use the clean 25 ml graduated cylinder to accurately measure 10.0 ml of 2m naoh from the dropper bottle. when nearing 10.0 ml mark, add drops slowly to ensure a measurement of exactly 10.0 ml.
1.enthalpy ΔH = -45.1872 Kj/mol
2.enthalpy ΔH = -2.092 Kj/mol
3.enthalpy ΔH = -13.888 Kj/mol
A thermodynamic system's internal energy and the product of its pressure and volume are added to form enthalpy, which is one of the system's properties. It is a state function that is frequently used to monitor chemical, biological, and physical systems at a constant pressure that is conveniently given by the sizable surrounding environment. The labor necessary to determine the system's physical dimensions, or to make room for it by displacing its surrounds, is expressed by the pressure-volume phrase. Under typical conditions, the pressure-volume term is very small for solids and liquids and moderately small for gases. As a result, in chemical systems, enthalpy serves as a stand-in for energy; bond, lattice, solvation, and other concepts referred to as "energies" in chemistry are actually differences in enthalpy.
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Find the volume of oxygen that has a mass of 250. 0 g
NEED HELP ASAP PLEASE!!!
At STP, the volume of oxygen of mass 250g is found to be 175mL.
Volume is the amount of space occupied by an item or substance. Volume is a measurement of how much 3-dimensional space an object occupies. Volume is the measurement of a limited quantity of area at a specific end.
Mass is a measurement of the quantity of matter in an item or substance. Mass is the physical quantity that represents the amount of matter in an object's body. The amount of weight accommodated in an item or stuff is measured in mass.
Density - The amount of space taken up by an item or substance (its volume) in proportion to the amount of matter in that thing or substance (its mass).
Given:
Mass = 250g = 0.25kg
Density at STP = 1.4291g/L
To find:
Volume = ?
Formula:
Density = Mass / Volume
Calculations:
Volume = Mass / Density
Volume = 0.25 / 1.4291
Volume = 0.175L
Volume = 175mL
Result:
The volume of oxygen of mass 250g is found to be 175mL at STP.
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What is the mass required to make a 311 mL of 7.5M NaCl solution?
Answer:
[tex]136.31\text{ g}[/tex]Explanation:
Here, we want to get the mass required to make the given volume
To get this we need to get the number of moles
To get the number of moles, we have to multiply the volume by the molarity
Mathematically, we have that as:
[tex]\begin{gathered} number\text{ of moles = volume }\times\text{ molarity} \\ \end{gathered}[/tex]The volume can be converted to liters by dividing by 1000
So we have the volume as 311/1000 = 0.311 L
Thus, we have the number of moles as:
[tex]number\text{ of moles = 0.311 }\times\text{ 7.5 = 2.3325 moles}[/tex]To get the mass, we have to multiply the number of moles by the molar mass
The molar mass of NaCl is 58.44 g/mol
Thus, we have the mass as:
[tex]2.3325\text{ }\times\text{ 58.44= 136.31 g}[/tex]Using the average atomic masses for each of the following elements calculate the mass in AMU of each of the following samples
Calculate the mass, in amu, of 278 atoms of Li.
1) We need to find Li (Lithium) in the periodic table.
1) The atomic mass of Lithium is 6.94 u.
[tex]\text{The mass of Lithium sample=}\frac{6.94\text{ u of Lithium}}{1\text{ mole of Lithium}}\cdot\frac{1\text{ mole of Lithium}}{6.022\cdot10^{23}\text{ atoms of Lithium}}[/tex]2) We can cancel some units and rearrange the equation.
[tex]\text{Lithium sample = }\frac{6.94\text{ u of Lithium}}{6.022\cdot10^{23}\text{ atoms of Lithium}}[/tex]3) Multiply the equation above by the number of atoms
[tex]\text{Lithium Sample = }\frac{6.94\text{ u of Lithium}}{6.022\cdot10^{23}\text{ atoms of Lithium}}\cdot\frac{278\text{ atoms of Lithium}}{\square}\text{ = 3.20}\cdot10^{-21}\text{ u of Lithium}[/tex]The mass of 278 atoms of Lithium is 3.20*10^-21 u
The oxidation number of " Z" in sodiumchromite, H₂ZO4, is
Answer:
[tex]Z\text{ = +6}[/tex]Explanation:
Here, we want to get the value of the oxidation number of Z
Generally, hydrogen has an oxidation number of +1, while oxygen has an oxidation number of -2
The total oxidation number is zero
Thus:
[tex]\begin{gathered} 2(+1)\text{ + Z + 4\lparen-2\rparen = 0} \\ 2+Z-8\text{ = 0} \\ Z-6\text{ = 0} \\ Z\text{ = +6} \end{gathered}[/tex]how shielding effect the ionization energy??
