Answer: thats alot of reading
Explanation:
calculate the amount of I - 125 that remains after 178.2 days if we started with 300 grams.
Answer:
38.3 g
Explanation:
The half life of a substance is the time taken for the substance to decay to about half of its amount.
Let us assume that I-125 have a half life of 60 days. It means that every 60 days, the amount of I - 125 would be halved.
The amount of I - 125 (A) that remains after t days is given by:
[tex]A=A_o*\frac{1}{2^n} \\[/tex]
Where Ao is the initial amount and n = t / half life
Given that:
Ao = 300 g, t = 178.2 days.
Therefore n = t / half life = 178.2 days / 60 days = 2.97
[tex]A=A_o*\frac{1}{2^n} \\A=300*\frac{1}{2^{2.97}}\\ A=38.3\ g[/tex]
How many moles of zinch oxide can be produced from 275 of zinc?
Answer:
[tex]\large \boxed{\text{4.21 mol}}[/tex]
Explanation:
We must do the conversions :
mass of Zn ⟶ moles of Zn ⟶ moles of ZnO
We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.
Mᵣ: 65.38
Zn + … ⟶ ZnO + …
m/g: 275
(a) Moles of Zn
[tex]\text{Moles of Zn} = \text{275 g Zn}\times \dfrac{\text{1 mol Zn}}{\text{65.38 g Zn}} = \text{4.206 mol Zn}[/tex]
(b) Moles of ZnO
The molar ratio is 1 mol ZnO:1 mol Zn
[tex]\text{Moles of ZnO} =\text{4.206 mol Zn} \times \dfrac{\text{1 mol ZnO}}{\text{1 mol Zn}} = \text{4.21 mol ZnO}\\\\\text{The reaction produces $\large \boxed{\textbf{4.21 mol}}$ of ZnO}[/tex]
PLEASE HELP ME OUTTTT
How many grams of Fe3O4 are required to react completely with 54.29 grams of H2?
Fe3O4 + H2 → Fe + H2O
Answer:
Balance the equation
Fe3O4 + 4H2---> 3Fe +4H2O
Molar mass H2=(2*1)=2g/mol
Mass of H2=54.29grams
mole of H2= 54.29/2=27.15mol
4 mol of H2 = 1 mol Fe3O4
27.15mol of H2= 6.79mol of Fe3O4
Moles of Fe3O4 =6.79mol
Molar mass of Fe3O4= (56×3)+(16×4)
=168+64=232g/mol
Grams of Fe3O4 required to react with 54.29 grams of H2 is 232g/mol× 6.79mol
=1575.28g
A sample of octane undergoes combustion according to the equation 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ. What mass of O2 (in grams) must react in order to generate 7280 kJ of energy?
Answer:
[tex]\large \boxed{\text{528.7 g} }[/tex]
Explanation:
It often helps to write the heat as if it were a reactant or a product in the thermochemical equation.
Then you can consider it to be 11018 "moles" of "kJ"
We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.
M_r: 32.00
2C₈H₁₈ + 25O₂ ⟶ 16CO₂ + 8H₂O + 11 018 kJ
n/mol: 7280
1. Moles of O₂
The molar ratio is 25 mol O₂:11 018 kJ
[tex]\text{Moles of O}_{2} = \text{7280 kJ} \times \dfrac{\text{25 mol O}_{2}}{\text{11 018 kJ}} = \text{16.52 mol O}_{2}[/tex]
2. Mass of O₂
[tex]\text{Mass of C$_{8}$H}_{18} = \text{16.52 mol O}_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol O}_{2}} = \textbf{528.6 g O}_{2}\\\text{The reaction requires $\large \boxed{\textbf{528.67 g O}_{2}}$}[/tex]
What does the law of conservation of matter show?
A. That the total number of atoms in matter will never change.
B. That matter can never change form.
C. That atoms will combine in the simplest possible arrangement.
D. That atoms in matter can never be rearranged.
Answer: A) That the total number of atoms in matter will never change.
Explanation: Matter cannot be destroyed nor created. Matter is made up of atoms. The amount of atoms in an object will never change, even when changed into a different form.
Ex. When ice cubes melt there is still the same amount of water just in a different form.
