration of 8.652 x 10¹³ Hz. What wavelength (in μm) corresponds to that frequency?
Answer:
(a) ν = 3.1 × 10¹³ s⁻¹
(b) λ = 3.467 μm
Explanation:
We can solve both problems using the following expression.
c = λ × ν
where,
c: speed of light
λ: wavelength
ν: frequency
(a)
c = λ × ν
ν = c / λ
ν = (3.000 × 10⁸ m/s) / (9.6 × 10⁻⁶ m)
ν = 3.1 × 10¹³ s⁻¹
(b)
c = λ × ν
λ = c / ν
λ = (3.000 × 10⁸ m/s) / (8.652 × 10¹³ s⁻¹)
λ = 3.467 × 10⁻⁶ m
λ = 3.467 × 10⁻⁶ m (10⁶ μm/ 1 m)
λ = 3.467 μm
Give all possible ml values for orbitals that have each of the following: (a) l = 2; (b) n = 1; (c) n = 4, l = 3.
Answer:
(a) ml = 0, ±1, ±2
(b) ml = 0
(c) ml = 0, ±1, ±2, ±3, ±4
Explanation:
The rules for electron quantum numbers are:
1. Shell number, 1 ≤ n
2. Subshell number, 0 ≤ l ≤ n − 1
3. Orbital energy shift, -l ≤ ml ≤ l
4. Spin, either -1/2 or +1/2
So in our exercise,
(a) l = 2; equivalent with with sublevel d
-l ≤ ml ≤ l, ml = 0, ±1, ±2, equivalent with dxy, dxz, dyz, dx2-y2, dz2
(b) n = 1;
n = 1, only 01 level
l = 0, equivalent with sublevel s
ml = 0
(c) n = 4, l = 3.
l = 3, equivalent with sublevel f
ml = 0, ±1, ±2, ±3, ±4
A hydrate of beryllium nitrate has the following formula: Be(NO3)2⋅xH2O . The water in a 3.41-g sample of the hydrate was driven off by heating. The remaining sample had a mass of 2.43 g .Find the number of waters of hydration (x) in the hydrate.
Answer:
The formula is Be(NO3)2*3H2O. The number of waters in the hydrate is 3
Explanation:
Step 1: Data given
Mass of the hydrate sample = 3.41 grams
Mass after heating = 2.43 grams
Step 2: Calculate mass of water
After heating, all the water is gone. So the mass of water can be calculated by
Mass of hydrate before heating - mass after heating
Mass of water = 3.41 -2.43 = 0.98 grams
Step 2 : Calculate moles H2O
Moles H2O = mass H2O / molar mass H2O
Moles H2O = 0.98 grams / 18.02 g/mol
Moles H2O = 0.054 moles
Step 3: Calculate moles Be(NO3)2
Moles Be(NO3)2 = 2.43 grams / 133.02
Moles Be(NO3)2 = 0.0183 moles
Step 4: Calculate molecules water
Molecules H2O = 0.054 moles / 0.0183 moles
Molecules H2O = 3.0
The formula is Be(NO3)2*3H2O. The number of waters in the hydrate is 3
The number of waters of hydration in the hydrate is 3.
Based on the given information,
• The formula of the beryllium nitrate hydrate is Be(NO3)2⋅xH2O.
• The weight of the sample is 3.41 grams.
• The weight of the sample after heating of the sample is 2.43 grams {weight of Be(NO3)2}.
Now, the mass of xH2O will be,
= 3.41 g - 2.43 g
= 0.98 grams
The moles of Be(NO3)2 will be calculated as,
Mass of Be(NO3)2/Molecular weight of Be(NO3)2 = 2.43 g/133 = 0.01827 moles
The moles of xH2O = 0.98/18 = 0.05444 moles
Now the value of x will be,
= 0.05444/0.01827
= 3
Thus, the number of waters of hydration in the hydrate is 3.
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Consider the following equilibria in aqueous solution (1) Ag++ Cl-ーAgCl(aq) (2) AgCl(aq)CAgC12 (3) AgCls)Ag*CI K = 20-103 K = 93 K= 1.8.10-10 (a) Find K for the reaction AgCI(s)AgCl(aq). The species AgCl(aq) is an ion pair consisting of Ag and Cl associated with each other in solution. (b) Find [AgCl(aq)] in equilibrium with excess AgCl(s).
