Electrons are emitted from the surface of a metal in photoelectric effect.
What is the photoelectric effect?The photoelectric effect is the emission of electron from the surface of a metal when light is shone on the surface..
For electrons to be emitted, the light must have a certain frequency known as threshhold frequency.
Therefore, electrons are emitted from the surface of a metal in photoelectric effect.
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~ What is meant by chlorination? How does it purify the water?
[tex] \\ \\ [/tex]
~ Define vitamins. What are the types of vitamins? Explain them.
;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-; ;-;
How many moles of Ar gas are
present in a container with a
volume of 78.4 L at STP?
1 mole of a gas at STP occupies 22.4 L volume
Now the volume is given =78.4 therefore,
No. of moles of gas = 78.4 ÷ 22.4 = 3.5 moles
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In terms of sturcture and bonding,explain why water Is a liquid at room temperature while hdrogen sulphide is a gas
Water is a liquid while hydrogen sulphide is a gas because the hydrogen bonding in water causes the water molecules to be associated with each other due to intermolecular forces of attraction.
how does the shape of a molecule affect its smell?
Answer:
it affects the speed of movement.Because the bigger the molecules the more time they will take to diffuse or smellWhat is the correct electron configuration of phosphorus (P)?
O A. 1s22s²2p³3s²3p³
B. 1s²2s²2p 3s²3p³
O C. 1s²2s²2p62d5
OD. 1s²2s22p63s¹3p4
Answer:
A
Explanation:
Phosphorus has an electron configuration of 1s2 2s2 2p6 3s2 3p3. Another way to write that is [Ne] 3s2 3p3. The [Ne] represents the fact that the beginning of phosphorus' electron configuration is the same as Neon's. so if you add all the superscripts they will give you 15. we didn't use choice d because we have to make the last p halffilled(3, half of the total electron held in p shell ) when we make "s shell 1 " not make it 4 because we are transfering that 1 electron .but nevertheless the correct answer is A.
What is the correct ratio of the atoms of the two elements present in a sample of the compound copper chloride, CuCl2?
Each answer will be formatted as Copper : Chlorine .
Select one:
a. 0:0
b. 2:1
c. 1:2
d. 1:1
The correct ratio of the atoms of the two elements in the sample of copper chloride compound would be 1:2.
Atoms of elementsCopper chloride has a chemical formula, [tex]CuCl_2[/tex].
Thus, an atom of copper, Cu, combines with 2 atoms of chlorine, Cl.
The 2 chlorine atoms are recipients of an electron each from the copper atom which happens to have 2 electrons in its outermost valence shell.
Therefore, the ratio of copper to chlorine atoms in the compound is 1:2.
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How many moles of oxygen are produced by decomposing 28.5 g of dihydrogen dioxide
(molar mass = 34.0 g/mol) according to the equation: 2H2O2(l) —> 2H2O(l) + O2(g)
Answer:
0.419 mol O₂
Explanation:
just took test
The constituents of leaf pigment can be separated by:
Answer:
Paper Chromatography
Explanation:
Most leaves are green due to chlorophyll pigments of different types like chlorophyll A, chlorophyll B, etc. All these pigments will be seperated according to their molecular composition. So, the correct option is 'Paper Chromatography'.
Which of the following is true about nuclear power?
A It is the cheapest source of energy.
B It produces harmful radiation.
C It pollutes the atmosphere.
D It uses fossil fuels.
Please help me :')
Answer:
I thinks is B
Explanation:
they just look harmful
I also researched and it says its harmful and causes sickness and death
4. Calculate the empirical formula for the following compounds Na=32.4% S=22.6 % O=45.0%
Answer:
Na2 S O4
Explanation:
Na mole wt 22.989
32.4 / 22.989 = 1.4093
S mole wt = 32.06
22.6/32.06 = .7049
O mole wt = 15.999
45 / 15.999 = 2.8127 Now divide all of the results by the smallest
Na 1.4093 / .7049 = 2
S .7049/.7049 = 1
O 2.8127 /.7049 = 4 so Na2 S O4
S + 6 HNO3 --> H2SO4 + 6 NO2 + 2 H2O
In the above equation how many moles of water can be made when 190.7 grams of HNO3 are consumed?
