Answer:
C) a halohydrin
Explanation:
In organic chemistry, a halohydrin is a compound whereby halogen and hydroxyl functional groups are bonded to adjacent carbon atoms in the molecule. Halohydrins are formed from alkenes such as cyclohexene in this case.
NBS is a very suitable alternative to Br2 in the synthesis of a halohydrin. Recall that the reactive intermediate when bromine reacts with an alkene is the brominium ion which is a three atom ring ion. If excess water is used as the solvent, then the water attacks the brominium ion to yield the product halohaydrin with trans a trans stereochemistry.
The molecular weight of table salt, NaCl, is 58.5 g/mol. A tablespoon of salt weighs 6.37 grams. Calculate the number of moles of salt in one tablespoon.
Finally, solve (remember significant figures):
Answer:
0.109 mol/tablespoon
Explanation:
6.37 g/ 58.5 mol = 0.10888888 mol (0.109 significantly)
Answer:
A: 0.109
Explanation:
Edge 2020
Discuss the contrary aspect of proton NMR and C-13 NMR by elucidating the structure of 2 chloro pentanal?
Answer:
See explanation
Explanation:
1H NMR
In the 2-chloro-pentanal we have 4 different types of hydrogens. Therefore, we will have 4 different signals. (See figure 1)
Red hydrogen
For the red hydrogens we have only 1 neighbor. So, if we follow the n+1 rule we can calculate the multiplicity of this hydrogen. In this case a doublet.
Blue hydrogens
In this case, we have 3 neighbors (one in the right, two in the left). Therefore we will have a quartet.
Purple hydrogens
For these hydrogens, we have also will have a quartet, because we have 3 neighbors (one in the right, two in the left).
Green hydrogens
In the green hydrogen,s we have 5 neighbors (2 in the right 3 in the left). Therefore a sextet would be produced.
Orange hydrogens
Finally, in these hydrogens, we have 2 neighbors. Therefore a triplet is expected.
13C NMR
For the 13C NMR, we have again 4 different kinds of carbons. Therefore we will have 4 signals. The most deshielded carbon, in this case, is the red one (see figure 2), so this carbon would be on the left side (around 190). Then the next deshield carbon is the blue one, due to the "Cl" atom placed on this carbon.
I hope it helps!
Compound X has the formula C7H14. X reacts with one molar equivalent of hydrogen in the presence of a palladium catalyst to form 3-methylhexane. Treatment of X with ozone follwed by zinc in aqueous acid gives a ketone plus formaldehyde (CH2=O). What is the structure of X?
Answer:
3-methylenehexane
Explanation:
In this case, we have two clues.
1) The hydrogenation reaction
2) The ozonolysis reaction
See figure 1.
With this in mind, lets analyze each clue. In the first reaction, we know that only 1 molecule of [tex]H_2[/tex] is added to the unknown molecule. This indicates that we only have 1 double bond in the molecule. Now, the next question is where is placed the double bond?
To answer this question, we have to use the second clue. In the ozonolysis reaction, a double bond is broken and is replaced with a carbonyl group. If, formaldehyde is formed the double bond is formed with a primary carbon. The primary carbons in the structure (given in the first reaction: 3-methylhexane) are carbons 1, 6, and 7. So, the double bond can be placed between carbons:
a) 6 and 5
b) 7 and 3
c) 1 and 2
To decide which one is the position of the double bond we have to keep in mind the second product of the ozonolysis reaction a ketone. With this in mind, the carbon bonded to the primary one (deduced by the formaldehyde) it has to be a tertiary carbon. The only option that has a primary carbon bonded to tertiary carbon is b). (See figure 2)
Finally, with this in mind the structure is 3-methylenehexane. To be sure, we can check the formula for the compound, [tex]C_7H_1_4[/tex] and the reactions. (See figure 3)
I hope it helps!