Explanation:
(a) Chemical reaction equation is given as follows.
[tex]Ag^{+} + Cl^{-} \rightarrow AgCl(aq) \rightarrow K_{1}[/tex]
Also,
[tex]AgCl(s) \rightarrow Ag^{+} + Cl^{-} \rightarrow K_{3}[/tex]
Therefore, the net reaction equation is as follows.
[tex]AgCl(s) \rightarrow AgCl(aq)[/tex]
Now, we will calculate the value of K for this reaction as follows.
K = [tex]K_{1} \rightarrow K_{2}[/tex]
= [tex]2.0 \times 10^{3} \times 1.8 \times 10^{-10}[/tex]
= [tex]3.6 \times 10^{-7 }[/tex]
Hence, the value of K for the given reaction is [tex]3.6 \times 10^{-7 }[/tex].
(b) As the reaction is given as follows.
[tex]AgCl(s) \rightarrow AgCl(aq)[/tex]
Therefore, when excess of AgCl(s) is added then the amount of [AgCl(aq)] present in equilibrium is as follows.
K = [AgCl(aq)] = [tex]3.6 \times 10^{-7 }[/tex]
Thus, the value of [AgCl(aq)] in equilibrium with excess AgCl(s) is [tex]3.6 \times 10^{-7 }[/tex].
(a) The equilibrium constant K for the reaction[tex]\(\text{AgCl(s)} \rightleftharpoons \text{AgCl(aq)}\) is \( 3.6 \times 10^{-9} \).[/tex]
(b) The concentration of AgCl(aq) in equilibrium with excess AgCl(s) is [tex]\( 3.6 \times 10^{-9} \, \text{M} \).[/tex]
Part (a): Finding K for the reaction-
We are given the following equilibria and their constants:
1. [tex]\(\text{Ag}^+ + \text{Cl}^- \rightleftharpoons \text{AgCl(aq)} \quad K_1 = 20\)[/tex]
2. [tex]\(\text{AgCl(aq)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad K_2 = 93\)[/tex]
3. [tex]\(\text{AgCl(s)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad K_3 = 1.8 \times 10^{-10}\)[/tex]
We need to find K for the reaction:
[tex]\[ \text{AgCl(s)} \rightleftharpoons \text{AgCl(aq)} \][/tex]
We can see that we need to combine these equilibria in a way that gets us from AgCl(s) to AgCl(aq)
Let's write the reactions again:
1. [tex]\(\text{Ag}^+ + \text{Cl}^- \rightleftharpoons \text{AgCl(aq)} \quad K_1 = 20\)[/tex]
2. [tex]\(\text{AgCl(aq)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad K_2 = 93\)[/tex]
3. [tex]\(\text{AgCl(s)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad K_3 = 1.8 \times 10^{-10}\)[/tex]
The relationship between these equilibria can be described as follows:
- [tex]\(\text{AgCl(s)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad (K_3)\)[/tex]
- [tex]\(\text{Ag}^+ + \text{Cl}^- \rightleftharpoons \text{AgCl(aq)} \quad (K_1)\)[/tex]
If we multiply K₃ by K₁, we will get the desired equilibrium:
[tex]\[ \text{AgCl(s)} \rightleftharpoons \text{Ag}^+ + \text{Cl}^- \quad (K_3) \][/tex]
[tex]\[ \text{Ag}^+ + \text{Cl}^- \rightleftharpoons \text{AgCl(aq)} \quad (K_1) \][/tex]
Multiplying these two equilibria together, the intermediate [tex]\(\text{Ag}^+\)[/tex] and [tex]\(\text{Cl}^-\)[/tex] ions cancel out, giving us:
[tex]\[ \text{AgCl(s)} \rightleftharpoons \text{AgCl(aq)} \][/tex]
The equilibrium constant for this reaction is:
[tex]\[ K = K_3 \times K_1 \][/tex]
Substituting the given values:
[tex]\[ K = (1.8 \times 10^{-10}) \times 20 \] \\[/tex]
[tex]\[ K = 3.6 \times 10^{-9} \][/tex]
So, the equilibrium constant K for the reaction [tex]\(\te{AgCl(s)} \rightleftharpoons \text{AgCl(aq)}\)[/tex] is [tex]\( 3.6 \times 10^{-9} \).[/tex]
Part (b): Finding AgCl(aq) in equilibrium with excess AgCl(s)
When AgCl(s) is in equilibrium with AgCl(aq), the equilibrium expression for this reaction is:
[tex]\[ K = [\text{AgCl(aq)}] \][/tex]
From Part (a), we found that:
[tex]\[ K = 3.6 \times 10^{-9} \][/tex]
Therefore, the concentration of [tex]\(\text{AgCl(aq)}\)[/tex] in equilibrium with excess [tex]\(\text{AgCl(s)}\)[/tex] is:
[tex]\[ [\text{AgCl(aq)}] = 3.6 \times 10^{-9} \, \text{M} \][/tex]
Calcium carbonate decomposes when heated to solid calcium oxide and carbon dioxide gas. The balanced equation is: CaCO3(s) → CaO(s) + CO2(g) Before this reaction was run, the reaction container, including the CaCO3, had a mass of 24.20 g. After the reaction, the container with product (and any unreacted reactant) had a mass of only 22.00 g because the CO2 gas produced did not remain in the container. What mass of CaCO3 reacted?