Answer:
A
Explanation:
When there is unequal sharing between two atoms of the electrons in a bond, which
type of bond is it?
Answer:
polar covalent bond
Explanation:
Molybdenum metal requires a photon with a minimum frequency of 1.09x1015s-1before it can emit an electron via the photoelectric effect.
a) What is the minimum energy needed to eject an electron?
b)What wavelength of radiation (in nm) will provide a photon of this energy?
c)How many electrons can be freed by a burst of radiation whose total energy is 1.00 μJ, assuming one photon causes one electron to be freed? (μ= micro = 10-6)
d) If molybdenum is irradiated with light of 122nm, what is the maximum kinetic energy of the emitted electrons?
Answer:
a) 7.22 × 10⁻¹⁹ J; b) 275 nm; c) 1.38× 10¹² electrons; d) 9.1 × 10⁻¹⁹ J
Explanation:
a) Minimum energy to eject photon
E = hf = 6.626× 10⁻³⁴ J·s × 1.09 × 10¹⁵ s⁻¹ = 7.22 × 10⁻¹⁹ J
b) Wavelength required
fλ = c
[tex]\lambda = \dfrac{c}{f } = \dfrac{2.998 \times 10^{8}\text{ m/s}}{1.09 \times 10^{15}\text{/s}} = 2.75 \times 10^{-7} \text{ m} = \textbf{275 nm}[/tex]
c) Electrons required
[tex]\text{No. of electrons} = 1.00 \times 10^{-6}\text{ J} \times \dfrac{\text{1 electron}}{7.22 \times 10^{-19}\text{ J}} = 1.38 \times 10^{12}\text{ electrons}[/tex]
d) Kinetic energy of electrons
a) Energy of photon
[tex]E = hf = \dfrac{\text{hc}}{\lambda} = \dfrac{6.626 \times 10^{-34} \text{ J$\cdot$ s}\times 2.998 \times 10^{8} \text{ m/s}}{122 \times 10^{-9}\text{ m}}= 1.63 \times 10^{-18} \text{ J}[/tex]
b) Maximum kinetic energy
The equation for the photoelectric effect is
hf = φ + KE, where
φ = the work function of the metal — the minimum energy needed to eject an electron
KE = hf - φ = 1.63× 10⁻¹⁸ J - 7.22× 10⁻¹⁹ J = 9.1 × 10⁻¹⁹ J
a. The energy of molybdenum to eject electron has been [tex]\rm \bold{7.22\;\times\;10^{-19}}\;J[/tex].
b. The wavelength of the radiation has been 275 nm.
c. The number of electrons present in [tex]\rm 1\;\mu J[/tex] energy has been [tex]\rm \bold{1.38\;\times\;10^1^2}[/tex].
d. The kinetic energy of the emitted electrons as been [tex]\rm \bold{9.1\;\times\;10^-^1^9\;J}[/tex].
The metal emits the energy when it returns from the excited state to ground state.
a. The energy (E) to eject electron has been given by:
[tex]E=h\nu[/tex]
Where, the value of constant, [tex]h=6.626\;\times\;10^{-34}\;\rm J.s[/tex]
The value of frequency has been given, [tex]\nu=\rm 1.09\;\times\;10^{15}\;s^{-1}[/tex]
Substituting the values for energy:
[tex]E=6.626\;\times\;10^{-34}\;\times\;1.09\;\times\;10^{15} \rm J\\\textit E=7.22\;\times\;10^{-19}\;J[/tex]
The energy of molybdenum to eject electron has been [tex]\rm \bold{7.22\;\times\;10^{-19}}\;J[/tex].
b. The wavelength ([tex]\lambda[/tex]) of the radiation has been given by:
[tex]\lambda=\dfrac{c}{\nu}[/tex]
Where, the speed of light, [tex]c=3\;\times\;\rm m/s[/tex]
The frequency has been given as, [tex]\nu=1.09\;\times\;10^{15}\;\rm s^-^1[/tex].
