Answer: Scientists make designs based on engineering knowledge and
then make it available for public use.
N2O4(g) + 4H2(g) → N2(g) + 4H2O(g), solve using standard enthalpies of formation
The standard enthalpy of formation (Δ[tex]H_f[/tex]) is a measure of the energy released or consumed when one mole of a substance is created under standard conditions from its pure elements.
Standard enthalpies (Δ[tex]H_f[/tex]) of formation for given reaction is 978.3 kJ
What is Standard enthalpies of formation?The standard enthalpy of formation is defined as the enthalpy change when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure elements under the same conditions.
Given reaction ;
[tex]N_2O_4(g) + 4H_2 (g) - > N_2(g) + 4H_2O(g)[/tex]
To Find : Δ[tex]H_f[/tex]
Δ[tex]H_f[/tex] = ∑np Δ[tex]H_f[/tex] (products) – ∑np Δ[tex]H_f[/tex] (reactants)
Δ[tex]H_f[/tex] = [1(Δ[tex]H_f[/tex] [tex]N_2[/tex]) + 4(Δ[tex]H_f[/tex] [tex]H_2O[/tex])] – [1(Δ[tex]H_f[/tex] [tex]N_2O_4[/tex]) + 4(Δ[tex]H_f[/tex] [tex]H_2[/tex])]
Δ[tex]H_f[/tex] = [1(0) + 4(-241.8)] – [1(+9.16) + 4(0)]
Δ[tex]H_f[/tex] = [4(-241.8)] – [1(+9.16)] = 978.3 kJ
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What is the Substance that is oxidized in 2K+ S > K2S
Answer :]
This is an oxidation-reduction (redox) reaction:
S0 + 2 e- → S-II (reduction)
2 K0 - 2 e- → 2 KI (oxidation)
S is an oxidizing agent, K is a reducing agent.
Answer:
K
Explanation:
Here, in this reaction 2 moles of potassium react with 1 mole of sulfur to form 1 mole of potassium sulfide.
Let's compare the electronic configurations of both elements :
⇒ K = {2, 8, 8, 1}
⇒ K can attain noble gas configuration by losing one electron
⇒ K exists as : K⁺
⇒ S = {2, 8, 6}
⇒ S can attain noble gas configuration by the addition of 2 electrons
⇒ S exists as S²⁻
Now, we know that will lose protons when oxidized. Hence, here the substance which is oxidized is K
Two identical syringes are filled to the same volume at the same temperature and pressure. If one
syringe is filled with chlorine gas and the other with nitrogen gas
A. the syringe filled with nitrogen gas contains more moles of gas.
B. the syringe filled with nitrogen gas contains more grams of gas.
C. the different gases have the same average kinetic energy.
D. the molecules of chlorine gas have a higher average velocity than the molecules of nitrogen gas.
Could someone explain why the answer is C?
The temperature is the same, so the amount of kinetic energy will also be the same.
Lipid-soluble hormones can't be stored within vesicles.
Select one:
O True
O False
Answer:
true
Explanation:
they can not be stored within the vesicles
1. When conducting this experiment, some procedures call for heating the substance several times and recording the mass after each heating, continuing until the mass values are constant. Explain the purpose of this process and how it might reduce errors.
The purpose of this process is to reduce the risk of having outliers of false results.
What is a good scientific experiment?It is important to bear in mind that a good scientific experiment usually tests one independent variable at a time, and that is why it is important to keep all other potential variables constant and to use a control group.
Although, the experiment you are referring to in your question is missing the general principle when conducting an experiment is the running of multiple tests before coming up with an actual test result.
Therefore, when completing a science experiment it is important to run multiple tests like heating the substance several times until a constant mass value is obtained, in other to ascertain the results. the reason why such process is undertaken is to reduce the risk of having outliers of false results.
A scientific experiment involves several procedures and this depends on the type and purpose of the experiment.
for example ;
An experiment with the purpose of determining how the mass of an object reacts to heat will require the mass of the object to be recorded after heating the object/substance several times.
Hence we can conclude that the purpose of the process is to reduce the risk of having outliers of false results.
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How many moles of au are in 66.4g of au
Answer:
0.3371 moles
Explanation:
gold is 196.967 grams per mole
66.4 grams divided by 196.967 grams per mole =
0.3371 moles
A chemical reaction can be reversed if?