Answer:
The mass of CaCO3 reacted is 5.00 grams
Explanation:
Step 1 :Data given
Before the reaction, the container, including the CaCO3, had a mass of 24.20 g
After the reaction the container with product had a mass of only 22.00 g because the CO2 gas produced did not remain in the container.
Molar mass of CO2 = 44.01 g/mol
Molar mass CaCO3 = 100.09 g/mol
Step 2: The balanced equation
CaCO3 → CaO + CO2
Step 3: Calculate mass of CO2
Mass of CO2 = 24.20 grams - 22.00 grams
Mass of CO2 = 2.20 grams
Step 4: Calculate moles CO2
Moles CO2 = mass CO2 / molar mass CO2
Moles CO2 = 2.20 grams / 44.01 g/mol
Moles CO2 = 0.0500 moles
Step 5: Calculate moles CaCO3
For 1 mol CaCO3 we'll have 1 mol CaO and 1 mol CO2
For 0.0500 moles CO2 we need 0.0500 moles CaCO3
Step 6: Calculate mass CaCO3
Mass CaCO3 = moles CaCO3 * molar mass CaCO3
Mass CaCO3 = 0.0500 moles * 100.09 g/mol
Mass CaCO3 = 5.00 grams
The mass of CaCO3 reacted is 5.00 grams
Final answer:
2.20 grams of calcium carbonate (CaCO3) reacted, as calculated by the difference in mass before and after the decomposition reaction, which released carbon dioxide gas from the container.
Explanation:
The initial mass of the reaction container with calcium carbonate (CaCO3) was 24.20 g, while the final mass after the reaction was 22.00 g. The mass of CaCO3 that reacted can be found by subtracting the final mass from the initial mass, because the only mass lost would be the carbon dioxide (CO2) gas that escaped from the container.
Mass of CaCO3 that reacted = Initial mass - Final mass
= 24.20 g - 22.00 g
= 2.20 g
Therefore, 2.20 grams of calcium carbonate reacted, decomposing into calcium oxide (CaO) and releasing carbon dioxide gas according to the reaction CaCO3(s) → CaO(s) + CO2(g).
Identify each element below, and give the symbols of the other elements in its group:
(a) [Ar] 4s²3d¹⁰4p⁴
(b) [Xe] 6s²4f¹⁴5d²
(c) [Ar] 4s²3d⁵
Answer:
In explanation
Explanation:
a. Selenium, atomic number 34
Argon is 18, adding the other electrons gives 34.
Other elements include: oxygen O , Sulphur S , Tellurium Te and Polonium Po
b. Hafnium, element 72
Xe is 54, adding the other electrons makes the total 72.
Other elements; Titanium Ti, Zirconium Zr, Rutherfordium Rf
c. Manganese, element 25
Other group members are Technetium Tc , Rhenium Re and Bohrium Bo
You are interested in thymol in mouthwash. The manufacturer lists the active ingredients as thymol (0.064%), menthol (0.042%), eucalyptol (0.092%) and methyl salicylate. The inactive ingredients include caramel, water and alcohol (21.6%) in addition to sodium benzoate, color, poloxamer 407 and benzoic acid.
