Explanation:
Entropy of a reaction ΔS∘rxn is the degree of disoderliness in a system. Gases generally have a higher degree of disorder compared to liquids. Hence for the reaction 2H2(g)+O2(g) ⟶ 2H2O(l), the entropy decreases sice the reactants are in the gaseous state and the products is in the liquid state of matter
Which of the following describes the change in atomic mass and atomic number during this reaction?
Which of the following is not an indication of a chemical change?
A. Fracture Formation
B. Energy transfer
C. Precipitate formation.
D. Gas production
Answer:
C. precipitate formation.
Explanation:
options C is correct answer.
Answer:
C. precipitate formation.
Explanation:
Porosities can have merits and demerits during manufacturing procedures of dental materials. Clarify this statement.
Answer:
The porosities in dental materials can be of merit and not merit since some dental materials need to be porous in order to reduce their weight and improve their properties and functions, whereas in those (which are the majority) porosities are not Merit, see the properties of the material, the function and can even influence dental rehabilitation.
An example of this is the use of vitreous ionomers, which is a dental material, where when it is spatulated it remains porous, it can give recurrence of infectious caries, since its permeability increases, the best cariogenic microorganisms are filtered and porosity works as a retentive site for these microorganisms that make up the dental biofilm.
In summary, the world of dental materials is very wide, some are resins, other cements, others have metallic claims, etc. To say that the presence of porosity is merit or demerit would be ideal because for some materials this is favorable and for others unfavorable since they are very versatile, with different qualities, different degrees of porosity, different molecules, different coefficients of thermal expansion, some do not set, others do not, some are light-cured, others do not, some withstand more mechanical forces and have more elastic modulus and less porosity, while others do not, and thus with many more variables.
Explanation:
In the manufacture of dental materials, much attention is always paid to what the manufacturer indicates in these indications that come on the reverse side of the material or on a paper inside the material container.
This is important to know, because the manufacturer is the one that indicates the mode of use and working time according to the trademark and the chemical composition of the dental material.
That a dental material in its manufacture is more or less porous, makes its density, weight and volume possibly be affected, there are materials that seek to increase porosity for a certain purpose, while others seek the opposite, depending on the function that is applied, will have more or less pores.
The example we gave above about the vitreous ionomer is an example that indicates that in the case of restorative dental materials where the function is to SEAL the porosity is almost nil, since otherwise it will not seal the cavity that was formed with caries and not the infectious problem would be solved.
On the other hand, in the surgical field of dentistry there are bone grafts or porous macroparticles that are for the purpose of bone replacement, which in order to be integrated need blood vessels that run over these pores, irrigating the area of bone neoformation well, in this case the merit of porosity if necessary and it is essential that they be very porous.
If 120.4 grams of reactant completely breaks down (decomposes) to produce 106.4 grams of chlorine. What mass of nitrogen gas could be expected? *
Answer:
[tex]m_{nitrogen}=14g[/tex]
Explanation:
Hello,
In this case, since we are talking about a chemical reaction in which a compound having nitrogen and chlorine is decomposed into chlorine and nitrogen, we must remember that the law of conservation of mass must be obeyed, for that reason, we notice that the mass of the whole reactants must equal the mass of the whole products, as shown below:
[tex]m_{reactants}=m_{products}[/tex]
Next, we know there is only one single reactant and products are constituted by both chlorine and nitrogen:
[tex]m_{reactant}=m_{chlorine}+m_{nitrogen}[/tex]
In such a way, we can compute the mass of nitrogen as shown below:
[tex]m_{nitrogen}=m_{reactant}-m_{chlorine}=120.4g-106.4g\\\\m_{nitrogen}=14g[/tex]
Best regards.
.
5.0 mg of radioactive nobelium-253 was removed from the reactor to be
used in an experiment. It took 291 seconds (just under 5 minutes) to
get the sample from the reactor to the laboratory. How many milligrams
of nobelium-253 remained upon arrival to the laboratory? The half-life
of nobelium-253 is 97 seconds.
Answer:
Explanation:
Half life of Nobelium-253 is 97 seconds . That means after every 97 seconds half of the Nobelium amount will be disintegrated .
