Answer:
A unit of substance that contains the Avogadro number of atoms or molecules is referred to as a mole of the substance.
Explanation:
The mole (symbol: mol) is the unit of measurement for amount of substance in the International System of Units (SI). A mole of a substance or a mole of particles is defined as exactly 6.02214076×1023 particles, which may be atoms, molecules, ions, or electrons. In short, for particles, 1 mol = 6.02214076×1023.
Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a supposedly active substance, X, with a molarity of 0.10 molL1 . Then you dilute 10. mL of that solution by doubling the volume, doubling it again, and so on, for 90 doublings in all. How many molecules of X will be present in 10. mL of the fi nal solution? Comment on the possible health benefi ts of the solution.
Answer:
a. 4.865 × 10⁻⁷ molecules. b. The possible health benefits of the drug might be minimal or non-existent.
Explanation:
a. Since we have 0.10 mol/L and 10 mL of solution, the number of moles in 10 mL of solution is n = CV where C = concentration and V = Volume. C = 0.10 mol/L and V = 10 mL = 0.01 L.
So n = CV = 0.10 mol/L × 0.01 L = 0.001 mol.
Since the initial volume of the solution is 10 mL and doubled, it is 2 × 10 mL = 20 mL. It is doubled again to 2 × 20 mL = 40 mL. It is doubled again to 2 × 40 mL = 80 mL. Our third doubling is thus 80 mL = 2 × 2 × 2 × 10 mL = 2³ × 10 mL. So the volume for our nth doubling is V = 2ⁿ × 10 mL. So four our 90 th doubling, the volume is V = 2⁹⁰ × 10 mL = 2⁹⁰ × 10 mL
Since we have 0.001 mol present, the concentration in this new volume is thus C' = 0.001 mol/2⁹⁰ × 10 mL.
So the number of moles in 10 mL of this solution is thus n = 0.001 mol/(2⁹⁰ × 10 mL) × 10 mL = 0.001/2⁹⁰ mol
To find the number of molecules of X present we use, number of moles, n = number of molecules, N/Avogadro's number of molecules, N'
n = N/N'
N = nN'
= 0.001/2⁹⁰ mol × 6.022 × 10²³ molecules/mol
= 8.078 × 10⁻³¹ × 6.022 × 10²³
= 48.65 × 10⁻⁸
= 4.865 × 10⁻⁷ molecules.
b. Since the number of molecules of X present in 10 mL solution of the final diluted solution is 4.865 × 10⁻⁷ molecules, this shows that the number of molecules of X is very little so, the possible health benefits of the drug might be minimal or non-existent.
¿Por qué un trozo de sal común es frágil y se puede romper fácilmente cuando se le somete a una fuerza y no ocurre lo mismo con un trozo de metal que se deforma antes de romperse?
Answer:
Explanation:
La sal común es un compuesto iónico, es decir que sus átomos (Na y Cl) están unidos entre sí por fuerzas electrostáticas, y el metal está unido entre sí por uniones metálicas. La naturaleza de estas uniones es diferente y en base a las fuerzas de atracción que hay entre los átomos en compuestos con este tipo de uniones, la propiedades físicas generales serán diferentes.
En el caso de los metales, los átomos metálicos están colocados unos sobre otros de forma ordenada, pero no fijamente retenida, y los electrones de valencia están delocalizados a través de todo el cristal metálico. Por esta razón, cuando se le aplica una fuerza a un metal, estos átomos pueden deslizarse unos sobre otros. Ésta es la propiedad que le da a los metales su maleabilidad.
En el caso de los compuestos iónicos, los aniones y cationes que lo componen están ordenados en el cristal de una forma más rígida y por eso cuando se les aplica una fuerza éstos compuestos se rompen mucho más fácil, ya que no pueden deformarse.
Which of the following best defines a basic solution?
2 The substance has a mass of 0.50 kg.
34 000 J of energy is transferred to the substance to completely melt it.
The temperature of the substance does not change during this time.
Calculate the specific latent heat of fusion of the substance.
Use an equation from the Equations List.
Answer:
68000J/kg
Explanation:
Given parameters:
Mass of the substance = 0.5kg
Quantity of heat transferred to the body = 34000J
Unknown:
Specific latent heat of fusion = ?