(a) Does thymol represent a major, minor or trace concentration?
(b) of the ingredients listed with concentration, which ones can be considered in trace amounts?
(c) Which substance(s) is/are the sample?
(d) Which substance(s) is/are the analyte?
(e) Which substance(s) is/are the matrix?
(f) If you were to prepare a blank for your measurement, what substance(s) would it contain?
Answer:
a) Thymol represents a minor concentration.
b) Of the ingredients listed, the ones that qualify as being contained in trace amounts are the ones with concentrations less than 0.01%, 100ppm or 0.1mg/L. And in this question, none of the given concentrations is less than 0.01%. Maybe one of the other constituents whose concentrations weren't given is in trace amounts.
c) The mouthwash brought for analysis is the sample.
d) Thymol is the analyte.
e) The matrix is every component of the mouthwash sample apart from the analyte constituent, thymol.
Menthol, eucalyptol, methyl salicylate, caramel, water, alcohol in addition to sodium benzoate, color, poloxamer 407 and benzoic acid are all member substances of the matrix.
f) The blank can contain every constituent apart from the analyte constituent, thymol.
Explanation:
a) The composition range for major, minor and trace components are given thus.
1-100% Major
0.01-1% Minor
1 ppb to 100ppm Trace
<1ppb ultra trace
In Chemistry terms,
•Major constituents: Substances in concentrations over 1mg/L
•Minor constituents: Substances in concentrations between 1mg/L and 0.1 mg/L
•Trace constituents: Substances in concentrations under 0.1 mg/L
Hence, thymol with a concentration of 0.064% represents a minor constituent.
b) Of the ingredients listed, the ones that qualify as being contained in trace amounts are the ones with concentrations less than 0.01%, 100ppm or 0.1mg/L. And in this question, none of the given concentrations is less than 0.01%. Maybe one of the other constituents whose concentrations weren't given is in trace amounts.
c) In chemical analysis or Analytical chemistry, a sample is a portion of material selected from a larger quantity of material.
Therefore, for this question, the mouthwash is the sample.
d) In Analytical Chemistry, an analyte or analyte component is a substance or chemical constituent that is of interest in an analytical procedure.
For this question, the analyte is thymol; the constituent the analyser is interested in.
e) In chemical analysis, matrix refers to the components of a sample other than the analyte of interest.
Therefore, the matrix is every component of the mouthwash sample apart from the analyte constituent, thymol.
Menthol, eucalyptol, methyl salicylate, caramel, water, alcohol in addition to sodium benzoate, color, poloxamer 407 and benzoic acid are all member substances of the matrix.
f) A blank solution is a solution containing little to no analyte of interest, so, the blank can contain every constituent apart from thymol.
Hope this helps!
The properties of several unknown solids were measured. Solid Melting point Other properties A >1000 °C does not conduct electricity B 850 °C conducts electricity in the liquid state, but not in the solid state C 750 °C conducts electricity in the solid state D 150 °C does not conduct electricity Classify the solids as ionic, molecular, metallic, or covalent. Note that covalent compounds are also known as covalent network solids or macromolecular solids. Ionic Molecular Metallic Covalent
Answer:
Explanation:
A >1000 °C does not conduct electricity : covalent ( usually do not conduct electricity, they are formed by the sharing of electrons)
B 850 °C conducts electricity in the liquid state, but not in the solid state: Ionic ( ionic or electrovalent compounds are formed between atoms where one loses an electron while the other gains e.g NaCl, they conduct electricity when dissolved in a polar solvent because they dissociate into ions and have high melting and boiling points)
750 °C conducts electricity in the solid state : Metallic ( metals generally have delocalized electrons that enables them to conduct electron since they are no associated with bond and are therefore free to move)
D 150 °C does not conduct electricity : Molecular ( consist mainly of molecules; they do not have charge)
Gold has a density of 0.01932 kg/cm3. What is the mass (in kg) of a 92.5 cm3 sample of gold?A) 1.79B) 0.560C) 92.5D) 0.000209E) 4790
Answer:
A. 1.79kg
Explanation:
The value of the mass of a particular substance could be obtained if there is adequate information about the volume of that particular substance and the density of that substance.
Mathematically expressed, the mass of a substance is the product of the density and the volume .
