Answer: When excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
Explanation:
Given: Wavelength = 589 nm
It is known that,
[tex]1 nm = 10^{-9} m[/tex]
Hence, 589 nm is converted into meters as follows.
[tex]589 nm = 589 nm \times \frac{10^{-9}m}{1 nm}\\= 589 \times 10^{-9} m[/tex]
Thus, we can conclude that when excited sodium atoms may emit radiation having a wavelength of 589nm. It's wavelength in meters is [tex]589 \times 10^{-9} m[/tex].
If a student drops 2.3g pieces of magnesium into a flask of hydrochloric acid, this reaction occurs: Mg + 2HCl= MgCl2 + H2
How many liters of hydrogen can be produced at a pressure of 2 atm and a temperature of 298 K
Answer:
1.2 L
Explanation:
Step 1: Write the balanced equation
Mg + 2 HCl ⇒ MgCl₂ + H₂
Step 2: Calculate the moles corresponding to 2.3 g of Mg
The molar mass of Mg is 24.31 g/mol.
2.3 g × 1 mol/24.31 g = 0.095 mol
Step 3: Calculate the moles of H₂ produced
0.095 mol Mg × 1 mol H₂/1 mol Mg = 0.095 mol H₂
Step 4: Calculate the volume occupied by the hydrogen
We will use the ideal gas equation.
P × V = n × R × T
V = n × R × T/P
V = 0.095 mol × (0.0821 atm.L/mol.K) × 298 K/2 atm = 1.2 L
The volume of an ideal gas is held constant. Determine the ratio P2/P1 of the final pressure to the initial pressure when the temperature of the gas rises (a) from 46 to 92 K and (b) from 35.4 to 69.0 oC.
Answer:
A. P₂ / P₁ = 2
B. P₂ / P₁ = 1.1
Explanation:
A. Determination of the ratio P₂/P₁
Volume = constant
Initial temperature (T₁) = 46 K
Final temperature (T₂) = 92 K
Final pressure /Initial pressure (P₂/P₁) =?
P₁/T₁ = P₂/T₂
P₁/46 = P₂/92
Cross multiply
46 × P₂ = P₁ × 92
Divide both side by P₁
46 × P₂ / P₁ = 92
Divide both side by 46
P₂ / P₁ = 92 / 46
P₂ / P₁ = 2
B. Determination of the ratio P₂/P₁
Volume = constant
Initial temperature (T₁) = 35.4 °C = 35.4 + 273 = 308.4 K
Final temperature (T₂) = 69.0 °C = 69 + 273 = 342 K
Final pressure /Initial pressure (P₂/P₁) =?
P₁/T₁ = P₂/T₂
P₁/308.4 = P₂/342
Cross multiply
308.4 × P₂ = P₁ × 342
Divide both side by P₁
308.4 × P₂ / P₁ = 342
Divide both side by 308.4
P₂ / P₁ = 342 / 308.4
P₂ / P₁ = 1.1
The molar ratio of HPO42- to H2PO4- in a solution is 1.4. Calculate the pH of the solution. Phosphoric acid (H3PO4) is a triprotic acid with 3 pKa values: 2.14, 6.86, and 12.4.
Given is the ratio of conjugate base and conjugate acid of phosphoric acid. pH of a substance is the concentration of the hydrogen ions in its solution and higher this concentration lower is the value of pH.
pKa value is a measure of the strength of acid, it is the negative log of acid dissociation constant Ka.
The metal thallium becomes superconducting at temperatures below 2.39K. Calculate the temperature at which thallium becomes superconducting in degrees Celsius. Round your answer to decimal places.
Answer:
-270.76°C
Explanation:
Given that metal Thallium becomes superconducting below the temperature of 2.39 kelvin i.e. this temperature is critical temperature for Thallium and below critical temperature a metal offers no resistance to the flow of electric current. Also the metal below its critical temperature expels the magnetic field in such a way that they do not penetrate the metal and pass through its surface only.
We have the relation between kelvin scale and degree Celsius scale of temperature measurement as:
[tex]C = K - 273.15[/tex]
[tex]C=2.39-273.15\\ C=-270.76^{o}C[/tex]
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Write the symbol for every chemical element that has atomic number less than 14 and atomic mass greater than 23.2 u.
