A scientist measures the standard enthalpy change for the following reaction to be -139.5 kj :
h2(g) + c2h4(g)c2h6(g)
based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of c2h4(g) is _____ kj/mol.
Answer:
A scientist measures the standard enthalpy change for the following reaction to be -139.5 kj :
h2(g) + c2h4(g)c2h6(g)
based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of c2h4(g) is _____ kj/mol
Explanation:
Hydrogen ΔHof (kJ/mol) ΔGof (kJ/mol) So (J/mol K)
H2 (g)
0
0
130.7
Carbon ΔHof (kJ/mol) ΔGof (kJ/mol) So (J/mol K)
C2H6 (g)
-84.7
-32.8
229.6
The liquids having same boiling point cannot be seperated from its mixture by distillation, why?
Answer:
Explanation:
They cannot be separated by distillation since it depends on a liquid's ability to boil at a certain temperature. If you have two liquids with the same boiling temperatures, the proportion of each in the vapor phase will be about equal, making it impossible to separate them. Although they presumably do not have the same freezing point, you might use a different method like chromatography or work with their freezing points instead. You could then selectively crystallize one component while leaving the other as a pure liquid.
____________
Definitions:
Distillation:
#1: The volatilization or evaporation and subsequent condensation of a liquid, as when water is boiled in a retort and then the steam is condensed in a cool receiver.
Answer:
Because different compounds often have different boiling points, the components often separate from a mixture when the mixture is distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid.
Explanation:
The cutoff frequency for a certain element is 1.22 x 1015 Hz. What is its work function in eV?
Hint: 1 eV 1.60 x 10-19 J
=[?] eV
someone please teach me how to solve this its gonna make me cry
The work function of the metal is obtained as 5.1 eV
What is the cutoff frequency?The cutoff frequency is the frequency below which photo electric effect can not occur as electrons are not removed from the metal surface.
Now;
fo = 1.22 x 10^15 Hz
Wo = hfo
Wo = 6.6 * 10^-34 * 1.22 x 10^15
Wo = 8.1 * 10^-19 J
If 1 eV = 1.60 x 10-19 J
x eV = 8.1 * 10^-19 J
x = 8.1 * 10^-19/ 1.60 x 10-19
x = 5.1 eV
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Mr. Auric Goldfinger, criminal mastermind, intends to smuggle several tons of gold across international borders by disguising it as lumps of iron ore. He commands his engineer minions to form the gold into little spheres with a diameter of exactly
8 cm and paint them black.
However, his chief engineer points out that customs officials will surely notice the unusual weight of the "iron ore" if the balls are made of solid gold (density
). She suggests forming the gold into hollow balls instead , so that the fake "iron ore" has the same density as real iron ore
One of the balls of fake "iron ore," sliced in half.
Calculate the required thickness of the walls of each hollow lump of "iron ore." Be sure your answer has a unit symbol, if necessary, and round it to 2
significant digits.
The thickness of the walls of each hollow lump of iron ore is: 0.295cm. This is determined using the knowledge of the Volume of a Hollow Sphere.
What is the Volume of a Hollow Sphere?
The formula for the Volume of a Hollow Sphere is give as:
Volume of a Hollow = 4/3 R³ – 4/3 r³
Step 1 - Find the apparent volume of 8cm diameter sphere including the wall the the hollow inside
V = 4/3 r³
V = (4/3) (8)³
V = (4/3) * (22/7) * 512
V = 2145.52cm³
Step 2 - Determine the mass of Gold required for the sphere to achieve the density of iron ore if the apparent volume is as given in Step 1 above.
Recall that Mass = Density * Volume
Mass = 5.15 * 2145.52
Mass = 11049.45
Step 3 - Find volume of gold based on mass calculated in Step 2 above
Recall that :
Volume = Mass/Density
Thus,
V = 11049.4/19.3
Thus, Volume = 572.51cm³
Step 4 - Find the width of the wall of a hollow sphere for the volume realized in step 3
Recall the initial formula:
Volume of a Hollow = 4/3 R³ – 4/3 r³
Thus, 572.51 = (4/3) (8³ - (8 - t)³)
572.51 = (4/3) *(22.7) *(8³ - (8 - t)³)
572.51 = (88/21) *(8³ - (8 - t)³)
Multiply both sides by 21 and we have
88 (512 - (8 - t)³) = 12,022.71
Simplify further
(8 - t)³ = 357.38
t = 0.9035cm
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What type of molecule is pentanal?
o a. aldehyde
o b. ester
o c. ketone
o d. alcohol
Answer:
aldehyde
Explanation:
it ends with "al" of "al"dehyde, always check the end
How many moles of LiCl will I have if I start off with .425 moles of CaC12?
