Answer:
1) No
2) The solvent contaminated the analyte
3) The solvent should be evaporated properly before washing and drying the analyte
Explanation:
During separation of organic compounds, solvents are used. These solvents are able to contaminate the analyte and lead to a large difference in melting point of solids obtained.
However, the error can be minimized by evaporating the solvent before washing, drying and melting point determination of the solid.
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The heater used in a 4.33 m x 3.43 m x 3.03 m dorm room uses the combustion of natural gas (primarily methane gas) to produce the heat required to increase the temperature of the air in the dorm room. Assuming that all of the energy produced in the reaction goes towards heating only the air in the dorm room, calculate the mass of methane required to increase the temperature of the air by 7.35 °C. Assume that the specific heat of air is 30.0 J/K-mol and that 1.00 mol of air occupies 22.4 L at all temperatures. Enthalpy of formation values can be found in this table. Assume gaseous water is produced in the combustion of methane.
Answer:
The answer is 7.89
Explanation:
Mass of methane required to increase the temperature of the air in the room by 7.35 °C is 7.95 g
The volume of air in the room is first calculated:
Volume of air in the room = 4.33 m x 3.43 m x 3.03 = 45.00 m³
1 m³ = 1000 L
45.00 m³ = 45.00 m³ * 1000 L/m³
Volume of air in L = 45000 L
Number of moles of air in 45000 L of air is then determined:
1.00 moles of air occupies 22.4 L
number of moles of air in 45000 L = 45000 L * 1 mole / 22.4 L
number of moles of air = 2008.93 moles of air
Energy that is needed to heat the room by 7.35 °C is then calculated:
Quantity of energy needed = Specific heat capacity * number of moles * temperature increase
Specific heat capacity of air = 30.0 J/K/mole
Quantity of energy needed = 30.0 * 2008.93 * 7.35
Quantity of energy needed = 442969.065 J = 443.00 kJ
The amount of methane required to produce that amount of energy is then calculated:
Equation of combustion of methane : CH₄ + 2 O₂ ---> CO₂ + 2 H₂O
Enthalpy of combustion of methane = −890.3 kJ/mole
Number of moles of methane required = 443.00 kJ / 890.8 kJ/mole = 0.497 moles
Mass of 1 mole of methane = 16.0 g
mass of 0.497 moles of methane = 16.0 * 0.497 = 7.95 g
Therefore, mass of methane required to increase the temperature of the air in the room by 7.35 °C is 7.95 g
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calculate the mol fraction of ethanol and water in a sample of rectified spirit which contains 95% of ethanol by mass
Answer:
We are given that there is 95% ethanol by mass in rectified spirit
so, we can say that in a 100g sample, we have 95 grams of ethanol and 5 grams of water
we will find the number of moles of ethanol and water in 100g solution of rectified spirit and use that to calculate the mole fraction
Moles of Ethanol:
Molar mass of ethanol = 46 grams / mol
Number of moles = Given mass / molar mass
Number of moles = 95 / 46
Moles of Ethanol = 2 moles (approx)
Moles of Water:
Molar mass of water = 18 grams per mol
Number of moles = Given mass / molar mass
Moles of water = 5 / 18
Moles of water = 0.28 moles (approx)
Mole Fractions:
Mole fraction of a specific compound is the number of moles of that compound divided by the total number of moles in the solution
Mole fraction of Ethanol:
Moles of ethanol / (moles of ethanol + moles of water)
2 / (2 + 0.28)
2 / (2.28) = 0.9 (approx)
Mole fraction of Water:
Moles of water / (Moles of ethanol + moles of water)
0.28 / (2 + 0.28)
0.28 / (2.28) = 0.1 (approx)
Choose all the answers that apply.
Ionic compounds _____.
-do not dissolve in water
-have high melting points
-have low melting points
-dissolve easily in water
-conduct electricity when melted
Answer:
high melting points, dissolve easily in water, conduct electricity when melted.
Explanation:
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What metalloid has commonly been used as an insecticide due
to its effectiveness as a poison.
Answer:
Arsenic.
Explanation:
Hello there!
In this case, since insecticides are substances that act as poisons to get rid of insects in order to prevent their presence and/or reproduction in houses, companies, crops and others, a substance that has been widely used is the metalloid arsenic due to its direct affection of the insect's body (movement, performance, cellular functions).
In addition, high levels of arsenic in food could cause arsenic poisoning in humans as well, that is why such practice must be properly performed and by using the correct security protocol.