Substituting the values for wavelength:
[tex]\lambda=\dfrac{3\;\times\;10^8}{1.09\;\times\;10^{15}}\;\rm m\\ \lambda=2.75\;\times\;10^-^7\;m\\\lambda=275\;nm[/tex]
The wavelength of the radiation has been 275 nm.
c. The electrons ([tex]e^-[/tex]) burst out can be given as:
[tex]e^-=\dfrac{E}{E'}[/tex]
Where, the energy of radiations, [tex]E=1\;\times\;10^{-6}\;\rm J[/tex]
The energy of each electron has been calculated as, [tex]E'=7.22\;\times\;10^{-19}\;\rm J[/tex]
Substituting the values for number of electrons:
[tex]e^-=\dfrac{1\;\times\;10^-^6}{7.22\;\times\;10^-^1^9} \\e^-=1.38\;\times\;10^1^2[/tex]
The number of electrons present in [tex]\rm 1\;\mu J[/tex] energy has been [tex]\rm \bold{1.38\;\times\;10^1^2}[/tex].
d. The maximum kinetic energy (K.E.) of the radiation has been given as:
[tex]K.E.=\dfrac{hc}{\lambda} -E^'[/tex]
Where, the value of constant, [tex]h=6.626\;\times\;10^{-34}\;\rm J.s[/tex]
The speed of light, [tex]c=3\;\times\;\rm m/s[/tex]
The wavelength of the radiation, [tex]\lambda=122\;\times\;10^-^9\;\rm m[/tex]
Energy of each electron, [tex]E'=7.22\;\times\;10^{-19}\;\rm J[/tex]
Substituting the values, for kinetic energy:
[tex]K.E.=\dfrac{6.626\;\times\;10^{-34}\;\times\;3.0\;\times\;10^8}{122\;\times\;10^-^9}\;-\;7.22\;\times\;10^-^1^9\;\rm J \\\textit {K.E.}=9.1\;\times\;10^{-19}\;J[/tex]
The kinetic energy of the emitted electrons as been [tex]\rm \bold{9.1\;\times\;10^-^1^9\;J}[/tex].
For more information about photoelectric effect, refer to the link:
https://brainly.com/question/9260704
how many grams of H20 will be produced by 18g H2
Answer:
160.86 g to the nearest hundredth.
Explanation:
H2 + O ---> H2O
2.016 g H2 produces 18.016 g H2O
1g .. .. .. .. .. 18.016 / 2.016 g H2O
18g .. .. .. .. .. . . (18.016 * 18) / 2.016 g H2O.
= 160.86 g.
review the types of elements that create ionic bonds as
well as the types of elements that create covalent bonds.
• N2 • CCl4 • SiO2
• AlCl3 • CaCl2 • LiBr
Answer:
N2 Covalent
CCl4 Covalent
SiO2 Covalent
AlCl3 Covalent
CaCl2 Ionic
LiBr Covalent
Explanation:
With covalent bonds, there is a sharing of electron pairs between the atoms.
With ionic bonds, there is complete transfer of valence electrons between atoms. Formed by the interaction of a metal with a non-metal.
Where:
Electrons aren't transferred in covalent bonds.
Protons aren't transferred in covalent bonds
Protons aren't shared in covalent bonds
N3-
C4+
Cl-
Si4+ = Metal
O2- = Non-metal
Al3+ = Metal
Li+ = Metal
Ca2+ = Metal
Br 1-, 1+, 5+ = Halogen
N2 = N3- and N3- Covalent
CCl4 = C4+ and Cl- x4 Covalent
SiO2 = Si4+ and O2- x 2 Metal with non metal Covalent
AlCl3 = Al3+ and Cl- x 3 Covalent Though this one is complex as to why because it seems like it should be ionic
CaCl2 = Ca2+ and Cl- x 2 Metal with non-metal Ionic
LiBr = Li+ and Br- Covalent as neither is a non-metal
The use of nuclear energy can have both positive and negative consequences. Which of the following is a positive consequence of using nuclear energy? a. Nuclear energy uses nonrenewable resources. b. Nuclear energy produces little air pollution. c. Uranium ore used for nuclear power plants must be mined and processed. d. Nuclear energy has no environmental impact. Please select the best answer from the choices provided A B C D
Answer
its B
Explanation:
B.
Nuclear energy produces little air pollution.
The volume of a gas is 450 mL when its pressure is 1.00 atm. If the temperature of the gas does not change, what is the
pressure when its volume is changed to 2.00 L?