Balanced
Moles of CaCl_2=0.425mol
1 mol CaCl_2 producees 1 mol LiCl
Moles of LiCl
0.425(1)0.425molesThe equation is
[tex]\\ \tt{:}\dashrightarrow LiOH+CalCl_2\longrightarrow LiCl+Ca(OH)_2[/tex]
This is balanced1mol of LiCl needs 1 mol CaCl_2
Then
0.425mol of CaCl_2 will produce 0.425mol LiCl
Look at pic and help
Answer:
Answer
Explanation:
1) Other gasses / or argon (based on what u took in ur school )
2) oxygen
3? Nitrogen
Answer:
By volume, the dry air (which i'm assuming that's what either the blue or red is) in Earth's atmosphere is about 78.09 percent nitrogen, and 0.93 percent argon (which might be what red is (if the red isn't dry air)). A brew of trace gases accounts for the other 0.03 percent (which I think that might be the yellow), including the greenhouse gases carbon dioxide, methane, nitrous oxide and ozone.
Explanation:
The energy produced by the snack in an experiment is calculated to be 41,800 J/g. What is the energy of the snack in Calories/
gram?
snack energy = [?] Cal/g or kcal/g
remember there are 4.18J per 1 calorie
The energy of the snack in calories per gram is 9983.3 Calories/gram.
What is the energy of a snack?The energy that is contained in a snack is obtained from a calorimeter when the snack is burnt in a calorimeter. The mass of the snack that is burnt is measured in terms of energy output of the calorimeter.
If 1 calorie = 4.18J
x calorie = 41,800 J
x = 41,800 J * 1 calorie/4.18J
x = 9983.3 Calories/gram
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Energy associated with the flow of electrons is?
Answer:
Electric current
Definition:
The time rate of flow of electric charge, in the direction that a positive moving charge would take and having magnitude equal to the quantity of charge per unit time: measured in amperes.
Electricity is the flow of electrons. Where do these electrons come from? How are they put into circulation and what happens to them?Everything begins inside in the battery. The battery's zinc metal undergoes oxidation; here is where the flow of electrons into the conductors begins. Electrical field attraction will lead the wire's existing electrons to move towards the battery's positive terminal, and the loose electrons caused by the zinc metal will begin to fill the wire's empty spaces. process continues until the zinc metal's oxidation ceases. At rechargeable batteries, the oxidation-reduction process is also reversed by charging the battery, allowing the stored electrons in the positive terminal to flow back to the zinc metal's negative terminal.
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The average temperature of healthy person is 98.6°F. What is it in
Celsius scale?
Answer:
37 Degrees Celsius
Explanation:
Which atomic models(Bohr, Thomson, Rutherford, Dalton) in task 1 are not supported by Thomson’s experimental evidence? For each of these models, explain the experimental results that the model would predict.
Rutherford model task 1 is not supported by Thomson’s experimental evidence.
What is an atom?
The atom consists of matter that may be split without releasing electrical charges.
It's also the smallest unit of matter with chemical element features. As a result, the atom is the fundamental unit of science.
The nuclear model of the atom was initially put out by Rutherford. His atomic model states that the majority of an atom's volume is empty,
The nucleus, which contains protons and neutrons, is located in the middle of the atom, and its electrons orbit the nucleus in well-defined paths.
If we discuss the research of some other scientists, like Dalton, Neil Bohr, and JJ Thomson, they are all mostly consistent with Rutherford's findings.
For instance, Dalton's atomic theory presupposed that all atoms are roughly the same size and that atoms interact to generate compounds.
According to Rutherford's theory, atoms have a fixed number of electrons that can be shared to create compounds.
The Bohr model, which posits that electrons orbit the nucleus in certain shells, is also consistent with Rutherford's findings, which gave rise to the idea of shells.
If we discuss Thomson's Plum Pudding Model, it describes atoms as negatively charged particles around a soup of positively charged ions. This is also consistent with Rutherford's findings, which show that positive nuclei are surrounded by negative electrons.
Although Rutherford's model was the greatest atomic model, it nevertheless drew on several earlier investigations and was therefore consistent with the outcomes of earlier models.
Hence rutherford model task 1 is not supported by Thomson’s experimental evidence.
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Which of the following most accurately describes a regulatory molecule that must be transported to its place of action within the body?
hormone
polypeptide
enzyme
Answer:
the answer is hormone
Explanation:
because it is
Zac releases the air from a balloon. Which statement best describes what will happen to the air that was inside the
balloon?
O It will become more compacted.
O will remain the shape of the balloon but not the size.
O It will remain the size of the balloon but not the shape.
It will expand to fill the room.
Answer: It will expand to fill the room.
Explanation:
Gases will expand or compact to fill the available space.
the aria ""batter my heart"" from doctor atomic has musical influences from which era?
The aria ""batter my heart"" from doctor atomic has musical influences from the era of Renaissance.