Solution:
The specific latent heat is usually involve in phase changes;
H = mL
H is the quantity of heat supplied
m is the mass
L is the specific latent heat
Insert the parameters and solve;
34000 = 0.5 x L
L = [tex]\frac{34000}{0.5}[/tex] = 68000J/kg
Why are molecular covalent compounds insoluble in water?
Answer:
Hope this will help.......
Explanation Covalent bonds are insoluble in water (H2O) , but covalent compounds are. This is because some organic compounds (covalent) contain the polar −OH group which can bond to a hydrogen ion to form water.
what is polling in chemistry?
Answer:
Polling is a method used for the purification of copper or tin which contains oxide impurities
Answer:
Polling is used for the purification of copper or tin which contains oxide impurities. The impure metal is melted and stirred with green logs of wood. The heat of molten metal makes the green logs to liberate hydrocarbon gases which in turn reduce the metal oxide into metal.
How are elliptical galaxies different from spiral galaxies?
a. They contain older stars and less gas and dust.
b. They contain younger stars and more gas and dust.
c. They are bigger than spiral galaxies.
d. They are smaller than spiral galaxies.
Answer:
A. They contain older stars and less gas and dust.
Explanation:
There are three types of galaxies:
elliptical galaxiesspiral galaxieslenticular galaxiesElliptical galaxies are galaxies shaped like an ellipse, while spiral galaxies consist of a flat, rotating disk that contains stars, gas, and dust, and a central concentration of stars called the bulge.
The difference between elliptical and spiral galaxies is in the amount of gas and dust they contain. Spiral galaxies contain large amounts of gas and dust, which means that new stars are born very often. This makes them brighter than relatively dim elliptical galaxies, which contain less gas and dust. This is why fewer new and brighter stars are born in elliptical galaxies, leaving them with older, dimmer stars.
What sport was used to demonstrate Newton's 3 Laws?
Gas laws mad question under it
Answer:
what are you asking tho?
Explanation:
Thx for the Free points tho.
What are the advantages of using resources such as geothermal energy, solar energy, and hydropower?
They produce large amounts of energy from burning fuels.
They can generate power by burning wastes.
They come from energy sources that never run out.
They increase the amount of greenhouse gasses.
A 2.9 kg model rocket accelerates at 15.3 m/s2 with a force of 44 N. Before launch, the model rocket was not moving. After the solid rocket engine ignited, hot gases were pushed out from the rocket engine nozzle and propelled the rocket toward the sky.
Which of Newton’s laws apply in this example? Check all that apply.
Answer:
newton's firts law
Explanation:
because it states that everybody continue its state in rest unless an external force is appy to change its state from rest to motion.
Answer:
A, B, C
Explanation:
How do you separate a mixture?
Answer:
We can seperate a mixture by various methods
Explanation:
Distillation, Evaporation, filtration and chromatography
Most earthquakes and volcanoes occur in areas of the Pacific Ocean called "The Ring of Fire." What is the main reason for this?
Group of answer choices
Large numbers of people live in this area.
That area of the Earth is hotter than any other area.
Lithosphere plate boundaries are found in that area.
The weight of the ocean water forces magma to the surface.
Answer:
Lithosphere plate boundaries are found in that area.
Explanation:
Answer:
C is the right answer
Explanation:
melting is considered a(n) ___ change because energy is gained by the substance as it changes state
A. Physical.
B. Chemical.
C. Volume.
D. Dynamic.
Which of the following set of atoms has the largest electronegativity difference?
a. H and P
b. N and C
c. Li and O
d. Cl and Ca
Answer:
C
Explanation:
Li has an electronegativity of 0.98, O has an electronegativity of 3.44. 3.44-0.98= 2.46 electronegativity differnece :)
A piece of silver is heated and added to a styrofoam cup calorimeter containing 26.0 mL (the density of water is 1 g/mL) of water at 19 oC. The water reaches a maximum temperature of 44 oC after the metal was added. If the specific heat of the silver is 0.240 J/g oC and it started at 93.8 oC
Answer:
m(Ag) = 227.5g
Explanation:
...what is the mass of the piece of silver?