A 5.024 mg sample of an unknown organic molecule containing carbon, hydrogen, and nitrogen only was burned and yielded 13.90 mg of CO2 and 6.048 mg of H2O. What is the empirical formula
Answer:
C8H17N
Explanation:
Mass of the unknown compound = 5.024 mg
Mass of CO2 = 13.90 mg
Mass of H2O = 6.048 mg
Next, we shall determine the mass of carbon, hydrogen and nitrogen present in the compound. This is illustrated below:
For carbon, C:
Molar mass of CO2 = 12 + (2x16) = 44g/mol
Mass of C = 12/44 x 13.90 = 3.791 mg
For hydrogen, H:
Molar mass of H2O = (2x1) + 16 = 18g/mol
Mass of H = 2/18 x 6.048 = 0.672 mg
For nitrogen, N:
Mass N = mass of unknown – (mass of C + mass of H)
Mass of N = 5.024 – (3.791 + 0.672)
Mass of N = 0.561 mg
Now, we can obtain the empirical formula for the compound as follow:
C = 3.791 mg
H = 0.672 mg
N = 0.561 mg
Divide each by their molar mass
C = 3.791 / 12 = 0.316
H = 0.672 / 1 = 0.672
N = 0.561 / 14 = 0.040
Divide by the smallest
C = 0.316 / 0.04 = 8
H = 0.672 / 0.04 = 17
N = 0.040 / 0.04 = 1
Therefore, the empirical formula for the compound is C8H17N
Which of the following describes green design?
A. Materials that will fail in a predictable and safe way
B. The use of new engineering technologies in building construction
c. Building structures made of composite materials to make them
safer
D. Materials and design techniques that reduce the negative
environmental impact of a structure
Answer: materials and design Techniques that reduce the negative environmental impact of a structure
Explanation:
Write the empirical formula
Answer:
See the explanation and answer below.
Explanation:
In chemistry, the empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound. The formula gives the proportions of the elements present in a compound but not the actual arrangement of atoms.
[tex]\mathrm{Molecular \:Formula}\quad \quad |\quad \quad \mathrm{Empirical \:Formula}[/tex]
[tex]1.\:\:\:NH_4OH\quad | \quad H_5NO[/tex] (Ammonium hydroxide)
[tex]2.\:\:\:Fe(OH)_3\quad |\quad FeH_3O_3[/tex] (Iron(III) hydroxide)
[tex]3.\:\:\:NH_4C_2H_3O_2\quad |\quad C_2H_7NO_2[/tex] (Ammonium acetate)
[tex]4.\:\:\:Fe(C_2H_3O_2)_3\quad |\quad C_6H_9FeO_6[/tex] (Iron(III) Acetate)
I hate chemistry but best regards!
Why is the separation of mixtures into pure or relatively pure substances so important when performing a chemical analysis?
Answer:
It is important to separate mixture into pure or relatively pure substances when performing a chemical analysis SO AS TO KNOW THE PROPERTIES COMING FROM EACH PART MIXTURE WHICH MAY INTERFERE WITH THE SEPARATION.
Explanation:
In chemistry, Mixture is the combination of two or more substances which are not combine chemically.
Mixture contain different substances with different physical and chemical properties.
It is important to purify the substances in a mixture so as to identify what properties are coming from each mixture and also some part of the mixture can interfere with the properties of other mixture present for skewing analysis.
Where would you find the following symbol on a diagram of a water molecule: δ+ ?
Answer:
On the 2 hydrogen atoms.
Explanation:
δ+ indicates the atom has a lower electronegativity than the other atom it is bonded with. This only exist in polar covalent bonds, where the 2 atoms have different electronegativity values. When they have different electronegativity values, the one with higher electronegativity has a higher tendency to "pull" the shared electrons towards itself, they have a δ- symbol.
Back to H2O, since the electronegativity of elements increases from left to right horizontally and upwards vertically in the periodic table (except for noble gases, they are unreactive. Note that fluorine has the highest electronegativity), O atom has a higher electronegativity than hydrogen (hydrogen sits at the centre top of the table). hence, we can find δ+ on the hydrogen atoms.
you mix 45 ml of .20M KOH in calorimeter. The temperature of both reactions before mixing is 21.5 C. The Cp of the calorimeter was 36 J/K. If the final temperature of the mixture is 23.6 C, what is the enthalpy change per mole of water produced?
Answer:
THE ENTHALPY CHANGE PER MOLE OF KOH IS 8400 Joules/ mole OF HEAT.