Use PV = P2V2.
0.225 atm
O 0.444 atm
O 2.25 atm
O 4.44 atm
Answer: 0.225 atm
Explanation:
For this problem, we have to use Boyle's Law.
Boyle's Law: P₁V₁=P₂V₂
Since we are asked to find P₂, let's manipulate the equation.
P₂=(P₁V₁)/V₂
[tex]P_{2} =\frac{(1.00atm)(0.45L)}{2.00L}[/tex]
With this equation, the liters cancel out and we will be left with atm.
P₂=0.225 atm
Which of the following represents a 1.00 M (M = mol/dm3) aqueous solution of glucose (C6H12O6)?
A. 180 g glucose per 1000 cm3 solution
B. 10.0 g glucose per 10.0 cm3 water
C. 90.0 g glucose per 500 cm3 water
D. 0.100 g glucose per cm3 solution
What is the best example of electromagnetic energy in everyday life
Answer:best
Explanation:
Best
Which molecule is an alkyne?
A. 2-ethylhexane
B. 2-nonyne
C. trans-2-pentene
D. Pentane
Answer:Ethyne
Explanation:
Ethyne is more commonly known under the trivial name acetylene. It is the simplest of the alkynes, consisting of two carbon atoms connected by a triple bond, leaving each carbon able to bond to one hydrogen atom. Since both carbon atoms are linear in shape, all four atoms lie in a straight line.
2-nonyne molecule is an alkyne. Hence, option B is correct.
What is alkyne?Alkynes are groups of hydrocarbons that have the general formula of {Cn H2n - 2}. They have a triple carbon-to-carbon bond (C≡C) in their structure. Ethyne (HC≡CH) is the first member of the alkyne series.
Ethyne is more commonly known under the trivial name acetylene. It is the simplest of the alkynes, consisting of two carbon atoms connected by a triple bond, leaving each carbon able to bond to one hydrogen atom.
Since both carbon atoms are linear in shape, all four atoms lie in a straight line.
Hence, option B is correct.
Learn more about alkyne here:
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When potassium chromate (K2CrO4) is added to a solution containing 0.500 g silver nitrate (AgNO3), solid silver chromate (Ag2CrO4) is formed. a) Determine the theoretical yield.
Answer:
Theoretical Yield = 0.4882 grams
Explanation:
Potassium Chromate = K2CrO4 Molar mass: 194.1896 g/mol
Silver Nitrate = AgNO3 Molar mass: 169.87 g/mol
Silver(I) Chromate = Ag2CrO4 Molar mass: 331.73 g/mol
Potassium Nitrate = KNO3 Molar mass: 101.1032 g/mol
K2CrO4 + 2AgNO3 = Ag2CrO4 + 2KNO3
Potassium Chromate + Silver Nitrate = Silver(I) Chromate + Potassium Nitrate
Ratio 1:2 = 1:2
0.5g AgNO3
AgNO3 Molar mass: 169.87 g/mol
2AgNO3 = 339.74grams
0.5/339.74 = 0.0014717
Ag2CrO4 Molar mass: 331.73 g/mol
0.4882 grams
Theoretical Yield = 0.4882 grams
Consider the unbalanced equation for the oxidation of butene. C4H8 + 6O2 CO2 + H2O For each molecule of C4H8 that reacts, how many molecules of carbon dioxide and water are produced?
two carbon dioxide molecules and two water molecules
four carbon dioxide molecules and four water molecules
two carbon dioxide molecules and four water molecules
four carbon dioxide molecules and two water molecules
Answer: Four carbon dioxide molecules and four water molecules
Explanation:
Answer:
D: four carbon dioxide molecules and two water molecules
Explanation:
There are four carbon dioxide molecules (CO₂) on the right side of chemical reaction, because there are four carbon atoms on the left side of balanced chemical reaction.
There are four water molecules (H₂O) on the right side of chemical reaction, because there are eight hydrogen atoms on the left side of balanced chemical reaction.
Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason?
Ava’s best friend has an indoor cat. Ava notices that she sneezes every time that she visits her friend. Ava suspects that she is allergic to cats but is unsure. What is the best thing for Ava to do next?