The heat given for the piece of silver is the same heat that is absorbed for the water, that is:
m(Ag)×C(Ag)×ΔT(Ag) = m(Water)×C(Water)×ΔT(Water)
m is mass of water in solution: 26.0mL = 26g of water
And m(Ag) is the mass of Ag, our incognite.
C is specific heat (0.240J/g°C for Ag), and 4.184J/g°C for water
ΔT is change in temperature (93.8°C - 44°C = 49.8°C) for Ag ad (44°C - 19°C = 25°C)
Replacing:
m(Ag)×C(Ag)×ΔT(Ag) = m(Water)×C(Water)×ΔT(Water)
m(Ag)×0.240J/g°C×49.8°C = 26g×4.184J/g°C×25°C
m(Ag)* 11.952J/g = 2719.6J
m(Ag) = 227.5g
How is a "decay event' recorded
Help pleasee I need help to write the formulas i’m so lost
Answer:
NH4
Explanation:
4-How does the concentration of ions in a strong acid differ from a weak acid?
Which of the following is TRUE about when two atoms form a bond? a. Repulsion is greater than attraction b. Neither atoms will have a full valence shell c. Potential energy is at a minimum
Answer:
b: Neither atoms will have a full valence shell
Explanation:
I think sooo
The movement of air caused by differences in air pressure is __________________.
Answer:
wind
Explanation:
it would be naturally caused by the pressure
Answer:
temperature or pressure differences
Explanation:
What is the mass of 1.794 mol Ba(NO3)2?
Explanation:
Molar mass of Ba(NO3)2 = 261.3368 g/mol
please help it’s due today
what does light emission(color) tell us about elements?
Answer:
The color of the light emitted depends on the energies of the photons emitted, which are in turn are determined by the energies required to move electrons from one orbital to another. Those colors are as distinctive to each element as fingerprints are to people. Hope this helps
Answer:
The color of the light emitted depends on the energies of the photons emitted, which are in turn are determined by the energies required to move electrons from one orbital to another. Depending on the element you put in the flame, various different energies of photons (colors) will appear. Those colors are as distinctive to each element as fingerprints are to people.
Explanation:
Select all that apply. Choose the chemical formulas that are matched with their
correct name.
MgF2, magnesium (II) fluoride
BeO, beryllium oxide
NaCl, sodium chloride
AlF3, aluminum trifluoride
CaCl2, calcium chloride
Answer:
i think just these
NaCl
CaCl2
When does nuclear fusion start during the life of a star?
Answer:
Try searching this on google
Explanation:
I might have an answer but I am not entirely sure sorry I really tried to help but there is also an app called socractic it also helps with questions
Once the temperature reaches 15,000,000 levels Celsius, nuclear fusion takes location in the center, or core, of the cloud. The high-quality heat given off by means of the nuclear fusion technique motives the gasoline to glow creating a protostar. This is the first step in the evolution of a star.
P4 (s) + Cl2 (g) → 4PCl3 (l)
which of the following lists show the elements in order, from those having the least protons to those having the most protons in the atoms?
A. K, Mg, N, O
B. C, Al, P, Cl
C. Li, Be, H, He
D. Na, Ne, He, H
The elements that have least protons to those having the most protons in the atoms are:
B. C, Al, P, Cl
Protons in an atom:There is an equal number of protons and electrons in an atom. So when moving across a period in a periodic table the number of electrons increases which also shows the increases in a number of protons. So as the atomic number increases, the number of protons and electrons also increases.
Thus, the order of elements having least to greatest protons are:
C, Al, P, Cl
C has 6 atomic number, Aluminium has 13 atomic number , Phosphorus has 14 atomic number and atomic number of chlorine is 17.
Thus, option B is correct.
Find more information about Atomic number here:
brainly.com/question/1805828
aluminum oxide is an ionic substance with formula al2o3. explain what this formula means.
Answer:
the 2 means there are 2 al and the 3 means there are 3 o
Explanation:
I hope this helps
WILL MARK YOU BRAINLEIST What do sound waves need to have to travel from one place to another?
What do sound waves need to have to travel from one place to another?
Question 5 options:
steel
water
air
a medium
Answer:
a medium!!!!
Explanation:
ITS CORRECT!!!! I GOT IT RIGHT ON MY TESTTTTT! I PROMISEEE