Which physical change is endothermic?
A) CO2(l) → CO2(s)
B) CO2(g) → CO2(s)
C) CO2(g) → CO2(l)
D) CO2(s) → CO2(g)
Physical change of a substance involves the change in phase or state. The physical change which is endothermic is, conversion of solid carbon to gaseous carbon.
What is endothermic reaction?Endothermic reactions are those which absorbs heat energy to give the products. Thus heat is taken into the reaction system hence the name endothermic.
In exothermic reactions, the heat energy is released by the reaction system, where the heat is exiting hence the name exothermic.
When solids changes to gaseous state, the tightly packed molecules in the solid state requires much energy to move apart and to overcome the intermolecular forces of attraction.
Liquid to gas does not require these much energy and gas to liquid evolves energy out. Therefore, the physical change given here which is endothermic is conversion of solid carbon dioxide to gas carbon dioxide.
Hence, option D is correct.
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The model shows the first three periods of the Periodic Table. Which statement BEST describes the trend in the number of protons and valence electrons across a period?
A. Across a period, elements gain a proton and lose a valence electron.
B. Across a period, elements gain a proton and gain a valence electron.
C. Across a period, elements lose a proton and gain a valence electron.
D. Across a period, elements lose a proton and lose a valence electron.
Moving across the period the elements gain a proton and gain a valence electron.
What is an element and why elements gain proton across the period?An element is the building block of inorganic chemistry , the basic fundamental unit of compounds.There are total of 118 elements discovered yet , out of which the 118th element is orgasson.Moving across the period that is from left to right the size of element decreases because of the addition of protons.Moving across the period the nucleus have increased capacity of attraction.With increase in the positive charge the nucleus gains a proton and a valence electron.To know more about periodic table visit:
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The group that fits neatly onto the end of the table, the
____ are unwilling to react with other elements
O alkaline earth metals
O halogens
O noble gases
O alkali
consider a gas cylinder containing 0.250 moles of an ideal gas in a volume of 6.00 l with a pressure of 1.00 atm. the cylinder is surrounded by a constant temperature bath at 292.0 k. with an external pressure of 3.00 atm, the cylinder is compressed to 2.00 l. calculate the w(gas) for this compression process, in j.
The work done by the isothermal compression of the gas is -666.7 J.
What is the work done by the compression of the gas in an isothermal process?The work done by the compression of a gas in an isothermal process or at constant temperature is given by the formula below:
Work done, W = nRT ln(Vf / Vi)
where;
Vi = final volume of gas Vf = initial volume of gasFrom the data provided:
number of moles, n = 0.250 moles
Molar gas constant, R = 8.314 J/K/mol
Temperature, T = 292 K
Vf = 2.00 L
Vi = 6.00 L
W = 0.25 * 8.314 * 292 * ln(2/6)
Work done = -666.7 J
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an elephant of mass 500kg stands on the ground.each foot has an area of 0.08m2.calculate the pressure exerted on the ground.g=10m/s2.
If an elephant of mass 500kg stands on the ground, each foot has an area of 0.08m2, the pressure exerted on ground is 15,625 Pa.
What is pressure?In the physical sciences, pressure is defined as the perpendicular force per unit area or the stress at a point within a confined fluid. A 42-pound box with a bottom area of 84 square inches will press down on a surface with a pressure equal to the force divided by the area over which it is applied, or half a pound per square inch.
Atmospheric pressure, which at sea level is roughly 15 pounds per square inch, is the weight of the atmosphere pressing down on each unit area of the Earth's surface. One pascal is equal to one newton per square meter when expressed in SI units, which is how pressure is calculated. Nearly 100,000 pascals of atmospheric pressure are present.
We have given that mass is 500kg and area of each leg is 0.08m²
The formula for Pressure is
Pressure = Force/Area
Let us find the weight first
⇒ weight = mass × g
= 500kg × 10N/kg
= 5000N
Total contact area = 0.08m² × 4
= 0.32m²
Finally, we will calculate the pressure
⇒ Pressure = Force/Area
= 5000N/0.32m²
= 15625 Pa
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NASA communicates with the Space Shuttle and International Space Station using Ku-band microwave radio. Suppose NASA transmits a microwave signal to the Space Shuttle using radio waves with a frequency of . Calculate the wavelength of these radio waves.
Be sure your answer has the correct number of significant digits.
The wavelength of these radio waves with a frequency 18GHz is equal to 0.0167m.
