Answer:
ΔH°f{IF(g)} = -127.58 kJ/mol
Explanation:
Hello.
In this case, since the information about the chemical reaction is:
IF7(g) + I2(g) → IF5(g) + 2 IF(g) ; ΔH°rxn = -89 kJ / mol
ΔH°f{IF7(g)} = -941 kJ / mol
ΔH°f{IF5(g)} = -840 kJ / mol
ΔH°f{I2(g)} =62.42 kJ / mol (it should be 0 since I2 is a pure element that is nor formed by other elements, however, we will use the given value).
Since we don't know the enthalpy of formation of IF, but the enthalpy of reaction for this one is:
ΔH°rxn = ΔH°f{IF5(g)} + ΔH°f{IF(g)} - ΔH°f{IF7(g)} - ΔH°f{I2(g)}
We can obtain it via:
ΔH°f{IF(g)} = ΔH°rxn - ΔH°f{IF5(g)} + ΔH°f{IF7(g)} + ΔH°f{I2(g)}
ΔH°f{IF(g)} = -89 - (-840) + (-941) + 62.42
ΔH°f{IF(g)} = -127.58 kJ/mol
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Volcanologists are scientists who study volcanic eruptions. However, most volcanologists rarely get to witness a volcanic eruptions actually occurring. Instead, many volcanologists use models to study volcanic eruptions. What is the most likely reason why volcanologists often rely on models to study volcanic eruptions?
A.
Volcanic eruptions are too large to be able to see with the naked eye.
B.
Volcanic eruptions are very dangerous events.
C.
Volcanic eruptions are rare occurrences so it is difficult to see them.
D.
Volcanic eruptions take too long to be able to be observed in their entirety.
Answer:
Volcanic Eruptions are a very dangerous event
Explanation:
Models represent objects, events, and processes in the real world. Models are often used when an object, event, or process occurs too slowly or too quickly; is too small or too large; is too complicated or too dangerous. Volcanic eruptions produce both molten lava and poisonous gases. Therefore, eruptions can be very dangerous. Many volcanologists have lost their lives while observing volcanic eruptions.
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A copper wire was cut into pieces and dropped into a test tube containing acid, Bubbles formed immediately, the liquid in the test tube turned green, and the pieces of wire were no longer visible, which most likely happened to the pieces of copper wire?
А. The copper wire was chemically changed when it was cut and placed in the acid,
B the copper wire was physically changed when it was cut and placed in the acid,
C The copper wire was physically changed when it was cut and chemically changed when it was placed in the acid,
D The copper wire was chemically changed when it was cut and physically changed when it was placed in the acid,
Answer: i think its A
Explanation:
Answer:
A
Explanation:
Becuase bubbles only come from chemical changes
Are homogeneous mixtures only able to be chemically separated into their own individual components?
Answer:
Are the components of a homogeneous mixture are chemically combined?
Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. ... A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Explanation:
In this periodic table, which color or colors represent the elements that are
metals?
A. Blue and green
B. Orange and green
C. Orange only
D. Blue only
Answer:
D
Explanation:
the metal are on the left and in the middle
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Therefore, the correct option is option D that is Blue only.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.
The elements which is colored blue are elements that are metals. Metals are mostly on the left side of the periodic table. Metals loose lectrons easily. Metals are lustrous, malleable and ductile.
Therefore, the correct option is option D that is Blue only.
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Which is a product of nuclear fusion?
a nucleus that has a greater mass number than the starting materials
two nuclei that are roughly half the mass of the starting materials
a nucleus that has the same atomic number as the starting materials
two nuclei that have greater atomic numbers than the starting materials
The Answer is: A
The product of nuclear fusion is a nucleus that has a greater mass number than the starting materials.
What is nuclear fusion?Nuclear fusion occurs when two or more atomic nuclei unite to generate one or more new atomic nuclei and subatomic particles.
The release or absorption of energy is caused by the mass differential between the reactants and products.
If absorption of energy takes place then the formed nuclei will have the higher mass than reactant nuclei.If release of energy takes place then the formed nuclei will have the lighter mass than reactant nuclei.Hence a nucleus that has a greater mass number than the starting materials is the product of the nuclear fusion is .
