The decay rate of the radioisotope on the previous morning at 10 am is 38.7 million decays per second.
Initial decay rate of the radioisotopeThe initial mass of the radioisotope is calculated as follows;
N = N₀(¹/₂)^t/h
where;
h is half life = 32 hourst is time of day, from 8 am to 10 am previous day = 22 hours24 M/s = N₀(¹/₂)^(22/32)
24 M/s = N₀(0.62)
N₀ = (24 M/s)/(0.62)
N₀ = 38.7 M/s
Thus, the decay rate of the radioisotope on the previous morning at 10 am is 38.7 million decays per second.
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I WILL MARK BRAINLIEST!!!
A 72.0-gram piece of metal at 96.0 °C is placed in 130.0 g of water in a calorimeter at 25.5 °C. The final temperature in the calorimeter is 31.0 °C. Determine the specific heat of the metal. Show your work by listing various steps, and explain how the law of conservation of energy applies to this situation.
Answer:
Approximately [tex]0.639\; {\rm J \cdot g^{-1} \cdot K^{-1}}[/tex].
Explanation:
Look up the specific heat of water:
[tex]c(\text{water}) = 4.18\; {\rm J \cdot g^{-1} \cdot K^{-1}}[/tex].
It is given that the mass of the water in this calorimeter is:
[tex]m(\text{water}) = 130.0\; {\rm g}[/tex],
The temperature of the water in this calorimeter has increased by:
[tex]\Delta T(\text{water}) = (31.0 - 25.5)\; {\rm K} = 5.5\; {\rm K}[/tex].
Thus, the energy that the water in this calorimeter absorbed would be:
[tex]\begin{aligned}& Q(\text{water})\\ =\; & c(\text{water}) \, m(\text{water}) \, \Delta T(\text{water}) \end{aligned}[/tex].
Let [tex]c(\text{metal})[/tex] denote the specific heat capacity of this piece of metal.
The mass of this piece of metal is:
[tex]m(\text{metal})[/tex].
The temperature of this piece of metal has been reduced by:
[tex]\Delta T(\text{metal}) = (96.0 - 25.5)\; {\rm K} = 70.5\; {\rm K}[/tex].
As this piece of metal cooled down, the energy it released would be:
[tex]\begin{aligned}& Q(\text{metal})\\ =\; & c(\text{metal}) \, m(\text{metal}) \, \Delta T(\text{metal})\end{aligned}[/tex].
Assuming that there is no exchange of energy between contents of this calorimeter and surroundings. By the law of conservation of energy, energy could neither be created nor destroyed.
Since energy could not be destroyed, the water in this calorimeter need to absorb the entirety of the energy that this piece of metal released. At the same, since no energy isn't created, the energy that the water absorbed would need to entirely come from this piece of metal. Therefore:
[tex]Q(\text{metal}) = Q(\text{water})[/tex].
[tex]\begin{aligned}& c(\text{water})\, m(\text{water})\, \Delta T(\text{water}) \\&= c(\text{metal})\, m(\text{metal})\, \Delta T(\text{metal}) \end{aligned}[/tex].
Rearrange and solve this equation for [tex]c(\text{metal})[/tex]:
[tex]\begin{aligned}& c(\text{metal}) \\=\; & \frac{c(\text{water}) \, m(\text{water})\, \Delta T(\text{water})}{m(\text{metal})\, \Delta T(\text{metal})} \\ =\; & \frac{4.18\; {\rm J \cdot g^{-1} \cdot K^{-1}} \times 130.0\; {\rm g} \times (31.0 - 25.5)\; {\rm K}}{72.0\; {\rm g} \times (96.0 - 25.5)\; {\rm K}} \\ \approx\; & 0.639\; {\rm J \cdot g^{-1}\cdot K^{-1}}\end{aligned}[/tex].
. Find the area of a circle with a
circumference
of 11 ( 3.14 )feel
?
Two identical metal spheres at 8 °C are put in equal amount of water in two beakers, as shown below.
Two beakers are side by side; one is labeled Beaker A and the other is labeled Beaker B. Both beakers are the same shape, size, and are about two-thirds full with water. Both beakers have a metal sphere with a temperature of eight degrees Celsius submerged in the water.
Heat flows from the metal sphere to the water in Beaker A and from the water to the metal sphere in Beaker B. Which statement is correct? (4 points)
The temperature of the water is greater than 8 °C in Beaker A.
The temperature of the water is lower than 8 °C in Beaker B.
The temperature of the water in Beaker A will increase.
The temperature of the water in Beaker B will increase.
Answer:The temperature of the water in both beakers is greater than 8 °C. in beaker B
Explanation:
When salt is mixed in water, what is the salt and water? A)salt is the solution, water is the solute. B)salt is the solvent, water is the solute. C)salt is the solute, water is the solvent. D)salt is the solvent, water the is the solution
Answer:
in a solution of salt in water, the solute is salt, and solvent is water.