What is microwave communication?Microwave transmission is the method of transmission of information by electromagnetic waves that lie in the microwave range (1 m - 1 mm) of the electromagnetic spectrum. Microwave signals are limited to the line of sight, so long-distance transmission using these signals needs a series of repeaters to create a microwave relay network.
The relationship between wavelength (λ) and frequency (ν) can be expressed as follow:
λ = c/ν
Given, the frequency of the radio wave = 18GHz
The frequency in (per second) = 18 × 10⁹ s⁻¹
The wavelength of the radiowaves, λ = c/ν
where c is the speed of light and has a value of 3× 10⁸ m/s.
λ = c/ν = 3× 10⁸ m/s./ 18 × 10⁹ s⁻¹
λ = 0.0167 m
Therefore, the wavelength of these radio waves is equal to 0.0167m.
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Your question was incomplete, most probably the complete question was,
NASA communicates with the Space Shuttle and International Space Station using Ku-band microwave radio. Suppose NASA transmits a microwave signal to the Space Shuttle using radio waves with a frequency of 18GHz. Calculate the wavelength of these radio waves.
Be sure your answer has the correct number of significant digits.
The half-life of colbalt-60 is 5.3 years. What percent of a colbalt-60 sample remains after 10.6 years
After one half life, the number of years needed for 1/4 of the cobalt-60 to remain after decay is computed as follows.
After another half life, only 1/4 of the original mass isotope is left; consequently, if one half life is 5.3 years, the number of years needed is 2 x 5.3 years, or 10.6 years.
What is an isotope ?A chemical element's isotope is any of two or more species of atoms that share the same atomic number, position in the periodic table, and virtually identical chemical behavior, but differ in atomic mass and physical characteristics. There are one or more isotopes for each chemical element.The sum of the protons and neutrons in an isotope's mass is what distinguishes it from another isotope. Isotopes are often written in one of two ways. Both use the atom's mass, which is calculated as mass = (number of protons) + (number of neutrons).
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cfc-11 has a global warming potential (gwp) of 4750. the current global mean concentration of cfc-11 is approximately 220ppt. calculate, relative to co2, the percentage of warming attributed to cfc-11.
The relative contribution of CO2 attributed to global warming is 60 % in the environment.
What is global warming , responsible gases and percentage attributed from these gases?The decrease in the amount of sunlight due the increasing CO2 and air pollutant in the atmosphere absorbing sunlight is owing to global warming.Global warming is caused by gases such as CO2, CH4, and lots of air pollutants.Global warming is causing great harm to the natural atmosphere and effecting the plant growth too.The relative concentration of CO2 attributed to global warming is 60% of the total.And cfc -11 is the chloroflorocarbons responsible for increasing global warming effects.To know more about global warming visit:
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a 25.0 ml sample of 0.100 m hbr solution is titrated with 0.050 m naoh solution. what is the ph after 25.0 ml of the naoh solution have been added?
The ph after 25.0 ml of the naoh solution have been added is 1.222.
You are aware that the balanced chemical equation states that sodium hydroxide and hydrochloric acid balance each other out in a 1:1 mole ratio.
NaOH (l) + HCl (l) = NaCl (l) + H2O (l)
As a result, equal amounts of sodium hydroxide and hydrochloric acid must be used to completely neutralize a substance, producing a neutral solution with a pH of 7 at ambient temperature.
Although the molarities of your two solutions are equivalent, the hydrochloric acid solution has a volume of 100 mL divided by 25.0 mL, which equals four.
[tex][H3O+]=(75⋅0.100103).moles H3O+125⋅103.L=(75⋅0.100125)mol L−1This means that you havepH=−log(75⋅0.100125)=1.222−−−−−[/tex]
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To calculate the heat absorbed or released, you need to measure which of the following?
A) Specific heat, change in temperature, and time to heat.
B) Mass, specific heat, and change in temperature.
C) Mass, volume, and change in temperature.
D) Mass, specific heat, and time to heat.
In case of exothermic or endothermic reactions where heat is absorbed or released there is a need to measure specific heat, change in temperature and time to heat.
What are exothermic reactions?An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.
In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.
Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.
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How are cellular respiration and photosynthesis similar?
Both processes break down glucose.
Both processes create food for organisms.
Both processes produce waste.
Both processes take place in chloroplasts.
Cellular respiration and photosynthesis similar is both processes break down glucose
Photosynthesis converts carbon dioxide and water into oxygen and glucose and glucose is used as food by the plant and oxygen in a byproduct whereas cellular respiration converts oxygen and glucose into water and carbon dioxide and both processes break down glucose and both are processes within the cell which make chemical energy available for life
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a substance that helps a reaction to take place, but does not participate in the reaction is called a(n) . activation energy reactant catalyst product
The correct answer is option C: Catalyst
A substance that helps a reaction to take place, but does not participate in the reaction is called a catalyst.
