Answer: [tex]1s^22s^22p^63s^23p^64s^2[/tex]
Explanation:
Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.
The electrons are filled according to Afbau's rule in order of increasing energies where orbital with higher value of (n+l) has higher energy as compared to orbital having lower (n+l) value. Thus the electronic configuration for calcium with atomic number of 20 and hence containing 20 electrons is :
[tex]Ca:20:1s^22s^22p^63s^23p^64s^2[/tex]
A chemistry student weighs out of ascorbic acid , a diprotic acid, into a volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with solution. Calculate the volume of solution the student will need to add to reach the final equivalence point. Round your answer to significant digits.
Answer:
14.3 mL
Explanation:
Assume the student used 0.113 g ascorbic acid and 0.0900 mol·L⁻¹ NaOH.
1. Balanced chemical equation.
The formula of ascorbic acid is H₂C₆H₆O₆ (MM = 176.12 g/mol).
However, for the balanced equation, let's write it as H₂A.
[tex]\rm H_{2}A + 2NaOH \longrightarrow Na_{2}A + 2H_{2}O[/tex]
2. Moles of ascorbic acid
[tex]\text{Moles of H$_{2}$A} =\text{0.113 g H$_{2}$A} \times \dfrac{\text{1 mmol H$_{2}$A}}{\text{0.176 12 mg H$_{2}$}A} = \text{0.6416 mmol H$_{2}$A}[/tex]
3. Moles of NaOH
The molar ratio is 2 mmol NaOH:1 mmol H₂A.
[tex]\text{Moles of NaOH}= \text{0.6416 mmol H$_{2}$A} \times \dfrac{\text{2 mmol NaOH}}{\text{1 mmol H$_{2}$A}} =\text{1.283 mmol NaOH}[/tex]
4. Volume of NaOH
[tex]V = \text{1.283 mmol NaOH}\times \dfrac{\text{1 mL NaOH}}{\text{0.0900 mmol NaOH}} = \textbf{14.3 mL NaOH}\\\\\text{The student will need $\large \boxed{\textbf{14.3 mL NaOH}}$}[/tex]
A beach has a supply of sand grains composed of calcite, ferromagnesian silicate minerals, and non-ferromagnesian silicate minerals. If it undergoes lots of chemical weathering, which sand grains will be quickly chemically weathered away?
a. Calcite
b. ferromagnesian silicate minerals
c. non-ferromagnesian silicate minerals
The sand that grained will be quickly chemically weathered away should be option b. ferromagnesian silicate minerals.
What are ferromagnesian silicate minerals?It should be considered as the Silicate minerals where cations of iron and the form of magnesium should be important for the chemical components. It is used for covering up the minerals. Also, calcite should be normal weather via the solution process so it required a lot of water that contains a high amount of carbonic acid.
Hence, the correct option is b.
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Use standard reduction potentials to calculate the equilibrium constant for the reaction: 2Cr3+(aq) + Pb(s)2Cr2+(aq) + Pb2+(aq) Hint: Carry at least 5 significant figures during intermediate calculations to avoid round off error when taking the antilogarithm. Equilibrium constant: G° for this reaction would be _________ than zero. Submit AnswerRetry Entire Group
Answer:
3.47 ×10^-10
Explanation:
The equation of the reaction is 2Cr3+(aq) + Pb(s)------->2Cr2+(aq) + Pb2+(aq)
A total of two moles of electrons were transferred in the process. The chromium was reduced while the lead was oxidized. Hence the lead species will constitute the oxidation half equation and the chromium will constitute the reduction half equation.
E°cell = E°cathode - E°anode
E°cathode = -0.41 V
E°anode = -0.13 V
E°cell = -0.41 -(-0.13) = -0.28 V
From
E°cell = 0.0592/n log K
n= 2, K= the unknown
-0.28 = 0.0592/2 log K
log K = -0.28/0.0296
log K = -9.4595
K = Antilog ( -9.4595)
K= 3.47 ×10^-10
9. In a certain chemical reaction, 2 hydrogen chloride molecules in aqueous solution react with solid zinc. The reaction produces zinc
chloride in aqueous solution and hydrogen gas. Which of the following reaction equations correctly describes this reaction?