Time taken in bringing the sample to laboratory = 291 seconds
291 second = 291 / 97 half life
n = 3
N = [tex]N_0 (\frac{1}{2})^n[/tex]
N₀ is original mass , N is mass after n number of half life.
N = 5 mg x [tex](\frac{1}{2})^3[/tex]
= .625 mg
Only 0.625 mg of Nobelium-253 will be left .
HELP ASAP!!!! PLEASE AND THANK YOU!!!! Aluminum, which has a specific heat capacity of 0.902 J/g◦C and a mass of 20.9 g absorbs 348.0 J of energy. The final temperature (T2) is 100.0◦C. Calculate the initial temperature (T1).
Answer:
81.54 °C
Explanation:
Use the equation
q = mcΔT
348 = 20.9(0.902)(100-t)
t = 81.54 °C
*note, you don't have to convert these to kelvin since the difference will be the same
State whether the following is an example of a physical or chemical change:! 21. Burning a log: ________________________________! 22. Folding a piece of paper: _________________________! 23. Freezing water: _________________________! 24. Bending a copper wire. _________________________!
Answer:
Physical change
Explanation:
Because it doesn't require any chemical to change
Answer:
Physical change
Physical change
Physical change
Physical change
Explanation:
If a solution has a pOH=12, what is its pH?
Answer:
2
Explanation:
pH+pOH=14
- Hope that helps! Please let me know if you need further explanation.
Answer:
2
Explanation:
Ph+PoH=14
a hot liquid located under earth's surface?
Answer:
Magma
Explanation:
Magma is the hot liquid under earths surface
The number of molecules in one mole of a substance The number of molecules in one mole of a substance depends on the molecular weight of the substance. depends on the temperature of the substance. depends on the atomic weight of the substance. is the same for all substances. depends on the density of the substance.
Answer: is the same for all substances.
Explanation:
The number of molecules in one mole of a substance is the same for all substances because
A mole (which is the quantity of a substance that has the same number (Avogadro's number, is 6.022 * 10^23) of particles as are found in 12.000 grams of carbon-12 of the substance) for any substance has the same number of atoms, molecules, or ions contained in any other substance.
1 mole = 6.022 x 10^23 atoms, molecules, or ions
Indicate the changes (increases, decreases, does not change) in its volume when the pressure undergoes the following changes at constant temperature and amount of gas. Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer. ResetHelp 1. The pressure increases to 6.0 atm. The volume The pressure increases to 6.0 a t m. The volume blank.. 2. The pressure drops to 0.40 atm. The volume The pressure drops to 0.40 a t m. The volume blank.. 3. The pressure remains at 2.0 atm. The volume The pressure remains at 2.0 a t m. The volume blank..
The question is missing information. Here is the complete question.
A gas at a pressure of 2.0 atm is in a closed container. Indicate the changes (if any) in its volume when the pressure undergoes the following changes at constant temperature and constant amount of gas. Match the words in the left with the column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.
1. The pressure increases to 6.0 atm. The volume ________
2. The pressure drops to 0.40 atm. The volume _________
3. The pressure remains at 2.0 atm. The volume _________
Answer: 1. Decreases
2. Increases
3. Does not change
Explanation: According to the Ideal Gas Law, Pressure, Volume and Temperature of an ideal gas is related, as the following: PV = nRT.
In this case, since temperature (T) and amount of gas (n) are constant, the Boyle's Law can be used.
The law states that the volume of a given gas, under the conditios of temperature and amount of it are constant, is inversely proportional to the applied pressure: P₁.V₁ = P₂.V₂
For case 1.)Initial P (P₁) = 2
Initial V (V₁) = V
Final P (P₂) = 6
P₁.V₁ = P₂.V₂
2.V = 6.V₂
V₂ = 1/3V
When the pressure increases to 6 atm, volume decreases by 1/3.
For case 2.)P₁ = 2
V₁ = V
P₂ = 0.4
2.V = 0.4V₂
V₂ = 5V
When pressure drops to 0.4 atm, volume increases by 5.
For case 3.)Since there are no change in the pressure, the volume is the same from the beginning, so does not change.
The tribute states of the ancient Aztec empire
were governed directly by the emperor.
made regular payments to the emperor.
acted as powerful independent city-states.
O surrounded the main Aztec city-state.
