Aluminium appears unreactive. This is because of the formation of aluminium oxide layer in its outer surface.
This is because aluminium reacts with oxygen present in air to form a thin layer of aluminium oxide on its surface. This oxide layer is very stable and acts as a protective coating by preventing further reaction of aluminium.
Also, Aluminium is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.
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Question 7 of 10
What causes areas closer to the equator to have warmer air than areas
farther away?
OA. The indirect rays of the sun at the equator
OB. The concentrated radiation from the sun at the equator
OC. The smaller amount of heat transferred from the sun at the
equator
OD. The greater angle at which the sun's rays strike Earth's surface at
the equator
The equator is warmer because of the greater angle at which the sun's rays strike Earth's surface at the equator i.e. option D.
What do you mean by the Equator?
An Equator is a hypothetical line that circles a planet or other celestial body in the center.
As the climate at the poles is cooler than that close to the equator. This is because Sun's rays are impinging at an angle on high latitudes due to the curvature of the Earth.
This is because as you walk away from the equator, the Earth's surface gradually tilts away from the sun (the sun is lower on the horizon).
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How would you define the flashlight as a system? What are the inputs and outputs? What are the parts of the system?
Answer:
A miniature keychain lamp produces one or two lumens
What is a planet's orbit?
Answer:
An orbit is a regular, repeating path that one object in space takes around another one.
a beaker containing 0.400g khp was titrated with naoh solution. the pale pink end point was reached after 18.66ml of naoh solution was dispensed. what is the molarity of the naoh solution
The molarity of the sodium hydroxide, NaOH solution, given that 18.66 mL was used is 0.107 M
How do I determine the molarity of NaOH?We'll begin by obtaining the mole of NaOH. This can be obatined as follow:
Mass of KHp = 0.4 gMolar mass of KHP = 204.22 g/molMole of KNO₃ = 0.4 / 204.22 = 0.002 moleKHP + NaOH -> KNaP + H₂O
From the balanced equation above,
1 mole of KHP reacted with 1 mole NaOH.
Therefore,
0.002 mole of KHP will also react with 0.002 mole of NaOH.
Finally, we shall determine the molarity of the NaOH solution. Details below:
Mole of NaOH = 0.002 moleVolume = 18.66 mL = 18.66 / 1000 = 0.01866 LMolarity of NaOH = ?Molarity = mole / volume
Molarity of NaOH = 0.002 / 0.01866
Molarity of NaOH = 0.107 M
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Question 11
A material whose particle composition allows heat and electricity to pass through it easily are described as having a high
OA) conductivity
O B) density
OC) hardness
OD) weight
Answer:
Coductivity
Explanation:
Because heat conducts to them!
3. Why is it important for other variables in an experiment to be controlled?
To derive precise results, it is important for other variables in an experiment to be controlled. Accuracy and precision are the key factors of every practical experiment carried out.
During the course of experiments, special emphasis is laid on the objective of the experiment. Procedures and precautions are highly objective-oriented. There are possibilities of errors as the surrounding becomes an integral part of the system in practicals.
Certain physical and chemical quantities are ignored in theoretical assessment, but they affect the practical work. Impurities and uncontrolled reactions can be barriers. Optimum conditions are sought before conducting experiments.
The hydrolysis of _____ is an exergonic reaction that drives many endergonic reactions in a cell.
The hydrolysis of ATP into ADP and inorganic phosphate is an exergonic reaction that drives many endergonic reactions in a cell.
ATP hydrolysis is a form of reaction, right?Adenosine triphosphate (ATP) is a molecule that can store chemical energy in high-energy phosphoanhydride bonds. These bonds can be split to release chemical energy, for example in muscles. This process is known as ATP hydrolysis.
ADP has a higher entropy than ATP, which is a measure of chaos. The reaction therefore happens spontaneously because it desires to be at a higher entropy level owing to thermodynamics. Additionally, ATP has a greater Gibbs free energy value than ADP.
In order to proceed, an endergonic reaction needs free energy. Photosynthesis is an instance of an endergonic process of biological importance.