The energy of the reactants exceeds the activation energy threshold.
The energy of the products exceeds the activation energy threshold.
The energy of the reactants is less than the activation energy threshold.
The energy of the products is less than the activation energy threshold.
Answer: The energy of the products exceeds the activation energy threshold.
Explanation:
In the reverse reaction, the reactants of the forward reaction are now the products of the reverse reaction and vice versa.
This means that normally since you would need the energy of the reactants of the forward reaction to exceed the activation energy threshold, in the reverse reaction, the energy of the products would need to exceed the activation energy threshold.
Is salmon fortified or enriched?
Which statement below is true about a nuclear power plant?
O There is no air pollution from its operation.
O It produces less electricity than a coal-burning power plant.
O No fuel is needed for this type of power plant.
O It is not possible for a leakage of nuclear material.
Answer:
There is no air pollution
Explanation:
Unless there is a meltdown.
Nuclear plants generate far more power than coal plants
FUEL is needed....nuclear fuel
Leakage CAN happen.... see info on Three Mile Island or Cchernobryl (Ukraine)
How can noble gas electron configuration be achieved?
Answer:
A noble gas configuration of an atom consists of the elemental symbol of the last noble gas prior to that atom, followed by the configuration of the remaining electrons. So for sodium we make the substitution of (Ne) for the 1s22s22p6 part of the configuration. Sodium's noble gas configuration becomes (Ne) 3s1.
The radius of a single atom of a generic element X is 169 picometers (pm) and a crystal of X has a unit cell that is body-centered cubic. Calculate the volume of the unit cell.
The volume of the unit cell is 2.67 x 10⁻²⁸ m³.
What is the volume of a unit cell of a body-centered cubic crystal?In a body-centered cubic unit cell, the volume occupied by the particles of the substance is about 68% of the total unit cell.
Assuming that a single atomic a sphere, the volume is:
Volume(atom) = 4/3 x π x r³
Volume(atom) = 4/3 x π x (169 x 10⁻¹²)³
Volume(atom) = 2.02 x 10⁻²⁹ m³
There are a total of 9 atoms in a body-centered unit cell, so the total volume occupied by atoms is:
2.02 x 10⁻²⁹ x 9
= 1.82 x 10⁻²⁸ m³
Volume of cell = (1.15 x 10⁻²⁸ ) / 0.68
Volume of cell = 2.67 x 10⁻²⁸ m³
Therefore, the volume of the unit cell is 2.67 x 10⁻²⁸ m³.
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The enzyme provided is a stock solution which should be diluted 50-fold with 0.001M HCl immediately before use.
Enzyme :1mg/ml chymotrypsin A in 0.001M HCl
How do I work out this calculation, if I want the 5ml of the diluted enzyme?
In order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
What is dilution?Dilution is a process whereby a solution of lower concentration is prepared from one of a higher concentration.
Dilution is done by using the dilution formula below:
C1V1 = C2V2C1; Initial concentration of enzyme = 1 mg/mL
C2; Final concentration of enzyme = 1/50 mg/ml = 0.02 mg/ml
V1; Initial volume of enzyme = y
V2; Final volume = 5.0 ml
V1 = C2V2/C1
V1 = 0.02 * 5/1 = 0.1 mL
Therefore, in order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
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the density of 190mg of a liquid is 0.0076g/cm calculate the volume in ml
[tex]\\ \rm\Rrightarrow Density=\dfrac{Mass}{Volume}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{Mass}{Density}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{0.19}{0.0076}[/tex]
[tex]\\ \rm\Rrightarrow Volume=25cm³[/tex]
[tex]\\ \rm\Rrightarrow Volume=25mL[/tex]
in an addition reaction, which bond of the reactant is broken?
A. carbon-hydrogen single bond
B. carbon-carbon single bond
C. carbon-carbon double bond
D. carbon-hydrogen double bond
Answer:
C. carbon-carbon double bond
Explanation:
A reaction in which two or more molecules combine together to result in the formation of a larger molecules then this type of reactions are known as addition reactions.
Usually compounds which contain a double bond undergo addition reactions.