Answer:
18.17 g
Explanation:
From the coefficients of the equation, we know that.for every 6 moles of nitric acid consumed, 2 moles of water are produced.
Nitric acid has a formula mass of 63.012 g/mol, so 190.7 g is about 190.7/63.012 = 3.0264 mol.
Thus, we need 3.0264(2/6) = 1.0088 mol of water.
Water has a formula mass of 18.015 g/mol, so the answer is (18.015)(1.0088), which is 18.17 g to 4 sf.
The combustion of glucose, c6 h12 o6 (s), produces carbon dioxide, co2 (g), and water, h2 o(g), according to the equation below. upper c subscript 6 upper h subscript 12 upper o subscript 6 (s) plus 6 upper o subscript 2 (g) right arrow 6 upper c upper o subscript 2 (g) plus 6 upper h subscript 2 upper o (l). the enthalpy of the reaction is –2,840 kj. what is the heat of combustion, per mole, of glucose?
The heat of combustion per mol of the glucose is 2840 kJ.
A reaction that involves the burning of a compound in the presence of air or oxygen is called combustion. In the absence of oxygen combustion of a compound cannot take place.
It is given that the combustion of glucose produces carbon dioxide and water. The balanced chemical reaction for the given process is expressed as:
C6H12O6 (s) + 6O2 (g) ------> 6CO2 (g) + 6H2O (l)
The energy released from this reaction is -2840 kJ. The above equation clearly shows that 1 mol of glucose is used during the reaction and the energy produced is -2840 kJ.
Therefore, the heat of combustion per mol of the glucose is 2840 kJ.
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Assume that you are provided with a 20-cm Hempel column having HETP of 10 cm to distill a mixture of 90 mol% toluene and the rest is benzene. What would be the composition of the first distillate you obtained
Column height is 20cm, and HETP is 10cm.
So this column will behave as 20/10=2 ideal trays.
Hence the distillate composition will be 45%benzene.
Chem 233 Islam AboalnadieSeparation of Liquids by Fractional Distillation and Analysis by Gas ChromatographyBackground and Methods: The purpose of this lab was to use the techniques of fractional distillation to separate a 1:1 mixture of Ethyl acetate and Butyl acetate then use gas chromatography to analyze the amount of each compound in each of three fractions obtained through the distillation. Fractional distillation will then be compared to simple distillation.
The first fraction was taken when the distillation apparatus was near the boiling point of Ethyl acetate (77.1ºC) (1). The second was taken when the distillation apparatus was in the process of increasing temperature from the boiling point of Ethyl acetate to the boiling point of Butyl acetate (126.1ºC) (1). The third and final fraction was taken around the boiling point of Butyl acetate until the distillation process was complete.
Please check the attached diagram for a more detailed answer.
10%benzene solution be separated as 2 timelines in txy diagram.
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Using the equation
C12H22O11+12O2-->12CO2+11H2O
if 156 L of O2 at STP are consumed how many moles of sucrose are required?
Answer:
0.5804 moles sucrose are required to react with 156 liters of oxygen.
Explanation:
Since the conditions of the gas are STP, standard temperature and pressure, we can use a very useful conversion factor that is valid for all gases at STP: All gases occupy 22.4 liters per mole of gas:
22.4 L/mole
156 liters of O2 at STP may be converted to moles O2 by dividing by the conversion factor:
(156 L)/(22.4 L/mole) = 6.96 moles O2
The balanced equation tells us that 12 moles of O2 are consumed for every 1 mole of sucrose. That's a molar ratio of (1 mole sucrose/12 moles O2).
We can use this ratio to determine the moles of sucrose required to react with 6.96 moles of O2:
(6.96 moles O2)*((1 mole sucrose/12 moles O2) = 0.5804 moles sucrose
Calculate the mass of water, in g, that can be evaporated at 100°C by the addition of 3500 kJ
Answer:
1548.67g
Explanation:
q=mL
since specific latent heat of vaporisation of water (L) = 2.260 kJ/g,
3500kJ = m(2.26)
m = 1548.67g
what is the force that holds atoms together
Explanation:
Chemical bond refers to the forces holding atoms together to form molecules and solids. This force is of an electric nature, and the attraction between electrons of one atom to the nucleus of another atom contributes to what is known as chemical bonds.
what made alchemy unscientific in its practice?