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Answer:
A
Explanation:
Identify the nucleic acid DNA
1. Cholesterol
2. Proteins
3. Disacharide
Answer:
DNA
Explanation:
A silver ring has a density of 10.50 g/mL. What is the mass of the ring that has a volume of 10.0 mL?
20.5 g?
105 g?
0.952 g?
Answer:
the answer is 105 g/mL
Explanation:
beacuse mass = density×volume
A liquid was known to be either methyl alcohol (CH3OH) or ethyl alcohol (CH3CH2OH). The Dumas method for determining molar masses was used to obtain an approximate molar mass, and this value was used to identify the alcohol. The gaseous alcohol at 98oC and 740Torr has a mass of 0.276g in a Dumas bulb of volume equal to 270mL. Which alcohol was present
Answer:
Methyl alcohol was present.
Explanation:
To solve this problem we use the PV=nRT formula:
P = 740 Torr ⇒ 740/760 = 0.973 atmV = 270 mL ⇒ 270/1000 = 0.270 LT = 98 °C ⇒ 98 + 273.16 = 371.16 KAnd solve for n:
n = PV/(RT)n = 0.973 atm * 0.27 L / (0.082atm·L·mol⁻¹·K⁻¹ * 371.16 K)n = 8.632 x 10⁻³ molNow we divide the mass and the moles to calculate the molar mass:
0.276 g / 8.632 x 10⁻³ mol = 31.97 g/molMethyl alcohol (CH₃OH) has that molar mass.
The image shows four organelles: which of these controls what enters and exits the cell?
Answer:
The cell membrane.
Explanation:
A 293.9 mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.10 M. What volume of solvent in mL has evaporated from the 0.275 M solution
Answer:
220.4mL were evaporated
Explanation:
First, we are going to calculate the moles of the solution. Then, with the new concentration we can solve the volume of the solution and the evaporated volume:
Moles initial solution:
293.9mL = 0.2939L * (0.275mol / L) = 0.08082 moles of solution.
As the new concentration is 1.10M, the new volume must be:
0.08082 moles of solution * (1L / 1.10mol) = 0.07348L =
73.5mL you have still present in you solution
And evaporated volume is:
293.9mL - 73.5mL =
220.4mL were evaporatedhow do you Pangea and plate tectonic differ?
Using the information in the table to the right, calculate the average atomic mass of copper. Report to two decimal places.
Answer: 63.55 amu
Answer:63.55
Explanation:
What is the shape of the hypothetical molecule XY3
Answer:
Trigonal planar
Explanation:
If a hypothetical molecule XY3 has three electron domains as shown and no lone pairs, the molecule will be trigonal planar in shape.
From the valence shell electron pair repulsion theory, the shape of molecules is dependent on the number of electron domains in a molecule and weather those electron pairs are lone pairs or bond pairs.
Since lone pairs cause more repulsion and take up more space around the central atom than bond pairs, bond pairs cause the bond angle and molecular geometry to deviate from that predicted on the basis of the valence shell electron pair repulsion theory.
Finally, remember that in a molecule, electron pairs are placed as far apart in space as possible to minimize repulsion.
If a sample contains 78.0 % of the R enantiomer and 22.0 % of the S enantiomer, what is the enantiomeric excess of the mixture?
Answer: The enantiomeric excess of the mixture =56%
Explanation:
As per given : R isomer = 78%
S isomer = 22%
In chiral substances, Enantiomeric excess is the measure of purity.
So, Enantiomeric excess of the mixture = [tex]|\frac{R-S}{R+S}|\times100[/tex]
[tex]=|\frac{78-22}{78+22}|\times100[/tex]
[tex]=|\frac{56}{100}|\times100\% \\\\=56\%[/tex]
Hence, the enantiomeric excess of the mixture =56%
In what ways is a model similar to the thing it represents?
A. A model must be identical to the thing it represents in every way.
B. model can be different from the thing it represents in either its size or the materials it is made of.
C. A model must be identical to the thing it represents in every way except that it can be made out of different materials.
