Bromine has two naturally occurring isotopes (br-79 and br-81) and has an atomic mass of
79.904 amu. the mass of br-81 is 80.9163 amu, and its natural abundance is 49.310%. what is
the mass of br-79?
Answer: 78.919 amu
Explanation:
If the natural abundance of Br-81 is 49.310%, then the natural abundance of Br-79 must be 100%-49.310%=50.690%
Substituting into the atomic mass formula,
[tex]79.904=(0.49310)(80.9163)+(0.50690)(x)\\79.904=39.89982753+(0.50690)(x)\\40.00417247=(0.50690)(x)\\x=\frac{40.00417247}{0.50690}=\boxed{78.919 \text{ amu}}[/tex]
Which reaction occurs at the anode in an electrochemical cell?
A. Zn(s) + Cu²+ (aq)
Zn²+ (aq) + Cu(s)
B. Zn(s) Zn²+ (aq) + 2e
C. Zn²+ (aq) + Cu(s)
→
Zn(s) + Cu²+ (aq)
OD. Zn²+ (aq) + 2e →
→ Zn(s)
SUBMIT
The reaction that occur at the anode of an electrochemical cell is Zn(s) Zn²+ (aq) + 2e. The correct option is B.
What is an electrochemoical cell?An electrochemical cell has two eletcrodes present in an solution. The one electrode is anode where oxidation occurs and second is cathode hwere reduction occurs.
The reaction Zn(s) = Zn²+ (aq) + 2e due to oxidation chrage is added here.
Thus, the correct option is B. Zn(s) = Zn²+ (aq) + 2e.
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Lab: Applications of electromagnetic
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Student Guide - Electromagnets project
Answer:Not the same class but it will give u 100%
Explanation:
1. This experiment was to find how mass and speed effect KE. This is important because if you were in a situation where you needed something to go higher, you would know to add more or less of mass/speed.
To test mass, we filled the bean bag with a certain amount of water, then dropped it. After, you recorded how high it made the bean bag go. The same with speed, but same amount in the bottle, just dropped from different heights.
My hypothesis is when you have more mass, the KE will be greater. This is also the same with speed, if it is dropped from a higher place, the bean bag will launch farther than the last time.
2. Data I collected from the lab was like my hypothesis explained. When the height of the bottle increased, it made the bean bag go higher than the last. And I tested 4 different masses, 0.125 kg, 0.250kg, 0.375kg and 0.500kg. Each time the bean bag went higher on a larger mass.
A lot of times on the speed test, the bean bag would go higher than the bottle drop point, but not every time. Also, when it was dropped from the same height each time, some results varied quite a bit, like when it was dropped from 1.28 the results were 1.14 then 1.30 1.30. Mass on the other hand was all in the same number range, only once the numbers were a bit off from each other.
3. Some formulas I used were KE= ½ mv^2 and Ht v^2/2g. The first was to calculate the kinetic energy of an object, m=mass v=speed. Second was for finding out what height I needed to drop something to reach a certain speed, Ht=Height and g= Gravitational Acceleration of 9.8 m/s^2.
I used these to figure out tables that showed relationships between different things like mass and KE or speed and height. The whole time I was doing the lab, my data was going up, when there was more mass/speed there were higher values in the table.
This means that my hypothesis at the beginning was correct, more of m/s means KE will increase proportionally because they are all linear. I found it surprising when the bean bag height went over the water bottle drop mark.
4. To conclude, my hypothesis matched my data. The data values went up when more mass or speed was added. This means if I were in a situation where I needed more kinetic energy for something, I would know to increase mass or the speed of the object giving it energy.
The reason that this hypothesis is correct is when you have more mass, you have more energy. So, when you drop let's say a baseball, it isn’t that heavy so it would only launch the bean bag so far. But a bowling ball is very heavy and has lots of energy when falling because of that, it would make the bean bag go very high.
To make this experiment better, I would use a smoother material for the lever so energy wouldn’t be lost by friction from wood rubbing together. Also, maybe a scanner or video camera to more accurately record how far the bean bag went. All of these would help the lab get more precise results, maybe they could be used in a future lab.