A. 2HCI (g) + 2Zn (s) - 2ZnCl2 (s) + H2 (9)
B. HCI (aq) + 2Zn (s) - 2ZnCl (aq) + H2 (9)
C. 2HCl (aq) + Zn (s) → ZnCl2 (aq) + H2 (g)
D. HCI (aq) + Zn (s) Zn,Cl (aq) + 2H2 (1)
Answer: [tex]2HCl(aq)+Zn(s)\rightarrow ZnCl_2(aq)+H_2(g)[/tex]
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products formed must be equal to the mass of reactants taken.
In order to get the same mass on both sides, the atoms of each element must be balanced on both sides of the chemical equation.
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.
The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas. Gases are represented by (g) after their chemical formulas.
Thus 2 hydrogen chloride molecules in aqueous solution react with solid zinc. The reaction produces zinc chloride in aqueous solution and hydrogen gas is represented as :
[tex]2HCl(aq)+Zn(s)\rightarrow ZnCl_2(aq)+H_2(g)[/tex]
A correct name for the following compound is:_________.a) 4-bromo-3,8-dimethylbicyclo[5.2.2]nonane b) 3,8-dimethyl-4-bromo-bicyclo[5.2.O)nonane c) 4-bromo-3,8-dimethylbicyclo[5.2.1]decane d) 7-bromo-2,6-dimethylbicyclo[5.2.0]nonane e) 4-bromo-3,8-dimethylbicyclo[5.2.0]nonane
Answer:
e) 4-bromo-3,8-dimethylbicyclo[5.2.0]nonane
Explanation:
The missing image of the the compound we are to name is attached below.
Before we can name an organic compound; It is crucial we know the guiding rules in naming them.
1. Select the longest continuous carbon chain as the root hydrocarbon and name according to the number of carbon atoms it contains, adding appropriate suffix to indicate the principal substituent group.
2. Number the carbon atoms in the root hydrocarbon from the end which gives the lowest number to the substituents.
3. If the same substituent is present two or more times in a molecule; the number of this substituent is indicated by the prefix di -(2), tri - (3) , tetra - (4) etc attached to the substituent name.
4. If there is more than one type of substituent in the molecule ; the substituents are named according to the alphabetical order but where there are mixed substituents ; the inorganic are named first.
5. In selecting and numbering the longest continuous chain, the functional groups are given preference over substituents., i.e the functional group is given the smallest possible number.
In the light of the above guiding rules; we were able to name the given compound because the compound contains nine carbons in the ring form which result to root name nonane. The two methyl are on the third and eight carbon; bromine is on the fourth carbon ; there are two cyclic ring present in the compound where we have 5 carbons in one structure, another 2 carbons in the second structure and zero carbon in the bridge structure which eventually result to the correct name:
4-bromo-3,8-dimethylbicyclo[5.2.0]nonane
The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. What is the final level of the electron?(c=3.00×10^8m/s, h=6.63×10^-34 J·s, RH=2.179×106-18J)a. 5
b. 6
c. 8
d. 9
e. 1
Explanation:
It is given that,
The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. It means that,
[tex]n_i=8[/tex]
[tex]\lambda=3745\ nm[/tex]
The amount of energy change during the transition is given by :
[tex]\Delta E=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}][/tex]
And
[tex]\dfrac{hc}{\lambda}=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}][/tex]
Plugging all the values we get :
[tex]\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{3745\times 10^{-9}}=2.179\times 10^{-18}[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\\dfrac{5.31\times 10^{-20}}{2.179\times 10^{-18}}=[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\0.0243=[\dfrac{1}{n_f^2}-\dfrac{1}{64}]\\\\0.0243+\dfrac{1}{64}=\dfrac{1}{n_f^2}\\\\0.039925=\dfrac{1}{n_f^2}\\\\n_f^2=25\\\\n_f=5[/tex]
So, the final level of the electron is 5.
What is the name of CaCl2 7H2o
Answer:
calcium chloride dihydrate
structure and correct name for 5-octyne
Answer:
Explanation:
(R)-5-octyne-4-ol
C8H140
Correct name for 5-octyne is 3-octane.
Structure is attached below.
3-Octane:Octane is a hydrocarbon and an alkane with the chemical formula C₈H₁₈, and the condensed structural formula CH₃(CH₂)₆CH₃. Octane has many structural isomers that differ by the amount and location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane) is used as one of the standard values in the octane rating scale.
The structure for 5-octyne is given below.