C) Test her suspicion by going to see an allergist to diagnose the allergy.
It's right
what are the steps to go from the names of compounds to the formulas
Answer:
Explanation:
write down the formulas, use the expressions and formulas to convert
An independent country in which people share a common culture is called
an aristocracy.
an ethnic group.
a nation-state.
a polity.
PLease help
TRUE OR FALSE
As the human population increases, demand for natural resources will also increase.
What happens at the particle level during a chemical reaction?
Answer:
Reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.RT
Explanation:
If 11 moles of A are combined with 16 moles of B and the reaction occurs to the greatest extent possible, how many moles of C form?
Unscramble the following words to form a complete sentence about the cycles of nature:
limited is through environment Matter recycled the on Earth is and
Answer: idk I have that question too , sorry to get ur hopes up high thinking this was an answer. PERIOTTTT
Explanation:
When 100 g of 20°C water is mixed with 50 g of 50°C water in a closed system, what is the final water
temperature?
A 20°C
B) 30°C
C) 35°C
D50°C
The final temperature of a mixture of 100g of water at 20°C and 50g of water at 50°C is 30°C.
What is the principle of method of mixtures ?
The amount of heat lost by the hotter sample = The amount of heat gained by the cooler water sample
The amount of heat gained by the cooler water sample is: -
Q1₁= m₁c(T – T₁)
The amount of heat lost by the hotter water sample is: -
Q₂ = m₂c(T₂ - T)
Q₁ = Q₂
m₁c(T – T₁) = m₂c(T₂ - T)
T = (m₁T₁ + m₂T₂)/(m₁+ m₂)
Let the final temperature of the mixture of 100g of water at 20°C and 50g of water at 50°C be T.
m₁ = 100g
T₁ = 20°C
m₂ = 50g
T₂ = 50°C
The final temperature of water = (100*20+50*50)/(100+50)
= (2000+2500)/(150)
=4500/150
=30°C
Therefore , the final temperature of a mixture of 100g of water at 20°C and 50g of water at 50°C is 30°C.
To know more about method of mixtures
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4. What is the name of A13+?
A)Aluminum ion
B)Aluminum
C)Aluminous ion
D)Aluminide ion
Answer:
Aluminum ion
Explanation:
I used Google tbh but it has a higher charge then a regular Aluminum atom
What is thought to be another cause of the large size of our brain compared to chimpanzees?
Answer:
Compared to early humans our brains seemed to have increased in size, and part of the cause may be because of things like Climage change, ecology and social competition
Explanation:
explain how redox reactions are the source of electron flow in batteries. how can a dead battery be said to have attained equilibrium?
Answer:
can u help me whith one of my qutions
Explanation:
Neutrons are in the nucleus of the atom. A neutron has
a) A positive charge
b) No charge
c) A negative charge
d) Twice as much positive charge as a proton
Answer: B. (No charge)
Explanation:
Protons have a positive charge, electrons have a negative charge.
Neutrons are neutral and therefore have no change.
How many grams of LiNO2 are required to make 250 mL of 0.75 Molarity solution?
Answer:
159 g OF LiNO2 WILL BE USED TO MAKE 0.25 L OF 0.75 M SOLUTION.
Explanation:
How many grams of LiNO2 are required to make 250 mL of 0.75 M?
First calculate the molarity in mol per dm3
0.75 M of LiNO2 reacts in 250 mL = 250 /1000 L volume
0.75 M = 0.25 L
In 1 L, the molarity of LiNO2 will be:
= (0.75 * 1/ 0.25) M
= 3 mol/dm3 of LiNO2
Next is to calculate the molarity in g/dm3:
Molarity in mol/dm3 = molarity in g/dm3 / RMM.
RMM of LiNO2
(Li = 7 , N =14 , 0 = 16)
RMM = ( 7 + 14 + 16 * 2) = 53 g/mol
Molarity in mol/dm3 = Molarity in g/dm3 / RMM
Molarity in g/dm3 = Molarity in mol/dm3 * RMM
Molarity in g/dm3 = 3 * 53
Molarity in g/dm3 = 159 g/dm3.
So therefore, to make 250 mL of 0.75 M of LiNO2, we use 159 grams of LiO2.