Answer:
that symbol less than atomic number 14 and greater than mass number 23.2 is mg
Suppose you are using distillation to separate cyclohexane and toluene. The boiling point of cyclohexane is ______ oC and the boiling point of toluene is ______ oC. Therefore, the liquid collected first should be ______
Please put an answer in each box.
Answer: The boiling point of cyclohexane is 81oC and the boiling point of toluene is 111oC. Therefore the liquid collected first should be
CYCLOHEXANE
Explanation:
In chemistry, there are various separation techniques that can be used to separate the components of a mixture and even isolate each of these components. A typical example of such separation techniques is DISTILLATION. This is a method of separation that makes use of different boiling points of liquids in a mixture. A mixture of any number of liquids could be separated as long as they boil at different temperatures. Example include:
--> mixture of cyclohexane (boiling point is 81°C) and toluene (boiling point is 111°C)
--> mixture of alcohol (boiling point is 78°C) and water (boiling point 100°C).
The process involves heating the mixture of liquids until the more volatile liquid ( that is the one with the lower boiling point) changes to vapour. The vapour is cooled by passing it through a condenser and collected in a liquid form known as distillate.
Therefore in the mixture of cyclohexane and toluene, the liquid collected FIRST should be CYCLOHEXANE.
Suppose that you move from a Suppose that you move from a town near the ocean to a town in the mountains. To what atmospheric changes would your body need to adjust? town near the ocean to a town in the mountains. To what atmospheric changes would your body need to adjust?
Answer:
all I can say is town near the ocean atmospheric changes will be cooler, warm, sea breeze, and fresh healthy air. Then when it comes to the mountain lot of change firstly there's a dry air
A compound has a formula mass of 228.0 and an empirical formula of C2H4O3. What is the molecular formula
Answer:
C₆H₁₈O₉
Explanation:
First we calculate the molar mass of the compound represented by the empirical formula:
Molar Mass = (Molar mass of C) * 2 + (Molar Mass of H) * 4 + (Molar Mass of O) * 3Molar Mass = 12 * 2 + 1 * 4 + 16 * 3 = 76 g/molThen we divide the given formula mass by the calculated molar mass:
228 / 76 = 3Thus we multiply by 3 the subscripts in the empirical formula:
The molecular formula is C₆H₁₈O₉Based upon the intermolecular forces present, rank the following substances according to the expected boiling point for the substance.
a. HCl
b. NaCl
c. N2
d. H2O
8.7 Two products are formed in the following reaction in a 50:50 mixture. Would the resulting solution be optically active
Answer:
Yes. The solution would be optically active.
Explanation:
Diastereomer are defined as the image that is non mirror and non -identical. It is made up of two stereoisomers. They are formed when the two stereoisomers or more than two stereoisomers of the compound have the same configuration at the equivalent stereocenters.
In the given context, as the product given is a diastereomeric mixture, the product would have an optical activity in total.
So the answer is Yes.
What differences does distillation rely on to separate out parts of a solution?
O A. Different densities
O B. Different molecular masses
C. Different boiling points
O D. Different molecular sizes
Different boiling point.
Because in distillation the substance with lower boiling point is evaporated, leaving the other material(s).
Distillation relies on different boiling points to separate out parts of a solution.
What is determined by calculating the slope of the position versus time graph distance
Answer:
Determining the Slope on a p-t Graph. It was learned earlier in Lesson 3 that the slope of the line on a position versus time graph is equal to the velocity of the object. ... If the object has a velocity of 0 m/s, then the slope of the line will be 0 m/s. The slope of the line on a position versus time graph tells it all.
Explanation:
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Which of the following ions is formed when an acid is dissolved in a solution?
H+
O−
OH−
SO42+
Answer:
H+
Explanation:
acid produce H+ when it is dissolved in a solution
Describe the electron configuration of an atom using principal energy level, sublevels, orbitals, and periodic table. Give one example others may not think about and why you made this selection.
Silicon is not allowed.
Explanation:
The electron density number as well as the sublevel letter are used to describe valence electrons in an atom. The third total energy and subbasement p, for example, is denoted by 3p. The electron configuration of oxygen, for example, is 1s^2 2s^2 2p^4, which means the first two electrons will couple up in the 1s orbital, while the following two protons will pair up in the 2s orbital.
The sample atom is Carbon with electron configuration; 1s² 2s² 2p².