In this particular question, the density is 0.01932kg/cm3 while the volume is 92.5cm3
The mass is thus = 92.5 * 0.01932 = 1.7871kg which is approximately 1.79kg
The mass of a 92.5 cm3 sample of gold is approximately 1.79 kg.
Explanation:The mass of an object can be calculated by multiplying its density by its volume. In this case, the density of gold is given as 0.01932 kg/cm3, and the volume of the gold sample is 92.5 cm3. To find the mass, we can use the formula:
mass = density * volume
Substituting the values, we have:
mass = 0.01932 kg/cm3 * 92.5 cm3
Calculating this, we find that the mass of the gold sample is approximately 1.79 kg.
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What is the electric potential, in volts, due to the proton in an orbit with radius 0.530 × 10–10 m?
Answer : The electric potential on proton is, 27.1 V
Explanation :
To calculate the electric potential we are using the formula.
[tex]V=\frac{1}{4\pi \epsilon_0}\frac{q}{r}[/tex]
where,
V = electric potential
q = charge on proton = [tex]1.6\times 10^{-19}C[/tex]
r = radius = [tex]0.530\times 10^{-10}m[/tex]
[tex]\frac{1}{4\pi \epsilon_0}=8.99\times 10^9[/tex]
Now put all the given values in the above formula, we get:
[tex]V=(8.99\times 10^9)\times \frac{1.6\times 10^{-19}}{0.530\times 10^{-10}}[/tex]
[tex]V=27.1V[/tex]
Thus, the electric potential on proton is, 27.1 V
. You transfer 25.00 mL of your Kroger brand vinegar solution via volumetric pipet to a 250.00 mL volumetric flask and dilute to the final volume using distilled water, after which you mix the solution well. Next, you take a 25.00 mL aliquot of this diluted commercial vinegar solution and transfer it to a 150 mL Erlenmeyer flask. Titration of this sample to the phenolphthalein endpoint with sodium hydroxide required 15.81 mL of the 0.1002 M NaOH titrant. Based on this data, what is the molar concentration of the acetic acid in the original Kroger brand commercial vinegar solution ?
Answer:
0.0634 M.
Explanation:
Equation of the neutralisation reaction:
CH3COOH + NaOH--> CH3COONa + H2O
Number of moles = molar concentration * volume
= 0.1002 * 0.01581
= 0.00158 mol.
By stoichiometry,
1 mole of acetic acid reacts with 1 mole of NaOH
Number of moles of acetic acid = 0.00158 mol.
Concentration in 2nd dilution = moles/ volume
= 0.00158/0.25
= 0.00634 M
At 25 ml,
Concentration =
C1 * V1 = C2 * V2
= (0.00634 * 0.25)/0.025
= 0.0634 M.
Given:
Molar concentration of NaOH = 0.1002 MVolume = 15.81 mL or, 0.01581 LNeutralization reaction's equation:
[tex]CH_3 COOH+ NaOH \rightarrow CH_3COONa+H_2O[/tex]Now,
The number of moles will be:
= [tex]Molar \ concentration\times Volume[/tex]
= [tex]0.1002\times 0.01581[/tex]
= [tex]0.00158 \ mol[/tex]
and,
The concentration of second dilution will be:
= [tex]\frac{Moles}{Volume}[/tex]
= [tex]\frac{0.00158}{0.25}[/tex]
= [tex]0.00634 \ M[/tex]
hence,
The concentration at 25 mL will be:
→ [tex]C_1\times V_1 = C_2\times V_2[/tex]
or,
→ [tex]C_2 = \frac{C_1\times V_1}{V_2}[/tex]
[tex]= \frac{0.00634\times 0.25}{0.025}[/tex]
[tex]= 0.0634 \ M[/tex]
Thus the above response is right.
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Which of the following has the largest number of molecules? a 1 g of benzene, C6H6 b 1 g of formaldehyde, CH2O c 1 g of TNT, C7H5N3O6 d 1 g of naphthalene, C10H8 e 1 g of glucose, C6H12O6
Answer: 1g of formaldehyde
Explanation:
Molar Mass of benzene (C6H6) = (12x6) + (6x1) = 78g/mol
1mole(78g) of benzene contains 6.02x10^23 molecules.