Gas Law- please help!!!
In a mixture of carbon dioxide and oxygen, 40.0% of the gas pressure is exerted by oxygen. If the total pressure is 115 mmHg, what is the pressure of the carbon dioxide in
atm?
The pressure of the carbon dioxide will be 0.09079 atm.
What is partial pressure?The pressure exerted by the individual gas is known as partial pressure.
The partial pressure is given as
[tex]\rm P_{Total} = P_1 + P_2 + ...[/tex]
In a mixture of carbon dioxide and oxygen, 40.0% of the gas pressure is exerted by oxygen.
If the total pressure is 115 mmHg.
The total pressure in atm will be
P = 115 mmHg
P = 0.15132 atm
We have
[tex]\rm P_T \ \ \ = P_{O_2} + P_{CO_2}\\\\0.15132 \ \ = 0.4 \times 0.15132 +P_{CO_2}\\\\ P_{CO_2} = 0.09079\ atm[/tex]
Then the pressure of the carbon dioxide will be 0.09079 atm.
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At what temperature would 0.46 moles of a gas occupy 13.3 L if the pressure is 734 mm Hg?
Answer: 339.84 K
Explanation:
[tex]$$We are given: \\$\mathrm{n}=0.46$ moles \\$V=13.3 \mathrm{~L}$\\$\mathrm{P}=734 \mathrm{~mm} \mathrm{Hg}=0.965 \mathrm{~atm}$\\Putting these values in ideal gas equation we get:\\$0.965$ batm * $13.3 \mathrm{~L}=0.46 \mathrm{~mol} * 0.0821 \frac{\mathrm{atmL}}{\mathrm{molK}} * \mathrm{~T}$\\$\mathrm{T}=\frac{0.965 * 13.3}{0.46 * 0.0821} \mathrm{~K}$$$\mathrm{T}=339.84 \mathrm{~K}$$[/tex]
Which statement best describes an advantage of describing a system with a mathematical model?
A.
It enables people to calculate how a change in one variable will affect other variables.
B.
It helps people visualize the way that systems are interconnected.
C.
It simplifies the system by describing only one variable at a time.
D.
It allows people to manipulate something that looks like the actual system.
An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.
Describes an advantage of a system with a mathematical model?A mathematical model usually describes a system by a set of variables and equations that formed relationships between the variables. Variables examples such as real or integer numbers.
So we can conclude that An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.
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The rate law for the reaction 3a ⟶⟶ c is rate = 4. 36 x 10–2 l • mol–1 • h–1[ a ]2 how long will it take in hours for the concentration of a to decrease from 0. 74 m to 0. 21 m?
The hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.
What is the rate law of a reaction?Rate law depicts the rate of a chemical reaction depend on the concentration of the reactant.
The given reaction is second order reaction
Thus, the hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.
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Describe the method you could use to investigate the volume of hydrogen produced during the electrolysis of sodium chloride.
Answer:
Gas tests include:
hydrogen - lighted splint goes out with a squeaky pop.
Explanation:
what is the specific heat capacity of propan-1-ol
Answer:
11–350°
Explanation:
Question 11
The modern periodic table is arranged by increasing atomic number of the elements.
O True
O False
Answer:
True
Explanation:
Answer:
Explanation:
Remark
It's true.
That's how the periodic table is designed. Hydrogen is #1 and #116 is the latest entry. It is known as flerovium and livermorium. I'm not sure if that and shouldn't be an or, but that is your answer.
phase changes lab, please! I need help fast deadline is really close.
Phase change occur in substances when the they change from one state of matter to another due to the addition or removal of heat.
What are phase changes?Phase changes refers to the changes that occur in substances in which they change from one state of matter to another due to the addition or removal of heat.
The phase changes that occur in substances are as follows:
change from solid to liquid known as meltingchange from liquid to gas known as vaporization change from solid to gas known as sublimation change from gas to solid known as deposition change from gas to liquid known as condensation change from liquid to solid known as freezingTherefore, phase change occur in substances when the they change from one state of matter to another due to the addition or removal of heat.