Correct name for it is 3-octane.
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Write a net ionic equation to show that benzoic acid, C6H5COOH, behaves as a Brønsted-Lowry acid in water.
Answer:
H⁺(aq) + H₂O(l) ⇄ H₃O⁺(aq)
Explanation:
According to Brönsted-Lowry acid-base theory, an acid is a substance that donates H⁺. Let's consider the molecular equation showing that benzoic acid is a Brönsted-Lowry acid.
C₆H₅COOH(aq) + H₂O(l) ⇄ C₆H₅COO⁻(aq) + H₃O⁺(aq)
The complete ionic equation includes all the ions and molecular species.
C₆H₅COO⁻(aq) + H⁺(aq) + H₂O(l) ⇄ C₆H₅COO⁻(aq) + H₃O⁺(aq)
The net ionic equation includes only the ions that participate in the reaction and the molecular species.
H⁺(aq) + H₂O(l) ⇄ H₃O⁺(aq)
Balance the chemical equation
Fe2O3 (s) + CO (g) 2 Fe(s) + CO2 (g)
Express your answer as a chemical equation. Identify all of the phases in your answer.
Answer:
[tex]Fe_2O_3+3CO\Rightarrow \:2Fe+3CO_2[/tex]
Explanation:
[tex]Fe_2O_3+CO\Rightarrow \:2Fe+CO_2\\\\Fe_2O_3+3CO\Rightarrow \:2Fe+3CO_2[/tex]
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which process is used to produce gases from solutions of salts dissolved in water or another liquid?
A.Electrolysis
B.Metallic bonding
C.Ionic bonding
D. Polar covalent bonding
Answer:
A.Electrolysis
Explanation:
A.Electrolysis
For example, electrolysis of solution of NaCl in water gives H2 and O2.
A beaker has 0.2 M of Na2SO4. What will be the concentration of sodium and sulfate ions?
Answer:
Na+-0.0648M
SO4²-0.1352M
Explanation:
First find the R.A.M of the sodium sulphate
(23×2)+(32)+(16×4)=142
Find the portion of sodium ions=46/142×0.2
=0.0648M
Sulphate=
0.2-0.0648=0.1352M
For the reaction, 2SO2(g) + O2(g) <--> 2SO3(g), at 450.0 K the equilibrium constant, Kc, has a value of 4.62. A system was charged to give these initial concentrations, [SO3] = 0.254 M, [O2] = 0.00855 M, [SO2] = 0.500 M. In which direction will it go?
Answer:
To the left.
Explanation:
Step 1: Write the balanced reaction at equilibrium
2 SO₂(g) + O₂(g) ⇄ 2 SO₃(g)
Step 2: Calculate the reaction quotient (Qc)
Qc = [SO₃]² / [SO₂]² × [O₂]
Qc = 0.254² / 0.500² × 0.00855
Qc = 30.2
Step 3: Determine in which direction will proceed the system
Since Qc > Kc, the system will shift to the left to attain the equilibrium.
Which best describes the relationship between heat internal energy, and thermal energy?
O Internal energy is heat that flows, and heat is the part of thermal energy that can be transferred.
O Internal energy is thermal energy that flows, and thermal energy is the part of heat that can be transferred.
O Thermal energy is heat that flows, and heat is the part of internal energy that can be transferred.
O Heat is thermal energy that flows, and thermal energy is the part of internal energy that can be transferred.