Answer:
made regular payments to the emperor.
Explanation:
The Aztec Empire was an alliance of three states: Mexico-Tenochtitlan, Texcoco, and Tlacopan. The area in and around the Valley of Mexico was ruled by these three city-states from 1428 to 1521. The state religion of the empire was polytheistic. The tribute states of the ancient Aztec empire made regular payments to the emperor.
Answer:
B
Explanation:
ellus
What is the pH of a 3.5 x 10-11 M
H+ solution?
pH = [?]
Answer:
[tex]pH=10.5[/tex]
Explanation:
Hello,
In this case, since we define the pH as:
[tex]pH=-log([H^+])[/tex]
We can directly compute it by using the given concentration of H⁺:
[tex]pH=-log(3.5x10^{-11})\\\\pH=10.5[/tex]
For which we conclude it is a basic solution as the pH is greater than 7.
Best regards.
How many milliliters of 0.200 M NH4OH are needed to react with 12.0 mL of 0.550 M FeCl3?
FeCl3 + 3NH4OH Fe(OH)3 + 3NH4Cl
Answer:
9.9 ml of 0.200M NH₄OH(aq)
Explanation:
3NH₄OH(Iaq) + FeCl₃(aq) => NH₄Cl(aq) + Fe(OH)₃(s)
?ml of 0.200M NH₄OH(aq) reacts completely with 12ml of 0.550M FeCl₃(aq)
1 x Molarity NH₄OH x Volume Am-OH Solution(L) = 2 x Molarity FeCl₃ x Volume FeCl₃ Solution
1(0.200M)(Vol Am-OH Soln) = 3(0.550M)(0.012L)
=> Vol Am-OH Soln = 3(0.550M)(0.012L)/1(0.200M) = 0.0099 Liter = 9.9 milliliters
The amount of [tex]0.200 M NH_{4} OH[/tex] required to react with [tex]12.0 ml[/tex] of [tex]0.550 M FeCl_{3}[/tex]would be [tex]9.9 ml.[/tex]
Given that,
Reaction:
[tex]3NH_{4} OH(Iaq) + FeCl_{3} (aq) => NH_{4} Cl(aq) + Fe(OH)_{3} (s)[/tex]
To find,
The amount of [tex]0.200 M NH_{4} OH[/tex]required to react with [tex]12.0 ml[/tex] of [tex]0.550 M FeCl_{3}[/tex] = ?
Procedure:
As we know,
[tex]1[/tex] × molarity of [tex]NH_{4}OH[/tex]× [tex]Volume (Am-OH) Solution(l)[/tex] [tex]= 2[/tex] × molarity of [tex]FeCl_{3}[/tex]× volume of solution [tex]FeCl_{3}[/tex]
By substituting the given values in this formula, we get
⇒ [tex]1(0.200M)[/tex][tex](Vol Am-OH Sol)= 3(0.550M)(0.012L)[/tex]
⇒ [tex]Vol Am-OH Soln = 3(0.550M)(0.012L)/1(0.200M)[/tex]
⇒ [tex]Vol Am-OH Solution = 0.099 liters[/tex]
[tex]= 0.099[/tex] × [tex]1000[/tex]
[tex]=[/tex] [tex]9.9 milliliters[/tex]
Thus, [tex]9.9 ml[/tex] is the correct answer.
Learn more about 'compounds' here:
brainly.com/question/13516179
A crystal of table salt (NaCl) is dissolved in water. Which of the following statements explains why the dissolved salt does not recrystallize as long as the temperature and the amount of water stay constant?
A crystal of table salt (NaCl) is dissolved in water. Which of the following statements explains why the dissolved salt does not recrystallize as long as the temperature and the amount of water stay constant?
Na+ and Cl- ions lose their charges in the water.
Water molecules surround the Na+ and Cl- ions.
Na+ and Cl- ions leave the water through vaporization.
Water molecules chemically react with the Na+ and Cl- ions.
Your answer: -
Answer: B - Water molecules surround the Na+ and Cl- ions.
You weighed out 0.020 g of your crude aspirin product in order to determine the amount of salicylic acid impurity. Following the procedure outlined in the manual, you dissolved the solid and diluted the solution to a final volume of 10.0 mL. If the absorbance of your sample solution was 1.07, what was the percent salicylic acid in your product
Answer:
The correct answer is 7.8 percent.