Explanation:
Heat = heat capacity * change in temperature
Heat capacity = 36 J/K
Temperature of the mixture before mixing = 21.5 C
Temperature of mixtire after mixing = 23.6 C
Calculate the change in temperature:
Change in temperature = 23.6 C - 21.5 C = 2.1 C
Heat = 36 * 2.1
Heat = 75.6 J of heat
In essence, 45 ml of 0.20 M of KOH produces 75.8 J of heat
The enthalpy change per mole of water:
It is important t obtain the number of moles involved in the reaction of 45 mL of 0.20 M of KOH
n = C V
n = 0.20 M * 45 *10^-3
n = 0.009 moles
Since number of moles = mass / molar mass
The mass of 45 ml of 0.20 M of KOH is then:
Molar mass = ( 39 + 16 + 1) g/mol = 56 g/mol
Mass = number of moles * molar mass
Mass = 0.009 * 56
Mass = 0.504 g
So therefore 0.504 g of KOH produces 75.6 J of heat
1 mole of KOH will produce x J of heat
1 mole of KOH = 56 g of KOH
0.504 g = 75.6 J
56 g = x J
x J = 56 * 75.6 / 0.504
x J = 8400 J / mole of KOH
What is the Percent composition of a pure substance that contains 7.22g of nickel, 2.53g of phosphorus and 5.25 g oxygen
Answer:
Explanation:
Total mass of substance = 7.22 + 2.53 + 5.25 g
= 15 g
percentage of nickel = 7.22 x 100 / 15
= 48.13
= 48.1 %
percentage of phosphorus = 2.53 x 100 / 15
= 16.87%
= 16.9%
percentage of oxygen = 5.25 x 100 / 15
= 35 %
The percent composition of the pure substance should be 48.1%, 16.9%, and 35%.
Calculation of the percent composition:
Total mass of substance = 7.22 + 2.53 + 5.25 g
= 15 g
Now
percentage of nickel = 7.22 x 100 / 15
= 48.13
= 48.1 %
And,
percentage of phosphorus = 2.53 x 100 / 15
= 16.87%
= 16.9%
And, finally
percentage of oxygen = 5.25 x 100 / 15
= 35 %
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How did Ernest Rutherford change the atomic model?
A. He showed that the atom could be divided into smaller particles.
B. He showed that electrons were located within an atom's nucleus.
C. He showed that the atom contained both positive and negative
charges
D. He showed that most of an atom's mass was located in the atom's
nucleus.
Answer:
D. He showed that most of an atom's mass was located in the atom's
nucleus.
Explanation:
Ernest Rutherford changed the atomic model because of his experiment which was the gold foil experiment. A beam of alpha particles was aimed at a piece of gold foil, most particles passed through but some were scattered backward which showed that the middle of an atom (nucleus) is the where most of the mass is located.
Rutherford's model of atoms is the improved version of Thomson's model. In the model, it is stated that most of an atom's mass is located in the nucleus. Thus, option D is correct.
What is Rutherford's model?Ernest Rutherford gave the improved atomic model that postulated the failure of Thomson's model. Rutherford's model described the atom to consist of a sub-atomic particle with a positively charged nucleus.
The nucleus is in the center of the atom and had nearly all mass concentrated in it due to the presence of the protons and neutrons. The electrons were called negatively charged species that were present in the shells around the nucleus like the planets around the Sun.
Therefore, Rutherford's model showed mass concentrated in the center of the nucleus.
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4. If 13 percent of the carbon-14 in a sample of cotton cloth remains, what's the approximate age of the cloth? Show your work
The approximate age of the cloth is 17190 years.
We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:
Original amount (N₀) = 100%Amount remaining (N) = 13%Number of half-lives (n) =?2ⁿ = 100 / 13
2ⁿ = 8
2ⁿ = 2³
n = 3
Finally, we shall determine the age of the cloth.