Answer:
Heat is thermal energy that flows, and thermal energy is the part of internal energy that can be transferred
Explanation:
Use the following reactions and given Δh values to find standard enthalpies of reactions (in kilojoules) given below.C(s)+O2(g)→CO2(g) ΔH= -393.5 kJ 2CO(g)+O2(g)→2CO2(g) ΔH= -566.0 kJ2H2(g)+O2(g)→2H2O(g) ΔH= -483.6 kJ
Answer:
The heat of the reaction or standard enthalpy of the reaction CO(g) + H₂O(g) → CO₂(g) + H₂(g) is ΔH(rxn) = -41.2 kJ
Explanation:
The reaction whose standard enthalpy is required, as obtained from the internet is
CO(g) + H₂O(g) → CO₂(g) + H₂(g)
The formation reaction for some of the reactants and products are given as
C(s) + O₂(g) → CO₂(g) ΔH = -393.5 kJ
2CO(g) + O₂(g) → 2CO₂(g) ΔH = -566.0 kJ
2H₂(g) + O₂(g) → 2H₂O(g) ΔH = -483.6 kJ
To find the standard enthalpies of the given reaction, we need the heat of formation of each of the species involved in the reaction
ΔH (CO₂(g)) = -393.5 kJ
ΔH (H₂O(g)) = -483.6 kJ ÷ 2 = -241.8 kJ (Because 2 moles of H₂O(g) are formed in the given formation reaction)
ΔH (O₂(g)) = ΔH (H₂(g)) = 0 kJ (No heat of formation for elements)
ΔH (CO(g)) = ? (This isn't given)
But it can be calculated from the second given reaction
2CO(g) + O₂(g) → 2CO₂(g) ΔH = -566.0 kJ
Heat of reaction = ΔH(products) - ΔH(reactants)
Heat of reaction = -566.0 kJ
ΔH (products) = 2 × ΔH (CO₂(g)) = 2 × -393.5 = -787 kJ
ΔH (reactants) = [2 × ΔH (CO(g))] + [1 × ΔH (O₂(g))] = 2 × ΔH (CO₂(g))
Hence, we have
-566 = -787 - [2 × ΔH (CO₂(g))]
2 × ΔH (CO₂(g)) = -787 + 566 = -221 kJ
ΔH (CO₂(g)) = -221 ÷ 2 = -110.5 kJ
CO(g) + H₂O(g) → CO₂(g) + H₂(g)
Heat of reaction = ΔH(products) - ΔH(reactants)
ΔH (products) = [ΔH (CO₂(g))] + [ΔH (H₂(g))]
= -393.5 + 0 = -393.5 kJ
ΔH (reactants) = [1 × ΔH (CO(g))] + [1 × ΔH (H₂O(g))] = -110.5 - 241.8 = -352.3 kJ
Heat of reaction = -393.5 - (-352.3) = -41.2 kJ
Hope this Helps!!!
Think about what you know about science today. How do you think scientific knowledge will be different in 100 years?
Answer:
I think we will know a lot more about the universe and the things around us. We may also know a lot more about other planets, such as Mars and Saturn, and we might also know a lot more about other stars in the universe.
Explanation:
4. The pH of an aqueous solution is determined to be 1.50.
Calculate the hydronium ion concentration.
b. Calculate the hydroxide ion concentration.
-lg[H+]=1.5
which means that [H+]=0.03M
pOH=14-pH=14-1.5=12.5
-lg[H+]=1.5
which means that [H+]=0.03M
pOH=14-pH=14-1.5=12.5
the hydroxide ion concentration. is 12.5.
How do you find hydronium ion concentration when given pH?The hydronium ion concentration can be found from the pH by the reverse of the mathematical operation employed to find the pH. [H3O+] = 10-pH or [H3O+] = antilog (- pH) Example: What is the hydronium ion concentration in a solution that has a pH of 8.34? On a calculator, calculate 10-8.34, or "inverse" log ( - 8.34).
What is the pH of a solution that has a hydronium ion concentration of 0.025 M?For a 0.025 M HCl solution the concentration of the hydrogen ions, [H+] , is 0.025 moles/liter (i.e. 0.025 M). pH is defined as −log[H+] . Substituting 0.025 into the equation for pH we find that the 0.025 M HCl solution has a pH of -log(0.025) = 1.60.
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Based on the properties of the compounds in the interactive, predict whether the given compounds behave as electrolytes or as nonelectrolytes.
1. LioH
2. C4H2O4
3. LiBr
4. HNo3
Explanation:
Before proceeding we have to understand what electrolytes and non electrolytes are;
An electrolyte is a substance that produces an electrically conducting solution when dissolved. An electrolyte is a compound that can dissociate into ions.
Non electrolytes: A substance whose molecules in solution do not dissociate to ions and thus do not conduct an electric current
Going through the options;
1. LiOH
This is a compound of hat would dissociate into Li+ and OH-. This is an electrolyte.
2. C4H2O4
This is an organic compound. Gnerally organic acids are non electrolytes, with the exception og the acids. This is a nonelectrolyte.
3. LiBr
This is an electrolyte because it would dissociate into Li+ and Br- ions.
4. HNO3
HNO3 is a strong acid. Because it is a strong acid it will dissociate completely into its ions (H+ and NO3-). Therefore we consider HNO3 to be a strong electrolyte.