Why is batter my heart attributed to to Renaissance era?The Renaissance era can be regarded as the era around 14th century and batter my heart was produced around the 13/14th century.
The batter my heart was among the Sicilian school of court poets, that was very famous which emphasizing the importance of the heart.
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What is a quantum of light energy called?
O A. A photon
OB. A frequency
O C. A proton
O D. An electron
Answer:
A) photon
Explanation:
hope it helps and give brainliest if its correct
Answer:
PhotonExplanation:
please mark brainliest please. What is the relationship between the speed of impact and the dropping height?
The relation between the speed of impact and the dropping height is
[tex]\rm h =\dfrac{1}{2g}v^2[/tex]
What is Speed of Impact ?It is defined as the speed of an object when it falls from a height and makes an impact with the ground or any other object.
As the object is falling from the height , its velocity will be continuously changing
Assuming it has no initial velocity , u = 0
let the final velocity is [tex]\rm v_f[/tex] = [tex]\rm \sqrt {2gh}[/tex]
the potential energy at the height h as mgh
the kinetic energy when it reaches the bottom as [tex]\rm \dfrac{1}{2}mv^2[/tex]
As the energy is always conserved
[tex]\rm mgh = \dfrac{1}{2}mv^2[/tex]
[tex]\rm h =\dfrac{1}{2g}v^2[/tex]
This is the relation between the speed of impact and the dropping height.
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Which of the following is NOT an example of combustion occurring?
A. A car engine
B. A rocket lifting off
C. Battery acid burning the floor
D. A bonfire
Answer:
C. Battery acid burning the floor
Explanation:
C. Battery acid burning the floor
in combustion fire is created
Battery acid burning the floor is NOT an example of combustion occurring.
The answer is option C.
What is combustion?Combustion is a chemical process or a reaction between the gas (Hydrocarbon) and Oxygen. while gasoline and oxygen react it releases warmth and light energy. heat and light energy then result in the flame. So, the system for Combustion reaction is Hydrobcarbon + Oxygen = warmness electricity.
Combustion in daily existence examples is: Burning of wooden or Coal for the family functions. Burning of Petrol or Diesel for using vehicles like vehicles. Combustion of herbal gas or LPG.
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For a particular chemical reaction, the enthalpy of the reactants is -400 kJ. The enthalpy of the products is -390 kJ. The entropy of the reactants is 0.2 kJ/K. The entropy of the products is 0.3 kJ/K. The temperature of the reaction is 25 degrees Celsius. What can you conclude about this reaction
Answer:
For a particular chemical reaction, the enthalpy of the reactants is -400 kJ. The enthalpy of the products is -390 kJ. The entropy of the reactants is 0.2 kJ/K. The entropy of the products is 0.3 kJ/K. The temperature of the reaction is 25oC. What can you conclude about this reaction?
It is exergonic
It is endergonic
it is a redox reaction
It is being catalyzed by an enzyme
Up late, a tired engineer calculated the molar mass of nitroglycerin (C3H5N3O9) to be 193.7 g/mol, but this incorrect. What is the percent error of this incorrect molar mass
So, the formula mass of nitroglycerin is[tex]3(12.011)+5(1.00794)+3(14.0007)+9(15.9994)=227.0694 \text{ g/mol}}[/tex]
Therefore, the percent error is
[tex]\frac{193.7-227.0694}{227.0694} \times 100=\boxed{-14.70 \% \text{ (to 4 sf)}}[/tex]
Dalton law states that the partial pressure of a gas in a mixture of gases is _____ to the total pressure of the mixture.
Answer:
Dalton law states that the partial pressure of a gas in a mixture of gases is equal to the total pressure of the mixture.
There are 8.421 g of dry ZnSO4 and
6.579 g H₂O in the sample.
Step 2: Determine the moles of water and anhydrous compound.
Zn = 65.38 g/mol, S = 32.07 g/mol,
H = 1.01 g/mol, O = 16.00 g/mol
How many moles of ZnSO4 are present?
[?] mol ZnSO4
The number of moles of H₂O is 0.36 mol.
The number of moles of LiClO₄ is 0.0521 mol.
What are moles?Mole is an important standard unit used for the measurement of large quantities of atoms, molecules, or other particles. One mole is equal to 6.022×10²³ units.