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Compare the arrangements of the molecules of a solid, liquid,
and gas by illustrating them in the boxes below.
(I’VE BEEN STUCK FOR 3 DAYS)
The arrangements of the molecules of a solid, liquid and gas as follows
1. Solid: In this state of matter, the particles are closely bonded to each other. This means that they are closely packed in a system and the arrangement is regular. The intermolecular space between the particles is minimum.
2. Liquid: In this state of matter, the particles are not so closely packed. The arrangement between the particles is not regular. The intermolecular spacing between the particles is more than solid but less than gaseous state.
3. Gases: In this state of matter, the particles are very far away from each other and the arrangement is not regular. The intermolecular spacing between the particles is very much in case of gases.
What are the Three States of Matter?The solid, liquid, and gaseous phases of matter are the three basic states of matter.
Every item we encounter every day—from ice cream to chairs to water is composed of matter. Based on intermolecular forces and the arrangement of the particles, matter can be divided into distinct states such as solid, liquid, and gas. By altering specific environmental variables, these three types of matter can change their state of matter (increasing or decreasing pressure and temperature, for instance). For instance, raising the temperature will cause ice to melt from a solid state.
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A certain red light has a wavelength of 680 nm.
a. What is the frequency of the light?
A certain red light has a wavelength of 680 nm. then, The frequency of the light is 4.4×10^14 s^-1 .
Given,
A certain red light had a wavelength = 680nm
frequency is given by,
f =c/λ
where, f = frequency
c = speed of light = 3×10^8 m/s
λ = wavelength = 680nm
f = (3×10^8 ) /(680× 10^-9 )
f = 0.0044×10^17 = 4.4×10^14 s^-1
Hence, the frequency of the light is 4.4×10^14 s^-1 .
What is wavelength?The distance between the two crests or troughs of the light wave is known as the wavelength of light. Using the Greek letter lambda (), it is identified. As a result, wavelength refers to the separation between one wave's crest or dip and the following wave.
The formula for wavelength is given by,
wavelength= speed of light /frequency
What is frequency?According to the definition of frequency, it is the quantity of full wave cycles that pass a spot in a unit of time.
Hertz is the SI unit for frequency (Hz).
The number of full oscillations that any wave element makes in one unit of time is the frequency of a sinusoidal wave.
Frequency is in periodic motion; after going through a number of different situations or postures and then returning to its initial place, it has completed one cycle.
The reciprocal of a wave's period is equal to the wave's frequency.
The frequency mathematical expression is:
frequency = speed of light / wavelength
The length of time it takes for any string element to complete an oscillation is known as a wave's oscillation period.
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a 150.0 – g sample of a metal at 75.0 oc is added to 150.0 g h2o at 15.0 oc. the temperature of the water rises to 18.3 oc in a closed and insolated container. calculate the specific heat capacity of the metal.
150.0 g of a metal sample heated to 75.0 oC is introduced to 150.0 g of water heated to 15.0 oC. In a sealed, dark container, the water's temperature rises to 18.3 oC. The metal's specific heat is 0.24 J/g of temperature.
Specific heat is the amount of energy needed to raise a substance's temperature by one degree Celsius per gramme. Typically, the units of specific heat are calories or joules per gramme per degree Celsius. The specific heat of water, for instance, is 1 calorie (or 4.186 joules) per gramme per degree Celsius. In the 18th century, the Scottish scientist Joseph Black noted that equivalent masses of various substances required varying quantities of heat to elevate them across the same temperature range. Based on this discovery, he developed the theory of specific heat. Early in the 19th century, French physicists Pierre-Louis Dulong and Alexis-Thérèse Petit proved that calculating a substance's atomic weight is possible by measuring its specific heat (see Dulong-Petit law).
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what mass of sodium chloride would need to be added to the blood to bring the sodium ion concentration up to 0.135 m m , assuming no change in blood volume?
7.89 g of NaCl is required to bring sodium ion concentration to 0.135 m.
Given:
The molality of NaCl in the given volume of blood=0.135 mol/ kg
1 mol of NaCl contains 1 mol of sodium ion.
Thus, 0.135 mol of sodium chloride is needed to give out 0.135 moles of sodium ion.
Therefore, the mass of sodium chloride needed=moles x molar mass=0.135 mol x 58.44 g/mo
l=7.89 g
What is molality?
The molality (m) is defined as the amount of solute (in moles) present in 1 kg solvent. It is calculated by dividing the moles of solute by the mass of the solvent (in kg). For example, a solution with a molality of 1 mol/kg is often described as 1 molal or 1 m.
Hence, 7.89g of NaCl would be needed.
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one mole of hydrogen gas has a mass of 2.02 g. use your value of the molar volume of hydrogen to calculate the mass of one liter of hydrogen gas at stp. this is the density of hydrogen in g/l. how does this experimental value of the density compare with the literature value? (consult a chemistry handbook for the density of hydrogen.)
The experimental value has a 0.278 % error when compared to the literature / actual value.
The absolute value of the difference between the measured or the experimental value and the literature or actual value is multiplied by 100 and divided by the actual value to get the percent (%) error calculation.
Serious repercussions might happen if the analysis contains a significant inaccuracy. Analytical chemistry is built on the principles of precision, repeatability, and dependability.
The following actions can help reduce % error: guarantee that observers and measurement takers have received enough training. Use the most precise measuring device for taking the reading. Measurements must be recorded in a controlled environment. Test your measurement equipment on a pilot.
Given:
1 mol of H2 = 2.02g
To find:
% error = ?
Formula:
% error = (experimental value – literature value) / literature value x 100
Calculations:
Recall that, at STP
most gases will occupy 22.4L if they are ideal gases
Therefore,
Density = Mass / Volume
Density = 2.02g / 22.4L = 0.09017g/L
This is the experimental value for density of H2
Literature value = 0.08992g/L
% error = (0.09017 - 0.08992) / 0.08992 x 100 = 0.278% error
Result:
The % error is found to be 0.278%.
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In which pair of elements are the chemical properties of the elements most similar? Explain your reasoning.
a. sodium and chlorine
b. nitrogen and phosphorus
c. boron and oxygen
Answer:
b. nitrogen and phosphorus
Explanation:
Elements in the same column of the Periodic Table have similar chemical properties. Both N and P are in the same column.
let's consider that ethyl acetate is the ideal solvent for this tlc experiment. what might have happened to the spots if you had used t-butyl methyl ether as the eluent instead of ethyl acetate.
The spots will remain towards the bottom of the TLC plate in the TLC experiment if the eluent is changed from ethyl acetate to t-butyl methyl ether.
The spots will remain at the bottom of the TLC plate because t-butyl methyl ether is less polar and cannot overcome attractions of sample to adsorbent.
TLC experiment concept is simple. In TLC, adsorbent is silica which is highly polar. Then the eluent we can use as in different percentage of ethyl acetate & ether solution depending upon the polarity of given products.
As we know that polar molecules strongly bind with other polar molecules, ethyl acetate and silica gel are highly polar, the solvent ethyl acetate overcomes the strong bonding between the spotted product and adsorbent and takes the spot with the solvent upto the top.
If in this TLC experiment, instead of ethyl acetate, t-Butyl methyl ether is used, which is a highly non-polar or less polar solvent, it does not overcome the bonding since polar spots don't have greater binding affinity towards this non-polar ether solvent, therefore, the spots will remain tightly bonded with silica on TLC plate and spots will remain at the bottom of the TLC plate.
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In what ways does the element hydrogen behave like elements from group 1 and sometimes like elements from group 17? Make an argument for which group you think hydrogen should be placed in.
It mimics alkali metals in several of its characteristics, such as its ease in forming cations.
What category does hydrogen fall under?Chemical element hydrogen has the atomic number 1 and the letter H after it. It is a diatomic gas with the chemical formula H2 that is colorless, odorless, nonmetallic, tasteless, and extremely combustible.
Because it shares some characteristics with alkali metals, such as the ability to form cations easily, hydrogen can be placed in both groups 1 and 17 of the periodic table. However, because it also shares characteristics with halogens, such as the ability to form H2, hydrogen can also be placed in group 17. While hydrogen can take electrons, it also has a propensity to reject them in order to maintain stability. It is the family's tiniest member.
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ammonia, nh3, is used as a refrigerant. at its boiling point of –33 c, the standard enthalpy of vaporization of ammonia is 23.3 kj/mol. how much heat is released when 50.0 g of ammonia is condensed at –33 c?
- 68.385 kJ amount of heat will be released when 50.0 g of ammonia is condensed at –33 °C.
The standard enthalpy of vaporization of ammonia = 23.3 kJ/mol
This means the energy required to vaporize one mole of ammonia at its boiling point = -33 °C
Let's calculate the heat released when 50.0 g of ammonia is condensed at -33 °C.
The heat released is the opposite of the enthalpy of vaporization i.e Q = -23.3 kJ/mol (-ve sign indicates the reaction is exothermic)
We are given
Mass of ammonia m(NH₃) = 50.0 g
Number of moles of ammonia n(NH₃) = 50.0 g ÷ 17.031 g/mol.
n(NH₃) = 2.935 mol
The amount of heat released when 2.935 mol moles condensed at -33 °C
Q = Hv x n(NH₃).
Q = 23.3 kJ/mol x 2.935 mol
Q = - 68.385 kJ
Thus, -68.4 kJ amount of heat is released when 50 g of ammonia is condensed at -33 °C, where negative sign signifies release of heat.
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How much heat is needed to raise the temperature of 10 grams of liquid water from 25°C to 50°C?
what is the percent ionization of a 0.427 m solution of ethylamine (ch3ch2nh2) in 0.113 m calcium hydroxide?
Percentage ionization of ethylamine is 4%.
What is the percent ionization?The portion of the original chemical that has undergone ionization is the percent ionized. So, we contrast the ion's concentration in solution with the neutral species' initial concentration.
Given,
Concentration of ethylamine =0.427 m,
Concentration of calcium hydroxide = 0.113 m,
As ethylamine(CH₃CH₂NH₂) is a weak base, it will not in equilibrium,
CH₃CH₂NH₂ ⇆ CH₃CH₂NH₃⁺ + OH⁻
also from CaOH₂ ; OH⁻ ions are coming which will show common ion effect
CaOH₂ → Ca⁺ + 2OH⁻
0.113 - -
- 0.113 0.113×2
=0.226
Now, CH₃CH₂NH₂ ⇆ CH₃CH₂NH₃⁺ + OH⁻
c - cα cα + 0.226 ≈ 0.226
Kₐ = [ OH⁻] [CH₃CH₂NH₃⁺]/[CH₃CH₂NH₃⁺]
=[tex]\frac{c\alpha \times 0.226}{c-c\alpha}\\[/tex]
= [tex]\frac{\alpha\times 0.226 }{c- c\alpha} \\[/tex]
0.01= α ×0.226
α= [tex]\frac{0.01}{0.226}[/tex]
α=0.44
now percentage ionization = 4%.
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in a 4.00 l pressure cooker, water is brought to a boil. if the final temperature is 115.0 °c at 4.50 atm, what quantity in moles of steam are in the cooker?
The no. of moles of steam present in the cooker is found to be 0.565 mol using the ideal gas equation.
The ideal gas equation, states that the sum of the universal gas constant and the absolute temperature of a gas is equal to the product of the volume and pressure of one gram of an ideal gas.
The ideal gas equation is PV = nRT. The ideal gas's pressure, volume, total no. of moles, universal gas constant, and temperature are all represented in this equation by the symbols P, V, n, R, and T, respectively.
The no. of moles of a substance is calculated by dividing its mass during a chemical reaction by the mass of one mole of that substance.
Given:
Pressure, P = 4.50atm
Volume, V = 4L
Temperature, T = 115℃ = 273 + 115 = 388K
To find:
No. of moles, n = ?
Formula:
PV = nRT
Calculations:
n = 4.50 x 4 / 0.082 x 388
n = 0.565 mol
Result:
By using the ideal gas equation, 0.565 mol of steam is found to be present in the cooker.
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the rate constant for a reaction is found to be 0.15 m-1s-1. if the initial concentration of the reactant is 0.30 m, how long (in seconds) does it take for the concentration to decrease to 0.15 m?
A reaction's rate constant is discovered to be 0.15 . If the initial concentration of the reactant is 0.30 m, 22.2 sec of time does it take for the concentration to decrease to 0.15 m.
1/[A]t=kt+1/[A]o
t=(1/[A]t−1/[A]o)/k=(1/0.15−1/0.30)/0.15=22.2seconds
Mathematically, time and other physical quantities can be coupled to create additional ideas like motion, kinetic energy, and time-dependent fields. The basis of recordkeeping is timekeeping, a complex of technological and scientific challenges. Time is change, or the span of time during which change takes place with motion. Without a change, it is impossible to detect the passage of time. Comparison with a standard is used to calibrate the length of time or change.The SI unit of time is called the second, abbreviated as s. Time can be used to quantify, compare, or even order events based on their duration or the intervals between them. One method of making efficient use of resources is to use time study and motion study, which enhance output and performance.
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The relationship between the energy of a photon and the frequency of light was determined by Ernst Planck (1858 - 1947). Here is the equation he discovered E = hf. Because photons of light have wave-like properties this equation may also be represented using the speed of light and wavelength, E = hc/λ.
Where h is Planck’s constant = 6.63 x 10-34 J*s)
c is the speed of light = 3.00x108 m/s
f is the frequency of the photon (in cycles/sec or s-1)
λ is the wavelength of light (in meters)
1. Show how you calculate the energy of light that has a frequency of f = 4.0 x 10^14 s^-1.
2. Use the information above to determine the wavelength of a photon of light that has the same energy
The energy of a photon can be calculated by multiplying Planck's constant by the frequency of the light.
According to this question, the relationship between the energy of a photon and the frequency of light was determined by Ernst Planck. He proposed a equation as follows:
E = hf
Where;
E = energy in joulesh = Planck's constant (6.626 × 10-³⁴J/s)f = frequency (Hz)The energy of a frequency 4.0 × 10¹⁴ Hz can be calculated as follows:
E = 6.626 × 10-³⁴ × 4 × 10¹⁴
E = 2.65 × 10-¹⁹J
λ = hc/E
λ = 6.626 × 10-³⁴ × 3 × 10⁸/2.65 × 10-¹⁹
λ = 1.988 × 10-²⁵/2.65 × 10-¹⁹
λ = 7.5 × 10-⁷m
Therefore, 7.5 × 10-⁷m is the wavelength of the photon.
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What is the equation for gravitational potential energy?
Answer:
PE=mgh
m=mass
g=gravity
h=height
Hello. The answer should be like this in below.
[tex]PE_{gravitational}=m.g.h[/tex]The variable "[tex]m[/tex]" represents the mass. It is a constant value for every substance and is assumed not to change over time.
The variable "[tex]g[/tex]" is the acceleration of gravity. It has a constant value and the numerical value of the gravitational constant for the planet we live on (Earth) is [tex]9.81m/s^2[/tex].
The variable "[tex]h[/tex]" is the distance between sea level and the center of mass of the object. (Height) The unit is meter.
Mass of empty Erlenmeyer Flask (g) 30.46 g Mass of flask 100 ml 10% vinegar (g) 85.56 g Mass of flask 100 ml NaOH (g) 90.23 g Mass of flask after mixing the NaOH with 10% vinegar (g) 175.79 g Mass of the flask after the reaction (g) 145.33 g Temperature of the solution before it is mixed 21.9oC Temperature of the solution after it is mixed 23.1oC 1. Find the combined mass of the two reactions that have taken place. 2. Calculate the combined mass of the contents of the flasks after the reaction has taken place. 3. Finally, calculate the percent deviation within the lab. If the percent deviation was not 0%, what do you think might have happened in the lab that caused it to not be zero? (hint: remember, matter cannot be destroyed).
The combined mass of the two reactions that have taken place is 145.33 g.
The combined mass of the contents of the flasks after the reaction has taken place is 114.87 g.
The percent deviation is 20.9 % and is not zero because some products escaped as gas.
What is the law of conservation of mass?The law of conservation of mass states that matter cannot be created nor destroyed.
This means that for a given chemical reaction, the total mass of the reactants will equal the total mass of the products.
The masses in the reaction are:
Mass of empty Erlenmeyer Flask (g) 30.46 g
Mass of the combined reactants = (175.79 - 30.46) g
Mass of the combined reactants = 145.33 g
Mass of the contents of the flask after the reaction has taken place = 145.33 - 30.46) g
mass of the contents after the reaction = 114.87 g
Percent deviation = (145.33 - 114.87) / 145.33 * 100%
Percent deviation = 20.9 %
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What controls the movement of air masses on the surface of the earth?
A. Movements of rain clouds
B. Directions of ocean currents
C. Gravitational pull of the moon
D. Patterns of heating and cooling
what happens to matter and energy when a substance combusts
Nothing is destroyed by burning or other modifications to matter. Before and after changes always occur, the mass of the substance remains constant. According to the principle of conservation of mass, matter cannot be created or destroyed.
Where does matter go when burned?Exothermic reactions characterize all combustion processes. A substance burns when it reacts with oxygen in a combustion reaction. Burning materials often release energy in the form of heat and light.In the chemical process of combustion, an object quickly combines with oxygen to produce heat. The original substance is referred to as the fuel, and the oxygen's source as the oxidizer.Nothing is destroyed by burning or other modifications to matter. Before and after changes always occur, the mass of the substance remains constant. According to the principle of conservation of mass, matter cannot be created or destroyed.combustion is a chemical reaction that often involves the presence of oxygen and produces heat and light in the form of flames.To learn more about : Combustion
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4. When you added the iron to the water, you saw a rise in temperature from 25 C to 47 C. If the amount of energy delivered to the water from the iron was 1100 j, what was the mass of the water in the beaker? Use specific heat of water as 4.2 j/gC.
5. How much energy would it take to covert the mass of that water from # 1 from room temperature to steam at 100 C?
6. Using the same mass of water, calculate the total energy needed to vaporize the water to 120 C from an ice cube at -20 C.
7. In the Energy systems tab of the lab, suppose the steam from the teapot that’s turning on the lightbulb is 100 C. If the mass of the steam coming out is 2.76 g, how much heat would you have to remove from the system to get the lightbulb to go out?
The mass of the water in the beaker is 11.9 grams. The energy needed to convert the mass is 3748.5 J. The total energy needed to vaporize the water is 6997.2 J.
What is energy?Energy is defined as the quantitative property that is imparted to a body or physical system and is visible in the performance of work as well as in the form of heat and light.
There are basically two types of energy.
Potential energyKinetic energyFormula for calculating the mass is
q = mcΔT
m = q / cΔT
m = 1100 J / 4.2 J / g °C x (47-25°C)
m = 11.9 grams
The energy can be calculated as
q = 11.9 g x 4.2 J / g °C x (100 - 25°C)
q = 3748.5 J
The total energy is
q = 11.9 g x 4.2 J / g °C x [120-(-20°C)]
q = 6997.2 J
The amount of heat removed is
q = 2.76 g x 4.2 J / g °C x (100 - 25)
q = 869.4 J
Thus, the mass of the water in the beaker is 11.9 grams. The energy needed to convert the mass is 3748.5 J. The total energy needed to vaporize the water is 6997.2 J.
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need help please answer
Answer:
True
Explanation:
The answer is True if it's wrong forgive me if its right heart it.
