Answer:
Explanation:
The essential though process is to ask oneself when converting grams to moles=> 'How many formula weights are in the given mass?' This directs one to divide the substance's formula weight into the given mass (in grams) on order to determine number of moles. That is ...
moles = Given Mass of Substance in grams / formula weight of substance in grams
= 1578 grams / 791 grams-mol.⁻¹ =1.995 mole ≅ 2 moles
If 160. g of a radioactive iron (59Fe) is received in the lab today, what percentage of the original is left after 180 days?
If 160.0 g of radioactive iron (59Fe ) is received in the lab today, Then the percentage of the original left after 180 days is 6.25 %.
Radioactive elements are those elements which are made up of those atoms whose nuclei is unstable and emits radiations or undergoes radioactive decay to attain stability or to form stable nuclei.
Given -
t = 180 days
t1/2 = 45 days
So,
n = t = 180 = 4
t1/2 45
Amount of the remaining radioactive iron,
R = R°
2n
where, n = 4
R = 1 = 0.0625
R° 2₄
To calculate percentage of original sample -
percentage of original sample of iron = R x 100
R°
= 0.0625 x 100
= 6.25 %
After 180 days, or 4 half lives, the percentage of radioactive iron remaining is 6.25%.
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BUFFERS BUFFERS AND BUFFER CAPACI
INTRODUCTION
LABORATORY SIMULATION
How to calculate the pH of a buffer solution
1) Calculate the pH of a solution prepared by dissolving 2.05 g of sodium acetate, CH3COONa, in 50.0 mL of 0.25 Macetic
acid, CH3COOH(aq). Assume the volume change upon dissolving the sodium acetate is negligible. K₂ of CH3COOH is
1.75 X 10-5.
pH =
The pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.
The above situation is a case of buffer solution.
The pH of a buffer solution can be calculated by the Henderson-Hasselbalch equation,
The equation is as follows:
pH = pKa + log[Salt]/[Acid]
In the above case, sodium acetate(CH3COONa) is the salt and acetic acid(CH3COOH) is the acid.
Putting [Salt] = 0.50 M and [Acid] = 0.25 M and pKa = 4.76 in the equation
pH = 4.76 + log[0.50]/[0.25]
pH = 4.76 + log2
pH = 4.76 + 0.30
pH = 5.06
Thus, the pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.
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Science Investigatory Project title ideas
Explanation:
What noise pollution affecting local fauna...what harmful particulates are in the air we breath?
Toxic Coliforms in drinking water? Is light pollution affecting diurnal plants? Chlorine is toxic, Why is it in our tap water?
What mass of mercury contains the same number of atoms as 90.15g of helium?
4.5g of mass of mercury contains the same number of atoms as 90.15g of helium.
What is mercury?With the atomic number 80 and the symbol Hg, mercury is a chemical element. Formerly known as hydrargyrum, which is a combination of the Greek terms hydor (water) and argyros), it is also known as quicksilver (silver). The only other element that is known to be liquid under these conditions is the halogen bromine, however metals like caesium, gallium, and rubidium melt just above ambient temperature. Mercury is a heavy, silvery d-block element.
All around the world, deposits of mercury, primarily in the form of cinnabar, are found (mercuric sulfide). Cinnabar, either natural or manufactured mercuric sulfide, is ground to create the crimson pigment vermilion.
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For a hydrogen atom, calculate the energy of the photon that would be emitted for the orbital transition of n(initial) = 5 to n(final) = 3. The Rydberg constant is 1.09678 x 10⁷ m⁻¹.
The energy of the photon is 1.5 * 10^-19 J
What is the Bohr model?According to the Bohr model of the atom, the atom is arranged in energy levels. It is possible for an electron to transition from a lower to a higher energy level by the gain of energy. The energy that is gained must be equal to the difference in energy between the lower and the higher energy levels of the atom.
No we know that we could use the Rydberg formula to obtain the wavelength of the photon that is emitted when an electron moves from a higher to a lower energy level with the emission of the energy that was taken in.
Thus;
1/λ = RH (1/n^2 final – 1/n^2 initial)
RH = 1.09678 x 10⁷ m⁻¹
n final = 3
n initial = 5
1/λ =1.09678 x 10⁷ (1/3^2 – 1/5^2)
1/λ = 1.09678 x 10⁷ (0.11 – 0.04)
λ = 1302 nm
E = hc/ λ
E = 6.6 * 10^-34 * 3 * 10^8/1302 * 10^-9
E = 1.5 * 10^-19 J
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how would you distinguish between hydrogen and carbon dioxide being evolved from a reaction?