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Answer:
As
Explanation:
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Identify the oxidizing and reducing agent in the following reaction, and determine which element is oxidized and which is reduced. Fe2+(aq) + ClO2(aq) → Fe3+(aq) + ClO2–(aq) ClO2 is the reducing agent and Fe2+ is the oxidizing agent . Fe is oxidized and Cl is reduced. g
Answer:
Explanation:
Fe⁺²(aq) + ClO₂(aq) → Fe⁺³(aq) + ClO₂⁻(aq)
Here oxidation number of Fe is increased from +2 to +3 , so Fe is oxidised .
The oxidation number of Cl is reduced from + 4 to +3 so Cl is reduced .
So ClO₂(aq) is oxidising agent and Fe⁺²(aq) is reducing agent .
Explain how plucking occurs
Answer:
plucking is usually extracting hair
Explanation:
example: pluck the chicken feathers
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what’s the most abundant isotope of lawrencium
Answer:
266Lr
Thirteen isotopes of lawrencium are currently known; the most stable is 266Lr with a half-life of 11 hours, but the shorter-lived 260Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale.
Explanation:
hopefully that helps you
A black object appears black because it reflects all light , and does not absorb any light. True or False
Answer:
False
Explanation:
It is the other way round, a black object appears black because it absorbs all the wavelength of light and does not reflect any light.
A black bucket will appear black because, it absorbs all wavelength of light incident on it. No other wavelength is reflected from the surface of the body. A black color suggests that a body is not reflecting any color. Instead such a body absorbing all the colors. For a white object, they reflect all the wavelength that is incident upon them.Determine whether the disruption of the bonds or attractions occurs during protein hydrolysis or protein denaturation.
Answer:
The disruption of the bonds or attractions occurs during protein hydrolysis which results in the loss for the primacy structure. The peptide bonds is the bond affected in this scenario.
The disruption of the bonds however only exist in the process of denaturation and this results in a change in the confirmation which could be secondary, tertiary, and quaternary structural related. And example of the bonds affected include salt bridges, disulfide bridges, hydrogen bonds etc.
The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the
А.
electron
B
proton
neutron
D
atom
Answer:
The answer is D - Atom
The smallest unit of an element that can exist either alone or in combination with other such particles of the same or different elements is the atom.
What is an atom?
An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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atmospheric pressure at elevations of 8000 feet averages about 0.72 atmospheres. Would a cabin pressurized at 500 mm hg meet federal standards
Answer:
Yes, but it must be kept at that value and do not let it to decrease more.
Explanation:
Hello.
In this case, in order to substantiate whether the cabin meet the federal standards, we need to convert the 500 mmHg to atm and compare the result with 0.72 atm by knowing that 1 atm equals 760 mmHg:
[tex]500mmHg*\frac{1atm}{760mmHg} \\\\=0.66atm[/tex]
Thus, since 0.66 atm is 0.06 atm away from the federal standard we can infer that it may meet the federal standard, however, it would not be recommended to let the pressure decrease more than that.
Yes, the cabin pressurized at 500 mm hg meets federal standards.
1 atm is approximately equal to 760 mm Hg. Therefore, the pressure is:
500 mm Hg / 760 mm Hg/atm ≈ 0.65789 atm
So, the cabin pressure of 500 mm Hg is approximately 0.65789 atmospheres. If the atmospheric pressure at an elevation of 8000 feet averages about 0.72 atmospheres, then the cabin pressure of 0.65789 atmospheres would be lower than the ambient atmospheric pressure.
To meet federal standards, cabin pressure should be maintained at an equivalent pressure that allows occupants to breathe comfortably.
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Why must you avoid touching the gas Spectrum tubes?
what is functional group of ethers?
Answer:
Explanation:The ether functional group consists of an oxygen atom that forms single bonds with two carbon atoms
A solution with a Ph of 13 would be classified as a_____
strong base
strong acid
weak acid
weak base
Answer:
strong base
Explanation:
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write the equation for the beta decay of 53/26 FE
Answer:
53/26Fe = 0/-1,B + 53/27 Co
What is the frequency of a wave having 4.90 x 10 -12 J of energy?