For example, a compound with carbon-carbon double bond, carbonyl group, imine group etc undergo addition reaction.
Thus, we can conclude that in an addition reaction, carbon carbon double bond of the reactant is broken.
Carbon-carbon double bonds (unsaturations) are found in naturally occurring fatty acids.
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The magnet below is cut in half. What will be the result
the cut pieces will have their own north and south pole
The vapor pressure of benzene at 25°C is 95.1 mm Hg and of toluene 28.4 mm Hg. The mass fractions of benzene and toluene in a solution are 0.5.
a) Calculate the partial pressure of benzene and toluene above the solution.
b) Calculate the total vapor pressure above the solution.
c) Calculate the vapor composition above the solution.
Answer:
df dffdffdfd dffd ff d
Explanation:
df fd df f df df dfdf f fdf df df df fd
To what temperature must a balloon, initially at 9°C and 4.00 L, be heated in order to have a volume of 6.00 L?
The balloon must be heated to a temperature of 150 °C in order to have a volume of 6.00 L.
How are volume and temperature of gases related?The volume of a gas is directly proportional to the temperature of the gas.
According to Charles' law: V1/T1 / = V2/T2
V1 =4.0 L
T1 = 9°C = (273. + 9) K = 282 K
V2 = 6.0 L
T2 = ?
T2 = V2×T1/V1
T2 = 6 × 282 / 4 = 423 K
423.2 K = 423 -273 = 150 °C
Therefore, the balloon must be heated to a temperature of 150 °C in order to have a volume of 6.00 L.
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What is the product of the unbalanced equation below?
H₂(g) + Cl₂(g) →
The Periodic Table
OA. H₂(g) + Cl₂(g)
OB. H₂Cl₂(9)
O C. HC1₂(g)
OD. HCI(g)
D
Explanation:
B/c both the hydrogen and chlorine have the same valance number so if a metal or non metal have the same valance number you should cancel out the numbers and you will have to put only the non metal or metals.
In a laboratory investigation, a student separates
colored compounds obtained from a mixture of
crushed spinach leaves and water by using paper
chromatography. The colored compounds
separate because of differences in
(1) molecular polarity
malleability
(3) boiling point
(4) electrical conductivity
Answer:
Molecular polarity
Explanation:
tell me if im right
What’s properties my change during a chemical reaction
Answer:
The signs of chemical change include changes in color, temperature, the production of light, changes in odor, and the formation of gases.
what is the shape of the molecule that has 2 atoms bonded to a central atom and 1 lone pair of electrons
When there are two bond pairs and one lone pair, the molecule will have a bent molecular shape.
What is the shape of a molecule?The shape of a molecule depends on the orientation and number of electron pairs on the valence shell of the central atom in the molecule. This is based on the postulates of the valence shell electron pair repulsion theory.
When there are two bond pairs and one lone pair, the molecule will have a bent molecular shape.
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A lead ball is added to a graduated cylinder containing 50.6 ml of water, causing the level of the water to increase to 93.0 mL. What is the volume in milliliters of the lead ball, Vieras? Viead =
42.4 ml is the volume in milliliters of the lead ball if a lead ball is added to a graduated cylinder containing 50.6 ml of water.
What is a graduated cylinder?A tall narrow container with a volume scale is used especially for measuring liquids.
The graduated cylinder contains water
mL is a volume unit.
Water volume = 50.6 ml
The lead ball caused an increase in volume from 50.6 ml to 93.0 mL.
The new volume is the lead ball volume plus the original water volume :
Final volume = Vlead ball+ Water original volume
[tex]93.0 mL= V_(lead ball) +50.6 ml[/tex]
[tex]V_(lead ball) = 93.0 mL - 50.6 ml[/tex]
[tex]V_(lead ball) = 42.4 ml[/tex]
Hence, 42.4 ml is the volume in milliliters of the lead ball.
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A piece of metal weighing 500g is put into a boiling (100 degrees C) water bath. After 10 minutes, the
metal is immediately placed in 250g of water at 40°C. The maximum temperature that the water reaches
is 50°C. What is the specific heat of the metal? (The Specific heat of water is 1.0 cal/g x°C). Show your
calculations!
thermometer
The specific heat of the metal is calculated using the change in temperature, heat, and mass. The specific heat of the metal is 0.21 J/g °C.