D. A model must be identical to the thing it represents in every way except that it can be a different size.
Answer: A
Explanation: A model has to be identical to the thing it represents in every way, or people may think something is different than it actually is, because they see it in the model. The answer to the question is A.
What is the speed of a rocket in units of meter/ second if its travels at a speed of 1000 km/minutes?
Answer:1,080 m
Explanation:
What is the order of a reaction with a half-life that is directly proportional to initial concentration? Select the correct answer below: Zero order First order Second order None of the above
Answer:
Zero order
Explanation:
A zero order reaction is one in which the rate of reaction is independent of the concentration of reactants.
In a zero-order reaction, the half-life of the reactants is directly proportional to the initial concentration of the reactants . As initial concentration increases, the half-life for the reaction increases likewise and vice versa.
What volume of 6.0 M HCl would you need to add to a 800.0 mL of 0.10 M NaAc to give a final pH = 4.30? The pKa of HAc is 4.78. Give the answer in milliliters, using 2 sig. figs.
Answer:
3.33 ml
Explanation:
We have
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
This is expressed as
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
From here we cross multiply to get
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
moles of HCl = 0.02 mol
Volume of Hcl = 0.02x1000 = 20
20/6.0
= 3.33 Ml
The volume of 6.0 M HCL should be 3.33 ml.
Calculation of the volume:Since
pH to be equal to pKa + log [ NaAc / HAc]
pH = 4.30
pKA = 4.78
Now we can do like
4.30 = 4.78 + log [ NaAc / HAc]
log [ NaAc / HAc] = - 0.48
[ NaAc / HAc] = 10^-0.48
= 0.33
Naac/HAc = 0.33
Now
NaAc = 0.33 HAc
The ratio can be given as 1 : 0.33 or 3:1
So,
Moles of NaAc = 800 x 0.10 / 1000
= 0.08
With a ratio of 3 : 1 NaAC and HAc
We have 0.06 mol NaAc and 0.02 mol HAc
And,
moles of HCl = 0.02 mol
So,
Volume of Hcl = 0.02x1000 = 20
= 20/6.0
= 3.33 Ml
hence, The volume of 6.0 M HCL should be 3.33 ml.
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Which of these terms describes an organism that eats green algae and shrimp?O A. a carnivore
O B. an omnivore
O C. a herbivore
O D. a detrivore
ASAP
Answer: C. a herbivore
Explanation: it's not a because omnivores eat plants and animals not Detritivores, are heterotrophs that obtain nutrients by consuming detritus
but herbivores eat vegetables and plants
i'm a herbivore i don't eat meat :)
What is the molarity of a solution that contains 2.5 g NaCl in 2 L of water?
A. 1.25 M
B. 0.02 M
C. 2.0 M
D. 0.125 M
Answer:
0.02
Explanation:
I'm not really sure ok so sorry
Please awnser asap!!! 20 points!!
According to the law of conservation of mass, how many hydrogen and chlorine atoms are required for this reaction?
A 1 hydrogen atom and 1 chlorine atom
B 1 hydrogen atom and 2 chlorine atoms
C 2 hydrogen atoms and 1 chlorine atom
D 2 hydrogen atoms and 2 chlorine atoms
Answer: d
Explanation:
Did this last year
Calculate the pH at of a solution of trimethylammonium chloride . Note that trimethylamine is a weak base with a of . Round your answer to decimal place.
Answer:
pH = 11.9
Explanation:
The solution is 0.93M. The pKb is 4.19
The general equation of a weak base, X, is:
Kb = [OH⁻] [XH⁺] / [X]
Where Kb is 10^-pKb = 6.457x10⁻⁵
[OH⁻] and [XH⁺] comes both from the same equilibrium and its concentration, X, is the same = [OH⁻] = [XH⁺] = X
And [X] could be taken as the initial concentration of the weak acid, 0.93M
Kb = [OH⁻] [XH⁺] / [X]
6.457x10⁻⁵ = X² / 0.93M
6x10⁻⁵ = X²
X = 7.749x10⁻³M = [OH⁻]
As pOH = -log[OH⁻]
pOH = 2.11
pH = 14 - pOH
pH = 11.9Compound 1 melts at 40 degrees Celsius. Compound 2 melts at 1310 degrees Celsius. Compound 3 melts at
240 degrees Celsius. Compound 4 melts at -62 degrees Celsius. Which is most likely to be an ionic compound?
