Answer:
сфоткай отправь. я не магу зделать
According to the concept of Avogadro's number, there are 29.056×10²³ molecules in 77.2 g of methane.
What is Avogadro's number?Avogadro's number is defined as a proportionality factor which relates number of constituent particles with the amount of substance which is present in the sample.
It has a SI unit of reciprocal mole whose numeric value is expressed in reciprocal mole which is a dimensionless number and is called as Avogadro's constant.It relates the volume of a substance with it's average volume occupied by one of it's particles .
According to the definitions, Avogadro's number depend on determined value of mass of one atom of those elements.It bridges the gap between macroscopic and microscopic world by relating amount of substance with number of particles.
Number of atoms can be calculated using Avogadro's number as follows: mass/molar mass×Avogadro's number
In the given example, number of moles=77.2/16=4.825 moles
If 1 mole has 6.023×10²³ molecules , then 4.825 moles will have 4.825×6.023×10²³ /1=29.056×10²³ molecules .
Thus, there are 29.056×10²³ molecules in 77.2 g of methane.
Learn more about Avogadro's number,here:
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The Chinese first began recording astronomical observations about 2,000 years ago.
True
False
52
p3
N?
Br1
CaBr2
Cas
Ca3P2
Cal2
Ca3N2
Cat2
K1
Mg2
Zn2
Fe3
3. Determine the [OH-] and pH of a solution that is [H3O+] = 3.7x10-2 M.
[OH⁻]= 2.7 x 10⁻¹³
pH = 1.431
Further explanationGiven
[H3O+] = 3.7x10⁻² M.
Required
the [OH-] and pH
Solution
pH = - log [H⁺]
pH = 2 - log 3.7
pH = 1.431
pOH = 14 - 1.431
pOH = 12.569
pOH = - log [OH⁻]
[OH⁻]= 2.7 x 10⁻¹³
or
[OH-][H3O+]=10⁻¹⁴
[OH-]=10⁻¹⁴ : 3.7 x 10⁻²
[OH-] = 2.7 x 10⁻¹³
47.4 grams of calcium carbonate (CaCO3) is dissolved in 450 mL of water. What is the molarity of this aqueous solution?
Answer:
[tex]M=1.05M[/tex]
Explanation:
Hello!
In this case, since the formula for the calculation of molarity is defined in terms of moles and volume in liters as shown below:
[tex]M=\frac{n}{V}[/tex]
Whereas the moles are computed by considering the molar mass of CaCO3 (100.09 g/mol):
[tex]n=47.4g*\frac{1mol}{100.09g}=0.4736mol[/tex]
Thus, we obtain:
[tex]M=\frac{0.4736mol}{0.450L}\\\\M=1.05M[/tex]
Best regards!
이
Determine the the nuclei indicated in blanks in the
right side when Radium (Ra-226) undergoes an
alpha decay
Ne
226/ 88
Ra -->
+
The daughter isotope : Radon-222 (Rn-222).
Further explanationGiven
Radium (Ra-226) undergoes an alpha decay
Required
The daughter nuclide
Solution
Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,
alpha α particles ₂He⁴ beta β ₋₁e⁰ particles gamma particles ₀γ⁰ positron particles ₁e⁰ neutron ₀n¹The decay reaction uses the principle: the sum of the atomic number and mass number before and after decay are the same
Radium (Ra-226) : ₈₈²²⁶Ra
Alpha particles : ₂⁴He
So Radon-226 emits alpha α particles ₂He⁴ , so the atomic number decreases by 2, mass number decreases by 4
The reaction :
₈₈²²⁶Ra ⇒ ₂⁴He + ₈₆²²²Rn
Consider a reaction that connects the ends of a chain of carbons to form a ring. The closure of the ring results in the formation of a new chemical bond, with the bonding electrons going into a bonding sigma molecular orbital at a lower energy. Which of the following statements correctly describes the resulting enthalpy, entropy, and heat changes? Mark all that are correct.
A. The entropy of the surroundings decreases (AS surr < 0) because the closure of the ring results in fewer conformations for the system.
B. The system releases energy to the environment, because its internal energy decreases.
C. The entropy of the surroundings increases (AS surr > 0) because the surroundings absorb heat released by the reaction, and become more disordered.
D. The entropy of the system decreases (AS sys < 0) because the closure of the ring reduces the number of conformations the ring can adopt.
E. The enthalpy or internal energy of the system decreases (AH sys < 0) because the electrons that form the bond enter an orbital that is at a lower energy.
Answer:
The system releases energy to the environment, because its internal energy decreases.
The entropy of the surroundings increases (AS surr > 0) because the surroundings absorb heat released by the reaction, and become more disordered.