1g of benzene with contain = (6.02x10^23) /78 = 7.72x10^21 molecules
Molar Mass of formaldehyde (CH2O) = 12 +2+16 = 30g/mol
1mole (30g) of formaldehyde contains 6.02x10^23 molecules.
1g of formaldehyde will contain = (6.02x10^23) /30 = 2.01x10^22 molecules
Molar Mass of TNT(C7H5N3O6) = (12x7)+(5x1)+(14x3)+(16x6) = 227g/mol
1mole(227g) of TNT contains 6.02x10^23 molecules.
1g of TNT will contain = (6.02x10^23)/227 = 2.65x10^21 molecules
Molar Mass of naphthalene (C10H8) = (12x10) +8 =128g/mol
1mole(128g) of naphthalene contains 6.02x10^23 molecules.
1g of naphthalene will contain = (6.02x10^23)/128 = 4.7x10^21 molecules
Molar Mass of glucose(C6H12O6) = (12x6) + 12 +(16x6) = 180g/mol
1mole(180g) of glucose contains 6.02x10^23 molecules.
1g of glucose will contain = (6.02x10^23)/180 = 3.34x10^21 molecules
Therefore, 1g of each of the compound contains the following:
Benzene = 7.72x10^21 molecules
Formaldehyde = 2.01x10^22 molecules
TNT = 2.65x10^21 molecules
Naphthalene = 4.7x10^21 molecules
Glucose = 3.34x10^21 molecules
From the above, we see clearly that formaldehyde has the largest number of molecules
Final answer:
The compound with the largest number of molecules is formaldehyde with 2.00 x 10^22 molecules.
Explanation:
The substance with the largest number of molecules can be determined by calculating the number of moles of each substance and then using Avogadro's number to convert moles to molecules. The formula to calculate the number of moles is moles = mass / molar mass. By using this formula:
For benzene: moles = 1g / 78.11g/mol = 0.0128 moles
For formaldehyde: moles = 1g / 30.03g/mol = 0.0333 moles
For TNT: moles = 1g / 227.13g/mol = 0.0044 moles
For naphthalene: moles = 1g / 128.2g/mol = 0.0078 moles
For glucose: moles = 1g / 180.16g/mol = 0.0055 moles
Then, we can use Avogadro's number (6.022 x 10^23 molecules/mol) to convert moles to molecules:
For benzene: molecules = 0.0128 mol x 6.022 x 10^23 molecules/mol = 7.72 x 10^21 molecules
For formaldehyde: molecules = 0.0333 mol x 6.022 x 10^23 molecules/mol = 2.00 x 10^22 molecules
For TNT: molecules = 0.0044 mol x 6.022 x 10^23 molecules/mol = 2.65 x 10^21 molecules
For naphthalene: molecules = 0.0078 mol x 6.022 x 10^23 molecules/mol = 4.68 x 10^21 molecules
For glucose: molecules = 0.0055 mol x 6.022 x 10^23 molecules/mol = 3.31 x 10^21 molecules
Therefore, the compound with the largest number of molecules is formaldehyde with 2.00 x 10^22 molecules.
Determine the moles of H+ reacting with the metal based on the following experimental data. 10.00 mL of 1.00 M HCl solution is added to a sample of Mg metal. The reaction goes to completion and all of the Mg metal is gone. 21.80 mL of 0.30 M NaOH solution is required to reach the end point when titrating the remaining HCl.
Answer:
0.01 mol of H+.
Explanation:
Equation of reaction:
Mg(s) + 2HCl(aq) --> MgCl2(aq) + H2(g)
Molar concentration = number of moles/volume
= 1*0.01
= 0.01 mol.
Dissociation:
2HCl --> 2H+ + 2Cl-
By stoichiometry,
If 2 mole of HCl dissociates to guve 2 moles of H+
Number of moles of H+ = 0.01 mol.
A 49.48-mL sample of an ammonia solution is analyzed by titration with HCl. It took 38.73 mL of 0.0952 M HCl to titrate the ammonia. What is the concentration of the original ammonia solution?
Answer:
M₂ = 0.0745 M
Explanation:
In case of titration , the following formula can be used -
M₁V₁ = M₂V₂
where ,
M₁ = concentration of acid ,
V₁ = volume of acid ,
M₂ = concentration of base,
V₂ = volume of base .
from , the question ,
M₁ = 0.0952 M
V₁ = 38.73 mL
M₂ = ?