Explanation:
C) salt is the solute, water is the solvent.
Answer:
C
Explanation:
:)
What is the mass of 61.9 L of oxygen gas collected at STP?
a 122 g 02
b 2.76 g 02
C 88.4 g 02
d 44.2 g 02
Answer:
D. 44.2 g O₂
General Formulas and Concepts:
Gas Laws
Stoichiometry
Dimensional AnalysisMole RatioExplanation:
Step 1: Define
Identify given.
61.9 L O₂ at STP
Step 2: Convert
We know that the oxygen gas is at STP. Therefore, we can set up and solve for how many moles of O₂ is present:
[tex]\displaystyle 61.9 \ \text{L} \ \text{O}_2 \bigg( \frac{1 \ \text{mol} \ \text{O}_2}{22.4 \ \text{L} \ \text{O}_2} \bigg) = 2.76339 \ \text{mol} \ \text{O}_2[/tex]
Recall the Periodic Table (Refer to attachments). Oxygen's atomic mass is roughly 16.00 grams per mole (g/mol). We can use a mole ratio to convert from moles to grams:
[tex]\displaystyle 2.76339 \ \text{mol} \ \text{O}_2 \bigg( \frac{16.00 \ \text{g} \ \text{O}_2}{1 \ \text{mol} \ \text{O}_2} \bigg) = 44.2143 \ \text{g} \ \text{O}_2[/tex]
Now we deal with sig figs. From the original problem, we are given 3 significant figures. Round your answer to the exact same number of sig figs:
[tex]\displaystyle 44.2143 \ \text{g} \ \text{O} \approx \boxed{ 44.2 \ \text{g} \ \text{O}_2 }[/tex]
∴ our answer is letter choice D.
---
Topic: AP Chemistry
Unit: Stoichiometry
A container with two gases, helium and argon, is 30.0% helium. Calculate the partial pressure of helium and
argon if the total pressure inside the container is 4.00 atm.
Answer:
helium=1,2atm
argon=2,8atm
Explanation:
partial is pressure exerted by each gas in a system since 30% is helium it means 70% is argon
argon =70%x4
helium=30%4
Dalton's law of partial pressure is applicable to only ideal gas not to the vanderwaal gases. The partial pressure of helium and argon is 1.2atm and 2.8atm respectively.
What is Dalton's law of partial pressure?According to Dalton's law of partial pressure, the total pressure of a mixture of gases is equal to the total sum of partial pressure of individual exerting on the walls of the container.
Mathematically,
Partial pressure=total pressure× mole fraction
Total pressure= 4.00 atm
percentage of helium = 30%=0.3
percentage of argon=100-30%=70%=0.7
Substituting the given values in above equation
Partial pressure of helium=4.00 atm× 0.3
Partial pressure of helium=1.2atm
Partial pressure of argon = 4.00 atm× 0.7
Partial pressure of argon = 2.8atm
Therefore, the partial pressure of helium and argon is 1.2atm and 2.8atm respectively.
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Which is not a conjugate acid-base pair?
Question 1 options:
H3O+ and H2O
H2O and OH-
NH3 and NH2--
NH4+ and NH3
HNO2 and H2O
Answer:
Explanation:
''A conjugate acid is formed when a proton is added to a base, and a conjugate base is formed when a proton is removed from an acid.''
In a conjugate acid-base pair, only difference between molecules is the amount of ''H''
One molecule must have 1 more H
in the last example HNO2 and H2O, difference is not only the H amount also H2O doesn't have N. So we can't say they are conjugate acid-base pair.
Sally fell off of her bike and scraped her knee. What cellular process would aid in the healing of her scrape? Group of answer choices meiosis mitosis
Answer:
Mitosis
Explanation:
you scrape your knee and the skin repairs itself
true or false. you would see a partial solar eclipse if you were within the moons penumbra.
Which of the following ions is formed when the positive hydrogen ions from an acid bond to water molecules?
H−
OH−
H2O+
H3O+
Answer:
H20 +
Explanation:
The ion that is formed when the positive hydrogen ions from an acid bond to water molecules is H₂O⁺. The correct option is C.
What are hydrogen ions?
Hydrogen is an element that is present in the first place on the periodic table, and its atom's number is 1. The nucleus of hydrogen contains only one electron, and it contains a positive 1 charge.
Hydrogen is called hydrogen ion when it participates in any chemical reactions. They become charged and participate in electron bonding to form compounds.
The positive Hydrogen ions, when forming a bond to water molecules, will be represented as H₂O⁺ because hydrogen only contains a positive charge on it. The unit positive charge on the hydrogen is the proton present in its nucleus.