The entropy of the system decreases (AS sys < 0) because the closure of the ring reduces the number of conformations the ring can adopt.
The enthalpy or internal energy of the system decreases (AH sys < 0) because the electrons that form the bond enter an orbital that is at a lower energy.
Explanation:
Now we know that when a reaction is exothermic heat is given off. In this case, we have a reaction that connects the ends of a chain of carbons to form a ring. The bonding electrons now move into a lower energy bonding sigma molecular orbital.
This leads to a decrease in the entropy and enthalpy of the system because energy is given off, the closure of the ring reduces the number of conformations the ring can adopt and the electrons that form the bond enter an orbital that is at a lower energy.
The entropy of the surroundings is increased as energy is given out. The surroundings absorb heat released by the reaction, and become more disordered.
A reversible reaction is said to have reached equilibrium when which of the following conditions is established?
The given question is incomplete. The complete question is:
A reversible reaction is said to have reached equilibrium when which of the following conditions is established?
a. concentration of reactants and products are equal
b. opposing reactions cease
c. speeds of opposite reactions become equal
d. temperature of opposite reactions become equal
Answer: c. speeds of opposite reactions become equal
Explanation:
Equilibrium state is the state when reactants and products are present but the concentrations does not change with time.The state of equilibrium refers to the dynamic state as both forward and backwad reactions continue.
For a chemical equilibrium reaction, equilibrium state is achieved when the rate of forward reaction becomes equals to rate of the backward reaction.
Thus at chemical equilibrium, the amount of product and reactant remains constant because the rates of the forward and reverse reactions are equal.
PLZZZ help asaap plzzz I give brainliest are the following reactions a SYNTHESIS, DECOMPOSITION, COMBUSTION, SINGLE REPLACEMENT or DOUBLE REPLACEMENT reactions?
N2 (g) + 3 H2 (g)→ 2NH3 (l) ______________
2 H2(g) + O2(g--> 2 H2O(g)
Answer:
Synthesis
Explanation:
Two reactants are becoming one product, so it is a synthesis reaction.
Decomposition is the opposite, so when one molecule becomes simpler atoms.
Example: 2NaCl -> Cl2 + Na
Combustion is reaction with a product of water and carbon dioxide.
Example: CH4 + 2O2 -> CO2 + 2H2O
Single displacement is when one atom takes the place of the other.
Example: K + NaCl -> KCl +Na (where K took the place of Na)
Double displacement is like single displacement but it happens twice. Think of it like the atoms exchanging partners.
Example: HCl +NaH -> NaCl + HOH
Answer:
(i) N2(g)+3H2(g) -->2NH3(g) - When the equilibrium changes, the concentrations of all substances involved in the equilibrium must also change. For our equilibrium reaction: N2(g) + 3H2(g) ⇔ 2NH3(g) + Heat
(ii) 2 H2(g) + O2(g) --> 2 H2O(g) - Synthesis Reaction
HENCE BOTH THE REACTIONS COULD BE CLASSIFIED AS SYNTHEYIC REACTION
PLEASE DO MARK MY ANSWER AS THE BRAINLIEST..
<HOPE IT HELPS>
What happens when a new star contracts?
Answer:
The outer shell of the new star will start to expand.
Explanation:
The new star will continue to glow for millions or even billions of years. As it glows, hydrogen is converted into helium in the core by nuclear fusion. The core starts to become unstable and it starts to contract. The outer shell of the star, which is still mostly hydrogen, starts to expand.
Explanation provided by:
StarChild: Stars - NASA
Convert 8.876 × 10^12 m^2 to units of km^2.
Answer:
[tex]8.876\times 10^{18}\ km^2[/tex]
Explanation:
In this problem, we need to convert [tex]8.876 \times 10^{12}\ m^2[/tex] to km².
We know that,
1 km = 1000 m
⇒ 1 km² = 10⁶ m²
So,
[tex]8.876 \times 10^{12}\ m^2=8.876 \times 10^{12}\times 10^6\ km^2\\\\=8.876\times 10^{18}\ km^2[/tex]
So, [tex]8.876 \times 10^{12}\ m^2[/tex] is equal to [tex]8.876\times 10^{18}\ km^2[/tex].
Calculate what will be the volume of 10.0 grams of
gaseous ammonia at STP?
Answer:
13.22 L
Explanation:
Given data:
Volume of ammonia = ?
Mass of ammonia = 10.0 g
Temperature = standard = 273.15 K
Pressure = standard = standard = 1 atm
Solution:
First of all we will calculate the number of moles of ammonia.