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What will be the efficiency of a machine which has an energy loss of 10%
The efficiency of the machine which has an energy loss of 10% is 90%
What is efficiency?This can be defined as the capacity to achieve a given task with little or no waste. Mathematically, it can be expressed as
Efficiency = (output / input) × 100
How to determine the efficiencyWe shall assume the following:
Input = 100 JOutput = 100 – 10 = 90 JEfficiency =?Efficiency = (output / input) × 100
Efficiency = (90 / 100) × 100
Efficiency = 90%
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What does Fe(NO3)2 + Cu stands for?
Suppose that 5-ml containers of helium (He), neon (Ne), and argon (Ar) are at pressures of 1 atm,
2 atm, and 3 atm, respectively. The He and Ne are then added to the container of Ar.
a. What is the partial pressure of He in the container after the three gases are mixed?
b. What is the total pressure in the container after the three gases are mixed?
The total pressure in the container after the three gases are mixed is 6 atm and the partial pressure of He is 1 atm.
What is Dalton's Law of Partial Pressure ?According to Dalton's Law of Partial Pressure , the pressure exerted by a mixture of gas is equal to the sum of the partial pressure of the gases in the mixture.
P(total) = p₁ +p₂+p₃+.....
As the volume of the containers are same and the
n = 1*5/RT for Helium
n = 2*5 /RT for Neon
n= 3*5/RT for Argon
Mole fraction = moles of the element/Total moles
Moles fraction of Helium is
[tex]\rm \dfrac{1*5}{1*5+2*5+3*5}[/tex]
= 1/6
Total Pressure in the container = 1 + 2 +3 = 6 atm
The partial pressure of Helium will be
=Mole fraction * Total pressure
=(1/6)*6 atm
= 1 atm , as the volume is same the temperature is same , the pressure will also be same.
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What is the molar mass of H₂CO₂?
Answer:
I think the Molar mass of H₂CO₂ should be 62..
Explanation:
I'm not too sure tho... Hope this helps!
calculate the molarity of 65.3 grams of sugar(342.3 g/mol), c12h22011 in 750 ml of solution.
Answer:
0.254 M
Explanation:
If the formula mass of sugar is 342.3 g/mol, and there are 65.3 g, then there are 65.3/342.3=0.190768 mol.
Also, 750 mL = 0.750 L.
molarity = (moles of solute)/(liters of solution)
molarity = 0.190768/0.750 = 0.254 M
The total mass of the reactants is equal to the total mass of products. this is known as the conservation of what?
Explanation:
the law of conservation of mass
Answer:
Explanation:
the law of conservation of mass
ILL GIVE BRAINLY!!!!!!
How many different elements are involved in the reaction shown below?
CH4 + 2 O2 → CO2 + 2 H2O
Answer:
four
Explanation:
There is four
CH 4 methane
O2 oxygen
CO2 carbon dioxide
H20 water
The volume of a gas is 6.10 l, measured at 1.50 atm. what is the pressure of the gas in
mmhg if the volume is changed to 9.74 l?
Answer:
713.96mmhg
Explanation:
p1v1=p2v2
6.10×1.50/9.74
=0.939atm
=0.939*760
=713.96mmhg
how do you treat a sulfuric acid burn with sodium hydroxide
What causes atoms to form covalent bonds?
Answer:
to attain stability atoms form covalent bonds
As you move upward, from level, in an energy pyramid, available energy ____.
1. is destroyed
2. decreases
3. stays the same
4. increases
The available energy decreases as one moves upward in an energy pyramid.
Energy pyramidThe energy pyramid represents a model of how energy is transferred from one trophic level to another in ecosystems.
Energy is transferred from producers to primary consumers, from primary to secondary consumers, from secondary to tertiary consumers, and so on.
Only about 10% of the available energy in one trophic level is transferred to the next with the remaining 90% being lost as heat to the environment.