Half-life (t½) = 5730 yearsNumber of half-lives (n) = 3Time (t) =?t = n × t½
t = 3 × 5730
t = 17190 years
Thus, the approximate age of the cloth is 17190 years
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4Ga + 3S2 → 2Ga2S3
1. How many grams of Gallium burned if 200.0 grams of Gallium(III)Sulfide formed?
Answer:
118.4 g
Explanation:
4 Ga + 3 S₂ → 2 Ga₂S₃
According to the equation, for every 4 moles of gallium burned, 2 moles of gallium(III) sulfide.
First, convert grams of Ga₂S₃ to moles. The molar mass is 235.641 g/mol.
(200.0 g)/(235.641 g/mol) = 0.8487 mol
Use the relationship above to convert moles of Ga₂S₃ to moles of Ga.
(0.8487 mol Ga₂S₃) × (4 mol Ga)/(2 mol Ga₂S₃) = 1.697 mol Ga
Convert moles of Ga to grams. The molar mass is 69.723 g/mol.
(1.697 mol Ga) × (69.723 g/mol) = 118.4 g
how many calories are in a 50g package of peanuts
Answer:
284 calories
Explanation:
There are 284 calories in 50 grams of peanuts.
Calorie breakdown: 73% fat, 11% carbs, 17% protein.
Q3. Which of the following objects are chiral and which are achiral? a
club b. teacup c. football d. corkscrew e. tennis racket f. shoe g. portrai
pencil (8 marks)
Q4. Write a structure for each of the compounds listed. Explain why th
name given is incorrect, and give a correct name in each case (20 mai
a. l-methylbutane
b. 1.1,3-trimethylhexane
c. 5-octyne
d. 2-ethyl-1-propanol
e. 2.2-dimethyl-3-butanol
Submit via aduwiejuah a uds.edu.gh and deadline for submission is
July, 2020 at 11:00 AM.
Answer:
See explanation
Explanation:
In this question, we have to follow the IUPAC rules. Lets analyze each compound:
a. 1-methylbutane
In this compound we have a chain of 5 carbons, so the correct name is Pentane.
b. 1,1,3-trimethylhexane
In this compound, we longest chain is made of 7 carbons, so, we have to use the name "heptane". Carbon one would be the closet one to the methyl group, so the correct name is 2,4-dimethylheptane.
c. 5-octyne
In this case, carbon 1 would be the closet one to the triplet bond. With this in mind, the correct name is oct-3-yne.
d. 2-ethyl-1-propanol
In this compound, we longest chain is made of 4 carbons, so, we have to use the name "butane". Carbon one would be the carbon with the "OH" group, so the correct name is 2-methylbutan-1-ol.
e. 2.2-dimethyl-3-butanol
In this case, carbon 1 would be the closet one to the "OH". With this in mind, the correct name is 3,3-dimethylbutan-2-ol.
See figure 1
I hope it helps!
Calculate the combustion of gaseous dimethyl ether CH 3 OCH 3 (g)+3O 2 (g) 2CO 2 (g)+3H 2 O(l) using standard molar enthalpies of formation Molecule AH H l ^ 0 (k)/mol) CH 3 OCH 3 (g) - 184.1
Answer:
[tex]\Delta _cH=-1328.3kJ/mol[/tex]
Explanation:
Helllo,
In this case, for the given chemical reaction in gaseous state:
[tex]CH_3OCH_3+3O_2\rightarrow 2CO_2+3H_2O[/tex]
We comoute the combustion enthalpy as the reaction enthalpy for one mole of fuel (dimethyl ether) considering the formation enthalpy of each given substance and whether they are reactants (subtracting) or products (adding), therefore we write:
[tex]\Delta _cH=2*\Delta _fH_{CO_2}+3*\Delta _fH_{H_2O}-\Delta _fH_{CH_3OCH_3}-3*\Delta _fH_{O_2}[/tex]
Whereas the formation enthalpies for carbon dioxide, water, dimethyl ether and oxygen are -393.5, -241.8, -184.1 and 0 kJ/mol respectively, thereby, the combustion enthalpy turns out:
[tex]\Delta _cH=2(-393.5)+3*(-241.8)-(-184.1)-3(0)\\\\\Delta _cH=-1328.3kJ/mol[/tex]
Notice that enthalpy of formation of oxygen is zero since forming an element has no chemical sense, it just exists as it has been early demonstrated.