The number of moles of a substance is calculated by:
Moles =[tex]\frac{mass}{molar \;mass}[/tex]
To find the number of moles of H₂O:
Mass of H₂O in the sample = 6.579 g
The molecular weight of H₂O = 18.02g
Moles = [tex]\frac{mass}{molar \;mass}[/tex]
Moles = [tex]\frac{6.579 g}{18.02g}[/tex]
Moles = 0.36
To find the number of moles of [tex]ZnSO_4[/tex]:
Mass of [tex]ZnSO_4[/tex] in the sample = 8.421 g
The molecular weight of [tex]ZnSO_4[/tex]= 161.47 g/mol
Moles =[tex]\frac{mass}{molar \;mass}[/tex]
Moles = [tex]\frac{8.421 g}{161.47 g/mol}[/tex]
Moles = 0.0521 moles
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A student needs to standardize a base solution by titration with an acid solution of known concentration. She finds the volume of the acid solution needed to reach the endpoint for a sample of the base solution. Arrange the steps in the order that will allow her to determine the concentration of the base solution.
The steps usually involves adding the known solution (the titrant) to a known quantity of the unknown solution (the analyte) until the reaction is complete which can be understood in detail as below with the help of through out process of titration.
What is Titration ?A titration is a technique used to work out the concentration of an unknown solution based on its chemical reaction with a solution of known concentration.
Steps in order to determine the concenteration of base solution ;
(Acid-Base Titration)
Choose the titrant.Choose the titrate.Select the normality of the titrate.Choose the volume of the liquid to be pipetted out.Select the indicator.Start titration.End point is noted at the colour change of the solution.From the final reading the normality of titrant can be calculated by the equation:N₁V₁=N₂V₂
After finding the normality, the amount of given substance in the whole of the given solution can be calculated by the equation:Mass = Equivalent weight x Normality \ Volume {1000}
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Silver has the density of 9.32 g/cm^3. Find the length of one side of a 184 g silver cube. Assume now that the silver cube above was melted and reshaped into a sphere. Find the sphere’s diameter
What is the change in
temperature when water goes
from 65.0 °C to 25.0 °C?
AT = [?] °C
Answer:
-40.0 °C
Explanation:
Change in temperature can be written as [tex]\displaystyle{\Delta T = T_2-T_1}[/tex]. The variables are defined below here:
[tex]\displaystyle{\Delta T}[/tex] means change in temperature.
[tex]\displaystyle{T_2}[/tex] means the final temperature value.
[tex]\displaystyle{T_1}[/tex] means the initial temperature value.
From the question, we know the temperature changes from 65.0 °C to 25.0 °C. Therefore, our initial temperature is 65.0 °C and final temperature is 25.0 °C.
Hence:
[tex]\displaystyle{\Delta T=25.0-65.0}\\\\\displaystyle{\Delta T = -40.0}[/tex]
Therefore, the change in temperature is -40.0 °C.
There are two common oxides of copper; one is 80% copper and the other is 89% copper by weight. Calculate the formula and name each compound.
80% copper (Cu)
Cu: 80 : 63.546 = 1.259
O: 20 : 16 = 1.25
Cu:O = 1 : 1
the formula: CuO
89% copper (Cu)
Cu: 89 : 63.546 = 1.4
O: 11 : 16 = 0.6875
Cu:O = 2:1
the formula: Cu₂O
Calculate the percent covalent character of a chemical bond between iodine and lithium.
Answer:
27966692
Explanation:
I don't know if this is right or not
the physical matter of which living or non living things are composed is called a
The physical matter of which living or non living things are composed is called a molecule
What is a molecule?A molecule is the smallest particle of an element or a compound which can normally exist alone and still retain the properties of that substance.
A molecule could be made up of an atom of an element of different atoms of elements such as:
HydrogenOxygenCarbonSodiumPotassiumMagnesiumSo therefore, the physical matter of which living or non living things are composed is called a molecule.
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A 5 Complete the sentences using words from the list. You may use them once, more than once, or not at all.
increases；decreases；stays the same
a) When liquid water boils, the distance between the particles ____
b) When liquid water boils, the strength of the attractive forces between the particles ___
c) When steam condenses, the speed of movement of the particles ___
Answer
Number 1. increase
number 2 . decrease
number 3. decrease
A, B, C, or D, thanks for the help
According to the label the true statement about the following substance is option c. It does not pose a health risk
What are lab labels ?
Specially designed labels with particularly specialised adhesive qualities are called "lab labels." In the pharmaceutical or medical industry, as well as in laboratories, they are used for labelling. For the labelling of tubes, test tubes, blood bags, and other types of vessels, special laboratory labels are created.
Labels on chemicals
The identify of the hazardous chemical(s) in the container (for example, chemical name) and the dangers present must both be listed on this label. This warning about hazards can be distributed in a variety of ways. Employers want to choose a solution that will function in each place.
The following label indicates that the chemical does not pose a health risk.
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Which industrial methods of preparing alcohol are more economical? Explain.
The industrial methods of preparing alcohol that is more economical is fermentation.
What is fermentation?Fermentation is defined as the industrial method by which starch is converted to ethyl alcohol by using some specific enzymes and microorganisms known as yeast
It is an economical method because the raw material which is starch is readily available.
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