V₂ = 49.48 mL
Using the above formula , the molarity of ammonia , can be calculated as ,
M₁V₁ = M₂V₂
0.0952 M * 38.73 mL = M₂* 49.48 mL
M₂ = 0.0745 M
A 1.0223 g sample of an unknown nonelectrolyte dissolved in 10.2685 g of benzophenone produces a solution that freezes at 31.7°C. If the pure benzophenone melted at 47.5°C, what is the molecular weight of the unknown compound?
Answer: The molecular weight of unknown non-electrolyte is 61.75 g/mol
Explanation:
Depression in freezing point is defined as the difference in the freezing point of water and freezing point of solution.
[tex]\Delta T_f=\text{Freezing point of benzophenone}-\text{Freezing point of solution}[/tex]
To calculate the depression in freezing point, we use the equation:
[tex]\Delta T_f=iK_fm[/tex]
or,
[tex]\text{Freezing point of benzophenone}-\text{Freezing point of solution}=iK_f\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}[/tex]where,
i = Vant hoff factor = 1 (for non-electrolyte)
[tex]K_f[/tex] = molal freezing point depression constant = 9.80°C/m
[tex]m_{solute}[/tex] = Given mass of unknown non-electrolyte = 1.0223 g
[tex]M_{solute}[/tex] = Molar mass of unknown non-electrolyte = ?
[tex]W_{solvent}[/tex] = Mass of solvent (benzophenone) = 10.2685 g
Putting values in above equation, we get:
[tex]47.5-31.7=1\times 9.80\times \frac{1.0223\times 1000}{M_{solute}\times 10.2685}\\\\M_{solute}=\frac{1\times 9.80\times 1.0223\times 1000}{15.8\times 10.2685}=61.75g/mol[/tex]
Hence, the molecular weight of unknown non-electrolyte is 61.75 g/mol
The molecular weight of the unknown nonelectrolyte dissolved in benzophenone can be calculated using the formula for freezing point depression and the information provided in the question. After performing the necessary calculations, the molecular weight of the unknown compound is found to be 331 g/mol.
Explanation:To calculate the molecular weight of the unknown compound, we use the formula for freezing point depression:
ΔT = iKfm
Where ΔT is the change in temperature, i is the van't Hoff factor which is 1 for nonelectrolytes, Kf is the cryoscopic constant for benzophenone, which, in this case, is 5.12°C kg/mol, and m is the molality of the solution. The change in temperature is the difference between the freezing points of pure benzophenone and the solution: 47.5°C - 31.7°C = 15.8°C.
The molality can be calculated by rearranging the formula:
m = ΔT / (iKf) = 15.8 / (1 * 5.12) = 3.086 mol/kg
Since we are given grams and want to convert to kilograms:
1.0223g of unknown compound / molar mass (unknown) = 3.086 mol/kg
Rearrange to find the molar mass (molecular weight) of the compound:
molar mass (unknown) = 1.0223g / 3.086 kg = 0.331 kg/mol = 331 g/mol
Hence the molecular weight of the unknown nonelectrolyte dissolved in benzophenone is 331 g/mol.
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cooling a sample of matter from 70°c to 10°c at constant pressure causes its volume to decrease from 873.6 to 712.6 cm3. classify the material as a nearly ideal gas, a nonideal gas, or condensed.
Explanation:
Expression for the coefficient of thermal expansion is as follows.
[tex]\alpha = \frac{1}{V}(\frac{\Delta V}{\Delta T})[/tex]
where, V = initial volume
[tex]\Delta V[/tex] = Final volume - initial volume
= (712.6 - 873.6) [tex]cm^{3}[/tex]
= -161 [tex]cm^{3}[/tex]
Now, we will calculate the change in temperature as follows.
[tex]\Delta T[/tex] = Final temperature - Initial temperature
= (10 + 273) K - (70 + 273) K
= 283 K - 343 K
= -60 K
Substituting these values into the equation as follows.
[tex]\alpha = \frac{1}{873.6} \times (\frac{161}{60}) K^{-1}[/tex]
= 0.00307 [tex]K^{-1}[/tex]
It is known that for non-ideal gases the value of alpha is 0.366% which is 0.00366 per Kelvin. As it is close to our result, hence the given sample of gas is a non-ideal gas.