What is heat energy?Heat energy is a transfer of the energy lost by a system to the energy gained by another system. The calorimeter is used to measure the specific heat of the system.
Given,
Mass of metal = 500 gm
Temperature = 100 °C
Mass of water = 250 gm
Temperature = 40 °C
Specific heat of water = 4.184 J/g °C
The specific heat (c) of metal is calculated as:
Q = mC ΔT
and, Q (metal) = Q (water)
Substituting values in the above equation:
(500 )(c)(100) = (250)(4.184)(50-40)
50000 c = 10460
c = 0.21 J/g °C
Therefore, the specific heat of metal is 0.21 J/g °C.
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Complete the balanced neutralization equation for the reaction below:
HNO3(aq) + Ba(OH)2(aq) →
The complete equation will look thus: [tex]2HNO_3(aq) + Ba(OH)_2(aq) --- > Ba(NO_3)_2 + 2H_2O[/tex]
Balancing equationsIn order for equations to be balanced, the component atoms in the reactants and products must be the same in terms of number.
Thus, in the given equation, the number of H, N, O, and Ba atoms in the reactants and the products must be equal.
Therefore, the overall equation becomes:
[tex]2HNO_3(aq) + Ba(OH)_2(aq) --- > Ba(NO_3)_2 + 2H_2O[/tex]More on balancing equations must be found here: https://brainly.com/question/12192253
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Answer:2HNO3 + Ba(OH)2 → Ba(NO3)2 + 2H2O
Explanation:
HNO3 + Ba(OH)2 = Ba(NO3)2 + H2O
This is what each element is....
H= 1+2=3 H=2
N=1 N=2
O=2+2=4 O=4+1=5
Ba=1 Ba=1
Now to balance each side.....
H=2+2=4 H=2++2=4
N=2 N=2
O=4+2=6 O=4+2=6
Ba=1 Ba=1
The balanced equation is now
2HNO3 + Ba(OH)2 → Ba(NO3)2 + 2H2O
Which of the following is ture about a scientific hypothesis?
Which statement below is NOT true of fission?
O It is the splitting of a large nuclide into 2 smaller nuclei.
O Slow neutrons are fired at a large nucleus.
Released neutrons can be used to start more fission reactions.
The only products are two smaller isotopes.
The statement that is NOT true of fission is B. slow neutrons are fired at a large nucleus.
What is Nuclear fissionThis is the splitting of large nuclei to smaller ones. It could be a natural or spontaneous dissociation by radioactive decay, or can be initiated in in a laboratory under required conditions. It involves;
Splitting of large nuclei to two smaller onesRelease of large amount of energyNeutrons released can be used to initiate chain reactionsHence, the statement that is not true about fission is that slow neutrons are fired at a large nucleus.
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advantages of artificial silk over natural silk
Answer:
Less expensive than natural fibers
Strong and long-lasting
Easily available
Easy to maintain
Dry up quickly
How many moles of aluminum oxide (Al2O3) are produced by reacting 5 moles of iron oxide (FeO)?
2AI+ 3FeO --> 3Fe + 1Al₂O3
Answer:
1.67 moles Al₂O₃
Explanation:
To find the amount of aluminum oxide produced, you need to start with 5 moles FeO and multiply it by the mole-to-mole ratio displaying the relationship between moles FeO and moles Al₂O₃. This ratio incorporates the coefficients from the equation. Remember, make sure to write the ratio in a way that allows for the cancellation of moles FeO.
2 Al + 3 FeO ---> 3 Fe + 1 Al₂O₃
5 moles FeO 1 mole Al₂O₃
-------------------- x ---------------------- = 1.67 moles Al₂O₃
3 moles FeO
you have a sample of.neon gas that you want to use to.make a glowing sign. you investigate that the gas sample is at 45c and has a volume of 10 liters. when you place the sample of neon gas your fridge you observe the temperature descreasing to 13.5
HELPP!!
Methane (CH4) undergoes combustion. Which products form?
A. CO₂ and H₂
B. C and H₂O
C. CO₂ and H₂O
D. CO₂, H₂O, and 02
Answer: C. CO₂ and H₂O
Explanation:
Combustion reactions produce carbon dioxide and water.