Answer:
H2
Explanation:
Critical temperature is the temperature above which gas cannot be liquefied, regardless of the pressure applied.
Critical temperature directly depends on the force of attraction between atoms, it means stronger the force of higher will be the critical temperature. So, from the given options H2 should have the highest critical temperature because of high attractive forces due to H bonding.
Hence, the correct option is H2.
Answer:
CBr4
Explanation:
Critical temperature is dependent on the strength of the intermolecular forces.
First consider the types of intermolecular forces and the order of their strengths.
Dispersion forces < dipole-dipole forces < hydrogen bonding < ionic bonding
Remember, dispersion forces are present in all cases
H2: only dispersion forces are present
CH4, CCl4, CBr4, CF4: only dispersion forces are present
In order to break the tie we must start considering molar mass because larger molar masses correspond to larger intermolecular forces. Calculating molar mass shows that CBr4 is the largest and will have the strongest intermolecular forces and therefore will have the highest critical temperature.
The answer is CBr4
Aqueous solutions of sodium sulfate and potassium chloride are mixed. What is the precipitate and how many molecules are formed?
Answer:
The two products of this reaction, Sodium Chloride and Potassium Sulfate, are both soluble in water, hence, there's no precipitate formed from this reaction.
Explanation:
Sodium sulfate is Na₂So₄
Potassium Chloride is KCl
When they both react, theres a double displacement where ions and radicals are exchanged
Na₂SO₄ + KCl → NaCl + K₂SO₄
The products are
NaCl - Sodium Chloride
K₂SO₄ - Potassium Sulfate
The two products are soluble in water, hence, there's no precipitate formed from this reaction.
And we would need numerical values of the number of moles of the two reactants mixed to obtain the number of moles of products formed and then the number of molecules from Avogadro's constant.
Hope this Helps!!!
where 1s, 2s, and 2p are the occupied subshells, and the superscript "2" is the number of electrons in each of these subshells. Use the rules for determining electron configurations to write the electron configuration for Ca. Express your answer in complete form in order of orbital filling. For example, 1s22s2 should be entered as 1s^22s^2.
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]
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 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
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.
The reduction of iron(III) oxide to iron metal is an endothermic process: Fe2O3(s) + 2 CO(g) → 2 Fe(s) + 3 CO2(g) ΔH = +26.3 kJ How many kilojoules of energy are required to produce 1.00 kilogram of iron metal?
Answer: Thus 234 kJ of energy are required to produce 1.00 kilogram of iron metal
Explanation:
To calculate the number of moles , we use the equation:
[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]
Putting values , we get:
[tex]\text{Moles of iron}=\frac{1000g}{56g/mol}=17.8moles[/tex] (1.00kg=1000g)
The balanced chemical reaction is:
[tex]Fe_2O_3(s)+2CO(g)\rightarrow 2Fe(s)+3CO_2(g)[/tex] [tex]\Delta H=+26.3kJ[/tex]
Given :
Energy released when 2 moles of [tex]Fe[/tex] is produced = 26.3 kJ
Thus Energy released when 17.8 moles of [tex]Fe[/tex] is produced =
= [tex]\frac{26.3kJ}{2}\times 17.8=234kJ[/tex]
Thus 234 kJ of energy are required to produce 1.00 kilogram of iron metal
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)
Why can liquids change shape but solids cannot
Answer:
Explanation:
the forces between the molecules are stronger in solid than in liquids
1. john needs to create a buffered solution at a ph of 3.5 for his biomedical laboratory
Answer:
Use a ratio of 0.44 mol lactate to 1 mol of lactic acid
Explanation:
John could prepare a lactate buffer.
He can use the Henderson-Hasselbalch equation to find the acid/base ratio for the buffer.
[tex]\text{pH} = \text{pK}_{\text{a}} + \log\dfrac{\text{[A$^{-}$]}}{\text{[HA]}}\\\\3.5 = 3.86 + \log\dfrac{\text{[A$^{-}$]}}{\text{[HA]}}\\\\\log\dfrac{\text{[A$^{-}$]}}{\text{[HA]}} = 3.5 - 3.86 = -0.36\\\\\dfrac{\text{[A$^{-}$]}}{\text{[HA]}} = 10^{-0.36} = \mathbf{0.44}[/tex]
He should use a ratio of 0.44 mol lactate to 1 mol of lactic acid.