Answer:
Because it was not based on evidence and experiment.
Why isn't alchemy considered a science?
Alchemy isn’t rigorous enough.
People began to realize that it was possible to transform one material into another in antiquity. The study of how to achieve this was known as alchemy. Alchemists would experiment on various substances, trying to turn lead into gold or to create the elixir of life.
They were unaware of what was taking place in the background, though. They weren't as rigorous as contemporary science. seldom ever exchanged their discoveries. And technically speaking, they carried out their experiments before the formalization of the scientific process.
In a way that made perfect sense to the alchemists but makes no sense at all to us, alchemy blurs the lines between empirical observation and experimentation, irrational conjecture, and mysticism. The last two render it unscientific.
Alchemy became known as chemistry once the scientific approach was established and mysticism was eliminated. Because alchemy particularly refers to the earlier, less scientific kind of chemistry, we no longer view it as a science.
A sample of oxygen gas (O2) has a volume of 7.51 L at a temperature of 19°C and a pressure of 1.38 atm. Calculate the moles of O2 molecules present in this gas sample.
Answer: 0.43molO₂
Explanation:
The ideal gas law for moles is [tex]n=\frac{PV}{RT}[/tex]. If you did not know, R is the ideal gas constant, [tex]0.0821\frac{L*atm}{mol*K}[/tex].
Since the temperature must be in Kelvin, we must convert our given temperature from ℃ to K. [tex]19C+273=292K[/tex]
Now that we have the temperature converted to Kelvin, we can plug in our information to the ideal gas law for the number of moles.
[tex]n=\frac{PV}{RT}[/tex]
[tex]n=\frac{1.38atm*7.51L}{0.0821\frac{L*atm}{mol*K} *292K} =0.43molO_{2}[/tex]
[tex]n=0.43molO_{2}[/tex]
Therefore, the number of moles is 0.43molO₂.
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In balancing an equation, we change the __________ to make the number of atoms on each side of the equation balance.
Calculate the amount of sucrose required to prepare 250g of 5%
solution of glucose by mass? Also determine the mass of solvent
used to prepare this solution.
The amount of sucrose required will be 12.5 grams and the mass of water required will be 250 g.
Stoichiometric problem5% by mass glucose solution is to be prepared. This means that 5g of glucose will be dissolved in 100 mL of water.
250g of such a solution will require 250 mL of water.
5% of 250g = 5/100 x 250 = 12.5 grams
Thus, the solution is prepared by dissolving 12.5 grams of sucrose in 250 grams (250 mL) of water.
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A sample of metal has a mass of 16.5916.59 g, and a volume of 5.815.81 mL. What is the density of this metal
Answer:
=> 2.8554 g/mL
Explanation:
To determine the formula to use in solving such a problem, you have to consider what you have been given.
We have;
mass (m) = 16.59 g
Volume (v) = 5.81 mL
From our question, we are to determine the density (rho) of the rock.
The formula:
[tex]p = \frac{m}{v}[/tex]
Substitute the values into the formula:
[tex]p = \frac{16.59 g}{5.81 mL} \\ = 2.8554 g/mL[/tex]
= 2.8554 g/mL
Therefore, the density (rho) of the rock is 2.8554 g/mL.
In general, when the addition of an unsymmetrical electrophilic reagent to an unsymmetrical alkene forms the product predicted by Markovnikov's rule, that occurs because: A) the product is statistically favored. B) steric hindrance favors its formation. C) it is formed via the more/most stable carbocation. D) it is the more/most stable product. E) All of these choices are reasons.
It is formed via the more/most stable carbocation.
What justification exists for Markovnikov's Rule?
A carbocation is created as a result of the protonation of the alkene by the protic acid. The carbocation that has the most alkyl substituents on its carbon holds the positive charge, making it the most stable carbocation. As a result, the addition of the halide to the carbon that has fewer hydrogen substituents makes up the majority of the product.