Thus, the correct option is C. H₂O⁺
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Convert 65 grams of oxygen to moles
65 grams of oxygen is approximately equal to 2.03125 moles.
To convert 65 grams of oxygen to moles, we need to use the molar mass of oxygen (O₂), which is approximately 32.00 g/mol. Oxygen exists as a diatomic molecule (O₂), so we use the molar mass of O₂ to convert from grams to moles.
The formula for converting grams to moles is:
Moles = Mass (in grams) / Molar mass (in grams per mole)
Given:
Mass of oxygen = 65 grams
Molar mass of oxygen (O₂) = 32.00 g/mol
Moles of oxygen = 65 grams / 32.00 g/mol
Moles of oxygen ≈ 2.03125 moles
Therefore, 65 grams of oxygen is approximately equal to 2.03125 moles.
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What is the best reason for using iron filings (shreds) instead of an iron nail in a chemical reaction?
a) to decrease the amount catalyst during the reaction
b) to increase the molecular structure during the reactions
c) to decrease the rate of reaction
d) to increase the surface area of the reaction
The best reason for using iron filings (shreds) instead of an iron nail in a chemical reaction is to increase the surface area of the reaction.
What is rate of chemical reaction?Rate chemical reaction is the speed at the which chemical compounds react which each other. Some factors can speed up the rate of chemical reaction and they include;
ConcentrationTemperatureSurface area, etc.A large surface area provides enough medium for chemical reaction to occur and hence speeds up the rate of chemical reaction.
Thus, the best reason for using iron filings (shreds) instead of an iron nail in a chemical reaction is to increase the surface area of the reaction.
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What is the total number of moles of solute in 2.0 liters of 3.0 m naoh
a) 1.0 mole
b) 2.0 moles
c) 3.0 moles
d) 6.0 moles
Answer:
d) 6.0 moles
Explanation:
M = moles of solute/liters of solution
3 0M = x/2.0
2.0L×3 0M = x/2.0L×2.0L
6.0 moles = x
What is effect of temperature on solubility?
detail please.
In general, solids become more soluble as the temperature increases. This is why sugar dissolves better in hot water than in cold water. The table shows three examples of the solubility (g of solute per 100 g water) of substances at different temperatures.
that's my answer15. Identify What types of bonds are present in an alkyne?
Answer:
Alkyne are hydrocarbons which contain carbon-carbon triple bonds.
? Question
Given:
H₂ + Br₂ → 2HBr
Bond
Bond Energy
(kJ/mol
H-H
432
Br-Br
190
H-Br
362
Calculate the enthalpy change when hydrogen reacts with bromine.
Type the correct answer in the box. Express the answer to three significant figures e.
ΔΗ =
kj
Answer:-102
Explanation:The equation shows that 1 mole of H-H bonds and 1 mole of Br/Br vines are broken from 2 miles of H-Br bonds
Answer: -102
Explanation:
What is the wavelength of an electromagnetic wave that has a frequency of
1.82 x 1018 Hz in a vacuum? (The speed of light in a vacuum is 3.00 × 108
m/s.)
O A. 6.07 × 109 m
OB. 5.46 × 1026 m
OC. 5.49 x 10-19 m
OD. 1.65 x 10-10 m
The wavelength of an electromagnetic wave that has a frequency of 1.82 x 10¹⁸ Hz in a vacuum is 1.65 × 10-¹⁰m.
How to calculate wavelength?The wavelength of a wave can be calculated by dividing the speed of the wave by its frequency.
According to this question, a wave has a frequency of 1.82 x 10¹⁸ Hz in a vacuum and speed of light in a vacuum is 3.00 × 10⁸ m/s.
wavelength = 3 × 10⁸ ÷ 1.82 × 10¹⁸
wavelength = 1.65 × 10-¹⁰m
Therefore, the wavelength of an electromagnetic wave that has a frequency of 1.82 x 10¹⁸ Hz in a vacuum is 1.65 × 10-¹⁰m.
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Question progr
when the reactants have less enthalpy than the products, then
a. none of these
ob. the reaction will be complete
c. heat energy is given out
d. heat energy is absorbed
Compounds that contain carbon-hydrogen bonding are collectively termed.
Answer:
collectively they're known as HYDROCARBONS
formation of water: 2H2 + 102 --> 2H20
How many moles of H2O can be produced from 7 moles of H2?
Help me please Answer or I’ll report
Answer:
It takes 7 mol H2 to produce 7 mol H2O
Explanation:
In 2H2O, there's 2 moles of H2 for every 1 mol O2.
So, if oxygen is limiting you'd only be able to produce 2 moles of H2O. I don't know if the question implies that, so it could also be that 7 mol H2 makes 7 mol H2O. Sorry for the confusion, I hope it helps a bit
How many moles of hydrochloric acid are needed to react with 0.64 moles of potassium permanganate?