For example, he could mix equal volumes of 0.044 mol·L⁻¹ lactate and 0.1 mol·L⁻¹ lactic acid.
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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A chemistry student weighs out of hypochlorous 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 equivalence point. Round your answer to significant digits.
Answer:
Volume of NaOH, aka V2 = 6.32 mL to 3 sig. fig.
A chemistry student weighs out 0.0941 g of hypochlorous acid (HClo) into a 250. ml. volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.2000 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Round your answer to 3 significant digits mL.
Explanation:
1 mole HClO = 74.44g
0.0941g = [tex]\frac{0.0941}{74.44}[/tex] = 0.00126 moles
Concentration = no. of moles/volume in L
Hence, Concentration of HClO = 0.00126/ 0.250L
= 0.005M.
C1V1 =C2V2
0.005 × 250 mL = 0.2 × V2
Volume of NaOH, aka V2 = 6.32 mL to 3 sig. fig.
For this assignment, the target compound that you should synthesize is 1-methyl-4-nitro-benzene. This is an electrophilic aromatic substitution reaction. Examine the product carefully and determine the substitution pattern. Which group will already be present in the substrate? Keep in mind the mechanism and how that will control the selectivity of the process. Remember, you can easily separate ortho and para isomers.
Answer:
The methyl group will already be present
Explanation:
You want to make 1-methyl-4-nitrobenzene.
The question is, "Do I start with the methyl group on the ring and then nitrate, or do I start with the nitro group on the ring and then add the methyl group?"
The methyl group is activating and ortho, para directing.
The nitro group is deactivating and meta directing.
You want a para-substituted product, so you choose to nitrate toluene, as in the reaction scheme below.
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?
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]
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.
A student mixed 115 g of sugar, 350 g of water and 5 g of spices. What will be the mass of the solution?
these are the options
470g
465g
350g
120g
Answer:
[tex]m_{solution}=470g[/tex]
Explanation:
Hello,
In this case, a solution is formed when a solute is completely dissolved in a solvent, thus, for this situation, the sugar is the solute and the water the solvent but in addition to them we find spices which are also considered in the total mass of the solution. In such a way, for computing the total mass we must add the mass of three constituents (115 g sugar, 350 g water and 5 g spices) as shown below:
[tex]m_{solution}=115g+350g+5g\\\\m_{solution}=470g[/tex]
Best regards.
Consider the addition of an electron to the following atoms from the fourth period. Rank the atoms in order from the most negative to the least negative electron affinity values based on their electron configurations.
Atom or ion Electron configuration
Br 1s22s22p63s23p64s23d104p5
Ge 1s22s22p63s23p64s23d104p2
Kr 1s22s22p63s23p64s23d104p6
Answer:
Ge: [Ar] 3d10 4s2 4p2 => 6 electrons in the outer shell
Br: [Ar] 3d10 4s2 4p5 => 7 electrons in the outer shell
Kr: [Ar] 3d10 4s2 4p6 => 8 electrons in the outer shell
Explanation:
The electron affinity or propension to attract electrons is given by the electronic configuration. Remember that the most stable configuration is that were the last shell is full, i.e. it has 8 electrons.
The closer an atom is to reach the 8 electrons in the outer shell the bigger the electron affinity.
Of the three elements, Br needs only 1 electron to have 8 electrons in the outer shell, so it has the biggest electron affinity (the least negative).
Ge: needs 2 electrons to have 8 electrons in the outer shell, so it has a smaller (more negative) electron affinity than Br.
Kr, which is a noble gas, has 8 electrons and is not willing to attract more electrons at all, the it has the lowest (more negative) electron affinity of all three to the extension that really the ion is so unstable that it does not make sense to talk about a number for the electron affinity of this atom.
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For the reaction of nitrogen gas and hydrogen gas to make methane, describe FOUR stresses that would shift the equilibrium to the left toward the reactants? N2(g) + 3 H2(g) ⇌ 2 NH3(g) + Energy
Answer:
- Addition of NH₃(g)
- Removal of N₂(g)
- Increase of temperature
- Pressure decrease
Explanation:
According to Le Chatelier's principle, if we apply an stress to a reaction at equilibrium, the system will try to shift the equilibrium in order to decrease the stress. If we add reactants, the equilibrium will shift toward the formation of more products (to the consumption of reactants) and vice versa.