A 5.00g of X, the product of organic synthesis is obtained in a 1.0 dm3 aqueous solution. Calculate the mass of X that can be extracted from the aqueous solution by a 50cm3 of ethoxy ethane. (KD (X) =40.
Answer:
mass of X extracted from the aqueous solution by 50 cm³ of ethoxy ethane = 3.33 g
Explanation:
The partition coefficient of X between ethoxy ethane (ether) and water, K is given by the formula
K = concentration of X in ether/concentration of X in water
Partition coefficient, K(X) between ethoxy ethane and water = 40
Concentration of X in ether = mass(g)/volume(dm³)
Mass of X in ether = m g
Volume of ether = 50/1000 dm³ = 0.05 dm³
Concentration of X in ether = (m/0.05) g/dm³
Concentration of X in water = mass(g)/volume(dm³)
Mass of X in water left after extraction with ether = (5 - m) g
Volume of water = 1 dm³
Concentration of X in water = (5 - m/1) g/dm³
Using K = concentration of X in ether/concentration of X in water;
40 = (m/0.05)/(5 - m)
(m/0.05) = 40 × (5 - m)
(m/0.05) = 200 - 40m
m = 0.05 × (200 - 40m)
m = 10 - 2m
3m = 10
m = 10/3
m = 3.33 g of X
Therefore, mass of X extracted from the aqueous solution by 50 cm³ of ethoxy ethane = 3.33 g
2C4H10(g)+13O2(g)→8CO2(g)+10H2O(g) Complete the following table
Answer:
1. 0.421 g (C₄H₁₀), 1.51 g (O₂), 1.28 g (CO₂), 0.653 g (H₂O)
2. 4.92 g (C₄H₁₀), 17.6 g (O₂), 14.9 g (CO₂), 7.63 g (H₂O)
3. 6.63 g (C₄H₁₀), 23.7 g (O₂), 20.12 g (CO₂), 10.3 g (H₂O)
4. 7.12 g (C₄H₁₀), 12.1 g (O₂), 10.2 g (CO₂), 8.84 g (H₂O)
5. 252 mg (C₄H₁₀), 903 mg (O₂), 763 mg (CO₂), 390 mg (H₂O)
6. 65 mg (C₄H₁₀), 234 mg (O₂), 198 mg (CO₂), 101 mg (H₂O)
Explanation:
1. First of all, we determine the moles of each reactant.
For the first case:
1.51 g . 1 mol/32 g = 0.0472 moles
Ratio is 13:2, 13 moles of oxygen needs 2 moles of C₄H₁₀ for the combustion,
Therefore 0.0472 mol will react with (0.0472 . 2)/13 = 7.26×10⁻³ mol.
Now we convert the moles to mass:
7.26×10⁻³ mol . 58 g/ 1mol = 0.421 g
Now we use stoichiometry to find the mass of the products.
Ratio is 13:8:10.
13 moles of oxygen can produce 8 moles of CO₂ and 10 moles of water
Then, 0.0472 mol would produce:
(0.0472 . 8)/13 = 0.0290 mol
We convert the moles to mass → 0.0290 mol . 44g /mol = 1.28 g
(0.0472 . 10)/13 = 0.0363 mol
We convert the moles to mass → 0.0363 mol . 18 g /1mol = 0.653 g
2. 4.92 g / 58 g/mol = 0.0848 moles of C₄H₁₀
2 moles of C₄H₁₀ react with 13 moles of O₂
So, 0.0848 moles will react with (0.0848 . 13) / 2 = 0.551 moles
We convert to mass: 0.551 mol . 32 g /mol = 17.6 g
Now we use stoichiometry to find the mass of the products.
Ratio is 13:8:10.