Explanation:
As mentioned in the given question, the absorbance (A) of the sample solution is 1.07. To find the concentration of aspirin, Beer's law is used, that is, A = ebc
Here, e is the extinction coefficient, which is equal to 139.322 M^-1cm^-1 as per the standard value for salicylic acid, b is the pathlength, which is equivalent to 1 cm. Now putting the values we get,
A = ebc
c = A / (eb)
c = 1.07 / (139.322 × 1)
c = 0.00768 M
Now to determine the percent salicylic acid in the sample, there is a need to compare the value of concentration determined with the concentration of aspirin given initially.
0.02 grams is the initial concentration of aspirin mentioned in the question. The molar mass of aspirin is 240 g/mol.
Therefore, the moles of aspirin will be,
0.02 / 240 = 8.33 × 10^-5 moles
The final volume of the diluted solution given is 10 ml or 0.01 liters.
The molarity of aspirin in the diluted solution will be,
c1 = 8.33 × 10^-5 / 0.01 = 8.33 × 10^-3 M or 0.00833 M
Now, the percent of salicylic acid in the product will be,
c1 - c / c1 × 100
(0.00833 - 0.00768) / 0.00833 × 100 = 7.8 %
Absorbance is directly proportional to the concentration of the solution. The absorbance can be calculated if the molar absorptivity, path length, and concentration of the absorbing species are known.
The percent of salicylic acid in the solution is 7.8%
Given that:
Absorbance of the solution is = 1.07
Path length = 1 cm.
Applying Beer's Law,
A = ε b c
where,
c = concentration, A = absorbance, ε = constant, and b = path length
Now, putting the values in above equation
c = [tex]\dfrac{\text{A}}{\text {(e b)}}[/tex]
c = [tex]\dfrac{1.07}{139.32 \times 1}[/tex] ( ε = 139.32)
c = 0.00768 M
Now, to calculate the percent of the salicylic acid in the solution, we will compare the given concentration of the aspirin.
As we know:
Given mass of aspirin = 0.02 g
Molar mass of aspririn = 240
Number of moles of aspirin = 0.02 / 240 = 8.33 x 10⁻⁵
Now, the molarity of aspirin is:
[tex]\text{Molarity}&= \dfrac{8.33 \times 10^{-5}}{0.01}\\\\\text{Molarity}&= 8.33 \times 10^{-5}[/tex]
Now, the percent of the salicylic acid is:
[tex]\dfrac{\text {C}_1 - \text C}{\text {C}_1 \times 100}[/tex]
[tex]\dfrac{(0.00833 - 0.00768)}{0.00833 \times 100}[/tex]
Percent of Salicyclic acid = 7.8%.
Thus, the percentage of the salicylic acid in the given solution is 7.8%.
To know more about Absorbance, refer to the following link:
https://brainly.com/question/17062521
An empty weighing dish has a mass of 1.0041 ± 0.0002 g. After you add dried sodium chloride to the dish, the mass is 3.2933 ± 0.0002 g. You quantitatively transfer the sodium chloride into a 500.00 ± 0.05 mL volumetric flask and dilute to the mark with deionized water. The molar mass of sodium chloride is 58.440 g/mol. What is the absolute error in the concentration of the resulting solution? Report your answer normally to the correct number of significant figures with the correct unit.
Answer:
The correct answer to the following question will be "0.0013%".
Explanation:
The given values are:
Weight of an empty dish = 1.0041 ± 0.0002 g
Weight of dish + sodium chloride (NaCl) = 3.2933 ± 0.0002 g
Weight of NaCl = 2.2892 ± 0.0002 g
Now,
Volume of the solution = 500.00 ± 0.05 ± 0.0002
= 500.00 ± 0.0502 ml
So,
Molarity = [tex]\frac{W \ NaCl}{M \ NaCl} \times \frac{1000}{Volumes \ of \ solution}[/tex]
On putting the values in the above formula, we get
= [tex]\frac{(2.2892\addeq +0.0002)}{58.440}\times \frac{1050}{(500.00+0.0502)}[/tex]
= ([tex]3.917[/tex] ± [tex]0.0002[/tex]) × ([tex]2[/tex] ± [tex]0.0502[/tex])
= ([tex]0.7834[/tex] ± [tex].00001004[/tex])
Now,
Absolute error = [tex]\frac{0.00001004}{0.7834}\times 100[/tex]
= [tex]0.0013[/tex]%
The pressure of a gas is 100.0 kPa and its volume is 500.0 mL. If the volume increases to 1,000.0 mL, what is the new pressure of the gas?