Markovnikov's rule
According to the Markovnikov rule, a proton is added to the carbon atom with the greatest number of hydrogen atoms connected in addition to processes involving alkenes or alkynes.
Anti-Markovnikov Rule
According to the Anti-Markovnikov Rule, in addition to reactions between alkenes or alkynes, The carbon atom with the fewest hydrogen atoms linked to it receives the proton.
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pls help mee with this question i will mark you as the brainliest
Answer:
1 2 1 2
2 1 1 2
2 1 3
2 3 3 1 3
Explanation:
Gina predicts that one really large cube of sugar will dissolve faster than the same
amount of sugar in several medium-sized cubes. She thinks that because there is only
one larger cube, it has more surface area and will dissolve faster than the several
medium-sized cubes. What is the best assessment of Gina's prediction?
The best assessment of Gina's prediction is that the several medium-sized cubes will dissolve faster than the large cube of sugar.
How does surface area affect solubility?The surface area of a substance refers to the total area on the surface of that object.
Surface area plays a vital role in the dissolution of a substance. When a solute dissolves, the action takes place only at the surface of each particle.
This suggests that when the total surface area of the solute particles is increased, the solute dissolves more rapidly, hence, the best assessment of Gina's prediction is that the several medium-sized cubes will dissolve faster.
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The hormone epinephrine is released in the human body during stress and increases the body's metabolic rate. Epinephrine, like many biochemical compounds, is composed of carbon, hydrogen, oxygen, and nitrogen. The percentage composition of the hormone is 59.0% C, 7.15% H, 26.2% O, and 7.65% N. Determine the empirical formula.
Answer:
C9 H13 N O3
Explanation:
Carbon mole wt = 12
59 /12 = 4.917
Hydrogen mole wt = 1
7.15 / 1 = 7.15
Oxygen mole wt = 16
26.2 / 16 = 1.6375
Nitrogen mole wt = 14
7.65 / 14 = .5464
Now divide the numbers by the smallest found
Carbon 4.917 / .5464 = 9
Hydrogen 7.15 / .5464 = 13
Oxygen 1.6375 / 3
Nitrogen .5464 /.5464 =1 emp form C9 H13 O3 N
An important industrial route to extremely pure acetic acid is the reaction of methanol with carbon monoxide:
The heat of reaction:
There has been a -22 kJ/mol heat of reaction. This is an exothermic reaction as the reaction has been indicated by the negative sign.
Definition of Heat of reaction:
The amount of energy that the system absorbs or releases to create the products is described as the heat of reaction.
The heat of reaction has been provided by:
ΔH = ΔH[tex]_{reactant}[/tex] - ΔH[tex]_{product}[/tex]
Calculation of Heat of reaction:
On the basis of the bond energies, the heat of the reaction has been estimated. The heat of the reactant served as the energy component of each bond in the reactant, while the heat of the product served as the energy of the product.
Step 1:
The heat of the reactant has been given as:
Reactant molecules: CH[tex]_{3}[/tex]OH and C≡O
ΔH[tex]_{reactant}[/tex] = 3 x C-H + C-O + O-H + C≡O
ΔH[tex]_{reactant}[/tex] = 3 x 413 +358 +465 + 1070 kJ/mol
ΔH[tex]_{reactant}[/tex] = 3134 kJ/mol
Step 2:
The heat of the product has been given as:
Product molecule: CH[tex]_{3}[/tex]COOH
ΔH[tex]_{product}[/tex] = 3 x C-H + C-O + O-H + C-C + C=O
ΔH[tex]_{product}[/tex] = 3 x 413 + 358 + 467 + 347 + 745 kJ/mol
ΔH[tex]_{product}[/tex] = 3156 kJ/mol
Step 3:
The heat of reaction has been given as:
ΔH = ΔH[tex]_{reactant}[/tex] - ΔH[tex]_{product}[/tex]
ΔH = 3134 - 3156 kJ/mol
ΔH = -22 kJ/mol
NOTE: Your question is incomplete, but most probably your full question was that an important industrial route to extremely pure acetic acid is the reaction of methanol with carbon monoxide. Use bond energies to calculate the heat of the reaction. Is the reaction exothermic or endothermic?