Number of moles = mass/molar mass
Number of moles = 10.0 g/ 17 g/mol
Number of moles = 0.59 mol
one mole of any substance at standard temperature and pressure occupy 22.41 L . Thus, 0.59 moles of ammonia will occupy,
0.59 mol × 22.4 L / 1 mol
13.22 L
Answer: 12.4L
Explanation:
mw NH3 18
1 mole = 22.4L
10g = 10/18 moles
I need help with the bottom two pls The first answer I will mark brainliest
Answer:
I dunno, what is the answer
Explanation:
What is the concentration of lithium ions in 0.400 M Li₂HPO₄?
Answer: 0.800 M
Basically, the ratio is 2:1, so when you have 1 M of Li2HPO4 it means you have 2 M in the concentration of lithium ions. So knowing the ratio, we know we just need to multiply 0.400 x 2.
I'm bad at explaining it, but got it right on chem101 sooo
The concentration of lithium ion, Li⁺ in 0.4 M Li₂HPO₄ is 0.8 M.
The concentration of a substance is simply the amount of the substance in 1 L of water.
To obtain the concentration of lithium ion, Li⁺ in Li₂HPO₄, we'll begin by writing the dissociation equation of Li₂HPO₄. This is illustrated below:
Li₂HPO₄ (aq) <=> 2Li⁺(aq) + HPO₄²¯(aq)From the balanced equation above,
1 mole of Li₂HPO₄ produced 2 moles of Li²⁺.
Finally, we shall determine the concentration of lithium ion, Li⁺ in 0.4 M Li₂HPO₄. This can be obtained as follow:
From the balanced equation above,
1 mole of Li₂HPO₄ produced 2 mole of Li⁺.
Therefore, 0.4 M Li₂HPO₄ will produce = 2 × 0.4 = 0.8M Li²⁺
Thus, 0.8 M lithium ion, Li⁺ is present in the solution.
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Convert 3.93 x 10-22 grams of X4Z3 into molecules/formula units of the same compound. (Assume that the molar mass of X is 59.45 grams per mole and the molar mass of Z is 13.84 grams per mole.)
Assume that Avogadro's number is 6.022 x 1023. Report your answer to three decimal places.
Answer:
0.847 molecule.
Explanation:
From the question given above, the following data were obtained:
Mass of X₄Z₃ = 3.93×10¯²² g
Number of molecules of X₄Z₃ =?
Avogadro's number = 6.022×10²³ molecules
Next, we shall determine the molar mass of X₄Z₃. This can be obtained as follow:
Molar mass of X₄Z₃ = (4×59.45) + (3×13.84)
= 237.8 + 41.52
= 279.32 g/mol
Finally, we shall determine the number of molecules in 3.93×10¯²² g of X₄Z₃. This can be obtained as follow:
From Avogadro's hypothesis,
1 mole of X₄Z₃ = 6.022×10²³ molecules
But 1 mole of X₄Z₃ = 279.32 g
Thus we can say that:
279.32 g = 6.022×10²³ molecules
Therefore,
3.93×10¯²² g = 3.93×10¯²² × 6.022×10²³ / 279.32
3.93×10¯²² g = 0.847 molecule.
Thus, 3.93×10¯²² g of X₄Z₃ contains 0.847 molecule.
A given compound has the following solubility properties. At room temperature, it is soluble in diethyl ether but insoluble in both ethanol and water. At higher temperatures, it is soluble in both diethyl ether and ethanol, but insoluble in water. Propose a procedure for purifying this compound by recrystallization.
Answer:
See explanation
Explanation:
If we desire to recrystallize the given compound then we must do the following;
1) Add the compound to ethanol and heat the system
2) As the solute dissolves, the solution is allowed to cool
3) The solution may be seeded or the vessel scratched to aid crystallization.
4) The pure crystals are now filtered out, washed and dried.
Remember that recrystallization has to do with dissolving a solute in a solvent in which it is only soluble at high temperature but insoluble at low temperature.
The solvent dissolves the impure solute while pure crystals emerges as the temperature decreases.
Which of the following is an example of a physical change, but not a chemical change?
Answer:
Boiling Water
Explanation:
Boiling water is an example of physical change and not and not a chemical change because the water vapor still has the same molecular structure as liquid water.If the bubbles were caused by the decomposition of a molecule into gas then boiling would be a chemical change.
Answer:
A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding
Explanation:
If you were to burn a candle inside of a closed jar and the mass of the
closed jar and candle was 50 grams to begin with, what would the mass of
the jar and smoke be after the candle is done burning?
Answer:
50g
Explanation:
At the end of the burning process, the mass of the jar and smoke should be 50g after the candle burning is done.