Answer:
[tex]P_2=50kPa[/tex]
Explanation:
Hello,
In this case, we can apply the Boyle's law in order to understand the pressure-volume relationship as an inversely proportional relationship relating the initial and the final volume:
[tex]P_1V_1=P_2V_2[/tex]
Next, we compute the final pressure P2:
[tex]P_2=\frac{P_1V_1}{V_2}=\frac{100.00kPa*500.0mL}{1000.0mL} \\\\P_2=50kPa[/tex]
Thus we validate, the higher the volume the lower the pressure.
Best regards.
Which sulfur is a gas that reacts with liquid water to produce aqueous sulfuric acid, or acid rain. What is the equation for this reaction
Answer:
Sulfur Trioxide
Explanation:
Sulfur trioxide is a gas that reacts with liquid water to produce aqueous sulfuric acid,or acid rain.
What is the molarity of a solution in
which 3.8 moles of sodium chloride
(NaCl) is dissolved in water to a final
volume of 2.5 L?
Answer:
1.52M in NaCl
Explanation:
Molarity = moles solute / volume solution in Liters
=> molarity (M) = 3.8 moles / 2.5 Liters solution = 1.52 molar solution in NaCl
Answer: 1.52
Explanation:
Methanol (CH3OH) is the simplest of the alcohols. It is synthesized by the reaction of hydrogen and carbon monoxide
CO(g)+2H2(g)=CH3OH
If 500 mol of CO and 750 mol of H2 are present, which Is the limiting reactant?
Answer:
By reacting carbon monoxide and hydrogen the formation of methanol takes place, the reaction is,
CO(g)+2H₂(g)⇔CH₃OH (g)
Based on the given reaction, one mole of methanol is obtained by reacting one mole of carbon monoxide (CO) with the two moles of hydrogen (H₂). It is mentioned in the question that for the reaction 500 mol of carbon monoxide and 750 moles of hydrogen are present.
Therefore for 500 moles of carbon monoxide, there is a requirement of 2 × 500 moles of hydrogen, which is equivalent to 1000 moles of hydrogen (H₂). However, only 750 moles of hydrogen is present. Therefore, the limiting reactant in the given case is H₂. The present moles of H₂ will react with 0.5 × 750 moles of CO = 375 mole of CO
The additional or excess concentration of CO, which is the excess reactant will be, 500-375 = 125 moles.
does the reaction Fe + CuNO3 occur
Answer:
yes
Explanation:
You have 0.00891 g of platinum. What is this in micrograms?
A chemist must prepare of nitric acid solution with a pH of at . He will do this in three steps: Fill a volumetric flask about halfway with distilled water. Measure out a small volume of concentrated () stock nitric acid solution and add it to the flask. Fill the flask to the mark with distilled water. Calculate the volume of concentrated nitric acid that the chemist must measure out in the second step. Round your answer to significant digits.
Answer:
The volume of concentrated nitric acid is
4.3mL
Explanation
Check the attachment
H2O(g) + Cl2O(g) ↔ 2 HOCl(g) (a) Initially, 0.0555 mol H2O and 0.0230 mol Cl2O are mixed in a 1.00 L flask. At equilibrium, there is found to be 0.0200 mol of HOCl(g). Calculate the concentrations of H2O(g) and Cl2O(g) at equilibrium. (b) Using your results from part (a), calculate the equilibrium constant, Kc. (c) 1.0 mol pure HOCl is placed in a 2.0 L flask. Use your Kc from part (b) to calculate the equilibrium concentrations of H2O(g) and Cl2O(g).