0.551 moles of O₂ will produce:
(0.551 . 8)/13 = 0.339 mol of CO₂
We convert to mass: 0.339 mol . 44g / mol = 14.9 g
(0.551 . 10)/13 = 0.424 mol of H₂O
0.424 mol . 18 g /mol = 7.63 g
3. In this case, we have the mass of one of the product
20.12 g . 1mol / 44 g = 0.457 moles of CO₂
According to stoichiometry:
8 moles of CO₂ are produced by the reaction of 13 moles of O₂ and 2 moles of C₄H₁₀
Then, 0.457 moles of CO₂ would be produced by:
(0.457 . 13)/ 8 = 0.743 moles of O₂
We convert to mass: 0.743 mol . 32 g/1mol = 23.7 g
(0.457 . 2)/8 = 0.114 moles of C₄H₁₀
We convert to mass: 0.114 mol . 58g/mol = 6.63g
Now we can determine, the mass of produced water:
(0.743 . 10)/13 = 0.571 mol of H₂O . 18g /mol = 10.3 g
4. We convert the moles of water:
8.84 g / 18g/mol = 0.491 moles
According to stoichiometry: 10 moles of water are produced by 13 moles of O₂ and 2 moles of C₄H₁₀
Then 0.491 moles will be produced by:
(0.491 . 10)/ 13 = 0.378 moles of O₂
We convert to mass: 0.378 mol . 32 g/1mol = 12.1 g
(0.491 . 2)/8 = 0.123 moles of C₄H₁₀
We convert to mass: 0.123 mol . 58g/mol = 7.12g
Now we can determine, the mass of produced carbon dioxide:
(0.378 . 8)/13 = 0.232 mol of CO₂ . 44g /mol = 10.2 g
5. Mass of mg, must be converted to grams
252 mg . 1 g/1000 mg = 0.252 g
It is the same as 2.
0.252 g of C₄H₁₀ . 1mol/58 g = 4.34×10⁻³ mol
2 mol of C₄H₁₀ react to 13 moles of O₂ then,
4.34×10⁻³ mol will react with (4.34×10⁻³ mol . 13) / 2 = 0.0282 mol
We convert the grams → 0.0282 mol . 32 g/mol = 0.903 g (903 mg)
0.0282 mol of oxygen will produced:
(0.0282 . 8)/13 = 0.0173 mol of CO₂
We convert to mass: 0.0173 mol . 44g / mol = 0.763 g (763 mg)
(0.0282 . 10)/13 = 0.0217 mol of H₂O
0.0217 mol . 18 g /mol = 0.390 g (390 mg)
6. We define the mass of CO₂ → 198 mg . 1g/1000 mg = 0.198 g
0.198 g / 44g/mol = 4.5×10⁻³ moles of CO₂
According to stoichiometry:
8 moles of CO₂ are produced by the reaction of 13 moles of O₂ and 2 moles of C₄H₁₀
Then, 4.5×10⁻³ moles of CO₂ would be produced by:
(4.5×10⁻³ . 13)/ 8 = 7.31×10⁻³ moles of O₂
We convert to mass: 7.31×10⁻³ . 32 g/1mol = 0.234 g (234 mg)
(4.5×10⁻³ . 2)/8 = 1.125×10⁻³ moles of C₄H₁₀
We convert to mass: 1.125×10⁻³ mol . 58g/mol = 0.065 g (65 mg)
Now we can determine, the mass of produced water:
(7.31×10⁻³ . 10)/13 = 5.62×10⁻³ mol of H₂O . 18g /mol = 0.101 g (101 mg)
"The pH of a solution of household ammonia, a 0.950-M solution of NH3, is 11.612. What is Kb" for NH3
Answer:
Kb = 1.77x10⁻⁵
Explanation:
When NH₃, a weak base, is in equilibrium with waterm the reaction that occurs is:
NH₃(aq) + H₂O(l) ⇄ NH₄⁺(aq) + OH⁻(aq)
And the dissociation constant, Kb, for this equilibrium is:
Kb = [NH₄⁺] [OH⁻] / [NH₃]
To find Kb you need to find the concentration of each species. The equilibrium concentrations are:
[NH₃] = 0.950M - X
[NH₄⁺] = X
[OH⁻] = X
Where X is reaction coordinate.
You can know [OH⁻] and, therefore, X, with pH of the solution, thus:
pH = -log [H⁺] = 11.612
[H⁺] = 2.4434x10⁻¹²
As 1x10⁻¹⁴ = [H⁺] [OH⁻]
1x10⁻¹⁴ / 2.4434x10⁻¹² = [OH⁻]
4.0926x10⁻³ = [OH⁻] = X
Replacing, concentrations of the species are:
[NH₃] = 0.950M - X
[NH₄⁺] = X
[OH⁻] = X
[NH₃] = 0.9459M
[NH₄⁺] = 4.0926x10⁻³M
[OH⁻] = 4.0926x10⁻³M
Replacing in Kb expression:
Kb = [NH₄⁺] [OH⁻] / [NH₃]
Kb = [4.0926x10⁻³M] [4.0926x10⁻³M] / [0.9459M]
Kb = 1.77x10⁻⁵The branch of science which deals with the chemical bond is called Chemistry.