Regards.
Given the specific heat for aluminum is 0.900 J/g.°C, how much heat is released when a 3.8 g sample
of Al cools from 450.0°C to 25°C?
A. 1.5 kJ
B. 54 J
C. 60J
D. 1.7 kJ
E. 86 J
Answer:
Q = 1.5 kJ
Explanation:
It is given that,
The specific heat for aluminum is 0.900 J/g°C
Mass of sample, m = 3.8 g
Initial temperature, [tex]T_i=450^{\circ} C[/tex]
Final temperature, [tex]T_f=25^{\circ} C[/tex]
We need to find the heat released. The amount of heat released is given by the formula:
[tex]Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\Q=3.8\times 0.9\times (25-450)\\\\Q=1453.5\ J\\\\Q=1.45\ kJ[/tex]
or
[tex]Q=1.5\ kJ[/tex]
So, the correct option is (A) i.e. 1.5 kJ.
The combustion of propane may be described by the chemical equation C3H8(g)+5O2(g)⟶3CO2(g)+4H2O(g) How many grams of O2(g) are needed to completely burn 56.3 g C3H8(g)?
Answer:
204.7 g
Explanation:
(taking the atomic mass of C, H, O as 12, 1 and 16 respectively).
no. of moles of C3H8 burnt = 56.3 / (12x3 + 1x8)
= 1.27955 mol
From the equation, the mole ratio of C3H8 : O2 = 1:5
Hence,
the no. of moles of O2 required will be
=1.27955 x 5
= 6.397727 mol
Mass of O2 required = 6.397727 x (16x2)
= 204.7 g
When 75.5 grams of phosphorus pentachloride react with an excess of water, as shown in the unbalanced chemical equation below, how many moles of hydrochloric acid will be produced? Please show all your work for the calculations for full credit. PCl5 + H2O --> H3PO4 + HC
Answer:
Explanation: M(PCL5)= 31 + 5(35.5)
=208.5g/mol
M(H20)= 18g/mol
n(PCL5) = 75.5÷208.5
= 0.362mol
n(HCl)/n(PCL5)= 5/1
n(HCl)= 5×0.362
=1.81mol of HCl
If 5.00 mL of a 0.5 M solution is diluted to a final volume of 100.0 mL, what is the concentration of the final dilute solution?
Answer:
0.025 M
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 5 mL
Initial concentration (C1) = 0.5 M
Final volume (V2) = 100 mL
Final concentration (C2) =..?
Using the dilution formula, we can obtain the final concentration of the diluted solution as follow:
C1V1 = C2V2
0.5 x 5 = C2 x 100
Divide both side by 100
C2 = (0.5 x 5)/100
C2 = 0.025 M
Therefore, the final concentration of the diluted solution is 0.025 M
The concentration of the final diluted solution is 0.025M
The dilution formula is expressed according to the formula:
[tex]C_1V_1=C_2V_2[/tex]
Given the following parameters
[tex]C_1=0.5M\\V_1=5.00mL\\V_2=100.0mL\\C_2=?[/tex]
Substitute the given parameters into the formula:
[tex]C_1V_1=C_2V_2\\0.5(5)=100C_2\\2.5=100C_2\\C_2=\frac{2.5}{100}\\C_2= 0.025M[/tex]
Hence the concentration of the final diluted solution is 0.025M
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Calculate the pH of a 0.0255 M solution of ammonium bromide (NH4Br). The Kb of ammonia is 1.76 x 10-5
Answer:
5.42
Explanation:
Step 1: Consider the dissociation of NH₄Br
NH₄Br(aq) ⇒ NH₄⁺(aq) + Br⁻(aq)
Br⁻ is the conjugate base of HBr, a strong acid, so it doesn´t react with water. NH₄⁺ is the conjugate acid of NH₃, so it does react with water.
Step 2: Consider the acid reaction of NH₄⁺
NH₄⁺(aq) + H₂O(l) ⇄ NH₃(aq) + H₃O⁺(aq)
Step 3: calculate the acid dissociation constant for NH₄⁺
We will use the following expression.