Answer:
a)
[H₂O] = 0.0455M
[Cl₂O] = 0.0130M
[HOCl] = 0.0200M
b) Kc = 0.676
c) [H₂O] = [Cl₂O] = 0.177M
Explanation:
Based on the reaction:
H₂O(g) + Cl₂O(g) ⇄ 2HOCl(g)
Kc is defined as:
Kc = [HOCl]² / [H₂O][Cl₂O] For molar concentrations in equilibrium
As volume of the flask is 1.00L, the initial molar concentrations of H₂O and Cl₂O is 0.0555M and 0.0230M, respectively.
In equilibrium, the concentrations are:
[H₂O] = 0.0555M - X
[Cl₂O] = 0.0230M - X
[HOCl] = 2x = 0.0200M → X = 0.0100M
Where X is reaction coordinate
a) Concentrations in equilibrium are:
[H₂O] = 0.0455M
[Cl₂O] = 0.0130M
[HOCl] = 0.0200M
b) Replacing in Kc:
Kc = [0.0200]² / [0.0455][0.0130] = 0.676
c) Initial concentration of HOCl is 1.0mol / 2.0L = 0.50M. In equilibrium concentrations are:
[H₂O] = X
[Cl₂O] = X
[HOCl] = 0.50M - 2X
Replacing in Kc formula:
0.676 = [0.50-2X]² / [X][X]
0.676X² = 4X² - 2X + 0.25
0 = 3.324X² - 2X + 0.25
Solving for X:
X = 0.177M
X = 0.425M → False answer, produce negative concentrations.
As X = [H₂O] = [Cl₂O]; equilibrium concentrations of both compounds is 0.177M
The radioactivity due to carbon-14 measured in a piece of a wooden casket from an ancient burial site was found to produce 20 counts per minute from a given sample, whereas the same amount of carbon from a piece of living wood produced 160 counts per minute. The half-life of carbon-14, a beta emitter, is 5730 years. Thus we would estimate the age of the artifact to be about?
Answer:
17202.6 years
Explanation:
Activity of the living sample (Ao) = 160 counts per minute
Activity of the wood sample (A) = 20 counts per minute
Half life of carbon-14 = 5730 years
t= age of the artifact
From;
0.693/t1/2= 2.303/t log Ao/A
Then;
0.693/ 5730= 2.303/t log Ao/A
Substituting values;
0.693/5730= 2.303/t log (160/20)
Then we obtain;
1.209×10^-4 = 2.0798/t
t= 2.0798/1.209×10^-4
Thus;
t= 17202.6 years
Therefore the artifact is 17202.6 years old.
_______ occurs when a body’s molecular wavelength sends vibrations to another body, resulting in the production of another sound wave
Answer:
Natural frequency
Explanation:
Answer:
Resonance
Explanation:
Consider the following intermediate chemical equations.
2 equations. First: upper P subscript 4 (s) plus 6 upper C l subscript 2 (g) right arrow 4 upper P upper C l subscript 3 (g) delta H 1 equals negative 4,439 kilojoules. Second: 4 upper P upper C l subscript 3 (g) right arrow upper P subscript 4 (s) plus 10 upper C l subscript 2 (g) Delta H 2 equals 3,438 kilojoules.
What is the enthalpy of the overall chemical reaction Upper P upper C l subscript 5 (g) right arrow upper P upper C l subscript 3 (g) plus Uper C l subscript 2 (g).?
-999 kJ
-250. kJ
250. kJ
999 kJ
Answer:
PCl3 or option C
Explanation:
For everyone taking edge, trust me. Most of the answers are half-fasted, and offer no explanation. My explanation is that this is the right answer and you can trust me. Im taking the courses just like all of you, so i have no reason to misslead. Hope this helps! if you require more information, i cannot offer it. I gain knowledge by my failures.
Answer:
The correct answer is 250. kJ
Also referred to as C or Option 3
Explanation:
I got the answer correct because of the help from the other answer. Therefore, please mark the other person brainliest, they deserve it!
How many kilograms of solvent (water) must 0.71 moles of KI be dissolved in to produce a 1.93 m solution?
Answer: kg= 0.37
Explanation:
Use the molality formula.
M= m/kg
4. A burning candle is an example of a chemical reaction taking place. What i
can be inferred about this reaction? Choose the correct answer."
A.Mass is not conserved.
B. The reaction absorbs energy. C.The reaction releases energy
D.There are reactants but no products,
Answer:
C
Explanation:
heat is energy