In most systems, the law of conservation of matter finds expression. According to this law "matter is neither created nor destroyed but atoms are rearranged".
In this kind of system, no matter is allowed to escaped and the starting mass of the reactants compared to that of the product will be the same.
Helppppp pleaseeee xxxxxx
Answer:
2812.6 g of H₂SO₄
Explanation:
From the question given above, the following data were obtained:
Mole of H₂SO₄ = 28.7 moles
Mass of H₂SO₄ =?
Next, we shall determine the molar mass of H₂SO₄. This can be obtained as follow:
Molar mass of H₂SO₄ = (1×2) + 32 + (16×4)
= 2 + 32 + 64
= 98 g/mol
Finally, we shall determine the mass of H₂SO₄. This can be obtained as follow:
Mole of H₂SO₄ = 28.7 moles
Molar mass of H₂SO₄ =
Mass of H₂SO₄ =?
Mole = mass / Molar mass
28.7 = Mass of H₂SO₄ / 98
Cross multiply
Mass of H₂SO₄ = 28.7 × 98
Mass of H₂SO₄ = 2812.6 g
Thus, 28.7 mole of H₂SO₄ is equivalent to 2812.6 g of H₂SO₄
How to get the density of this unknown liquid?
Answer:
Measure the volume of water poured into a graduated cylinder, then place the object in the water and remeasure the volume. The difference between the two volume measurements is the volume of the object. Now simply divide the mass by the volume to calculate the density of the object.
Disaccharides are held together by a glycosidic bond. Hydrolysis of the disaccharide requires_____
Answer:
monosaccharides and glycosidic, I think
Explanation:
Answer:
pasagottt po plss
Explanation:
edi wow
Sound waves are longitudinal, mechanical, compression waves.
A. True
B. False
Answer:
True
Explanation:
Sound waves traveling through air are indeed longitudinal waves with compressions and rarefactions. As sound passes through air (or any fluid medium), the particles of air do not vibrate in a transverse manner.
Answer:
true
Explanation:
ape x
How are the cells made by meiosis different from the original parent cell that
produced them?
2. Methyl dichloroacetate (Cl2CHCO2CH3) decays into methanol (CH3OH) and dichloroacetic acid (Cl2CHCO2H) on reaction with water. Given a rate constant of 2.7 x 10-4/sec and an initial concentration of 1-ppm methyl dichloroacetate in the water, how much methanol will be present in the water after 30 min
Answer:
2.69 * 10^-6 Mol/L
Explanation:
The equation of the reaction is;
Cl2CHCO2CH3 -------------------> Cl2CHCO2H + CH3OH
To convert from ppm concentration to Mol/L, we have
M = ppm/MM * 1000
Where;
M = mol/l
MM= Molar mass
M = 1/142.97 g/mol * 1000 =
M= 6.99 * 10^-6 Mol/L
For first order reaction;
ln[A] = ln[A]o -kt
Given that
[A]o = 6.99 * 10^-6 Mol/L
[A]=??
k= 2.7 x 10-4/sec
t= 30 mins * 60 = 1800 s
ln[A] = ln[6.99 * 10^-6] - (2.7 x 10-4 * 1800)
ln[A] = -11.87 - 0.486
ln[A] = -12.356
[A] = e^(-12.356)
[A] = 4.3 * 10^-6 Mol/L
Concentration of methanol present after 30 mins= 6.99 * 10^-6 - 4.3 * 10^-6 = 2.69 * 10^-6 Mol/L
How many elements are present in the compound RbMnO4?
1. Which list of nuclear emissions is arranged in order from the least penetrating power to
the greatest penetrating power?
A) alpha particle, beta particle, gamma ray
B) alpha particle, gamma ray, beta particle
C) gamma ray, beta particle, alpha particle
D) beta particle, alpha particle, gamma ray
Answer:
A) alpha particle, beta particle, gamma ray
Explanation:
Alpha beta and gamma radiations are the examples of ionizing radiations. When an atom is an excited state and having high energy, the atom is in unstable state. The excess of energy is released by the atom to get the stability. The released energy is in the form of radiations which may include alpha, beta, gamma, X-ray etc.
Properties of alpha radiation:
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy
Beta radiations:
The mass of beta particle is smaller than the alpha particles.
They can travel in air in few meter distance.
These radiations can penetrate into the human skin.
The sheet of aluminum is used to block the beta radiation
⁴₆C → ¹⁴₇N + ⁰₋₁e
The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.
Gamma radiations:
Gamma radiations are high energy radiations having no mass.
These radiations are travel at the speed of light.
Gamma radiations can penetrate into the many materials.
