Answer:
See explanation
Explanation:
TLC is a chromatographic method in which the solute is spotted on a plate and the plate is placed in an air tight chamber containing a solvent. The solvent is maintained below the level of the spot. The capillary movement of the solvent through the plate achieves the required separation.
If two spots have Rf values of 0.25 and 0.26 respectively and then the plate was removed from the developing chamber, subsequently, the residual solvent was allowed to evaporate from the plate, and then the plate was returned to the developing chamber.
It will be observed after the second development is complete that the new Rf values will be 0.50 and 0.52 respectively. It will just be as though the second chromatogram picked up from where the first chromatogram stopped.
Steel is an alloy consisting of Fe with a small amount of C. Elemental Cr can be added to steel to make the steel less likely to rust
a. True
b. False
To make the steel less likely to rust, element like chromium is added to it. Therefore, the given statement is correct.
What is steel?Steel can be described as an alloy composed of iron with a few tenths of a percent of carbon to enhance its strength and fracture resistance. In steel, alloying elements inclusions within the iron act as hardening agents as they stop the movement of dislocations.
Stainless steels are corrosion- and oxidation-resistant but they need an additional 11% chromium. This type of steel is used in buildings, infrastructure, ships, trains, machines, electrical appliances, weapons, and rockets because of its high tensile strength and low cost.
It can take two crystalline forms body-centered cubic and face-centered cubic depending on the temperature. The interaction of the allotropes of iron with elements such as carbon gives the steel its range of unique properties.
Therefore, the given statement is true that chromium is used in steel formation.
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HELLP I NEEED HELP NOWW NO GUESSING FRFR
What will happen when a piece of magnesium metal is dropped into a beaker
containing a 1 M solution of copper(II) chloride?
Mg2+ + 2e → Mg(s) ° =- 2.37 V
Cu2+ + 2e → Cu(s) £° = + 0.34 V
(A) Calculate the wavelength (in nm) of light with energy 1.89 × 10–20 J per photon, (b) For light of wavelength 410 nm, calculate the number of photons per joule, (c) Determine the binding energy (in eV) of a metal if the kinetic energy possessed by an ejected electron [using one of the photons in part (b)] is 2.93 × 10–19 J.
Answer:
For A: The wavelength of the light is [tex]1.052\times 10^4nm[/tex]
For B: The number of photons per joule is [tex]2.063\times 10^{18}[/tex]
For C: The binding energy of a metal is 1.197 eV.
Explanation:
The equation used to calculate the energy of a photon follows:
[tex]E=\frac{hc}{\lambda}[/tex] ......(1)
where,
E = energy of a photon
h = Planck's constant = [tex]6.626\times 10^{-34}J.s[/tex]
c = speed of light = [tex]3\times 10^{8}m/s[/tex]
[tex]\lambda[/tex] = wavelength
For A:Given values:
E = [tex]1.89\times 10^{-20}J[/tex]
Putting values in equation 1, we get:
[tex]\lambda=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{1.89\times 10^{-20}J}\\\\\lambda=1.052\times 10^{-5}m[/tex]
Converting the wavelength into nanometers, the conversion factor used is:
[tex]1m=10^9nm[/tex]
So, [tex]\lambda=1.052\times 10^{-5}m\times \frac{10^9nm}{1m}=1.052\times 10^4nm[/tex]
Hence, the wavelength of the light is [tex]1.052\times 10^4nm[/tex]
For B:Given values:
[tex]\lambda=410nm=410\times 10^{-9}m[/tex]
Putting values in equation 1, we get:
[tex]E=\frac{(6.626\times 10^{-34}J.s)\times (3\times 10^8m/s)}{410\times 10^{-9}m}\\\\E=4.848\times 10^{-19}J[/tex]
To calculate the number of photons, we use the equation:
[tex]\text{Number of photons}=\frac{\text{Total energy}}{\text{Energy of a photon}}[/tex]
Total energy = 1 J
Energy of a photon = [tex]4.848\times 10^{-19}J[/tex]
Putting values in the above equation:
[tex]\text{Number of photons}=\frac{1J}{4.848\times 10^{-19}J}\\\\\text{Number of photons}=2.063\times 10^{18}[/tex]
Hence, the number of photons per joule is [tex]2.063\times 10^{18}[/tex]
For C:To calculate the binding energy of a metal, we use the equation:
[tex]E=K+B[/tex] .....(2)
E = Total energy
K = Kinetic energy of a photon
B = Binding energy of metal
Converting the energy from joules to eV, the conversion factor used is:
[tex]1eV=1.602\times 10^{-19}J[/tex]
Using the above conversion factor:
[tex]K=2.93\times 10^{-19}J=1.829eV\\\\E=4.848\times 10^{-19}J=3.026eV[/tex]
Putting values in equation 2:
[tex]B=(3.026-1.829)eV=1.197eV[/tex]
Hence, the binding energy of a metal is 1.197 eV.
Write a balanced equation for the complete combustion of 2,3,3-trimethylpentane. Use the molecular formula for the alkane (C before H) and the smallest possible integer coefficients.
Answer:
C8H18 + 25/2O2 ----> 8CO2 + 9H2O
Explanation:
2,3,3-trimethylpentane has the molecular formula C8H18.
The general formula for the combustion of an alkane is;
CnH2n+2 + 3n+1/2O2 ----->nCO2 + (n+1)H2O
In writing a balanced chemical reaction equation, the number of atoms of each element on the left hand side of the reaction equation must be the same as the number of atoms of the same element on the right hand side of the reaction equation.
For C8H18, the balanced chemical reaction equation for combustion is;
C8H18 + 25/2O2 ----> 8CO2 + 9H2O
Help me please , I got 0.003 for a I need help with b and c
Answer:
(a) The moles of CuSO₄ is 3.125 × 10⁻³ moles.
(b) The moles of Cu is 3.125 × 10⁻³ moles.
(c) The mass of Cu is 0.2 g.
Explanation:
Given:
Mass of CuSO₄ = 0.5 g
Molar mass of CuSO₄ = 160 g/mol
The given balanced chemical equation is:
[tex]2Al+3CuSO_4\rightarrow 3Cu+Al_2(SO_4)_3[/tex]
Part (a):
Calculating the moles of CuSO₄.
[tex]\text{Moles of } CuSO_4=\frac{\text{Mass of }CuSO_4}{\text{Molar mass of }CuSO_4}\\\\\text{Moles of } CuSO_4=\frac{0.5g}{160g/mol}\\\\\text{Moles of } CuSO_4=3.125\times 10^{-3}mol[/tex]
Thus, the moles of CuSO₄ is 3.125 × 10⁻³ moles.
Part (b):
Calculating the moles of Cu.
From the balanced chemical equation, we conclude that:
As, 3 moles of CuSO₄ reacts to give 3 moles of Cu
So, 3.125 × 10⁻³ moles of CuSO₄ reacts to give 3.125 × 10⁻³ moles of Cu
Thus, the moles of Cu is 3.125 × 10⁻³ moles.
Part (c):
Calculating the mass of Cu.
Mass of Cu = Moles of Cu × Molar mass of Cu
Molar mass of Cu = 64 g/mol
Mass of Cu = (3.125 × 10⁻³ mole) × (64 g/mol)
Mass of Cu = 0.2 g
Thus, the mass of Cu is 0.2 g.
2.The rate constant of a first order reaction is 66 s-1. What is the rate constant in units of minutes
Answer:
66s^-1 will be 1/66
then to convert to minute you multiply by 69
1/66 x 60 = 3960 mins
The bond order denotes:_____.1. the order of filling of bonding vs. antibonding orbitals. 2. the pattern in which Lewis dot structures of atoms combine to form bonds. 3. the order that orbitals are filled in electron configurations. 4. an estimate of the polarity or dipole moment of a bond. 5. an estimate of the strength of a bond.
Answer:
an estimate of the strength of a bond.
Explanation:
The bond order is given as;
1/2(number of bonding electrons - number of anti bonding electrons)
The bond order tells us about the strength of bond. As the bond order increases, so does the strength of the bond because atoms involved in bonding come closer to each other as the bond length decreases.
Hence, bond order is an index of bond strength. Triple bonds are stronger than double bonds which are stronger than single bonds.
The reaction below was carried out in an acidic solution l-+10-3--->l2 Which statement is true about this equation? Although it is unbalanced, it can be balanced by using the half-reaction method It has been balanced by using the half-reaction method. It has been balanced by directly using spectator ions. O Although it is unbalanced, it can be balanced by directly using spectator ions.
Answer:
answer is b. : It has been balanced by using the half-reaction method.
Explanation:
edge 2021
Answer:b
Explanation:cuz it is
A sample of drinking water was tested for Pb2 and was found to have a Pb2 concentration of 17.50 ppb. A 9.00 mL sample of the drinking water was spiked with 1.00 mL of a 2.29 ppb Pb2 standard. Analysis of the spiked sample gave a concentration of 15.93 ppb Pb2 . Find the percent recovery of the spike.
Answer:
[tex]X=75\%[/tex]
Explanation:
From the question we are told that:
Concentration [tex]C_1=17.50ppb[/tex]
Volume [tex]v=9mL[/tex]
Spike Volume [tex]V_s=1.00mL[/tex]
spike Conc [tex]C_2=2.29 ppb[/tex]
Analysis Conc [tex]C_s=15.93 ppb[/tex]
Generally the equation for percent recovery is mathematically given by
[tex]X=\frac{C_s'-C_1'}{C_2'}[/tex]
Where
Concentration of spiked sample C_s'
[tex]C_s'=C_s*(v+v_s)[/tex]
[tex]C_s'=15.92*(9+1)[/tex]
[tex]C_2=159.2[/tex]
Concentration of unspiked sample C_1'
[tex]C_1'=17.50*9mL[/tex]
[tex]C_1'=157.5[/tex]
Concentration of spike sample C_2'
[tex]C_2=2.29*1[/tex]
[tex]C_2=2.29[/tex]
Therefore
[tex]X=\frac{159.2-157.5}{2.29}[/tex]
[tex]X=75\%[/tex]
The carbon-carbon bonds in benzene are:
O a) Easily broken in chemical reactions
b) A hybrid between double bonds and single bonds
c)
Identical to the carbon-carbon bonds in cyclohexene
d) Identical to the carbon-carbon bonds in cyclohexane
please hurry
Answer:
a
Explanation:
Easily broken in chemical reactions
The combustion of ethylene proceeds by the reaction
C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (g)
When the rate of disappearance of C2H4 is 0.13 M s-1, the rate of appearance of CO2 is ________ M s-1.
What is the source of coal?
A. Compressed ancient plants
B. Crystallized magma
O C. Compressed ancient sea life
D. Modern forests
Coal and Energy obtained from coal are formed as a result of decomposed life matter such as plants
A. Compressed ancient plants
Fossil FuelsIt should be noted that coal is also a type of fossil fuel formed by prolong compaction of fossil material e.g dead plants over millions of years, forest lives etc. and as a result of high pressure and heat acting on these fossil matter they are transformed to fuel.
In summary, fossil fuels are formed as a result of age long compressed matter.
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An OH group attached to a hydrocarbon is called a _________ group whereas ______________ is a polyatomic ion with a charge of _______.
An OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.
What is OH group?OH group is also called hydroxyl group. Alcohol is a type of organic compound that is characterized by one or more hydroxyl (―OH) groups attached to a carbon atom of an hydrocarbon chain so we can conclude that an OH group attached to a hydrocarbon is called an alkyl group whereas hydroxide is a polyatomic ion with a charge of -1.
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Calculate the number of molecules of carbon (IV) oxide
produced when 10g of CaCO3 is treated with 100cm of
0.2mol dm HCl. The equation of the reaction is
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(1) + CO2(g)
ICa=40 (=12 O=161
Answer: The mass of [tex]CO_2[/tex] produced is 0.44 g
Explanation:
For calcium carbonate:The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of calcium carbonate = 10 g
Molar mass of calcium carbonate = 100 g/mol
Plugging values in equation 1:
[tex]\text{Moles of calcium carbonate}=\frac{10g}{100g/mol}=0.1 mol[/tex]
For HCl:The formula used to calculate molarity:
[tex]\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (mL)}}[/tex] .....(2)
Molarity of HCl = [tex]0.2mol/dm^3=0.2mol/L[/tex] (Conversion factor: [tex]1L=1dm^3[/tex]
Volume of solution = [tex]100cm^3=100mL[/tex] (Conversion factor: [tex]1mL=1cm^3[/tex]
Putting values in equation 2, we get:
[tex]0.2=\frac{\text{Moles of HCl}\times 1000}{100}\\\\\text{Moles of HCl}=\frac{0.2\times 100}{1000}=0.02mol[/tex]
For the given chemical reaction:
[tex]CaCO_3(s)+2HCl(aq)\rightarrow CaCl_2(aq)+H_2O(l)+CO_2(g)[/tex]
By stoichiometry of the reaction:
If 2 moles of HCl reacts with 1 mole of calcium carbonate
So, 0.02 moles of HCl will react with = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of calcium carbonate
As the given amount of calcium carbonate is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Thus, HCl is considered a limiting reagent because it limits the formation of the product.
By the stoichiometry of the reaction:
If 2 moles of [tex]HCl[/tex] produces 1 mole of [tex]CO_2[/tex]
So, 0.02 moles of [tex]HCl[/tex] will produce = [tex]\frac{1}{2}\times 0.02=0.01mol[/tex] of [tex]CO_2[/tex]
We know, molar mass of [tex]CO_2[/tex] = 44 g/mol
Putting values in equation 1, we get:
[tex]\text{Mass of }CO_2=(0.01mol\times 44g/mol)=0.44g[/tex]
Hence, the mass of [tex]CO_2[/tex] produced is 0.44 g
please help! what is the correct answer to this picture
Answer:
i think its c [everything is so blury]
Explanation:
3 what is the hybridization of each
of the Carbon atoms in the compound
а) +
CH₃ CH = CH CH₂=CH
HC=CH
Answer:
what is the hybridization of each of the carbon atoms in the compounds
а) CH₃ CH = CH2
b) CH₂=CH2
c) Acetylene. (CH triple bond CH).
Explanation:
The hybridization of carbon atom in the organic compounds can be determined by counting the number of surrounding atoms that are in bond with it.
If carbon is directly bonded with two atoms, then it has sp hybridization.
If carbon is directly bonded with three atoms, then it has [tex]sp^2[/tex] hybridization.
If carbon is directly bonded with four atoms, then it has [tex]sp^3[/tex] hybridization.
For the given molecules, the hybridization of each carbon atom is shown below:
PLZ HELP!!!! NO LINKS
Answer:
the answer would be 6.720
Simply subtract the combined mass by the mass of the beaker.
The answer has 3 decimal places because the least amount of decimal places in the equation is 3.
An atom that ______ electrons is called a positive ion. A. has 0 B. has 8 C. loses D. gains
Answer:
Gains
Explanation:
It gets more electrons
Chromosomes contain the genetic material found in cells. true or false?
1. true
2. false
Answer:
1) True
Explanation:
Suppose an element has two naturally occurring isotopes
42
X
20
44
X
20
with atomic masses 42.00 amu and 45.00 amu, respectively. Determine the percent abundance of the
45
X
20
isotope given an average atomic mass of 43.22 amu.
Answer:
Chlorine
Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.
Explanation:
hope it helps thanks❤
Chlorine has two naturally occurring isotopes. In a sample of chlorine, 75.77% of the atoms are Cl-35, with a mass of 34.97amu.
How do you calculate the atomic mass in percentage by isotopes?
List the known and unknown values and edit the problem. Convert each percentage value into a decimal by dividing it by 100. Multiply this number by the atomic mass of that spot. Mix together each isotope to find the median atomic mass.
How do you get the maximum amount of two isotopes?To calculate the maximum percentage of each isotope in a sample of something, chemists usually divide the atomic number of a particular isotope by the total number of atoms of all that isotope and multiply the result by 100.
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Classify each amino acid by the chemical properties of its side chain (R group) at pH 7 . Select the amino acid that fits best in each category. Each amino acid will be selected only once. Which amino acid has a positively charged R group
Answer: The amino acid that has a positively charged R group are LYSINE and ARGININE.
Explanation:
AMINO ACIDS are the basic structural units of proteins. Each amino acid contains an amino group ( -NH2) and a carboxyl group (-COOH) in its molecule. The carbon atom of amino acid to which the functional groups are attached is know as the alpha-carbon. In neutral solution, amino acids are mainly in the form of dipolar ions. Amino acids can be prepared through hydrolysis of protein by boiling with dilute hydrochloric acid.
Amino acids can be classified according to the chemical properties of its side chain (R group) at pH 7, these include:
--> Amino acids with POSITIVELY CHARGED R group
--> Amino acids with negatively charged R group
--> Amino acids with neutral polar R group
--> Amino acids with nonpolar aliphatic R group.
Amino acids with POSITIVELY CHARGED R group are those amino acids that has side chains which contain nitrogen and resemble ammonia, which is a base. Their pKa's are high enough that they tend to bind protons, gaining a positive charge in the process. Example include LYSINE and ARGININE.
Regions of compressed air caused by the sound of an explosion correspond to the ___?_____ of the sound waves
Explanation:
Compressions and Rarefactions
A vibrating tuning fork is capable of creating such a longitudinal wave. As the tines of the fork vibrate back and forth, they push on neighboring air particles. The forward motion of a tine pushes air molecules horizontally to the right and the backward retraction of the tine creates a low-pressure area allowing the air particles to move back to the left.

Because of the longitudinal motion of the air particles, there are regions in the air where the air particles are compressed together and other regions where the air particles are spread apart
Regions of compressed air caused by the sound of an explosion correspond to the compressions and rarefactions of the sound waves.
What is a sound wave?A sound wave is any distortion in the movement of energy transported by a suitable environment (e.g., air).
Sound waves can be transmitted by different environments such as air (atmosphere) and aquatic media.In humans, sound waves are captured by the ear and then processed by the nervous system.In conclusion, regions of compressed air caused by the sound of an explosion correspond to the compressions and rarefactions of the sound waves.
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Identify the item that does not have kinetic energy.
A. A worm crawling
B. A falling leaf
C. An airplane flying
D. A butterfly sitting on a twig
Answer:
D
Explanation:
there is no other answer choice that does not move. This is a fool-proof question because all the other answer choices contain movement except the butterfly resting
please answer all if you can!
Answer:1.b 2.A (i think it might be c) 3 (i have no clue) 4.(no clue) Sorry i only got 1 and 2 witch i think are right its been a while sense i have done this....
Explanation:
Liquid nitrogen becomes a gas when it is poured out of its container. The nitrogen is
Answer:
aasjajiakjka
Explanation:
A student named a particular compound 2-ethyl-3-methyl-2-butene. Assuming that the student's choice actually corresponded to the correct distribution of the double bond and the substituents, what is the correct IUPAC name for this compound
Answer:
2-ethyl-3-methylbut-2-ene
Explanation:
The whole idea of IUPAC nomenclature is to devise a universally accepted system of writing the name of a compound from its structure.
According to IUPAC nomenclature, the root of the compound is the longest carbon chain. The substituents are named in alphabetical order and in such a way as to give each one the lowest number. The position of the functional group is indicated accordingly.
For the compound in question, its correct IUPAC name is 2-ethyl-3-methylbut-2-ene.
The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.
a. True
b. False
Answer:
The product of an organic reaction is analyzed by column chromatography using silica as the stationary phase and toluene as the mobile phase.
Explanation:
The given statement is true.
In chromatography silica gel is used as the predominant stationary phase.
Since silica gel is a good adsorbent.
It is a polar adsorbent.
In order to remove polar components, silica gel is used as the stationary phase.
Answer is a.true.
65. Which of the following heavy metal is not
toxic?
(1 Point)
Hg
Pb
O As
O Ni
If you keep adding sugar to water and there comes a point that you cannot dissolve any more sugar into it then this is called?
A) solvent solution
B) solute solution
C) saturated solution
D) Dilute solution
Answer:
the answer is letter D, Dilute solution
Dugongs are animals that live in the ocean and eat underwater grasses. The sun is shining on the shallow ocean water where the grasses and dugongs live.
What is happening to the carbon in the water around the grasses and the dugongs? Is carbon moving into the water, moving out of the water, or both?
Answer:
please mark as brainliest
Explanation:
The sun is shining on the shallow ocean water where the grasses and dugongs live. What is happening to the carbon in the water around the grasses and the dugongs? Is carbon moving into the water, moving out of the water, or both? Carbon is not moving into the water; it is only moving out of the water.