Answer:
The answer is
[tex] \huge 7.40 \times {10}^{21} Hz[/tex]
Explanation:
To find the frequency of the wave we use the formula
[tex]f = \frac{E}{h} \\ [/tex]
where
E is the energy
f is the frequency
h is the Planck's constant which is
6.626 × 10-³⁴ Js
From the question
E = 4.90 × 10-¹² J
So we have
[tex]f = \frac{4.90 \times {10}^{ - 12} }{6.626 \times {10}^{ - 34} } \\ [/tex]
We have the final answer as
[tex]7.40 \times {10}^{21} \: \: Hz[/tex]
Hope this helps you
If 200.00 mL of a solution of sugar and water contains 0.0025 moles of sugar, what is the concentration of the solution in units of moles per unit volume? Round decimals to the nearest thousandth where applicable. Do not include trailing zeros in decimal answers (e.g., 0.05 instead of 0.050).
Answer:
0.013 mol/L
Explanation:
Molarity, which is molar concentration or moles per unit volume, can be calculated using the formula:
M = n/V
Where; M = Molar concentration of solution
n = number of moles of solute
V = Volume of solvent
n = 0.0025 moles of sugar
V = 200.00mL of solution
Since 0.001L = 1mL
200mL = 0.200L
Therefore, M = n/V
M = 0.0025/0.200
M = 0.0125 mol/L
Round up to the nearest thousandth ~ 0.013mol/L
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Answer:
d
Explanation:
A hydrocarbon molecule contains carbon and hydrogen atoms in equal numbers. Its molar mass is 130.18 g/mol. What is the molecular formula for the hydrocarbon
Answer:
The molecular formula of the hydrocarbon is C10H10
Explanation:
Here, we are interested in finding the molecular formula for the hydrocarbon.
Since there are equal number of moles of carbon and hydrogen, then we have the molecular formula looking like;
CnHn
Kindly recall that the atomic mass of carbon is 12 a.m.u while that of hydrogen is 1 amu
so calculating the atomic mass of the compound, we have;
12(n) + 1(n) = 130.18
13n = 130.18
n = 130.18/13
n = 10.01
So the molecular formula will be C10H10
Answer:
C10H10
Explanation:
A hydrocarbon is a binary compound of carbon and hydrogen. Hence a hydrocarbon is a compound of the general formula (CH)n
Thus;
(12 + 1) n = 130.18
n= 130.18/13
n = 10
Hence the molecular formula of the compound is C10H10
Item 4
Which statement is one of the three parts of cell theory?
Cell organelles can be membrane-bound or not membrane-bound.
Cells make up tissues, tissues make up organs, organs make up systems, systems make up organisms.
The smallest living things are single cells, and cells are the functional units of multicellular organisms.
There are three types of cells, prokaryotic, eukaryotic plant, and eukaryotic animal.
For each of the following molecules draw the Lewis structure on a separate sheet of paper. MAKE SURE TO FOLLOW THE RULES FROM CLASS (ie do not break the octet rule unless necessary to connect all the atoms). Then based on your structure indicate:
the total number of valence electrons.
the electronic and molecular shapes (choose from: linear, trigonal planar, bent, tetrahedral, trigonal pyramidal, trigonal bipyramidal, seesaw, T-shaped, octahedral, square pyramidal, or square planar).
whether or not the molecule is polar (Y/N).
Note: The central atom is the first atom listed, except for HCN, H2CO, and OCN-, where carbon is the central atom (underlined).
Formula Valence electrons Electronic Shape Molecular Shape Polar (Y/N)
HCN
PH3
CHCl3
NH4+
H2CO
SO42-
SeF2
CO2
O2
ClO4-
HBr
PF5
BeH2
PO43-
BH3
Br3-
Answer:
Kindly check the explanation section.
Explanation:
Without mincing words let us dive right into the solution to the question above, taking each compound at a time.
NB: Kindly Check attachment for the Lewis Structure of each of the chemical compounds.
Therefore, the number of valence electrons, electronic shape, molecular shape and whether the molecules are polar(Polarity) is given below for each chemical compound.
(1). Compound: HCN
(a). number of valence electrons = 10.
(b). electronic shape =linear.
(c). molecular shape = linear.
(d). Polarity = Y.
(2). Compound: PH3
(a). number of valence electrons = 8.
(b). electronic shape = Tetrahedral.
(c). molecular shape = Trigonal Pyramidal.
(d). Polarity = Y.
(3). Compound: CHCl3.
(a). number of valence electrons = 26.
(b). electronic shape = tetrahedral.
(c). molecular shape = tetrahedral.
(d). Polarity = Y.
(4). Compound: NH4^+
(a). number of valence electrons = 8
(b). electronic shape = tetrahedral
(c). molecular shape = tetrahedral
(d). Polarity = Y.
(5). Compound: H2CO
(a). number of valence electrons = 12.
(b). electronic shape = Trigonal planar.
(c). molecular shape = Trigonal planar
(d). Polarity = Y.
(6). Compound: SO4^2-
(a). number of valence electrons = 32.
(b). electronic shape = Tetrahedral.
(c). molecular shape = Tetrahedral.
(d). Polarity = N.
(7). Compound: SeF2.
(a). number of valence electrons = 20.
(b). electronic shape = Tetrahedral.
(c). molecular shape = bent.
(d). Polarity = Y.
(8). Compound: CO2.
(a). number of valence electrons = 16.
(b). electronic shape = linear.
(c). molecular shape = linear.
(d). Polarity = N.
(9). Compound: O2
(a). number of valence electrons = 32.
(b). electronic shape = Trigonal planar.
(c). molecular shape = Linear.
(d). Polarity = N.
(10). Compound: ClO4-.
(a). number of valence electrons = 32.
(b). electronic shape = Tetrahedral.
(c). molecular shape = Tetrahedral.
(d). Polarity = N.
(11). Compound: HBr.
(a). number of valence electrons = 8.
(b). electronic shape = Linear.
(c). molecular shape = Linear.
(d). Polarity = Y.
(12). Compound: PF5.
(a). number of valence electrons = 40.
(b). electronic shape = Trigonal Bipyramidal.
(c). molecular shape = Trigonal Bipyramidal.
(d). Polarity = N.
(13). Compound: BeH2.
(a). number of valence electrons = 4.
(b). electronic shape = Linear.
(c). molecular shape = Linear.
(d). Polarity = N.
(14). Compound: PO4^3-.
(a). number of valence electrons = 32.
(b). electronic shape = Tetrahedral.
(c). molecular shape = Tetrahedral.
(d). Polarity = N.
(15). Compound: BH3.
(a). number of valence electrons = 6.
(b). electronic shape = Trigonal planar.
(c). molecular shape = Trigonal planar.
(d). Polarity = N
(16). Compound: Br3-.
(a). number of valence electrons = 32.
(b). electronic shape = Trigonal Bipyramidal.
(c). molecular shape = Linear.
(d). Polarity = N.
Define a function compute_gas_volume that returns the volume of a gas given parameters pressure, temperature, and moles. Use the gas equation PV
Answer:
def compute_volume(pressure,moles,temperature):
volume = (8.314 * moles * temperature)/pressure
print("Volume: "+str(volume))
Explanation:
This line defines the function
def compute_volume(pressure,moles,temperature):
This line calculates the volume
volume = (8.314 * moles * temperature)/pressure
This line prints the calculated volume
print("Volume: "+str(volume))
6 CO2 + 6 H2O
How many atoms of each element are in
the equation?
Answer:
There are 6 Carbon dioxides, and 6 waters, but there are 6 carbons, 18 oxygens, and 12 hydrogens.
Explanation:
Answer:
6 carbon atoms
18 oxygen atoms
12 hydrogen atoms
where are electrons found in an atom
Answer:
The electrons are found on the outer shell of the atom.
Explanation:
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Under the Law of Multiple Proportions, Carbon Dioxide has a ratio of 2.666 g
Oxygen for every 1 g Carbon. Given this, how much oxygen is present in a sample
of carbon dioxide that has 16 g of carbon?
Answer:
In carbon dioxide, on the right, there is 2.666 g of oxygen for every gram of carbon. So the ratio of oxygen in the two compounds is 1:2, a small whole number ratio
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All of the following conditions in Earth can cause metamorphic rock to form EXCEPT
O pressure
O heat
the presence of hot, plastic like material
O exposure to air
Explanation:
heat
the presence of hot, plastic like material
A student determines that the mass of a sample of aluminum is 8.3 g. How many moles are in the sample?
Answer:
0.307
Explanation:
use the formula of n=mass /molar mass
Our universe is made up of at least a
Given the following balanced equation:
9 Fe2O3 + 2 NH3 → 6 Fe3O4 + N2 + 3 H2O
A) how many grams of NH3 are needed to react with 125 grams of Fe2O3?
B) how many grams of Fe3O4 will be produced?
Answer:
What mass of sodium hydroxide is needed to react completely with 10.0 g of iron( III) chloride? The conversion sequence is: A. B.
Explanation:
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What is anology?
What is microscope?