The principal energy level of an electron refers to the shellp in which the electron is located relative to the atom's nucleus. In this case only 2 energy levels exist in a carbon atom; which are energy level 1 and 2
The sublevels exist within a principal energy and the electron configuration of an atom is described with consideration of energy sublevels. The sublevels in a carbon atom are;
s and p energy sublevels.The orbitals in this configuration are: 1s 2s 2px 2py 2pz in which case; each orbital can accommodate 2 electrons each.
Ultimately, the location of an element on the periodic table with respect to group and period are used to determine the valency and no. of energy levels in the atom of that Element.
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When Hg2+ concentration is 6.35x10^-4 M, the observed cell potential at 298K for an electrochemical cell with the following reaction is 1.499V. What is the Cr3+ concentration?
3H^2+ (aq) + 2Cr(s)= 3Hg(l) + 2Cr^3+(aq)
Answer:
10.5 × 10^5 M
Explanation:
E°cell = E°cathode - E°anode
E°cell = 0.85 - (-0.74) = 1.59 V
From Nernst's equation;
Ecell = E°cell - 0.0592/n log Q
1.499 = 1.59 - 0.0592/6 log [Cr^3+]/6.35x10^-4
1.499 - 1.59 = - 0.0592/6 log [Cr^3+]/6.35x10^-4
-0.091 = -0.00987 log [Cr^3+]/6.35x10^-4
-0.091/ -0.00987 = log [Cr^3+]/6.35x10^-4
9.22 = log [Cr^3+]/6.35x10^-4
Antilog (9.22) = [Cr^3+]/6.35x10^-4
1.66 × 10^9 = [Cr^3+]/6.35x10^-4
[Cr^3+] = 1.66 × 10^9 × 6.35x10^-4
[Cr^3+] = 10.5 × 10^5 M
What is the gravitational potential energy of a 1500-kg truck resting on top of a 550-m hill on earth?( earth’s gravitational pull is 9.8m/s2).
Answer:
E = 8085 kJ
Explanation:
Given that,
The mass of a truck, m = 1500 kg
Height, h = 550 m
We need to find the gravitational potential energy of the truck. It can be calculated as follows :
[tex]E=mgh[/tex]
Put all the values,
[tex]E=1500\times 9.8\times 550\\\\E=8085000\ J\\\\or\\\\E=8085\ kJ[/tex]
So, the gravitational potential energy is 8085 kJ.
Given 200ul of a 0.5mg/ml stock solution of BSA, how much do you pipet into a test tube so that you are adding 5ug of BSA to the test tube
Answer: [tex]10\mu L[/tex] of volume needs to be pipetted out in the test tube.
Explanation:
We are given:
Mass of BSA to be formed = [tex]5\mu g=0.005mg[/tex] (Conversion factor: [tex]1mg=1000\mu g[/tex]
Volume of stock solution = [tex]200\mu L=0.2mL[/tex] (Conversion factor: [tex]1mL=1000\mu L[/tex]
It is also given that for the mass of BSA is 0.5 g, the volume used up is 1 mL
In order to have, 0.005 g, the volume of stock solution needed will be = [tex]\frac{1mL}{0.5g}\times 0.005g=0.01mL=10\mu L[/tex]
Hence, [tex]10\mu L[/tex] of volume needs to be pipetted out in the test tube.
What is the phase change from solid to gas?
O A. Condensation
O B. Sublimation
O C. Freezing
O D. Vaporization
Answer:
The answer is B, sublimation.
Answer:
The correct answer
B . Sublimation
Pl hep help help me
What is the cell potential of an electrochemical cell that has the half-reactions shown below?
Ag⁺ + e⁻ → Ag
Fe → Fe³⁺ + 3e⁻
Answer:
E°(Ag⁺/Fe°) = 0.836 volt
Explanation:
3Ag⁺ + 3e⁻ => Ag°; E° = +0.800 volt
Fe° => Fe⁺³ + 3e⁻ ; E° = -0.036 volt
_________________________________
Fe°(s) + 3Ag⁺(aq) => Fe⁺³(aq) + 3Ag°(s) ...
E°(Ag⁺/Fe°) = E°(Ag⁺) - E°(Fe°) = 0.800v - ( -0.036v) = 0.836 volt
It takes to break an carbon-chlorine single bond. Calculate the maximum wavelength of light for which an carbon-chlorine single bond could be broken b
The question is incomplete, the complete question is;
It takes 338. kJ/mol to break an carbon-chlorine single bond. Cal broken by absorbing a single photon Iculate the maximum wavelength of light for which an carbon-chiorine single bond could be Round your answer to 3 significant digits
Answer:
3.55 × 10^-7 m or 355 nm
Explanation:
Now, the energy of the photon = 338 × 10^3/6.02 × 10^23 = 5.61 × 10^-19 J
Recall that;
E= hc/λ
h= planks constant
c= speed of light
λ = wavelength
λ =hc/E
λ = 6.63 ×10^-34 × 3 × 10^8/5.61 × 10^-19
λ =3.55 × 10^-7 m or 355 nm
Which statement is true about molarity and percent by mass? (3 points)
They have the same unit.
They are inversely related.
They are different units of dilution.
They are different units of concentration.
Answer:
The guy above used photoshop here is the actual answer.
Explanation:
The true statements about molarity and percent by mass is that they are the different units of concentration
What is concentration?Concentration of any substance present in any solution guves idea about their relative amount in that and it can de described in terms of molarity and percent by mass.
Molarity is define as the moles of solute present in per unit volume of the solution and has a unit of mol/L.Percent by mass is define as the mass of solute present in total mass of solution and it is a unit less quantity.They both gives idea about the concentration, not of the dillutions.They are not inversely related else they are directly related to each other as they are depends on the moles or mass of solute.Hence, molarity and percent by mass are the different units of concentration and directly related to each other.
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Which of the following lists describes characteristics of an acid? (3 points)
Bitter taste, high pH, and caustic
Sour taste, low pH, and dissolves metals
Sour taste, high pH, and dissolves metals
Slippery, low pH, and caustic
Acids have sour taste, low pH and dissolves metals.
The list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.
Characteristics of an acidAn acid is a chemical substance that has the ability to donate hydrogen ions when involved in a chemical reaction.
The following are the characteristics or features of an acid:
They have a sour taste when tasted.When measured using a pH scale it is less than 7(low pH).They react with active metals to yield hydrogen gas.Therefore, the list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.
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D
Question 2
1 pts
How many moles of carbon tetrachloride are present in
18.Og of CC14?
i think .117018
now to get to the 20charaeactrs minimum.
Calculate the individual percent recoveries of benzoic acid, naphthalene and 3-nitroaniline if you were able to collect 9.75 g of benzoic acid, 6.41 g of naphthalene, and 7.71 g of 3-nitroaniline from a set of extractions. The starting mass of the mixture was 26.24 g. (0.6 pt)
Answer:
Benzoic acid= 37.16%
Naphthalene = 24.43%
3-Nitroaniline= 29.38%
Explanation:
Data given:
percentage recovery of benzonic acid = 9.75/26.24 * 100 = 37.16%
Percentage recovery of napthalene = 6.41/26.24 * 100 = 24.43%
Percentage recovery of 3-nitroaniline = 7.71/26.24 * 100 = 29.38%
Suppose a 0.042M aqueous solution of phosphoric acid (H3PO4) is prepared. Calculate the equilibrium molarity of HPO4^−2.
Answer:
2.89x10⁻⁵M = [HPO₄²⁻]
Explanation:
The equilibrium of H3PO4 in water occurs H2PO4-:
H3PO4(aq) + H2O(l) ⇄ H3O⁺(aq) + H2PO4⁻(aq)
pKa = 2.16. And as pKa = -log Ka; Ka = 10^-2.16
Ka = 6.9183x10⁻³ = [H3O⁺] [H2PO4⁻] / [H3PO4]
As both [H3O⁺] and [H2PO4⁻] comes from the same equilibrium,
[H3O⁺]=[H2PO4⁻] :
[H3O⁺] = X
[H2PO4⁻] = X
[H3PO4] = 0.042 - X
Where X is reaction coordinate
Replacing:
6.9183x10⁻³ = [X] [X] / [0.042 - X]
6.9183x10⁻³ = X² / 0.042 - X
2.905686x10⁻⁴ - 6.9183x10⁻³X - X² = 0
Solving for X:
X = -0.02M. False solution. There is no negative concentration.