Answer:
I don't understand snap the equation and send it
4. Study the flow diagram below the answer the questions that follow C Mg (a) Write the chemical formulae of products () A B (b) Write the equations for the reactions that form products (1) (11) C...... D and E
Answer:
where is flow diagram.....
.........
What number of hydrogen atoms is in 0.48 mol of Prevacid?
There are 4 * 10^24 atoms of hydrogen in 0.48 moles of prevacid.
What is prevacid?The drug prevacid is used as an antacid. What is does is to reduce the amount of acid that could be produced in the stomach of a person. As a result of this, the drug prevacid is able to relieve a person of heartburn and stomach ulcer.
Thus time, we want to obtain the number of hydrogen atoms that id present in one 0.48 moles of the drug prevacid.
We have that there are 14 hydrogen atoms in prevacid. Thus;
14 * 0.48 * 6.02 * 10^23 = 4 * 10^24 atoms of hydrogen.
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Percocet contains oxycodone at varying strengths. Every strength also contains 325
mg of oxycodone per tablet. If the dose is not to exceed 3.9 g of oxycodone
daily, what is the maximum number of Percocet tablets a patient can take daily?
12 tablets maximum number of Percocet tablets a patient can take daily
Percocet is a prescription medicine used to treat the symptoms of acute pain and moderate-to-severe pain percocet may be used alone or with other medications percocet belongs to a class of drugs called Analgesics, Opioid Combos every strength also contains 325 this is the weakest dose of Percocet and is what most doctors will start with to help avoid side effects like respiratory depression this dosage is also used to gradually reduce Percocet dosage after dependence has developed, and to limit withdrawal symptoms percocet is a pain reliever for moderate to severe symptom over dose of percocet show side effect on body thats why 12 tablets maximum number of Percocet tablets a patient can take daily.
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Calculate the number of O atoms in 0.994 g of CaSO4 · 2H2O.
A calcium sulfate crystal weighing 0.150 grams contains 0.00523 moles of oxygen.
White crystalline calcium sulfate, or CaSO4, is a material. Calcium sulphate is hydrate in the mineral or natural substance known as gypsum. As a food additive, calcium sulfate serves as a thickener, anti-caking agent, dough conditioner, dough strengthener, flour treatment agent, and yeast food. It is a thin, odorless powder that is white or white yellow.
Crystallized calcium sulfate mass = m = 0.150 g
Crystallized calcium sulfate's molecular mass is M = 172 g/mol.
Magnesium nitrate moles are equal to n=0.150/172 g/mol = 0.000872 mol.
6 moles of oxygen atoms make up 1 mole of the calcium sulfate crystal. The calcium sulfate crystal will then have 0.004446 moles.
A calcium sulfate crystal weighing 0.150 grams contains 0.00523 moles of oxygen.
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f Earth suddenly weighed twice as much as it currently does, how would this change the tides? Explain.
Answer:
yes and no
Explanation:
mostly yes because of the gravity but we would de dead
As the weighed of the earth doubled, gravity also increases. So, there will be fewer or no high tides.
What is gravity? The force that pulls items toward the centre of a planet or other entity is called gravity. All of the planets are kept in orbit around the sun by gravity.Gravity applies to everything that has mass. Gravity is stronger for objects with higher mass. Along with distance, gravity weakens as well.The gravitational pull of two things becomes stronger the closer they are to one another. The mass of the Earth is what creates gravity. The combined gravitational force of all of its mass acts on the mass in your body. What gives you weight is that. The moon is maintained in its orbit around Earth by gravity, as are the planets in their orbits around the sun. Ocean tides are a result of the moon's gravitational effect on the oceans. The stuff that stars and planets are comprised of is pulled together by gravity to form them.To learn more about gravity, refer to
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Calculate the number of moles in 5.68 X 10^25 atoms of gold?
Answer:
196.96657 g/m
Explanation:
The molar mass of gold = 196.96657 g/m. The molar mass of gold is defined as the mass of 1 mole of gold atoms - typically specified in grams. Therefore the molar mass of gold is stated in units of grams/mole or g/m. It is also frequently called the Molecular Weight of Gold.
A student wants to measure the volume of a rock. The student should measure
the volume using?
Answer:
To measure the volume of a large rock, fill a glass measuring cup up to one half with water. Put your large rock in and measure the new water level. Subtract the original half cup volume of water and the difference is the volume or space that your rock takes up.
Answer:
if the rock is small use a measuring cylinder
Explanation:
The density of mercury is 13.6 g/mL. What is this density in lb/ft3? (1 kg =
2.2046 lb; 1 in = 2.54 cm (exact); 1 mL = 1 cm3) [This problem MUST be solved all in one
string.]
The density of mercury is 13.6 g/ml, then the density in Ib/ft³ is 21.57 Ib/ft³.
What is density?Density can be defined as the measure to how much matter is contained in a specific volume. It can also be defined as a expression of relationship between the mass and the volume.
Dimension of density are ML⁻³
1 kg = 2.2046, 1 ml = 1 cm³
Then, 13.6 g/ml = 13.6 x 2.2046 x 2.54
= 76.16 Ib/cm³ = 21.57 Ib/ft³
Thus, the density of mercury is 13.6 g/ml, then the density in Ib/ft³ is 21.57 Ib/ft³.
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The atomic mass of an element on the periodic table is based on which of the following? Explain why or why not for each answer.
a. The number of protons
b. The average atomic mass of all isotopes
c. The average number of electrons and neutrons from all isotopes
d. The number of neutrons
The correct answer to the given question is b) The average atomic mass of all isotopes is what an element’s atomic mass is based on in the periodic table.
An element has many isotopic masses, in which elements have same number of protons but different number of neutrons. An element in the periodic table has the average of all the isotopes. Atomic mass is the sum of protons and neutrons, without the involvement of electrons. For example, Chlorine has 2 isotopes Chlorine-35 having atomic mass 35 and Chlorine- 37 having atomic mass 37. The element Chlorine which is found in the periodic table has atomic mass 35.5 u, based on the average atomic masses and their relative abundance.
Therefore, atomic mass of an element on the periodic table is the average of their atomic mass of all isotopes.
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A canister with fixed volume at 97.2 kPa and 23.0°C is
to a pressure of 1.88 atm. What is the final
in the canister in degrees Celsius?
compressed
temperature
The final temperature of the canister is 312.76 degrees celsius.
The relation between temperature and pressure is given by the Gay Lusaac’s Law.
According to this law at constant volume, pressure is directly proportional to the temperature.
Mathematically it is as follows,
Pressure (P) ∝ Temperature(T)
P = K T
P/T = K(constant)
Thus the ratio of P/T will remain the same if volume remains constant.
So, P1/T1 = P2/T2
Here P1= initial pressure of the canister = 97.2 kPa = 0.95 atm
P2 = Final pressure of the canister = 1.88 atm
T1 = Initial temperature = 23 c = 296 K
T2 = Final temperature = ?
Putting these values
0.95/296 = 1.88/T2
T2 = 585.76 K or 312.6°C.
Thus, the final temperature of the canister is 312.76 degrees celsius.
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Which factor affects the temperature of ocean water?
depth
salinity
number of organisms
amount of dissolved gases
The factor affecting the temperature of ocean water among the given options is depth of the ocean.
The temperature of ocean water varies with the depth. Ocean is divided into the three layers depending on the depth. In the ocean, solar energy reflects in upper surface and rapidly gets absorbed with the depth. Upper layer has depth of around 500 m and temperature 20°C - 25°C.
Second layer is thermocline layer with relatively low temperature of water. It indicates that, the deeper you go into the ocean, less sunlight is there. Therefore, deeper oceans are colder.
Deep ocean water is around 90% of the volume of oceans. It has uniform temperature of around 0-3°C.
Temperature and depth are related in such a way that the temperature decreases when the depth increase.
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Answer:
It is A. DepthExplanation:
Hope this helps
Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?
A:Unlike all other elements, hydrogen and helium are gases
B:Unlike all other elements, hydrogen and helium are not considered metals
C:Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons
D:Unlike all other elements, hydrogen and helium have very limited properties
What makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons (option C).
What properties of hydrogen and helium makes them unique?Hydrogen and Helium are two elements in the periodic table. They are the lightest elements in the periodic table.
Also, they both exist as gases at room temperature and are the two most common elements in the universe.
However, hydrogen and helium are removed from other groups of the periodic table. Thisis because hydrogen and helium atoms only have two electrons and the outermost energy level is the first energy level, hence, there can only be two valence electrons.
Therefore, what makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.
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My water bottle contains 500 grams of water, H2O. How many moles of water is this?
Answer:
18g6.02×1023molecules=500gx. 18 g 6.02 × 10 23 molecules = 500 g x .
Explanation:
Which of the following accurately describes circuits? Question 11 options: A) In a parallel circuit, there's only one path for the current to travel. B) In a series circuit, the amount of current passing through each part of the circuit may vary. C) In a series circuit, the current can flow through only one path from start to finish. D) In a parallel circuit, the same amount of current flows through each part of the circuit.
In a series circuit, the current can flow through only one path from start to finish.
What is a circuit?The term circuit has to do with the path that current can pass through. Charge flows in a circuit in the direction that current is flowing. Also, resistors in a circuit could be connected in series or in parallel.
In a series connection, the resistors are connected end to end an current flows in one direction.
Thus, the statement that is true is that; In a series circuit, the current can flow through only one path from start to finish.
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Answer: C. In a series circuit, the current can flow through only one path from start to finish.
(just took the test so C is right)
Density measurements can be used to analyze mixtures. For example, the density of solid sand (without air spaces) is about 2.84 g/mL. The density of gold is 19.3 g/mL. If a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL (without air spaces), what is the percentage of gold in the sample?
The percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
Let S be the solid sandy mass which is inside the blend
Let G be the gold mass in such a blend
We have to find the percent G by mass
Mixture density can be calculated as
= total blend mass / total blend volume
= 3.10 g/mL
Mixture sum is
S + G = 1 Kg. = 1000g
Complete mixing volume = sand volume + gold volume
Complete mixing volume can be calculated as
=[tex](\frac{sand mass}{sand density} ) + (\frac{gold mass }{gold density} )[/tex]
Total mixture volume:-
[tex]= (\frac{S}{2.84} ) + (\frac{G}{19.3} )\\\\= \frac{(19.3 S + 2.84 G)}{54.812 mL} \\\\Mixture Density = \frac{mass mixture}{mixture volume}\\ \\= 3.10 \frac{g}{mL}[/tex]
⇒ [tex]3.10 = \frac{1000 g}{ \frac{(19.3 S + 2.84 G)}{54.812 mL}}[/tex]
[tex]19.3 S + 2.84 G = 17681\\\\When S+ G = 1000 g\\\\Solving equation:[/tex]
⇒[tex]19.3 S + 2.84 G = 17681[/tex]
∴ [tex]S + G = 1000 g[/tex]
⇒ 19.3 S + 2.84 = 17681
⇒ -2.84 S - 2.84 = -2840
________________________
⇒ 16.46 S = 14841
⇒ S = 901.7g Sand
Given,
⇒ S + G = 1000
⇒ G = 1000 - 901.7 g
⇒ G = 98.3 g Gold
Percentage of gold in the solution is
(98.3/1000) × 100 = 9.83%
Thus, we concluded that the percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.
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Which point would map onto itself after a reflection across the line y = –x?
The point that would map onto itself after a reflection across the line y = –x is (4, –4). The correct option is d.
What is a map?A point would have to be on the line in the first place for it to map onto itself following a reflection over the line.
To calculate the point on the given line, just substitute the x-values of the given points and solve for y.
There are three different x-values: -4, 0, and 4
Substituting these into y = -x
x = -4 ⇒ y = -(-4) = 4 → (-4, 4)
x = 0 ⇒ y = -(0) = 0 → (0, 0)
x = 4 ⇒ y = -(4) = -4 → (4, -4)
Therefore, the correct option is d, (4, –4).
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The question is incomplete. Your most probably complete question is given below:
(–4, –4) (–4, 0) (0, –4) (4, –4)
Mg in chlorophyll, C55H72MgN4O5 (the green pigment in plant cells)
Express your answer using five significant figures. Determine the percent, by mass, for Mg
The percent by mass of Magnesium (Mg) in chlorophyll is 2.69%.
How to calculate percent by mass?The percent by mass of an element in a compound can be calculated by dividing the atomic mass of the element by the molar mass of the compound multiplied by 100.
The molar mass of chlorophyll is as follows: 12(55) + 1(72) + 24 + 14(4) + 16(5) = 660 + 72 + 24 + 56 + 80 = 892g/mol
Percent mass of Mg = 24/892 × 100
Percent mass of Mg = 0.0269 × 100
Percent mass of Mg = 2.69%
Therefore, the percent by mass of Magnesium (Mg) in chlorophyll is 2.69%.
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Calculate the energy of an electron at n=2 in butadiene.
The energy of an electron at n=2 is determined as -3.4 eV.
What is energy level an electron?The energy level of an electron is the fixed distances from the nucleus of an atom where electrons may be found.
Energy of an electron at a known energy levelThe energy of an electron at a known energy level can be calculated using the following formula as shown below.
En = -13.6/n²
where;
n is the energy level of the electronSubstitute the given parameters and solve for the energy of the electron at the given energy level.
En = (-13.6)/(2²)
En = -3.4 eV
Thus, the energy of an electron at n=2 is determined as -3.4 eV.
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What is the density of a piece of metal that weighs 12 g and has a volume of 500 mL?
Answer:
0.024 g/mL
Explanation:
The denisty of a substance is a ratio comparing its mass per every 1 unit of volume. Therefore, if you have been given a mass in grams and a volume in milliliters, the unit for denisty (in this case) is g/mL.
Density = ? grams / ? mL
Density = 12 g / 500 mL
Density = 0.024 g/ 1 mL = 0.024 g/mL
Part C
How many grams of H₂ are needed to produce 12.13 g of NH3?
Grams of H[tex]_{2}[/tex] are needed to produced 12.13 g of NH[tex]_{3}[/tex] are 2.13 g
The balanced chemical equation is :
N[tex]_{2}[/tex] + 3H[tex]_{2}[/tex] ------> 2NH[tex]_{3}[/tex]
H = 1 g/mol and N =14 g/mol
NH[tex]_{3}[/tex] = 17 g/mol =
6g of H[tex]_{2}[/tex] ( 3×2) = 34 g of NH[tex]_{3}[/tex] (2× 17)
mass of hydrogen in coumpond ( % mass ) = 6 / 34
= 0.1764 or 17.64%
mass of H[tex]_{2}[/tex] required = % mass × mass of ammonia
= ( 0.1764 × 12.13 ) g
2.13 g
Thus , Grams of H[tex]_{2}[/tex] are needed to produced 12.13 g of NH[tex]_{3}[/tex] are 2.13 g
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Question 5
The process by which a gas condenses is referred to as
exothermic.
endothermic.
ectodermic.
exotic.
Express each of the following numbers in exponential notation:SHOW YOUR WORK
1) 10,000
2) 0.0001
3) 10,000,000,000
4)0.000 000 000 000 001
5)400,000
Answer:
1 a
2 b
3 c
4 d
5 e
Explanation:
i know is corret
What Is The hypothesis for,What Effect Does Using Plant Food Have On Plant Growth?
Answer: If the amount of fertilizer applied to plants is increased, then plant growth (height) will increase. As the amount of fertilizer increases the plant growth increases.
Explanation: It's correct
Periodic trends answer key chemistry 10th grade
Trends in modern periodic table are:
variation of valency, atomic size , metallic properties and electronegativity
Valency - number of valence electrons . Elements of each group have same number of valence electrons. So, they have the same valency.
Atomic size- It is distance from the centre of the nucleus to the valence shell of the atom.
Along the period – Atomic radius decreases as effective nuclear charge increases . It pulls valence electrons closer to the nucleusDown the group – Atomic radius increases because new shells are added , thus the distance between nucleus and valence electrons increases.Metallic properties -
Along the period – Metallic character decreases because tendency to lose valence electrons decreases due to the increasing nuclear charge.Down the group – As the distance between nucleus and outermost electron increases, nuclear pull decreases. This increases the tendency of an atom to lose valence electrons, thus metallic character increases.Electronegativity-
Along the period – Electronegativity increases as the tendency to gain electrons in valence shell increases due to increasing nuclear charge. Down the group – Since distance between the nucleus and valence shell increases, nuclear pull decreases. This decreases tendency of atom to gain an electron, thus electronegativity decreases.So we can conclude that periodic trends are specific patterns which are present in the periodic table, that illustrate different aspects of a certain element
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