Answer:
5.12 moles of hydrochloric acid.
Explanation:
The balanced equation is:
2KMnO4 + 16HCl ---> 2KCL + 2MnCl2 + 5Cl2 + 8H2O
So 2 moles of potassium permanganate reacts with 16 moles of HCl.
So 0.64 moles KMnO4 react with (16/2) * 0.64
= 5.12 moles.
Why is the bermuda triangle deadly? or is it just a myth?
Answer:
Its neither a myth nor deadly
Explanation:
Bizarre hexagonal clouds forming above the Bermuda Triangle may be the reason why dozens of ships and planes have mysteriously vanished in the notorious patch of sea, according to scientists.
According to the new theory, clouds over the Bermuda Triangle are like “air bombs” strong enough to cause ship and plane wrecks. The strange “hexagonal” shaped clouds were discovered using radar satellite imagery, which were between 20 and 50 miles wide forming over the water.
At home, your parents replace your house lights with lower-watt bulbs. Is this energy conservation or energy sustainability? Explain
This is actually electricity
The replacing of house lights with lower-watt bulbs represents energy conservation not energy sustainability because energy conservation is the efficient use of energy without wasting it.
What is energy conservation?Energy conservations refer to the practice of using less energy for doing various activities. Turning off the light when you leave the room is the example of energy conservation.
So we can conclude that replacing of house lights with lower-watt bulbs represents energy conservation not energy sustainability because energy conservation is the efficient use of energy without wasting it.
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Grilling food creates a chemical compound known as benzo-[a]-pyrene; high levels of this compound are linked to the development of cancer. Therefore, benzo-[a]-pyrene is a/an
Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon found in coal tar with the formula [tex]C_{20}H_{12}[/tex].
What is the meaning of Grilling food?Grilling involves cooking food on a rack over a heat source, usually a charcoal fire or ceramic briquettes heated by gas flames.
A chemical that comes from certain substances when they are not burned completely.
Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon found in coal tar with the formula [tex]C_{20}H_{12}[/tex].
The compound is one of the benzopyrenes, formed by a benzene ring fused to pyrene, and is the result of incomplete combustion at temperatures between 300 °C (572 °F) and 600 °C (1,112 °F).
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When a chemical reaction occurs, what happens
to the atoms of the two reactants
Joanne added iron filings to copper sulphate solution. she observed the reaction after one week. what is the name of the compound formed in this reaction?
The iron filings react with copper sulfate, the copper is displaced and iron sulfate results.
Copper sulfate + Iron reactionThe reaction between iron filings and copper sulfate is represented by the equation below:
[tex]Fe + CuSO_4--- > FeSO_4 + Cu[/tex]
The iron filings displace the copper from copper sulfate to form iron sulfate. Thus, elemental copper and iron sulfate are formed.
Iron is able to displace copper from copper sulfate because iron ranks higher than copper in the reactivity series.
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Select the correct answer. what is the solution to the problem rounded to the correct number of significant figures? 8.01 × 4.1 = ? a. 32.8 b. 32.84 c. 32.841 d. 33
The solution to the problem rounded to the correct number of significant figures is 32.841. Details about multiplication can be found below.
How to multiply to correct significant figures?Multiplication is the process of computing the sum of a number with itself a specified number of times.
According to this question, a mathematical value of 8.01 is multiplied by 4.1.
8.01 × 4.1 = 32.841 (5 s.f)
Therefore, the solution to the problem rounded to the correct number of significant figures is 32.841.
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Which functional group is found in methanol? r single bond o single bond r. single bond n h subscript 2 single bond o h. r single bond x.
The functional group found in methanol is as follows: R single bond OH (R-OH). Details about methanol can be found below.
What is functional group?A functional group is a specific grouping of elements that is specific to a class of compounds, and determines the chemical properties of that class.
Each hydrocarbon or organic compound have a specific functional group characteristics of its group.
Alcohol (OH) is the functional group of certain organic compounds like methanol, ethanol etc. Therefore, the functional group found in methanol is as follows: R single bond OH (R-OH).
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Answer:
R single bond O single bond R.
Single bond N H Subscript 2
Single bond O H.
R single bond X.
Explanation:
Stacy made the following table to compare the functions of plant and animal structures, but she is missing a row title. Which of the following would best replace the X?
a table comparing the functions of different animal and plant structures. There is an unknown 'X' in the table. The skeleton in animals and the stem in plants provide support. The fur in animals and the waxy covering in plants provide protection. The ovaries in animals and the pistil in plants make 'X'
Answer:
female reproductive structures
7 Calculate What is the atomic number of a sodium atom that has 11 protons and 12 neutrons?
Answer:
22 and 24
Explanation:
neutron i is bigger thañ protons