X = 0.014M. Right solution
[H2PO4⁻] = 0.014M
In the second equilibrium:
H2PO4⁻(aq) + H2O(l) ⇄ HPO4-(aq) + H3O+(aq)
Based on the same principles of the last equilibrium:
pKa2 = 7.21
Ka2 = 6.166x10⁻⁸ = [HPO4-] [H3O+] / [H2PO4⁻]
[HPO4-] = X
[H3O+] = X
[H2PO4⁻] = 0.014M - X
6.166x10⁻⁸ = X² / [0.014M - X]
8.3623x10⁻¹⁰ - 6.166x10⁻⁸X - X² = 0
Solving for X:
X = -0.0000289485. False solution.
X =
2.89x10⁻⁵M = [HPO₄²⁻]What is the formula of the compound Pentasilicon trioxide ?
Answer: the molecular formula of trioxide is ClOClO3 or Cl2O4
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If 0.250 L of a 5.90 M HNO₃ solution is diluted to 2.00 L, what is the molarity of the new solution?
Answer:
0.74 M
Explanation:
From the question given above, the following data were obtained:
Molarity of stock solution (M₁) = 5.90 M
Volume of stock solution (V₁) = 0.250 L
Volume of diluted solution (V₂) = 2 L
Molarity of diluted solution (M₂) =?
The molarity of the diluted solution can be obtained by using the dilution formula as illustrated below:
M₁V₁ = M₂V₂
5.90 × 0.250 = M₂ × 2
1.475 = M₂ × 2
Divide both side by 2
M₂ = 1.475 / 2
M₂ = 0.74 M
Thus, the molarity of the diluted solution is 0.74 M
Calculate the percent dissociation of benzoic acid C6H5CO2H in a 1.3M aqueous solution of the stuff. You may find some useful data in the ALEKS Data resource. Round your answer to 2 significant digits.
Answer:
the percent dissociation is 0.69 %
Explanation:
Given the data in the question;
benzoic acid C₆H₅CO₂H
C₆H₅COOH[tex]_{(aq)[/tex] ⇔ C₆H₅COO[tex]_{-(aq)[/tex] + H[tex]_{+(aq)[/tex]
Ka = [C₆H₅COO- ][ H+ ] / [ C₆H₅COOH ] = 6.28 × 10⁻⁵
given that it dissociated in a 1.3 M aqueous solution.
so Initial concentration is;
[ C₆H₅COOH ] = 1.3
[C₆H₅COO- ] = 0
[ H+ ] = 0
Change in concentration
[ C₆H₅COOH ] = -x
[C₆H₅COO- ] = +x
[ H+ ] = +x
Concentration equilibrium
[ C₆H₅COOH ] = 1.3 - x
[C₆H₅COO- ] = +x
[ H+ ] = +x
Hence,
x² / ( 1.3 - x ) = 6.28 × 10⁻⁵
6.28 × 10⁻⁵( 1.3 - x ) = x²
8.164 × 10⁻⁵ - 6.28 × 10⁻⁵x = x²
x² + 6.28 × 10⁻⁵x - 8.164 × 10⁻⁵ = 0
solve for x
ax² + bx - c = 0
x = [ -b ± √( b² - 4ac ) ] / [ 2a ]
we substitute
x = [ -6.28 × 10⁻⁵ ± √( (6.28 × 10⁻⁵)² - (4 × 1 × -8.164 × 10⁻⁵ ) ) ] / [ 2 × 1 ]
x = [ -6.28 × 10⁻⁵ ± 0.01807 ] / [ 2]
x = [ -6.28 × 10⁻⁵ - 0.01807 ] / [ 2] or [ -6.28 × 10⁻⁵ + 0.01807 ] / [ 2]
x = -0.0090664 or 0.0090036
so x = 0.0090036
hence
[ H+ ] = +x = 0.0090036 M
[C₆H₅COO- ] = +x = 0.0090036 M
Initial concentration of [ C₆H₅COOH ] = 1.3 M
concentration of C₆H₅COOH dissociated = 0.0090036 M
percent dissociation of C₆H₅COOH will be;
⇒ ( 0.0090036 M / 1.3 M ) × 100 = 0.69 %
Therefore, the percent dissociation is 0.69 %
9. Which property is not important when selecting a material to use as a light bulb filament?
d
high melting point
high vapor pressure
high ductility
Answer:
high melting point
Explanation:
The filament of a bulb is often heated to very high temperatures as the bulb is in operation.
Many times, electric bulbs may have to be on for a whole day and they may reach temperatures that are outrageously high in the process.
The material of the filament must have a very high melting point so that it doesn't melt while the bulb is still in operation.
Answer:
Actually the answer is High Vapor pressure
Explanation:
