Answer:
The roasting process is a delicate combination of art and science . Roasters are familiar with how the beans look and the smells Well, familiarity with the machine makes things much easier to predict, but the best way is to do many different tests .Well, familiarity with the machine makes things much easier to predict, but the best way is to do many different tests.Smelting is a process of applying heat to ore in order to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals.In zone refining, solutes are segregated at one end of the ingot in order to purify the remainder, or to concentrate the impurities. For example, in the preparation of a transistor or diode semiconductor, an ingot of germanium is first purified by zone refining. In zone refining, solutes are segregated at one end of the ingot in order to purify the remainder, or to concentrate the impurities. ... For example, in the preparation of a transistor or diode semiconductor, an ingot of germanium is first purified by zone refining.Polling is the process where the computer or controlling device waits for an external device to check for its readiness or state, often with low-level hardware. For example, when a printer is connected via a parallel port, the computer waits until the printer has received the next character.Explanation:
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An atom has 20 electrons. Find out
i. It’s atomic numbers and total number of p-electrons
ii. The value of azimuthal quantum number (l) and magnetic quantum number (m) of the 19th electron of the atom.
iii. It’s group position in the periodic table.
Answer:
it's atomic number is 5 and total number is 10
The atom has an atomic number of 20 and has a total of 12 p electrons.
The azimuthal quantum number (l) of the 19th electron is 0 and the magnetic quantum number (m) of the 19th electron is 0.
It is an element of group 2
The number of electrons in the neutral atom is equal to the number of protons and is also the atomic number of an atom.
An atom is known to be electrically neutral. This is because the number of electrons in the atom is equal to the number of protons in the neutral atom.
The number of protons in the neutral atom is called the atomic number of the atom.
For an element that has 20 electrons, its electronic configuration is;
1s2 2s2 2p6 3s2 3p6 4s2.
The 19th electron is in the 4s orbital hence both the azimuthal and magnetic quantum numbers are zero.
The element has outermost electron configuration ns2 so it mus belong to group 2 of the periodic table.
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Which equation obeys the law of conservation of
mass?
Answer:2C4H10+2C12+12O2 4CO2+CC14+H20
1) Rank the following elements in order of decreasing atomic radius. Rank from largest to smallest radius. To rank items as equivalent, overlap them.
a. k
b. Li
c. Rb
d. Na
1. Largest
2. Smallest
2) Rank the following elements in order of decreasing atomic radius. Rank from largest to smallest radius. To rank items as equivalent, overlap them.
a.Mg
b. Al
c. Na
d. Si
Answer:
1) Ra
K
Na
Li
2) Na
Mg
Al and Si
Draw 2,3-dichloro octane
Answer:
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Liquid ethyl mercaptan, C2H6S, has a density of 0.84 g/mL. Assuming that the combustion of this compound produces only CO2 , H2O, and SO2 , what masses of each of these three products would be produced in the combustion of 3.15 mL of ethyl mercaptan
Answer:
Mass CO2 = 3.75 grams
Mass H2O = 2.30 grams
Mass SO2 = 2.73 grams
Explanation:
Step 1: Data given
Density of Liquid ethyl mercaptan, C2H6S = 0.84 g/mL
Volume of ethyl mercaptan = 3.15 mL
Step 2: The reaction
2C2H6S + 9O2 → 4CO2 + 6H2O + 2SO2
Step 3: Calculate mass of ethyl mercaptan
Mass = Volume * density
Mass ethyl mercaptan = 3.15 mL * 0.84 g/mL
Mass ethyl mercaptan = 2.646 grams
Step 4: Calculate moles ethyl mercaptan
Moles = mass / molar mass
Moles ethyl mercaptan = 2.646 grams / 62.13 g/mol
Moles ethyl mercaptan = 0.04259 moles
Step 5: Calculate moles of other products
For 2 moles ethyl mercaptan we need 9 moles O2 to produce 4 moles CO2, 6 moles H2O and 2 moles SO2
For 0.04259 moles we need 0.1917 moles O2 to produce:
2*0.04259 = 0.08518 moles CO2
3*0.04259 = 0.1278 moles H2O
1*0.04259 = 0.04259 moles SO2
Step 6: Calculate mass produced
Mass = moles * molar mass
Mass CO2 = 0.08518 moles * 44.01 g/mol
Mass CO2 = 3.75 grams
Mass H2O = 0.1278 moles * 18.02 g/mol
Mass H2O = 2.30 grams
Mass SO2 = 0.04259 moles * 64.07 g/mol
Mass SO2 = 2.73 grams
a laser emits light with a frequency of 4.69 x 10 to the 14th power s - 1 calculate the wavelength of this light.
Answer:
6.40x10^-7
Explanation:
answer with work is attached.
Design an experiment to demonstrate phototropism.
Answer:
Object: To demonstrate phototropism
equipments: A black box, window with light source, a well watered potted plant.
Experiment: A wellwatered potted plant is placed inside a darkened black box that is having a small window on one side. This is called as phototropic chamber. Window is remain closed for a day the plant shows normal growth.
Whereas if window is opened atwo days it will be found that shoot tip bends and grows towards light proving that it is positively phototropic.
Calcium chloride and magnesium sulfate are common drying agents. What type of solvent should be dried with calcium chloride, and what type with magnesium sulfate
Answer: The type of solvent that should be dried with calcium chloride is esters while magnesium sulfate is diethyl ether
Explanation:
Drying agents are mainly hygroscopic substances that has the ability to absorb water on exposure to the atmosphere but not enough to form solutions. They are used in desiccators. Examples of drying agents include:
--> CALCIUM CHLORIDE: This is a compound of calcium that is found in soil water and sea water. It is prepared by the action of dilute hydrochloric acid on calcium trioxocarbonate(IV). The anhydrous salt is used in drying a wide variety of solvent including esters.
--> MAGNESIUM SULFATE: This is a slightly acidic drying agent. It works well in solvents like diethyl ether. It is a fast drying agent because it comes as a fine powder with a large surface area.
A sample of calcium fluoride was decomposed into the constituent elements. Write a balanced chemical equation for the decomposition reaction. If the sample produced 294 mg of calcium, how many g of fluorine were formed
Answer:
A sample of calcium fluoride was decomposed into the constituent elements. Write a balanced chemical equation for the decomposition reaction. If the sample produced 294 mg of calcium, how many g of fluorine was formed
Explanation:
The balanced chemical equation for the decomposition of calcium fluoride is shown below:
[tex]CaF_2(s)->Ca(s)+F_2(g)[/tex]
The sample produced 294 g of calcium then, how many grams of fluorine is formed?
From the balanced chemical equation,
1 mol of CaF2 forms 1mol of calcium and 1 mol of fluorine.
That is:
40g of calcium and 38.0 g of fluorine are formed.
then,
If 294 g of calcium is formed then how many grams of fluorine is formed?
[tex]294g Ca * 38g F2 / 40g Ca\\=279.3 g F_2[/tex]
Hence, 279.3 g of fluorine will be formed.
Why do gases act more ideal at
lower pressures?
Answer:
Gases act more ideal at lower pressure beacuse the attractive forces between molecules will decrease or become less significant compared to the empty space between them.
Explanation:
Generally, a gas behaves more like an ideal gas at higher temperature and lower pressure as the potential energy due to intermolecular forces becomes less significant compared with the particles "kinetic energy" and the size of the molecules become less significant compared to the empty space between them.
Attractive forces between molecules, decrease the pressure of a reak gas, slowing the molecules and reducing collisions with the walls.The higher the value of a gas, the greater the attraction between molecules and the more easily the gas will compress.
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Methanol has the formula CH3OH. What is the predominant intermolecular force between methanol molecules?
ANSWER:
dispersion forces
dipole forces
ionic bonds
hydrogen bonds
Answer:
hydrogen bonds
Explanation:
similarly CH3OH also has a OH group and H hydrogen thus it will also form h-bonding.
formula of
Al³⁺ and SO₄²⁻
Answer:
The formula of Al³⁺ and SO₄²⁻ is aluminum sulfate.
Explanation:
The formula for aluminum sulfate is Al₂(SO₄)₃. If we say in terms of ions. The ions are Al³⁺. It is a positive ion or the cation. Other ion is SO₄²⁻. It is sulfate ion. It is anion.
Aluminum sulphate is used in water purification and as a mordant in dyeing and printing textiles.
Hence, the formula of Al³⁺ and SO₄²⁻ is aluminum sulfate.
liquid junction potential arise due to?
Answer:
liquid junction potentials
when a cell contains a boundary between two electrolytic solutions of different composition or concentration, a liquid junction potential is developed due to the "diffusion of the various components at characteristic rates in the boundary zone."
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4.005 X 74 X 0.007 = 2.10049
Answer:
2.07459
Explanation:
this is the correct answer.
You titrate 41.27 mL of 0.108 M Ca(OH)2 into 25.00 mL of citric acid (C6H307) (triprotic). What is the balanced equation and the molarity of the acid?
Select both an equation and a molarity.
CoH2O2 (aq) + Ca(OH)2 (aq) + H20 (1) + Ca(C6H507)2 (aq)
2C6H807 (aq) + 3Ca(OH)2 (aq) + 6H20 (1) + Ca3(C6H507)2 (aq)
C6H2O7 (aq) + Ca(OH)2 (aq) + H20 (1) + CaC6H50% (aq)
3C6H307 (aq) + 2Ca(OH)2 (aq) + 6H20 (1) + Caz(C6H507)2 (aq)
0.267 M
0.178 M
0.0654 M
0.119 M
Answer:
3Ca(OH)2 + 2C6H8O7 → 6H2O + Ca3(C6H5O7)2
And 0.119M is the concentration of the citric acid.
Explanation:
In an acid-base reaction, the proton H+ and the hydroxil ion OH- reacts producing water. The ions of the acid and base (C6H5O7³⁻ and Ca²⁺ ions produce the respective salt) as follows:
Ca(OH)2 + C6H8O7 → H2O + Ca3(C6H5O7)2
To balance the Calcium ions:
3Ca(OH)2 + C6H8O7 → H2O + Ca3(C6H5O7)2
To balance the C6H5O7³⁻ ions:
3Ca(OH)2 + 2C6H8O7 → H2O + Ca3(C6H5O7)2
And to balance the oxygens of water:
3Ca(OH)2 + 2C6H8O7 → 6H2O + Ca3(C6H5O7)2
And this is the balanced reaction.
The moles of Ca(OH)2 that reacts are:
41.27mL = 0.04127L * (0.108mol/L) = 0.004457 moles Ca(OH)2
Moles of citric acid:
0.004457 moles Ca(OH)2 * (2mol C6H8O7 / 3mol Ca(OH)2) = 0.002971 moles C6H8O7
In 25.00mL = 0.02500L:
0.002971 moles C6H8O7 / 0.0250L =
0.119M
An electron-dot structure is a convenient method of representing
A. The complete electron configuration of the atom.
B. all electrons of the atom.
C. valence electrons of an atom.
D. core electrons of an atom.
Answer:
all electrons of the atom
All light waves can be described in terms of their speed, frequency, and___
Answer:
all light waves can be described in terms of their speed, frequency and wavelength
Explanation:
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2- A 0.60 sample an unknown organic acid found in muscle cells is burned in air and found to contain 0.24 grams of carbon, 0.040 grams of hydrogen, with the rest being oxygen. If the molecular weight of the substance is 90 grams/n, what is the molecular formula
Answer:
C₃H₆O₃
Explanation:
To solve this question we need to find, as first, the moles of each atom in order to find empirical formula (Simplest whole-number ratio of atoms present in a molecule).
With the molar mass of the substance and the empirical formula we can find the molecular formula as follows:
Moles C -Molar mass:12.0g/mol-
0.24g * (1mol/12.0g) = 0.020 moles C
Moles H = Mass H because molar mass = 1g/mol:
0.040 moles H
Moles O -Molar mass: 16g/mol-
Mass O: 0.60g - 0.24g - 0.040g = 0.32g O
0.32g O * (1mol/16g) = 0.020 moles O
Ratio of atoms (Dividing in moles of C: Lower number of moles):
C = 0.020 moles C / 0.020 moles C = 1
H = 0.040 moles H / 0.020 moles C = 2
O = 0.020 moles O / 0.020 moles C = 1
Empirical formula:
CH₂O.
Molar mass CH2O:
12g/mol + 2*1g/mol + 16g/mol = 30g/mol
As molecular formula has a molar mass 3 times higher than empirical formula, the molecular formula is 3 times empirical formula:
C₃H₆O₃The molecular formula of the organic acid would be C3H6O3
Molecular formulaMolecular formula = [empirical formula]n
Where n = molar mass/mass of empirical formula
Empirical formula
C = 0.24/12 = 0.02
H = 0.040/1 = 0.04
O = 0.6 - (0.24+0.04) = 0.32/16 = 0.02
Divide by the smallest
C = 1
H = 2
O = 1
Empirical formula = CH2O
Empirical formula mass = 12 + 2 + 16 = 30
n = 90/30 = 3
Molecular formula = [CH2O]3
= C3H6O3
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Identify the change in state that does NOT have an increase in entropy. Identify the change in state that does NOT have an increase in entropy. water evaporating dry ice subliming steam condensing water boiling popsicle melting
Answer:
condensing water
Explanation:
Entropy refers to the level of disorderliness in a system. The entropy of liquids is greater than that of solids. The entropy of gases is greater than that of liquids.
A process of physical change involving a change of state from solid to liquid or liquid to gas is accompanied by increase in entropy.
However, a change of state involving a change from liquid to solid or gas to liquid is accompanied by decrease in entropy.
Hence, steam condensing to water leads to decrease and not increase in entropy of the system.
Which Group is in the second column of the periodic table?
O A. Noble gases
O B. Alkaline earth metals
O C. Alkali metals
O D. Halogens
Answer:
O B. Alkaline earth metals
Explanation:
Noble gases → 8th column.
Alkali metal → first column.
Halogen → 7th
Answer:
B. Alkaline earth metals
Explanation:
Alkaline-earth metals: The alkaline-earth metals make up Group 2 of the periodic table, from beryllium (Be) through radium (Ra). Each of these elements has two electrons in its outermost energy level, which makes the alkaline earths reactive enough that they're rarely found alone in nature. But they're not as reactive as the alkali metals. Their chemical reactions typically occur more slowly and produce less heat compared to the alkali metals.
What is oxygen's half-equation?
answer; 1/ 20_2[2-] +2e - ->0.
22 Agas that is collected by upward delivery is likely to be A heavier than air B insoluble in water C lighter than air D Soluble in water
Answer:
joib
Explanation:
Calculate the Experimental Molar Volume in L/mol of the Hydrogen gas, H2, if the volume of H2 at STP is 52.8 mL and the mass of Magnesium metal, Mg, used in the experiment is 0.055 g.
Answer:
The Experimental Molar Volume in L/mol of the Hydrogen gas=23.36L/mol
Explanation:
We are given that
Volume of H2 at STP=52.8mL
Mass of magnesium metal ,M(Mg)=0.055g
We have to find the Experimental Molar Volume in L/mol of the Hydrogen gas.
Molar mass of Mg=24.305 g/mol
Number of moles=[tex]\frac{given\;mass}{molar\;mass}[/tex]
Using the formula
Number of moles of Mg=[tex]\frac{0.055}{24.305}[/tex]moles
Number of moles of Mg=0.00226moles
Number of moles of Mg=Number of moles of H2
Number of moles of H2=0.00226moles
Molar volume of Hydrogen gas (H2)=[tex]\frac{volume\;at\;STP}{No\;of\;moles\;H_2}[/tex]
Molar volume of Hydrogen gas (H2)=[tex]\frac{52.8}{0.00226}mL/mol[/tex]
Molar volume of Hydrogen gas (H2)=[tex]\frac{52.8}{0.00226}\times 10^{-3}L/mol[/tex]
[tex]1L=1000mL[/tex]
Molar volume of Hydrogen gas (H2)=23.36L/mol
Hence, the Experimental Molar Volume in L/mol of the Hydrogen gas=23.36L/mol
Silver has two naturally occurring isotopes with the following isotopic masses: 10747Ag 10947Ag 106.90509 108.9047 The average atomic mass of silver is 107.8682 amu. The fractional abundance of the lighter of the two isotopes is ________.
Answer: The fractional abundance of lighter isotope is 0.518
Explanation:
Average atomic weight is the sum of the masses of the individual isotopes each multiplied by its fractional abundance. The equation used is:[tex]\text{Average atomic weight}=\sum_{i=1}^{n}\text{(Atomic mass of isotope)}_i\times \text{(Fractional abundance)}_i[/tex] ......(1)
Let the fractional abundance of Ag-107 isotope be 'x'
For Ag-107 isotope:Atomic mass = 106.90509 amu
Fractional abundance = x
For Ag-109 isotope:Atomic mass = 108.9047 amu
Fractional abundance = (1 - x)
Average atomic mass of silver = 107.8682 amu
Plugging values in equation 1:
[tex]107.8682=(106.90509 \times x) + (108.9047 \times (1-x))\\\\107.8682=106.90509x+108.9047-108.9047x\\\\1.99961x=1.0365\\\\x=0.518[/tex]
Fractional abundance of Ag-107 isotope (lighter) = x = 0.518
Hence, the fractional abundance of lighter isotope is 0.518
The energy levels of hydrogenlike one-electron ions of atomic number Z differ from those of hydrogen by a factor of Z^2. Predict the wavelength of the 2s--->1s transition in He+.
Answer:
[tex]\mathbf{\lambda \simeq 3.039 \times 10^{-8} \ m}[/tex]
Explanation:
For a hydrogen-like atom, the spectral line wavelength can be computed by using the formula:
[tex]\bar v = Z^2 R_H \Big(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}\Big)[/tex]
where:
emitted radiation of the wavenumber [tex]\bar v[/tex] = ???
atomic no of helium Z = 2
Rydberg's constant [tex]R_H = 1.097*10^7 \ m^{-1}[/tex]
the initial energy of the principal quantum [tex]n_1[/tex] = 2
the initial energy of the principal quantum [tex]n_1[/tex] = 2
Now, the emitted radiation of the wavenumber can be computed as:
[tex]\bar v = (2)^2 (1.097*10^7 \ m^{-1} ) \Big(\dfrac{1}{1^2}-\dfrac{1}{2^2}\Big)[/tex]
[tex]\bar v = 3.291 \times 10^ 7/m[/tex]
Now, the wavelength for the transition can be computed by using the relation between the wavelength λ and the emitted radiation of the wavenumber [tex]\bar v[/tex], which is:
[tex]\bar v = \dfrac{1}{\lambda}[/tex]
[tex]\lambda = \dfrac{1}{\bar v}[/tex]
[tex]\lambda = \dfrac{1}{3.291 \times 10^{7}}\times \dfrac{m}{1}[/tex]
[tex]\mathbf{\lambda =3.03859 \times 10^{-8} \ m}[/tex]
[tex]\mathbf{\lambda \simeq 3.039 \times 10^{-8} \ m}[/tex]
A scientific hypothesis is
ANSWER:
predictive.
testable.
explanatory.
all of the above.
Answer:
All of the above.
Explanation:
For a scientific hypothesis to be considered a hypothesis, it has to be testable. When conducting a lab experiment, it also allows the tester to predict what might occur during and after the experimentation. They are also explanatory. For example, theories are hypotheses that have been verified and can explain why something in nature takes place.
How do you predict the geometrical shape of NH3 on VSEPR model
Answer:
NH3 Ammonia
Explanation:
Ammonia has 4 regions of electron density around the central nitrogen atom (3 bonds and one lone pair). These are arranged in a tetrahedral shape. The resulting molecular shape is trigonal pyramidal with H-N-H angles of 106.7°.
Chlorine can be prepared in the laboratory by the reaction of manganese dioxide with hydrochloric acid, HCl(aq) , as described by the chemical equation
MnO2(s)+4HCl(aq)⟶MnCl2(aq)+2H2O(l)+Cl2(g)
How much MnO2(s) should be added to excess HCl(aq) to obtain 185 mL Cl2(g) at 25 °C and 745 Torr ?
mass of MnO2:
Answer:
0.605 g
Explanation:
MnO₂(s) + 4HCl(aq) ⟶ MnCl₂(aq) + 2H₂O(l) + Cl₂(g)First we calculate how many Cl₂ moles need to be produced, using the PV=nRT formula:
P = 745 Torr ⇒ 745 / 760 = 0.980 atmV = 185 mL ⇒ 185 / 1000 = 0.185 Ln = ?R = 0.082 atm·L·mol⁻¹·K⁻¹T = 25 °C ⇒ 25 + 273.16 = 298.16 KInputting the data:
0.980 atm * 0.185 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 298.16 Kn = 0.00696 molThen we convert 0.00696 moles of Cl₂ to MnO₂ moles:
0.00696 mol Cl₂ * [tex]\frac{1molMnO_2}{1molCl_2}[/tex] = 0.00696 mol MnO₂Finally we convert 0.00696 moles of MnO₂ to grams, using its molar mass:
0.00696 mol MnO₂ * 86.94 g/mol = 0.605 gSuppose an electron is transferred from a potassium atom to an unknown halogen atom. For which of the following halogen atoms would this process require the least amount of energy?
A. Cl
B. Br
C. I
Answer:
Cl
Explanation:
Electronegativity is the ability of an electron to attract electrons.
Now, due to the fact that halogens need just one more electron to become stable in their outermost shell, it means all halogens are electronegative.
However, the smaller the atomic number, the bigger the charge density and thus the more electronegative.
Thus, it is the halogen element with the highest atomic number further down the periodic table that will have the least electro negativity and thus require highest amount of energy to attract other electrons.
Thus, since chlorine (Cl) has the least atomic number of 17, then it means that it will be the one that will easily accept the electrons the most from other elements. Therefore the process of transferring electrons from potassium to chlorine will take the least amount of energy.
When electrons in a molecule are not found between a pair of atoms but move throughout the molecule, this is called Group of answer choices
Answer:
delocalised electrons
Explanation:
they are called delocalised electrons because that can move freely in the molecule