Compound 4
Compound 2
Compound 3
Compound 1
Explanation:
We know that,
Ionic compound have high melting point.Here,
Compound 2 has high melting point.
So,
Compound 2 is most likely to be an ionic compound.
Choose all the answers that apply.
DNA contains coded information for _____.
hibernation
body structure
eye color
height
photosynthesis
Answer: Hibernation, Eye color and height
Explanation: DNA is the most important molecule of life. Many behaviors are controlled by DNA, such as telling bears how long to hibernate. All of the physical and chemical characteristics of an organism are also controlled by DNA, some cells will form bone, While others will form skin, hair and lungs.
An atom of argon has a radius of and the average orbital speed of the electrons in it is about . Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of argon. Write your answer as a percentage of the average speed, and round it to significant digits.
Here is the full question:
An atom of argon has a radius of 71 .pm and the average orbital speed of the electrons in it is about 3.9 × 10⁷ m/s. Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of argon. Write your answer as a percentage of the average speed, and round it to significant digits.
Answer:
Explanation:
From the above information:
The radius of an atom of argon = 71 .pm = 71 × 10⁻¹² m
The diameter of the atom of argon Δx =142 × 10⁻¹² m
According to Heisenberg's Uncertainty Principle,
[tex]\Delta x. \Delta p_x \geq \dfrac{h}{2}[/tex]
[tex]\Delta x. \Delta V \geq \dfrac{h}{4 \pi m_e}[/tex]
[tex]\Delta V \geq \dfrac{h}{4 \pi m_e \Delta_x}[/tex]
[tex]\Delta V \geq \dfrac{6.634 \times 10^{-34} \ J.s}{4 \pi \times 9.1 \times 10^{-3} \ kg \times 142 \times 10^{-12} \ m}[/tex]
[tex]\Delta V \geq \dfrac{6.634 \times 10^{-34} \ J.s}{1.62382641 \times 10^{-11} \ kg.m}[/tex]
[tex]\Delta V \geq 4.08 \times 10^5 \ m/s[/tex]
where; the average speed [tex]V_{avg}[/tex] = 3.9 10⁷ m/s
∴
The percentage of the average speed is expressed as a fraction of:
[tex]\% = \dfrac{4.08 \times 10^5}{3.9 \times 10^7}\times 100[/tex]
[tex]\% =1.0462[/tex]
[tex]V_{avg } = 1.046 \times 10^0[/tex]
[tex]\mathbf{V_{avg }\simeq 1.0 \%}[/tex]
how many moles of oxygen gas can 0.88 mole of hydrogen
Answer:
0.44 mole of oxygen gas can 0.88 mole of hydrogen peroxide (h2o2) produce, if decomposition is complete.
stion 1/2 Which of the following is a physical property?
A. The boiling point o a certain alcohol is 78 degrees Celsius
B. Diamond is very hard
C. Sugar ferments to form alcohol
D. A metal wire conducts an electric current
The image below shows a fault.
a zap
A diagram showing plate movement with labels. The footwall is on the left and the hanging wall is on the right. The plates are moving away from each other.
Which describes the motion of the plates?
The hanging wall and footwall both move vertically.
Shearing is causing the plates to slide past each other.
The hanging wall moves down in relation to the footwall.
Compression is causing the plates to move toward each other.
Answer:
This is a normal fault. Normal faults usually result from tensile stresses so D is an answer.
Additionally we can see that the hanging wall has moved down relative to the footwall so C is the other answer. =^.^=
Explanation:
this may help you >:3
Answer:
C
Explanation:
Which substance is oxidised 2MgO + O2 → 2MgO
Answer:
Here the oxidizing agent is Mg and the reducing agent is the O2.
This is because Mg is getting taking in O and is reducing itself to form MgO.
This Magnesium oxide, or magnesia, so formed is a white hygroscopic solid mineral that occurs naturally as percales and is a source of magnesium.
Explanation: