Answer:
7836.6 J
Explanation:
The following data were obtained from the question:
Heat of fusion (Hf) = 0.148 KJ/g
Mass (m) = 52.95 g
Heat (Q) required =..?
The heat (Q) required to melt the sample of nephthalene can be obtained as follow:
Q = m·Hf
Q = 52.95 × 0.148
Q = 7.8366 KJ
Finally, we shall convert 7.8366 KJ to Joule (J) in order to obtain the desired result. This can be obtained as follow:
1 kJ = 1000 J
Therefore,
7.8366 KJ = 7.8366 KJ × 1000 J / 1 KJ
7.8366 KJ = 7836.6 J
Therefore, 7.8366 KJ is equivalent to 7836.6 J
Thus, 7836.6 J of heat energy is required to melt the sample of nephthalene.
The heat required for melting of 52.95 g of naphthalene has been 7.8366 kJ.
The heat of fusion has been the energy required by 1g for the change in the substance.
The heat required to melt naphthalene can be given as:
Heat = mass × Heat of fusion
The given mass = 52.95 g
The heat of fusion = 0.148 kJ/g
The heat required can be given as:
Heat = 0.148 × 52.95 kJ
Heat = 7.8366 kJ.
The heat required for melting of 52.95 g of naphthalene has been 7.8366 kJ.
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How can environmental science help you?
Answer:
Organisms and humans depend on each other to get by. Environmental science is important because it enables you to understand how these relationships work.
For example, humans breathe out carbon dioxide, which plants need for photosynthesis. Plants, on the other hand, produce and release oxygen to the atmosphere, which humans need for respiration.
Animal droppings are sources of nutrients for plants and other microorganisms. Plants are sources of food for humans and animals. In short, organisms and humans depend on each other for survival.
Explanation:
liquid containing a mixture of neon and xenon was cooled down. One gas solidified at -249 °C and the other at –112 °C. Identify which noble gas solidified at -249 °C and which at -112 °C. Justify your answer.
Answer:
The noble gases (Group 18) are located in the far right of the periodic table and were previously referred to as the "inert gases" due to the fact that their filled valence shells (octets) make them extremely nonreactive. The noble gases were characterized relatively late compared to other element groups.
The History
The first person to discover the noble gases was Henry Cavendish in the late 180th century. Cavendish distinguished these elements by chemically removing all oxygen and nitrogen from a container of air. The nitrogen was oxidized to NO2 by electric discharges and absorbed by a sodium hydroxide solution. The remaining oxygen was then removed from the mixture with an absorber. The experiment revealed that 1/120 of the gas volume remained un-reacted in the receptacle. The second person to isolate, but not typify, them was William Francis (1855-1925). Francis noted the formation of gas while dissolving uranium minerals in acid.
Argon
In 1894, John William Strutt discovered that chemically-obtained pure nitrogen was less dense than the nitrogen isolated from air samples. From this breakthrough, he concluded that another, unknown gas was present in the air. With the aid of William Ramsay, Strutt managed to replicate and modify Cavendish's experiment to better understand the inert component of air in his original experiment. The researchers' procedure differed from the Cavendish procedure: they removed the oxygen by reacting it with copper, and removed the nitrogen in a reaction with magnesium. The remaining gas was properly characterized and the new element was named "argon," which originates from the Greek word for "inert."
Helium
Helium was first discovered in 1868, manifesting itself in the solar spectrum as a bright yellow line with a wavelength of 587.49 nanometers. This discovery was made by Pierre Jansen. Jansen initially assumed it was a sodium line. However, later studies by Sir William Ramsay (who isolated helium on Earth by treating a variety of rare elements with acids) confirmed that the bright yellow line from his experiment matched up with that in the spectrum of the sun. From this, British physicist William Crookes identified the element as helium.
Neon, Krypton, Xenon
These three noble gases were discovered by Morris W. Travers and Sir William Ramsay in 1898. Ramsay discovered neon by chilling a sample of the air to a liquid phase, warming the liquid, and capturing the gases as they boiled off. Krypton and xenon were also discovered through this process.
Radon
In 1900, while studying the decay chain of radium, Friedrich Earns Dorn discovered the last gas in Group 18: radon. In his experiments, Dorn noticed that radium compounds emanated radioactive gas. This gas was originally named niton after the Latin word for shining, "nitens". In 1923, the International Committee for Chemical Elements and International Union of Pure Applied Chemistry (IUPAC) decided to name the element radon. All isotopes of radon are radioactive. Radon-222 has the longest half-life at less than 4 days, and is an alpha-decay product of Radium-226 (part of the U-238 to Pb-206 radioactive decay chain).
The Electron Configurations for Noble Gases
Helium 1s2
Neon [He] 2s2 2p6
Argon [Ne] 3s2 3p6
Krypton [Ar] 3d10 4s2 4p6
Xenon [Kr] 4d10 5s2 5p6
Radon [Xe] 4f14 5d10 6s2 6p
Explanation:
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How does a circuit with a 1.5-volt battery compare to a circuit with a 9-volt battery?
what are the benefits of using supercritical fluids in EGS
Answer:
See detailed explanation.
Explanation:
Hello.
In this case, it is firstly necessary to cite that EGS accounts enhanced geothermal systems which are man-made reservoirs, placed where lots of hot rock is present but there is lack natural permeability, which requires a fluid to be injected into the subsurface to re-open it and therefore creating permeability.
Typically, water has been used for this purpose, but due to the current issue on saving water alternative methods such as supercritical fluids has been being implemented because they have better dynamic properties such as lower viscosities and therefore larger flow velocities, supercritical CO2 is easy and cheap to get as low temperatures are required to turn it in supercritical condition.
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When a helium balloon rises in the air, it expands. If the volume of the balloon doubles, what happens to the density of the helium inside it?
a.The density decreases by half
b.The density doubles
c.The density triples
d.The density stays the same
How many moles of methane are produced when 48.1 moles of carbon dioxide gas react with excess hydrogen gas?
5. What gases was produced from decomposing hydrogen peroxide? What non-gaseous product formed from the reaction
Answer:
H2O
Explanation:
The equation for the decomposition of hydrogen peroxide is shown below;
2H2O2(l)-----> 2H2O(l) + O2(g)
Hence, the decomposition of H2O2 yields oxygen gas and water. Water is a non gaseous product of the reaction as clearly seen in the equation above.
In which Earth system does the rock cycle take place?
cryosphere
atmosphere
geosphere
biosphere
Answer:
geosphere
Explanation:
geo means rocks this is the area
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which of the following Ph levels would indicate the weakest base?
15
8
6
2
Answer:
8
Explanation:
7 is neutral any anything above it is basic and anything below is acidic which means 8 would be the lowest base
Answer:
The pH of a weak base falls somewhere between 7 and 10.
Explanation:
Like weak acids, weak bases do not undergo complete dissociation; instead, their ionization is a two-way reaction with a definite equilibrium point
What are the conjugate base and conjugate acid for HSO4−? What is the term used to describe species that can behave as either an acid or a base, depending on the chemical environment?
Answer:
Conjugate acid- H^+
Conjugate base- SO4^2-
Terminology- Amphoteric
Explanation:
Consider the equilibrum shown below;
HSO4^-(aq)<-------> H^+(aq) + SO4^2-(aq)
Hence, When HSO4^- is dissolved in aqueous solution, it's conjugate acid is H^+ and it's conjugate base is SO4^2- as shown in the equation above.
If a substance behaves both as an acid and as a base, then the substance is Amphoteric in nature.
The conjugate acid [tex]H^+[/tex]and base [tex]SO4^2-[/tex] and the term would be Amphoteric.
Conjugate acid-
What is Amphoteric?Amphoteric is described as the term employed to denote a substance that possesses the characteristics of both an acid, as well as, a base.
Given equilibrium:
[tex]HSO4^-(aq)[/tex] → [tex]H^+(aq) + SO4^2-(aq)[/tex]
Therefore, the dissolution of [tex]HSO4^-[/tex] in water leads to the display acid that is conjugate [tex]H^+[/tex] and the conugate base [tex]SO4^2-[/tex].
In case, the properties of both are reflected, it shows amphoteric nature.
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80.20%, 11.01 amu
19.80%, 10.81 amu
What is the Average Atomic Mass?
When nitrogen, oxygen, fluorine, sodium, magnesium and aluminum ionize, they all will have:
a. different electron configuration from each other.
b. an unchanged electron configuration.
c. the same charge.
d. the same electron configuration (isoelectronic) as neon.
[Definition: The word isoelectronic means that when you write out the electron configuration they are the same. An exam would be He and Li whereby both of them have 2 electrons and therefore they are both are 1s2 in their electron configurations.]
Answer: d. the same electron configuration (isoelectronic) as neon.
Explanation:
Isoelectronic species are defined as the molecules which have the same number of electrons.
Atomic number of nitrogen is 7 and thus has 7 electrons. Nitrogen has electronic configuration of 2,5 and thus can gain 3 electrons and thus [tex]N^{3-}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Atomic number of oxygen is 8 and thus has 8 electrons. Oxygen has electronic configuration of 2,6 and thus can gain 2 electrons and thus [tex]O^{2-}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Atomic number of flourine is 9 and thus has 9 electrons. Flourine has electronic configuration of 2,7 and thus can gain 1 electron and thus [tex]F^{-}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Atomic number of sodium is 11 and thus has 11 electrons. Sodium has electronic configuration of 2,8,1 and thus can lose 1 electron and thus [tex]Na^{+}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Atomic number of magnesium is 12 and thus has 12 electrons. Magnesium has electronic configuration of 2,8,2 and thus can lose 2 electrons and thus [tex]Mg^{2+}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Atomic number of aluminium is 13 and thus has 13 electrons. Aluminium has electronic configuration of 2,8,3 and thus can lose 3 electrons and thus [tex]Al^{3+}[/tex] will have electronic configuration of 2,8 ( same as that of neon)
Our universe is made up of at least a
Forty milliliter of a liquid has a mass of 80 grams. What is the density of this substance?
Answer:
2.00g/ml
Explanation:
If water has a density of 1.00g/ml, and theres
40ml of it, it would weigh 40g
The substance is twice as dense as water, making its density 2.00g/ml
Suppose you are studying the kinetics of the iodine-catalyzed decomposition of hydrogen peroxide. 2 H 2 O 2 ⟶ 2 H 2 O + O 2 If you determine the initial rate is 7.50 × 10 − 4 M/s when [ H 2 O 2 ] = 0.546 M and [ K I ] = 0.212 M , what is the rate constant? Assume that the order of both reactants is 1.
Answer:
[tex]k=6.48x10^{-3}M^{-1}s^{-1}[/tex]
Explanation:
Hello.
In this case, based on the given information, we can write the rate law as shown below:
[tex]r=k[H_2O_2][KI][/tex]
Since the overall order of reaction is 2 being 1 for reach reactant. Thus, by knowing the initial rate and concentrations, the rate constant turns out:
[tex]k=\frac{r}{[H_2O_2][KI]}=\frac{7.50x10^{-4}M/s}{0.546M*0.212M}\\ \\k=6.48x10^{-3}M^{-1}s^{-1}[/tex]
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The rate constant, k is [tex]6.48x10^{-3}M^{-1}s^{-1}[/tex]
Rate law:The rate law should be
[tex]r = k[H_2O_2]{KI}[/tex]
Since the total order of the reaction is 2 being 1 for reach reactant. So, by knowing the beginning rate and concentrations, the rate constant turns out:
[tex]k = \frac{r}{k[H_2O_2]{KI}} = \frac{7.50x10^{-4}M/s}{0.546M\times 0.212M}[/tex]
k = [tex]6.48x10^{-3}M^{-1}s^{-1}[/tex]
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for the following reaction, provide the missing information
Answer:
19. Option B. ⁰₋₁B
20. Option D. ²¹⁰₈₄Po
Explanation:
19. ²²⁸₈₈Ra —> ²²⁸₈₉Ac + ʸₓZ
Thus, we can determine ʸₓZ as follow:
228 = 228 + y
Collect like terms
228 – 228 = y
y = 0
88 = 89 + x
Collect like terms
88 – 89 = x
x = –1
Thus,
ʸ ₓZ => ⁰₋₁Z => ⁰₋₁B
²²⁸₈₈Ra —> ²²⁸₈₉Ac + ʸₓZ
²²⁸₈₈Ra —> ²²⁸₈₉Ac + ⁰₋₁B
20. ᵘᵥX —> ²⁰⁶₈₂Pb + ⁴₂He
Thus, we can determine ᵘᵥX as follow:
u = 206 + 4
u = 210
v = 82 + 2
v = 84
Thus,
ᵘᵥX => ²¹⁰₈₄X => ²¹⁰₈₄Po
ᵘᵥX —> ²⁰⁶₈₂Pb + ⁴₂He
²¹⁰₈₄Po —> ²⁰⁶₈₂Pb + ⁴₂He
The equilibrium constant _____________. For an ___________ reaction, heat is a reactant. An increase in temperature and heat favors the ____________ reaction and the value of K c _____________.
Answer:
The equilibrium constant change. For an endothermic reaction, heat is a reactant. An increase in temperature and heat favors the forward reaction and the value of Kc increases.
Explanation:
Hello.
In this case, regarding reactions in equilibrium in which heat is a reactant as those exemplified by:
[tex]Heat+Reactants \rightleftharpoons Products[/tex]
We infer that the heat of reaction is positive since the reactants have more energy in their ground state than the products making them endothermic. Moreover, since the Le' Chatelier's principle states that increasing the reaction temperature in endothermic reactions, the forward reaction (towards products) is favored because endothermic reactions absorb heat in the form temperature raise, the required statement is:
The equilibrium constant change. For an endothermic reaction, heat is a reactant. An increase in temperature and heat favors the forward reaction and the value of Kc increases.
Regards.
Answer:
The equilibrium constant increases. For an endothermic reaction heat is a reactant. An increase in temperature and heat favours the forward reaction and the value of KC increases.
Explanation:
It took 70 seconds for 280cm³ of nitrogen to diffuse through a membrane. If Carbon(IV)Oxide is allowed to diffuse through the same membrane, how long will it take the gas to do so ?
Answer:
t = 125.3 seconds
Explanation:
Molar mass of CO2 = 12+2(16) = 66
Molar mass of N2 = 2(14)= 28
rate of diffusion of N2 = volume/ time = 280cm³/70s
= 4cm³/s
let rate of CO2 = rate of diffusion of CO2 = volume/time
= 400/t
Using Graham's law of diffusion,
rN2/rCO2 = √M(CO2)/M(N2)
4/400/t =√44/28 = 4t/400= √11/7
t/100 = 1.253 , t= (100)(1.253)
t = 125.3 seconds
hence it takes CO2 125.3 seconds to diffuse through the membrane
Which is the dependent variable in an experiment? 1.what I observe. 2. what I keep the same 3.What I change in the experiment. HELP NOW
Answer:
1.what I observe.
Explanation:
The dependent variable in an experiment is what is being observed in the experimental procedure.
This variable is the one that is closely tied to the effects originating from changing the independent variables.
Independent variables are the ones that cause the observation being studied. The effects produced and then studied are the dependent variables.magnesium: atomic number
Answer:
Magnesiums atomic number is 12
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Which is an example of a current research focus in chemistry?
A. applying gene therapy to treat certain diseases
B. using hook-and-loop tape in the clothing industry
C. developing smoke detectors for common use
D. studying coal combustion as an energy source
Answer:
b is the correct answer
do not trust answer one
Explanation:
Which element contains one set of paired and three unpaired electrons in its fourth and outer main energy level?
Explanation:
Phosphorus (P) because of the 5 valence electrons total, 3 of them are in the 3p sublevel, and according to Hund's rule, they "single-fill" each orbital first.
C. Where is sugar removed from the blood?
and how can you tell
Answer:During absorption and digestion, the carbohydrates in the food you eat are reduced to their simplest form, glucose. Excess glucose is then removed from the blood, with the majority of it being converted into glycoge, the storage form of glucose, by the liver's hepatic cells via a process called glycogenesis
Explanation:
Which of the following substances will form a base when dissolved in water?
Question 14 options:
A)
HCl
B)
HBr
C)
KOH
D)
SO2
Answer:
Its D) SO2
Explanation
Did the test
How many grams of NaCl are needed to prepare 50.0 grams of a 35.0% salt solution?
17.5 grams of NaCl are needed to prepare 50.0 grams of a 35.0% salt solution.
What is Solution?
A solution is a homogenous mixture composed of two or more substances. In a solution, the components are evenly distributed throughout the mixture, resulting in a uniform appearance and properties.
The substance that is present in the largest amount is called the solvent, while the other substances present in lesser amounts are called solutes. When the solute dissolves in the solvent, the resulting mixture is called a solution.
To calculate the grams of NaCl needed to prepare a 35.0% salt solution, we can use the formula:
grams of NaCl = (percent salt / 100) x grams of solution
grams of NaCl = (35.0 / 100) x 50.0
grams of NaCl = 0.35 x 50.0
grams of NaCl = 17.5
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How many grams of Cl are in 31.2g CF2Cl2
Answer:
Mass = 42.6 g
Explanation:
Given data:
Mass of CF₂Cl₂ = 31.2 g
Mass of Cl₂ = ?
Solution:
Number of moles of CF₂Cl₂ = mass/molar mass
Number of moles = 31.2 g/121 gmol
Number of moles = 0.3 mol
1 mole of CF₂Cl₂ contain 2 moles of Cl atom.
0.3 mol × 2 = 0.6 mol
Mass of Cl₂:
Mass = number of moles × molar mass
Mass = 0.6 mol × 71 g/mol
Mass = 42.6 g
Which of the following characteristics will not help which of the following characteristics WILL NOT help you tell whether two solids are the same or are different substances?
A. Color
B. Hardness
C. Shape
D. Melting point
What does a dissolved salt look like?
Answer:(trick question) once the salt has dissolve in the water it is no longer visible
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which element has the highest ionization energy?B, Al, Ga, In
Answer:
BORON
Ionization energy decreases down the group and going from left to right the period,
Luckily you have the elements from the same group that is Group III A also called boron family,
The position of Elements in this group are
Boron (B)Aluminium (Al)Gallium (Ga)Indium(In)ThalliumNihoiumso keeping rules in mind the first element in the group has highest I.E. that is boron
Similar properties recur periodically when elements are arranged according to increasing atomic number is the statement of the ______. g
Answer:
Modern periodic law
Explanation:
There are many ways of stating the modern periodic law. Generally, the modern periodic law states that the properties of elements are a periodic function of their atomic numbers. That means, similar properties recur periodically when elements are arranged according to increasing atomic number.
Two scientists were largely responsible for our present day understanding of the modern periodic law, they are, Mendeleev and Moseley. Their work laid the foundation for the periodic table in its current form.