The correct answer to the question is [tex]Kb = 1.77*10^{-5[/tex]
Explanation:
When NH₃, is acts as a weak base it forms an equilibrium with water the reaction occurs is:
[tex]NH_3(aq) + H_2O(l) ---><NH_4^+(aq) + OH^-(aq)[/tex]
The formula we gonna use is as follows:-
[tex]Kb = \frac{[NH_4^+] [OH^-]}{[NH_3]}[/tex]
The data is given in the question is as follows:-
[NH₃] = 0.950M - X [NH₄⁺] = X [OH⁻] = X
Where X stands for reaction coordinate.
After solving the ph of the compound the value is as follows:-
[NH₃] = [tex]0.9459M[/tex] [NH₄⁺] = [tex]4.0926*10^{-3}M[/tex] [OH⁻] = [tex]4.0926*10^{-3}M[/tex]
Putting the value in the formula.
[tex]Kb = \frac{[4.0926*10^{-3}M] [4.0926*10^{-3}M]}{[0.9459M]}[/tex]
After solving the equation the value of Kb is [tex]1.77*10^{-5[/tex]
Hence, the correct answer is [tex]1.77*10^{-5[/tex]
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What is the pH of a solution prepared by dissolving 0.140 g of potassium hydroxide in sufficient pure water to prepare 250.0 ml of solution
Answer:
pH= 12
Explanation:
Potassium hydroxide (KOH) is a strong base, so it dissociates completely in water by giving OH⁻ anions as follows:
KOH⇒ K⁺ + OH⁻
Since dissociation is complete, it is assumed that the concentration of OH⁻ is equal to the initial concentration of KOH:
[OH⁻]= [KOH]
In order to find the initial concentration of KOH, we have to divide the mass (0.140 g) into the molecular weight of KOH (Mw):
Mw (KOH)= K + O + H = 39 g/mol + 16 g/mol + 1 g/mol = 56 g/mol
moles KOH: mass/Mw= 0.140 g/(56 g/mol) = 2.5 x 10⁻³ moles
The molality of the solution is the number of moles of KOH per liter of solution:
V= 250.0 ml x 1 L/1000 ml= 0.250 L
M = (2.5 x 10⁻³moles)/(0.250 L)= 0.01 M
Now, we calculate pOH:
pOH = -log [OH⁻]= - log [KOH]= -log (0.01) = 2
Finally, we calculate pH from pOH:
pH + pOH = 14
⇒pH = 14 - pOH= 14 -2 = 12
Which land feature supports the theory of continental drift?
A.canyons B.volcanoes C.coal fields D.oceans
Answer:
Coals
Explanation:
The land feature that supports the theory of continental drift is ; ( C ) coal fields
Continental drift is the gradual shift in position of the earth tectonic plates ( i.e. gradual shift in the continents in relation to ocean basins) and this due to the heat from the earths' mantle.
Coal fields supports this theory because the it is an area where coal is found in large quantities and mined for commercial purposes. coal fields areas are found as a result of continental drift.
Hence we can conclude that the land feature that supports the theory of continental drift is coal fields
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Why at night, under the mercury or sodium vapor lights in a mall parking lot, do cars seem to be peculiar colors?
Answer:
Here's what I find
Explanation:
Sodium vapour produces mostly yellow light.
Mercury vapour produces mostly blue light.
A white car reflects all colours back to our eyes.
A coloured car, say green, absorbs all the other colours and reflects the green.
Under a sodium light, a white or a yellow car will appear yellow. A red car will be nearly black because there is no red light to reflect.
Under a mercury light, a white or a blue car will appear blue. A yellow car will be quite dark, but there will be a yellowish tinge because there is some yellow in the Hg spectrum for it to reflect.
The picture below shows a red car and a black car under sodium light. Can you tell which is which?
Elvira Walks 4 miles to the west from school and stops at the store. She then walks 3 miles south.
What is the Distance and the displacement?
Answer:
distance = 7 miles
displacement = 5 miles
Explanation:
Distance is a scalar quantity as it takes account of magnitude traveled but not the direction traveled from starting point.