[tex]K_a \times K_b = K_w\\K_a = \frac{K_w}{K_b} = \frac{1.00 \times 10^{-14} }{1.76 \times 10^{-5}} = 5.68 \times 10^{-10}[/tex]
Step 4: Calculate the concentration of H₃O⁺
We will use the following expression.
[tex][H_3O^{+} ]= \sqrt{K_a \times C_a } = \sqrt{5.68 \times 10^{-10} \times 0.0255 } = 3.81 \times 10^{-6}M[/tex]
Step 5: Calculate the pH
We will use the following expression.
[tex]pH = -log [H_3O^{+} ] = -log (3.81 \times 10^{-6}) = 5.42[/tex]
The pH of 0.0255 M solution should be 5.42.
Calculation of the pH of 0.0255 M solution:Since we know that
ka * kb = kw
So,
ka = kw/kb
= 1.00*10^-14 / 1.76*10^-5
= 5.68*10^-10
Now the concentration of H3O should be
= √ka * Ca
= √5.68*10^-10 * 0.0255
= 3.81*10^-6M
Now the pH value should be
= -log(H3O+)
= -log(3.81*10^-6)
= 5.42
hence, The pH of 0.0255 M solution should be 5.42.
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The element potassium forms a _______ with the charge . The symbol for this ion is , and the name is . The number of electrons in this ion is
Answer:
The element potassium forms a cation with the charge +1 . The symbol for this ion is K⁺, and the name is potassium ion. The number of electrons in this ion is 18.
Explanation:
Potassium is a metal. It belongs to the group 1 elements. Metals form cations by losing electrons. Since potassium is a group element, it forms a cation by losing one electron. The charge it has is +1 due to the excess of the protons compared t the electrons by 1.
Potassium has 19 electrons. Potassium io on the other hand has 19-1 = 18 electrons.
Write a balanced equation for the single-displacement reaction of Al(s) with CuSO4(aq). Include states of matter in your answer.
Answer:
2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
Explanation:
Let's consider the single displacement reaction of Al(s) with CuSO₄(aq). Copper has a higher reduction potential than aluminum, so aluminum will take the place of copper to form aluminum sulfate and metallic copper. The corresponding balanced chemical equation is:
2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
The chemical equation is 2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
Chemical equation:
here we considered the single displacement reaction of Al(s) with CuSO₄(aq). Also, Copper contained a higher reduction potential as compared to aluminum, due to this aluminum will take the place of copper to create aluminum sulfate and metallic copper. So the above should be the balance chemical equation.
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Click the "draw structure" button to launch the drawing utility. Draw the product of the reaction of propanal with lithium aluminum hydride, followed by water.
Answer:
Product: propan-1-ol
Explanation:
IIn this case, we have to remember that [tex]LiAlH_4[/tex] is a reduction agent. So, this is a reduction reaction. The [tex]LiAlH_4[/tex] has the ability to produce hydride ions [tex]H^-[/tex]. This ion can attack the carbonyl group generating a negative charge in the oxygen. In the next step, the negative charge in the oxygen can attack a water molecule to protonate the molecule and produce propan-1-ol.
See figure 1
I hope it helps!
Silver crystallizes in a face-centered cubic structure. What is the edge length of the unit cell if the atomic radius of silver is 144 pm?
Answer:
Edge length of the unit cell is 4.07x10⁻¹⁰m
Explanation:
In a face-centered cubic structure, the edge, a, could be obtained using pythagoras theorem knowing the hypotenuse of the unit cell, b, is equal to 4r:
a² + a² = b² = (4r)²
2a² = 16r²
a = √8 r
That means edge lenght is = √8 r
adius
As radius of Silver is 144pm = 144x10⁻¹²m:
a = √8 r
a = √8 ₓ 144x10⁻¹²m
a = 4.07x10⁻¹⁰m
Edge length of the unit cell is 4.07x10⁻¹⁰mWhich type of rock is formed from existing rock or organisms?
Answer:
Sedimentary rocks
Explanation:
My explanation is that when an animal decomposes it body returns to the ground eventually being used in the rock cycle and rocks form this through the rock cycle when broken down by weathering and erosion.