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Calculate the pH during the titration of 40.00 mL of 0.1000 M HCl after adding 50 mL of 0.1000 M NaOH:
the pH during the titration of 40.00 mL of 0.1000 M HCl after adding 50 mL of 0.1000 M NaOH is pH = 13.39
NaOH + HCl → NaCl + H2O
40.00 ml 0.5M NaOH solution
mol NaOH = 40 ml / 1000 ml / L * 0.5 mol / L = 0.02 mol NaOH
25 mL 0.1 M HCl
mol HCl = 25 mL / 1000 mL / L * 0.1 mol / L = 0, 0025 mol
This reacts with 0.0025 mol NaOH
[NaOH] = 0.269 M
[OH-] = 0.269 M
pOH = - log 0.269
pOH = 13.43
You titrate with 30 mL 0.100 M HCl
Mol HCl = 30 mL / 1000 mL/L * 0.100 mol /L = 0.003 mol HCl
This will react with 0.003 mol NaOH
Mol unreacted NaOH = 0.02 mol - 0.003 mol = 0.017 mol NaOH in 40mL + 30 mL = 70 mL solution
Molarity of NaOH solution = 0.017 mol / 70 mL * 1000 mL/L = 0.243 M
[OH-] = 0.243 M
pOH = - log 0.243
pOH = 0.61
pH = 13.39
40 mL
Titration is defined as "the process of determining the amount of substance A by adding a measured amount of substance B, which is a titrator that reacts until an accurate chemical equivalence point is reached."
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Which type of molecule carries genetic information?
OA. Triglyceride
OB. Polypeptide
OC. Nucleic acid
OD. Polysaccharide
Answer:
Nucleic acid
Explanation:
Because nucleic acid is the molecule that carries genetic information because it helps to develop or functioning an organism
108g of HCl reacts with excess Al what mass of AlCl3 forms
Taking into account the reaction stoichiometry, 108 grams of HCl form 131.70 grams of AlCl₃.
Reaction stoichiometryIn first place, the balanced reaction is:
2 Al + 6 HCl → 2 AlCl₃ + 3 H₂
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
Al: 2 moles HCl: 6 moles AlCl₃: 2 moles H₂: 3 molesThe molar mass of the compounds is:
Al: 27 g/mole HCl: 36.45 g/mole AlCl₃: 133.35 g/moleH₂: 2 g/moleThen, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:
Al: 2 moles ×27 g/mole= 54 gramsHCl: 6 moles ×36.45 g/mole= 218.7 gramsAlCl₃: 2 moles ×133.35 g/mole= 266.7 gramsH₂: 3 moles ×2 g/mole= 6 gramsMass of AlCl₃ formedThe following rule of three can be applied: if by reaction stoichiometry 218.7 grams of HCl form 266.7 grams of AlCl₃, 108 grams of HCl form how much mass of AlCl₃?
[tex]mass of AlCl_{3} =\frac{108 grams of HClx266.7 grams of AlCl_{3}}{218.7 grams of HCl}[/tex]
mass of AlCl₃= 131.70 grams
Then, 108 grams of HCl form 131.70 grams of AlCl₃.
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Write the empirical formula of a list for binary ionic compounds that could be formed from the following ions
Answer:
CaBr₂, CaO, FeBr₂, FeO
Explanation:
Per binary compound, there must be 1 cation (Ca²⁺, Fe²⁺) and 1 anion (Br⁻, O²⁻). The compound should have a charge of 0 (neutral). For this to occur, there sometimes needs to be more than one cation/anion present in the compound. Below I have included the math that displays why there are more ions necessary in some compounds.
CaBr₂
-----> Ca = +2 and Br = -1
-----> +2 + (-1) + (-1) = 0
CaO
-----> Ca = +2 and O = -2
-----> +2 + (-2) = 0
FeBr₂
-----> Fe = +2 and Br = -1
-----> +2 + (-1) + (-1) = 0
FeO
-----> Fe = +2 and O = -2
-----> +2 + (-2) = 0