You heat 3.970 g of a mixture of Fe3O4 and FeO to form 4.195 g Fe2O3. The mass percent of FeO originally in the mixture was:
FeO + Fe3O3 + 1/2O2 → 2Fe203
→ Molar mass of Fe2o3 = 159.69g/mol
→ Molar mass of FeO = 71.84g/mol
→Molar mass Fe3o4 = 231.53g/mol
1. first of all , let consider the amount of Fe in Fe2O3
Atomic Mass of Fe = 58.845 g/mol
Percentage of Fe in Fe2)3 = ( 2 x mass of Fe / Molar Mass Fe203) = 2x(55.845) /159.69g/mol
= 0.6994 * 100 = 69.94 %
2. Mass of Fe in 4.195g of Fe2O3 will then be :
0.06994 * 4.195g = 2.934 g
3.(i) percentage of Fe in FeO = (55.845 / 71.84g/mol ) = 0.77735* 100 =77.735
(ii)percentage of Fe in Fe3O4 = (3x 55.845)/231.53g/mol= 0.72359*100 =72.359
(remember , we only have molar mass of FeO as well as molar mass for Fe3O4 , we do not have their mass)
4. so we will say; let x be the mass for Fe3O4
and ; let y be the mass of FeO
However , the mass of FeO and FeO3O4 must equal 3.970 as given in the question.
meaning x +y = 3.970; therefore x = (3.970-y)
But, we also know from the above percentage calculations; that :
• Mass of Fe in FeO = 0.77735 = 0.77735 ,y
,• Mass of Fe in Fe3O4 = 0.72359 = 0.72359,x
5. now lets solve for x and y by equating the above:
0.77735 y + 0.72359x =2.934 g
0.77735 y + 0.72359(3.970-y) =2.934 g
solving for y; you will get :
0.07735y + 2.8726 -0.72359y = 2.934
0.05385y = 0.061347
therefore y = 1.142 g = mass of FeO
Finally :
Mass percentage= (Mass FeO /given mass of the mixture ) * 100
= 1.142g/3.970 *100
= 28. 7 %
Which of the following statements explains why atoms are always neutral in charge
They have the same number of protons as the atoms of all other elements.
They have protons that are identical to the protons of all other elements.
They have the same size as the atoms of all other elements.
They have the same number of protons as electrons.
Answer:
D. They have the same number of protons as electrons.
Explanation:
Protons are found in the nucleus of the atom and have a positive charge while electrons orbit around the nucleus and have a negative charge. Usually, in a neutral atom of an element, the number of protons is equal to the number of electrons. This is why the atom has no charge because the positive and negative charges cancel out. When an atom loses an electron its charge turns positive while when it gains an electron its charge turns negative.
What is the atomic mass of hafnium if, out of every 100 atoms, 5 have a mass of 176, 19 have a mass of 177, 27 have a mass of 178, 14 have a mass of 179, and 35 have a mass of 180. 0?.
The atomic mass of hafnium is 178.55 amu based on the mass of the given isotopes.
To determine the average atomic mass of hafnium, we first determine the mass fractions of the isotopes as follows;
m(1) = 5 ÷ 100 = 0.05
m(2) = 19 ÷ 100 = 0.19
m(3) = 27 ÷ 100 = 0.27
m(4) = 14 ÷ 100 = 0.14
m(5) = 35 ÷ 100 = 0.35
Now the average atomic mass of hafnium can be calculated by the addition of the products of the mass fractions of the isotopes and their respective atomic masses.
Average atomic mass = [m(1) × 176] + [m(2) × 177] + [m(3) × 178] + [m(4) × 179] + [m(5) × 180]
Average atomic mass = (0.05 × 176) + (0.19 × 177) + (0.27 × 178) + (0.14 × 179) + (0.35 + 180)
Average atomic mass = 8.8 + 33.63 + 48.06 + 25.06 + 63
Average atomic mass = 178.55
Hence the average atomic mass of Hafnium is calculated to be 178.55 amu.
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