Answer:
you don't know the answer?ha me too
please help! what is the correct answer to this picture
Answer:
i think its c [everything is so blury]
Explanation:
(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.
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 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
Chromosomes contain the genetic material found in cells. true or false?
1. true
2. false
Answer:
1) True
Explanation:
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
Which event is an example of melting?
A. Wax drips down the side of a lit candle.
B. Perspiration dries on a person's skin.
C. Rain turns to ice pellets.
D. A mirror fogs up when someone takes a hot shower.
I’m just curious tbh
Answer:
A. Wax drips down the side of a lot candle.
Explanation:
The chemical change from solid to liquid. This is a combustion reaction, so carbon dioxide gas and water vapour is also produced but you can't see them
Answer:
A. Wax drips down the side of a lot candle.
Explanation:
What are the two types of addition compounds
Answer:
electrophilic addition and
nucleophilic addition.
Answer:
the two types of addition compoundsare:
1.electrophilic addition
2. nucleophilic addition.
Calculate the mass of water produced when 9.57 g of butane reacts with excess oxygen.
Express your answer to three significant figures and include the appropriate units.
Answer:
14.9 g
Explanation:
Step 1: Write the balanced equation
C₄H₁₀ + 6.5 O₂ ⇒ 4 CO₂ + 5 H₂O
Step 2: Calculate the moles corresponding to 9.57 g of C₄H₁₀
The molar mass of C₄H₁₀ is 58.12 g/mol.
9.57 g × 1 mol/58.12 g = 0.165 mol
Step 3: Calculate the moles of H₂O produced from 0.165 moles of C₄H₁₀
0.165 mol C₄H₁₀ × 5 mol H₂O/1 mol C₄H₁₀ = 0.825 mol H₂O
Step 4: Calculate the mass corresponding to 0.825 mol of H₂O
The molar mass of H₂O is 18.02 g/mol.
0.825 mol × 18.02 g/mol = 14.9 g
Which of the following colors has the highest energy? O A. Red O B. Green O C. Blue O D. Yellow
Answer:
C. BlueExplanation:
This is because, Blue color highest frequency of energy after Violet and Indigo.
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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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
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.
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:
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.
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.
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
How many milliliters of a 6.00 M NaCl solution are needed to make 250.0 milliliters of a 0.500 M NaCl solution?
Answer:
20,8ml NaCl 6M
Explanation:
C1V1 = C2V2
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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.What shape does each galaxy have?
Answer:
as in shapes
Explanation:
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
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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What is the quantity of
heat required to raise the
temperature of 500 g of
iron by 2°C?
The specific heat capacity
of iron is 500 J/(kg °C)
Answer:
The quantity of heat required to raise the temperature of 500 g of iron by 2°C is 500 J.
Explanation:
Calorimetry is responsible for measuring the amount of heat generated or lost in certain physical or chemical processes.
The sensible heat of a body is the amount of heat received or transferred by a body when undergoing a temperature variation (Δt) without there being a change in physical state (solid, liquid or gaseous).
Its mathematical expression is the fundamental equation of calorimetry. This is:
Q = c * m * ΔT
where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.
In this case:
Q= ?c= 500 [tex]\frac{J}{kg*C}[/tex]m= 500 g= 0.500 kgΔT= 2 CReplacing:
Q= 500 [tex]\frac{J}{kg*C}[/tex] *0.500 kg*2 C
Solving:
Q= 500 J
The quantity of heat required to raise the temperature of 500 g of iron by 2°C is 500 J.
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.
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
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
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