The stresses we can apply to this equilibrium are the following:
- Addition of NH₃(g) : it is a product, thus its addition will result in a shift toward reactants.
- Removal of N₂(g): it is a reactant, thus its removal from the reaction mixture will result in a shift toward reactants.
- Increase of temperature: the reaction is exothermic, so it releases energy. Energy is a product. If we add energy (increase the temperature), we are adding a product, so the equilibrium will shift toward the reactants.
- Pressure decrease: because both reactants and products are in the gas phase. A decrease in pressure shifts an equilibrium to the side of the reaction with greater number of moles of gas. In this case, the reactants side has greater number of moles of gas (1 mol + 3 moles= 4 moles) than the products side (2 moles). Thus, the equilibrum will shift toward reactants.
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]
Best Regards!
Please help to answer these questions please just give the option, no need explanation. Thanks
Answer:
Well hey there!
There isn't any info on what you need help with!
Sorry...
Given the chemical equation: 2 Pb + O2 → 2 PbO, if 51.8 grams of Pb are formed in this reaction, then 8.00 grams of O2 must have reacted.
Answer:
If 51.8 of Pb is reacting, it will require 4.00 g of O2
If 51.8 g of PbO is formed, it will require 3.47 g of O2.
Explanation:
Equation of the reaction:
2 Pb + O2 → 2 PbO
From the equation of reaction, 2 moles of lead metal, Pb, reacts with 1 mole of oxygen gas, O2, to produce 2 moles of lead (ii) oxide, PbO
Molar mass of Pb = 207 g
Molar mass of O2 = 32 g
Molar mass of PbO = 207 + 32 = 239 g
Therefore 2 × 207 g of Pb reacts with 32 g of O2 to produce 2 × 239 g of PbO
= 414 g of Pb reacts with 32 g of O2 to produce 478 g of PbO
Therefore, formation of 51.8 g of PbO will require (32/478) × 51.8 of O2 = 3.47 g of O2.
If 51.8 of Pb is reacting, it will require (32/414) × 51.8 g of O2 = 4.00 g of O2
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.
A volume of 0.800 L of a 2 x 10–4 M Ba(NO3)2 solution is added to 0.200 L of 5 x 10–4 M Li2SO4. Does BaSO4 precipitate? Explain your answer
Answer:
The BaSO₄ precipitates as a solid.
Explanation:
In order to determine the precipitation, we need to look at the reactants, we have: Ba(NO₃)₂ and Li₂SO₄
Salts from nitrate are all soluble and sulfates can make precipitate if they react to elements from group 2. (Solubility rules) So this reaction, has a precipitate but we can predict it, if we look at the reaction and we take acount the Kps:
Ba(NO₃)₂ (aq) + Li₂SO₄ (aq) → 2LiNO₃ (aq) + BaSO₄ (s) ↓
Let's find out the moles of each ion:
Ba(NO₃)₂ (aq) → Ba²⁺ (aq) + 2NO₃⁻ (aq)
0.8 L . 0.0002 M = 1.6×10⁻⁴ moles. These are the moles of Ba²⁺ in 1 L of solution, so [Ba²⁺] = 1.6×10⁻⁴ M
Li₂SO₄ (aq) → 2Li⁺ (aq) + SO₄⁻² (aq)
0.2 L . 0.0005 M = 1×10⁻⁴ M. These are the moles of sulfate, in 1 L of solution so [SO₄⁻²] = 1×10⁻⁴ M
BaSO₄ (s) ⇆ Ba²⁺ (aq) + SO₄⁻² (aq) Kps = 1.08×10⁻¹⁰
We need to compare Kps to [ Ba²⁺] . [SO₄⁻²]
[ Ba²⁺] . [SO₄⁻²] = 1.6 ×10⁻⁸ > Kps → Precipitate.
If [Ba²⁺] . [SO₄⁻²] = Kps → Solution is saturated
If [ Ba²⁺] . [SO₄⁻²] < Kps → There is no precipitate formed, or if it is formed, it will be quickly dissolved to reach saturation.