In Chemistry, a catalyst is defined as a substance that increases the rate of a chemical reaction without itself undergoing any changes. This process is called catalysis.
There are 3 different types of catalysts: enzymatic, homogeneous, and heterogeneous.
The catalytic substance remains unchanged and does not consume during the reaction, Their only job is to speed up the reaction by breaking bonds and saving time and energy.
For example, during the commercial preparation of ammonia also called the 'Haber process' iron is added as a catalyst to accelerate the reaction rate.
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1. Starting with a 0. 1525 m hcl stock solution, three standard solutions are prepared by sequentially diluting 5. 00 ml of each solution to 100. 0 ml. What is the concentration of each solution?.
Each solution has a concentration of 7.625 x 103 m, 3.8125 x 104 m, and 1.90625 x 105 m, respectively.
Dilution is the process of lowering a sample's concentration by incorporating more solvent, according to its definition. The following is the dilution formula.
C₁V₁ = C₂V₂
where C1 is the sample's initial concentration.
V1 is the initial sample volume.
After dilution, the ultimate concentration is C2.
After dilution, the ultimate total volume is V2.
Calculate the concentration of the diluted solution by entering the numbers into the formula.
first common answer
C₁V₁ = C₂V₂
0. 1525 m(5.00 ml) = C₂(100.0 ml) (100.0 ml)
C₂ = 7.625 x 10⁻³ m
Second common solution
C₁V₁ = C₂V₂
7.625 x 10⁻³ m(5.00 ml) = C₂ (100.0 ml)
C₂ = 3.8125 x 10⁻⁴ m
Third accepted option
C₁V₁ = C₂V₂
3.8125 x 10⁻⁴ m(5.00 ml) = C₂(100.0 ml) (100.0 ml)
C₂ = 1.90625 x 10⁻⁵ m
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The image shows Mary happily swinging in the park. There are tree positions shown in the image: A, B, and C. PositionB is located at the very bottom of the swing arc and has the lowest height. Which of the following equations best describes the energy at point C, assuming energy is conserved?
Equation B. PEa = KEc + PEc best describes the energy at point C, assuming energy is conserved.
As we are provided,
Three particular points A,B and C are described.
The point A is the point at the top, the point B is the point at the bottom and point C is the point somewhere in the middles when merry is swinging.
According to law of conservation of energy,
The sum of total energy is conserved at every point of the motion.
As point A is the highest point. The body will come at momentary rest. The whole of energy will be stored as the potential energy of the girl.
At point B, the swing will have maximum velocity and the whole energy will be found in the form of kinetic energy.
At point C, the total energy will be a sum of potential plus kinetic energy.
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The image shows Mary happily swinging in the park. There are tree positions shown in the image: A, B, and C. PositionB is located at the very bottom of the swing arc and has the lowest height. Which of the following equations best describes the energy at point C, assuming energy is conserved?
A. PEa= KEc
B. PEa= KEc + PEc
C. PEg= KEc + PEc
D. PEg = PEc
HELP ASAP WILL MARK BRAINLIEST
Consider the reaction:
A + 3B → 2C
How does the reaction rate of B compare to the reaction rate of C?
A The rate of B is -½ the rate of C.
B The rate of B is -3/2 the rate of C.
C The rate of B is -⅔ the rate of C.
D The rate of B is -⅓ the rate of C.
To solve this we need to have knowledge of differential rate law which relate the rate to the concentration and time The option B is correct option.
What is differential rate law?A differential rate law represents the rate of a reaction . According to this rate is directly proportional to changes in the concentration of reactants and inversely proportional to specific interval of time. There is another expression of rate law which is integrated rate law which is just opposite of differential rate law
The given equation is
[tex]A+3B\rightarrow2C[/tex]
Rate of B= rate of C
[tex]\frac{1}{3}d\frac{[B]}{dt} =\frac{1}{2}d\frac{[C]}{dt}[/tex]
[tex]d\frac{[B]}{dt} =\frac{3}{2}d\frac{[C]}{dt}[/tex]
Thus option B is correct option.
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A tortoise uses its eyes to see something moving nearby. The tortoise feels threatened by the movement. It pulls its head, legs, and tail into its shell. The tortoise's shell is hard and thick. This helps protect the turtle's soft body parts from any danger. Which of these describes a response of the tortoise to sensory information processed by its brain?