These radiations are also used to treat the cancer.
Lead is used for the protection against gamma radiations because of its high molecular density.
The lead apron are used by the person when treated with gamma radiations.
Lead shields are also used in the wall, windows and doors of the room where gamma radiations are treated, in-order to protect the surroundings.
3. Match each of the following descriptions with one of the beakers in Model 1. In each case, assume the change in volume as the solid(s) are added is minimal. a. A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of water in beaker . b. A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.500 M sodium hydroxide solution in beaker . c. A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M sodium hydroxide solution in beaker . d. A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M calcium nitrate solution in beaker . 4. Based on the solubility product constant, Ksp, for calcium hydroxide given in Model 1, do you expect most of the 1.00 mole sample of solid to dissolve in any of the four beakers
Answer:
Explanation:
When calcium hydroxide is dissolved in water , it ionizes as follows .
Ca( OH)₂ = Ca⁺² + 2 OH ⁻
When it is dissolved in water which contains minimal OH⁻ , so there is almost no common ion effect . Hence calcium hydroxide is fully dissolved in pure water solvent .
When 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.500 M sodium hydroxide solution in beaker , it is not fully dissolved due to common ion of hydroxide ion ( OH⁻ )
NaOH = Na⁺ + OH⁻
OH⁻ ion from NaOH , suppresses the dissolution of calcium hydroxide .
Similarly
When A 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M sodium hydroxide solution in beaker , it is not fully dissolved due to common ion of hydroxide ion ( OH⁻ )
NaOH = Na⁺ + OH⁻
OH⁻ ion from NaOH , suppresses the dissolution of calcium hydroxide
When 1.00 mole sample of solid calcium hydroxide is added to 500.0 mL of 0.200 M calcium nitrate solution , it is not fully dissolved due to common ion of calcium ion ( Ca⁺² )
Ca( NO₃)₂ = Ca⁺² + 2NO₃⁻
Ca⁺² ion from Ca( NO₃)₂ , suppresses the dissolution of calcium hydroxide .
The weather is warm and dry
Which change would bring a cold front in
A.several days of gray skies
A.dry air and sunny skies
B.rain or thunderstorms
C.extended period of rain or snow
because im d and god is go od and 9 x 10 is 99999because im god and god is good a nd 9 x 10 i d and god is goo d and 9 x 10 is 99999because im god and god is good a nd 9 x 10 is 99999because im god and god is good and 9 x 10 is 99999
Answer:the answer is c
Explanation:
Which bond would require more energy to break apart? (Short bond or Long bond). Explain
a) longer bond. because the charges are further apart
b) shorter bond. because the charges are closer together
c) shorter bond. because the charges are both positive
d) longer bond. because the charges are closer together
Answer:
shorter bond, because charges are close apart
Explanation:
shorter the bond length more is the energy required to break the bond for example if you take three pencils of different sizes one longer One medium sized One Shot sized if you try to break them the longer pencil will break much faster than the other two because the greater the length the lesser the strength the lesser energy you need to apply to break them apart ...
hope you understand
explain the difference between aldehyde and ketones
Answer:
You will remember that the difference between an aldehyde and a ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketones don't have that hydrogen. ... Aldehydes are easily oxidized by all sorts of different oxidizing agents: ketones are not.
2. What is the final temperature when a 32.0 g piece of diamond at 33.5°C is heated with 360 J of energy?
(Cp = 0.509
Answer:
55.6 °C
Explanation:
From the question given above, the following data were obtained:
Mass (M) of diamond = 32.0 g
Initial temperature (T₁) = 33.5°C
Heat (Q) required = 360 J
Specific heat capacity (C) of diamond = 0.509 J/gºC
Final temperature (T₂) =?
Next, we shall determine the change in temperature. This can be obtained as follow:
The final temperature can be obtained as follow:
Mass (M) of diamond = 32.0 g
Heat (Q) required = 360 J
Specific heat capacity (C) of diamond = 0.509 J/gºC
Change in temperature (ΔT ) =?
Q = MCΔT
360 = 32 × 0.509 × ΔT
360 = 16.288 × ΔT
Divide both side by 16.288
ΔT = 360 / 16.288
ΔT = 22.1 °C
Finally, we shall determine the final temperature. This can be obtained as follow:
Initial temperature (T₁) = 33.5°C
Change in temperature (ΔT ) = 22.1 °C
Final temperature (T₂) =?
ΔT = T₂ – T₁
22.1 = T₂ – 33.5
Collect like terms
22.1 + 33.5 = T₂
T₂ = 55.6 °C
Therefore, the final temperature is 55.6 °C.