Thus, as one moves up the energy pyramid, the available energy decreases. This is why organisms at the higher end of the energy pyramid have to devise an efficient way of extracting energy from their foods.
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Among K, Ca and Ba, which element possess low ionization energy?
Among the elements Barium has the lowest Ionization Energy.
What is Ionization Process ?The process by which any neutral atom gets converted into electrically charged by gaining or losing electron is called Ionization Process.
K is an alkali metal it has to lose one electron to attain stable electronic configuration of an inert gas
For removing second electron , a stable configuration has to be broken and so will require high amount of energy.
Ca and Ba are alkaline earth metals.
They both have to lose 2 electrons to attain stable electronic configuration of noble gas.
They have low Iow Ionization Energy as compared to K.
Ca has higher Ionization Energy as compared to Ba because when we move down the periodic table , The ionization energy decreases.
Hence , Among the elements Barium has the lowest Ionization Energy.
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please help meeeeeeeee
3.
Explanation:
all Chemical mixtures have the same amount of numbers making them all balanced.
(that's the simple way of putting it, but hoped it helped ✌)
If you have 3 moles of gas at a pressure of 2.5 atmospheres and a volume of 8 liters, what is the temperature? Pay attention to the unit of pressure used.
A.) 81.27 K
B.) 0.81 K
C.) 57.86 K
D.) 25 K
The temperature of the gas would be 81.2 K
Ideal gas equationThe ideal gas equation is given by:
PV = nRT, where P, V, n, R, and T equals pressure, volume, number of moles, constant, and temperature respectively.
In this case, V = 8L, n = 3 moles, R = 8.317, and P = 2.5 atm or 253.3125 kpa
T = PV/nR = 253.3125 x 8/3 x 8.317 = 2026.5/24.951 = 81.2 K
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The general form AB àA + B represents which type of reaction?
Answer:
hope this helps and if you have any questions please feel free to ask me any time
Does anyone know what 5.7365 x 10^-5 + 3.4891 x 10^-8 is? in scientific notation preferably?
Answer:
5.7400 × 10⁻⁵
Explanation:
A 10.00 g sample of wood from an archaeological site produced 3072 counts in a 10-hour measurement owing to the presence of carbon-14, while a 10.00 g sample of new wood produced 9216 counts in the same period of time. The half-life of carbon-14 is 5730 years. How old is the wood from the archaeological site
From the calculation, the age of the sample of carbon - 14 is 9156 years.
What is radioactivity?The term radioactivity refers to the fact that a substance could disintegrate spontaneously when left alone.
Now, given that;
0.693/t1/2 = 2.303/t log (No/N)
t1/2 = half life
t = age of the sample
No = amount of sample originally present
N = amount of sample present at time t
Hence;
0.693/5730 = 2.303/t log (9216/3072)
1.2 * 10^-4 = 2.303/t * 0.4771
1.2 * 10^-4 = 1.09876/t
t = 1.09876/1.2 * 10^-4
t = 9156 years
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A sample of gas occupies 300 mL at 100K. What is its volume when the
temperature is increased to 200K? (P and n= constant)
If the temperature of the sample of gas increases to the given value, the volume also increases to 600mL.
What is Charles's law?
Charles's law states that "the volume occupied by a definite quantity of gas is directly proportional to its absolute temperature.
It is expressed as;
V₁/T₁ = V₂/T₂
Given the data in the question;
Initial temperature of gas T₁ = 100KInitial volume of gas V₁ = 300mLFinal temperature T₂ = 200KFinal volume V₂ = ?V₁/T₁ = V₂/T₂
V₂ = V₁T₂ / T₁
V₂ = ( 300mL × 200K ) / 100K
V₂ = 60000mLK / 100K
V₂ = 600mL
Therefore, if the temperature of the sample of gas increases to the given value, the volume also increases to 600mL.
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A base is a substance that can __________ a hydroxide ion.
Answer:
An Arrhenius base is a substance that dissociates in water to form hydroxide (OH–) ions. In other words, a base increases the concentration of OH– ions in an aqueous solution.