A. The tortoises shell is hard and thick.
B. The tortoise pulls its head, legs, and tail into its shell.
C. The tortoises soft body parts are protected from any danger.
D. The tortoise uses its eyes to see something moving nearby.
Which atom has the largest number of neutrons?
a. silicon-30
b. sulfur-36
c. argon-39
d. calcium-40
Answer:
Sulfur has the most neutrons (it has 4).
To eliminate the y-terms and solve for x in the fewest steps, by which constants should the equations be multiplied by before adding the equations together?
First Equation: 5x − 4y = 28
Second equation: 3x - 9y = 30
The first equation should be multiplied by 3 and the second equation by 5.
The first equation should be multiplied by 3 and the second equation by −5.
The first equation should be multiplied by 9 and the second equation by 4.
The first equation should be multiplied by 9 and the second equation by −4.
Answer: the answer is D) The first equation should be multiplied by 9 and the second equation by −4.
Explanation:edge 2022
The atomic number of an element:
Question options:
Tells you the mass of the atom
Tells you the number of energy levels there are around the atom
Tells you the identity of the atom
Tells you how many valence electrons the atom has
Answer:tells you the identity of the atom
Explanation:
number of protons=atomic number
Answer: C
Explanation: The answer would be C, it tells you the identity of the atom.
40. Write electron configurations for the elements
that are identified by these atomic numbers:
a. 7
b. 9
c. 12
d. 36
Electron configurations for the elements follow 3 principles , Aufbau principle, Pauli Exclusion Principle and Hund's Rule of Multiplicity
What is Aufbau principle ?
It states that electrons fill lower-energy atomic orbitals before filling higher-energy ones.
The order in which the orbitals are filled with electrons are:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
Element with electronic configuration of atomic number:
a. 7 is Nitrogen : 1s2 2s2 2p3 or [He] 2s2 2p3
b. 9 is Fluorine : 1s2 2s2 2p5 or [He] 2s2 2p5
c. 12 is Magnesium : 1s2 2s2 2p6 3s2 or [Ne] 3s2
d. 36 is Krypton : 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 or [Ar] 4s2 3d10 4p6
Thus we can conclude that electron configurations for the elements follow 3 principles , Aufbau principle, Pauli Exclusion Principle and Hund's Rule of Multiplicity
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Which is the balanced version of the half-reaction below?
H₂S → S + H+
OA. H₂S → S+H* + e
OB. H₂S + 2e → S + 2H+
OC. H₂S →S + 2H*
OD. H₂S →S + 2H+ + 2e
The balanced version of the half reaction is H2S - S + 2H+ , this is how we balance half reactions.
What is half reaction and how the half reaction is balanced?We must have studied redox reaction , which is the reaction in which one component of reactant undergoes oxidation and other undergoes reduction.Half reaction is either only the oxidation or only the reduction of the redox reaction.Whenever we balance a equation or reaction we always try to balance by equalizing the coefficients of the components .Here in this question in which only half reaction is given to balance , there will be one sulphur and two hydrogen in the product .To know more about half-reaction visit:
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what other chemical could be used to make barium sulfate
Answer:
Barium sulfate, BaSO4, is made by reacting barium hydroxide and other barium sources with sulfuric acid and has a long history as a translucent white pigment.
What are the products from the following reactants: Na₂O + Ca →
A. CaO + Na
B.Ca₂O + Na₂
C.CaO₂ + Na
D. CaO + Na₂
please help
A sample of natural sulfur consists of three isotopes:
95.0% sulfur-32 (31.97 amu)
0.75% sulfur-33 (32.97 amu)
4.21% sulfur-34 (33.96 amu)
Based on this information, what is the average molar mass of sulfur?
The average molar mass of sulfur is 32.84g/mol
The average atomic mass of a chemical element is calculated by taking into account the atomic masses of its naturally occurring isotopes and their respective abundances
Here given data is natural sulfur consists of three isotopes :
95.0% sulfur-32 = 31.97 amu
0.75% sulfur-33 = 32.97 amu
4.21% sulfur-34 = 33.96 amu
So, we have to find average molar mass of the sulfur = ?
Formula for average molar mass = ∑i × isotope i × abundance i
³²S = 95.0% abundance = 31.97 amu
³³S = 0.75% abundance = 32.97 amu
³⁴S = 4.21% abundance = 33.96 amu
This means that average molar mass of sulfur is
Average molar mass = 31.97 amu×95.0 + 32.97 amu× 0.75 + 33.96 amu×4.21
Average molar mass = 32.84g/mol
Average molar mass of sulfur is 32.84g/mol
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