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]
the iupac name of the compound
Answer:
3-Pentyn-1-ol
Explanation:
tripple bond is at 3 postion from alochol
carbon are 5 atoms so pent
yn becauese its alkyne
Is carbon or oxygen more electronegative?
Answer:
Oxygen is more electronegative than carbon.
Explanation:
Electronegativity increases from left to right across the periodic table. Since oxygen is further right than carbon, it is more electronegative. Also, if you look at a chart of electronegativity, oxygen has an electronegativity of 3.44 while carbon has an electronegativity of 2.55.
So oxygen is more electronegative than carbon. Hope this helps.
Label the following reactions as oxidation or reduction. Cr+3(aq) + 3e-s → Cr ________ Ag(s) → 1e-s + Ag+1(ag) ________ Mn(s) → 5e-s + Mn+5(aq) ________ Sn+2(aq) + 2e-s → Sn ________
Answer:
See the explanation
Explanation:
Our reactions for this question are:
a) Cr+3(aq) + 3e- → Cr(s) ________
b) Ag(s) → 1e- + Ag+1(ag) ________
c) Mn(s) → 5e- + Mn+5(aq) ________
d) Sn+2(aq) + 2e- → Sn(s) ________
Now, we have to remember the definition of oxidation and reduction. In a reduction reaction, the substance will gain electrons, in other words: "The electrons would be placed on the left side, in the side of the reagents. In an oxidation reaction, the substance will lose electrons, in other words: "The electrons would be placed on the right side, in the side of the products".
With this in mind we will have:
a) Cr+3(aq) + 3e- → Cr (s)(Reduction)
b) Ag(s) → 1e- + Ag+1(ag) (Oxidation)
c) Mn(s) → 5e- + Mn+5(aq) (Oxidation)
d) Sn+2(aq) + 2e- → Sn(s) (Reduction)
I hope it helps!
100. mLmL of 0.200 MMHClHCl is titrated with 0.250 MMNaOHNaOH. Part A What is the pH of the solution at the equivalence point? Express the pH numerically.
Answer:
pH = 7.0
Explanation:
When HCl reacts with NaOH, H₂O and NaCl are produced, thus:
HCl + NaOH → H₂O + NaCl
At equivalence point, all HCl reacts with NaOH. The only you will have is water.
Equilbrium of water is:
H₂O(l) ⇄ H⁺(aq) + OH⁻(aq)
K = 1x10⁻¹⁴ = [H⁺] [OH⁻]
As H⁺ = OH⁻ because both are produced from the same water-
1x10⁻¹⁴ = [H⁺]²
1x10⁻⁷M = [H⁺]
As pH = -log= [H⁺]
pH = 7.0-The pH at equivalence point in the titration of a strong acid with a strong base is always 7.0-
A student titrates a 20.00 mL sample of an aqueous borax solution with 1.03 M H2SO4. If 2.07 mL of acid are needed to reach the equivalence point, then what is the molarity of the borax solution
Answer:
The concentration of the borax solution is 0.1066 M
Explanation:
Step 1: Dtaa given
Volume of a sample of aqueous borax solution = 20.00 mL = 0.020 L
Molarity of H2SO4 = 1.03 M
Volume of the H2SO4 = 2.07 mL = 0.00207 L
Step 2: The balanced equation
Na2B4O7*10H2O(borax) + H2SO4 ⇆ Na2SO4 + 4 H3BO3 + 5 H2O
Step 3: Calculate molarity of borax solution
b*Ca*Va = a * Cb*Vb
⇒with B = the coefficient of H2SO4 = 1
⇒with Ca = the concentration of borax = TO BE DETERMINED
⇒with Va = the volume of borax = 0.020 L
⇒with a = the coefficient of borax = 1
⇒with Cb = the concentration of H2SO4 = 1.03 M
⇒with Vb = the volume of H2SO4 = 0.00207 L
Ca*0.020 L = 1.03 M * 0.00207 L
Ca = (1.03 * 0.00207) / 0.020
Ca = 0.1066 M
The concentration of the borax solution is 0.1066 M
What is the name of CaCl2 7H2o
Answer:
calcium chloride dihydrate