Hope this helps you
Answer:
sedimentary rocks
They form from deposits that accumulate on the Earth's surface.
1. What form of matter is made from only one type of atom?
A molecule
B compound
C element
6.66%
D material
Answer:
A molecule is the answer.
What is the boiling point of an aqueous solution that has a vapor pressure of 23.0 torr at 25 ∘C? (P∘H2O=23.78 torr; Kb= 0.512 ∘C/m).
Answer:
Boiling point of the solution is 100.964°C
Explanation:
In this problem, first, you must use Raoult's law to calculate molality of the solution. When you find the molality you can obtain the boiling point elevation because of the effect of the solute in the solution (Colligative properties).
Using Raoult's law:
Psol = Xwater × P°water.
As vapour pressure of the solution is 23.0torr and for the pure water is 23.78torr:
23.0torr= Xwater × 23.78torr.
0.9672 = Xwater.
The mole fraction of water is:
[tex]0.9672 = \frac{X_{H_2O}}{X_{H_2O}+X_{solute}}[/tex]
Also,
[tex]1 = X_{H_2O}+X_{solute}[/tex]
You can assume moles of water are 0.9672 and moles of solute are 1- 0.9672 = 0.0328 moles
Molality is defined as the ratio between moles of solute (0.0328moles) and kg of solvent. kg of solvent are:
[tex]09672mol *\frac{18.01g}{1mol}* \frac{1kg}{1000g} = 0.01742kg[/tex]
Molality of the solution is:
0.0328mol Solute / 0.01742kg = 1.883m
Boiling point elevation formula is:
ΔT = Kb×m×i
Where ΔT is how many °C increase the boiling point regard to pure solvent, Kb is a constant (0.512°C/m for water), m molality (1.883m) and i is Van't Hoff factor (Assuming a i=1).
Replacing:
ΔT = 0.512°C/m×1.882m×1
ΔT = 0.964°C
As the boiling point of water is 100°C,
Boiling point of the solution is 100.964°C
Boiling point of the solution is 100.964°C.
Raoult's Law:It says that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present.
Using Raoult's law:[tex]P_{sol} = X_{water} * P^o_{water}[/tex]
Given:
Vapor pressure of the solution = 23.0torr Vapor pressure of pure water = 23.78torrSubstituting the values:
[tex]23.0torr = X_{water} * 23.78torr\\\\0.9672 = X_{water}[/tex]
The mole fraction of water is:[tex]0.9762=\frac{X_{water}}{X_{water}+X_{solute}}[/tex]
The sum of the mol fractions of water and solute is 1.
We can consider,
Moles of water = 0.9672
Moles of solute = 1- 0.9672 = 0.0328 moles
Calculation for Molality:It is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.
[tex]\text{Mass of solvent}=0.9672*\frac{18g/mol}{1mol} *\frac{1kg}{1000g}\\\\\text{Mass of solvent} =0.01745kg[/tex]
Molality of the solution is:[tex]\text{Molality}= \frac{0.0328mol}{0.01742kg} \\\\\\text{Molality}= 1.883m[/tex]
Calculation of Boiling point:[tex]\triangle T = K_b*m*i[/tex]
Substituting the values in the above formula:
[tex]\triangle T = 0.512^oC/m*1.882m*1\\\\\triangle T = 0.964^oC[/tex]
Thus, Boiling point of the solution is 100.964°C, since boiling point of water is 100°C.
Find more information about Boiling point here:
brainly.com/question/40140
help please i have 5 minutes to do this !!!
Answer:
A) One that occurs on its own
The half-life of element X is 500 years. If there are initially 8 g of X, how much will remain after 1500 years
Answer:
1 g
Explanation:
From the formula;
N/No = (1/2)^t/t1/2
Where;
N= mass of radioactive element left after a time t = the unknown
No= mass of radioactive element originally present in the sample = 8g
t= time taken for N mass of the sample to remain = 1500
t1/2= half-life of the radioactive element = 500 years
Substituting values, we have;
N/8 = (1/2)^1500/500
N/8 = (1/2)^3
N/8 = 1/8
N= 1/8 ×8
N= 1 g
Therefore; mass of radioactive element left after 1500 years is 1 g