The distance traveled is the sum total of distances moved
distance = 4 + 3 = 7 miles
Displacement however, is a vector and measure the shortest possible distance traveled in a given direction from the starting point.
The path of Elvis' walking forms a right-angle triangle with the hypotenuse being the displacement and the other two sides being the distance traveled west and south.
Using Pythagoras' theorem; c² = a² + b²
where c = hypotenuse and a and b are the other two sides
c² = 4² + 3²
c² = 16 + 9 = 25
√c² = √25
c = 5
Therefore, displacement = 5 miles
A burning match releases 838.2 J of energy. Convert the energy released by 20 matches to the following energy units: (provide an answer in 4 significant figures)
________ Kilojoules
________ Calories
________ Food Calories
________ calories
________ kcal
Answer:
See explanation
Explanation:
In this case, we can start with the calculation of the total energy released by the 20 matches. One match release 838.2 J of energy ( 1 match = 838.2 J). So:
[tex]20~matches\frac{838.2~J}{1~match}=16764~J[/tex]
With this in mind, we have to find al the conversion ratios to "Jolues", so:
[tex]1~KJ=1000~J[/tex]
[tex]1~Cal=4.184~J[/tex]
[tex]1~KCal=4184~J[/tex]
[tex]0.000239~food~calories=1~J[/tex]
Now, we can do the conversions:
[tex]16764~J\frac{1~KJ}{1000~J}=16.76~KJ[/tex]
[tex]16764~J\frac{1~Cal}{4.184~J}=4.005x10^3~Cal[/tex]
[tex]16764~J\frac{1~KCal}{4184~J}=4.007~KCal[/tex]
[tex]16764~J\frac{0.000239~food calories}{1~J}=4.006~food calories[/tex]
I hope it helps!
8. A 25.0 mL sample of an H2SO4 solution is titrated with a 0.186 M NaOH solution. The equivalence point is reached with 12.9 mL of base. The concentration of H2SO4 is ________ M. (Hint: write a balanced chemical equation first!)
Answer:
0.0480 M
Explanation:
The reaction is ...
H₂SO₄ + 2NaOH ⇒ Na₂SO₄ +2H₂O
That is, 2 moles of NaOH react with each mole of H₂SO₄. Then the molarity of the H₂SO₄ is ...
moles/liter = (0.186 M/2)(12.9 mL)/(25.0 mL) ≈ 0.0480 M
differentiate between satured and unsatured fats
Answer:
...
Explanation:
in saturated fats there is no double bond between the acids and are tightly packed and unsaturated fats arent tight and loosely packed/put together
saturated- solid at room temperature
unsaturated= liquid at room temperature
two types of unsaturated fats, Polyunsaturated fats and Monounsaturated fats
An atom of element number 33 (As) is in its ground electronic state. Which one of the following sets quantum numbers could not apply to any of its electrons?
A) n=2 l=1 ml= -1 ms= 1/2
B) n=3 l=0 ml=0 ms= -1/2
C) n=3 l=2 ml=-2 ms= -1/2
D) n=4 l=0 ml=0 ms= -1/2
E) n=4 l=2 ml=1 ms= 1/2
Answer:
E) n=4 l=2 ml=1 ms= 1/2
Explanation:
Arsenic is a member of group 15 in the periodic table. Its electronic configuration is;
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3. Its condensed electronic configuration can be written as [Ar]4s2 3d10 4p3. This electronic configuration shown here can now enable us to consider each option given in the question in order to meaningfully arrive at a logical answer.
If we look at option E, the data given for that electron is; n=4 l=2 ml=1 ms= 1/2. This refers to an electron in a 4d orbital. In the ground state configuration of arsenic shown above, there is no 4d orbital, hence option E must be the correct answer.
c) What is the pH of the buffer system in part a when 0.030 moles of strong acid are added (without a change in volume)
Answer:
remain the same
Explanation:
The pH of the buffer system remain the same when 0.030 moles of strong acid are added because buffer system has the property to resist any change in the pH when acid or base is added to the solution. In buffer system, one molecule is responsible for neutralizing the pH of the solution by giving H+ or OH-.This molecule is known as buffer agent. If more base is added, the molecule provide H+ and when more acid is added to the solution, then the molecule add OH- to the solution.