Students as a chemical reaction that absorbs thermal energy for the design of cold packs for the treatment of injuries can combine manganese oxide (MnO2) with hydrogen peroxide (H2O2)
By controlling the amounts of the reactants they can control the temperature, keeping it between 0 °C and 4 °C for 20 minutes or more.
This type of chemical reaction is called endothermic, because energy is absorbed in the form of light or heat, causing the resulting products to have higher energy than the reactants.
Chemical reaction that absorbs thermal energy fpr cold compresses for the treatment of injuriesThe most widely used endothermic chemical reaction in the treatment of injuries is the melting of ice, at least in warm environments, which occurs according to the following reaction:
H2O (s) + Energy ----- H2O (l)
Decomposition of manganese oxide absorbs thermal energyThe effect of an endothermic reaction is absorbs heat energy and in the case of manganese oxide the following decomposition occurs:
MnO2 (s) → MnO (s) + ½ O2 (g); ∆HR = 134kJ
Students can design cold packs for treating injuries with manganese dioxide bcause it breaks down into two products, manganese oxide and oxygen, making the enthalpy greater than zero (∆HR > 0).
MnO2 is a solid between gray and black in color and is present in minerals such as pyrolusite and nsutite, when combined with hydrogen peroxide it acts as a catalyst so that it accelerates chemical reaction
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When the equation 4. 78X^2-2. 14x-1. 60=0 is solved the two values of unknown x are ____ and _____
x has the values (2.14 + √(23.288)) / 9.56 and (2.14 - √(23.288)) / 9.56.
What Is a Quadratic Equation?Quadratic equations are the degree two, one-variable polynomial equations of the form f(x) = ax^2 + bx + c = 0 with a, b, c, and R R and a 0 being the variables. In its most basic form, it is a quadratic equation where "a" denotes the leading coefficient and "c" is the absolute term of f(x). The values of x that satisfy the equation (, ) are the quadratic equation's roots.
The name "quadratic equation" is for what?Intricate relationships exist between square and quadrangle (another name for rectangle) difficulties and quadratic equations.
The Latin term quadratus, which means square, is where the word "quadratic" originates.
The quadratic formula or factoring can be used to get the solution to the problem 4.78x^2-2.14x-1.60=0.
x = (-b (b^2 - 4ac)) / (2a) where a = 4.78, b = -2.14, and c = -1.60 is the quadratic formula.
Plugging in the values we get:
x = (-(-2.14) ± √((-2.14)^2 - 4(4.78)(-1.60)) ) / (2(4.78))
x = (2.14 ± √(4.6016 + 18.688)) / 9.56
x = (2.14 ± √(23.288)) / 9.56
So the two values of x are:
x = (2.14 + √(23.288)) / 9.56 and x = (2.14 - √(23.288)) / 9.56
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32P has a half life of 14 days calculate the time taken for a given amount of 32P to decay to one - eight of its original activity
The time taken for a given amount of 32P to decay to one-eight of its original activity is 42 days.
A substance's half-life is the amount of time it takes for half of it to decompose. Given that each half-life period diminishes the activity by a factor of 2, if a given amount of a material with a half-life of 14 days decays to one-eighth of its initial activity, it must have gone through three half-life periods. Therefore, it would take 14 x 3 = 42 days for a given amount of 32P to decay to one-eighth of its initial activity.
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28. How many formula units are found in 0.250 moles of potassium nitrate?
2.41 x 1024 formula units
O 1.5x1023 formula units
4.15x10-25 formula units
O 6.022 x 1023 formula units
Answer:
[tex]\boxed {\boxed {\sf B. \ 1.5 *10^{23} \ formula \ units}}[/tex]
Explanation:
1 mole of any substance contains the same number of particles. The particles can vary (atoms, molecules, formula units), but there are always 6.022*10²³ particles. In this case, the particles are formula units of potassium nitrate or KNO₃.
Let's create a ratio.
[tex]\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]
Since we are trying to find the formula units in 0.250 moles, we multiply by that number.
[tex]0.250 \ mol \ KNO_3 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 \ mol \ KNO_3}[/tex]
The units of moles of potassium nitrate cancel.
[tex]0.250 *\frac {6.022*10^{23} \ formula \ units \ KNO_3}{1 }[/tex]
The denominator of 1 can be ignored, so we can make a simple multiplication problem.
[tex]0.250 *{6.022*10^{23} \ formula \ units \ KNO_3}[/tex]
[tex]1.5055 * 10^{23} \ formula \ units \ KNO_3[/tex]
If we round to the nearest tenth, the 0 in the hundredth place tells us to leave the 5 in the tenth place.
[tex]1.5 *10^{23} \ formula \ units \ KNO_3[/tex]
0.250 moles of potassium nitrate is approximately equal to 1.5*10²³ formula units of potassium nitrate and choice B is correct.
The reaction of ethane gas C2H6 with chlorine gas produces C2H5Cl as its main product along with HCl. (In addition, the reaction invariably produces a variety of other minor products, including C2H4Cl2, C2H2Cl3, and others. Naturally, the production of these minor products reduces the yield of the main product.) (a) Write out the complete, balanced chemical reaction of main reaction taking place. (b) Calculate the percent yield of C2H5Cl if the reaction of 300. grams of ethane with 650. grams of chlorine produced 490. grams of C2H5Cl.
a) The balanced equation is :
C₂H₆ + Cl₂ ---> C₂H₅Cl + HCl
b) The percent yield is the 83.0 % %.
a) The balanced equation is given below :
C₂H₆ + Cl₂ ---> C₂H₅Cl + HCl
b) mass of the ethane = 300 g
molar mass of the ethane = 30 g/mol
moles of the ethane = 300 / 30
= 10 mol
mass of chlorine = 650 g
molar mass of the chlorine = 71 g /mol
moles = 650 / 71
= 9.15 mol
it is clear the the chlorine is the limiting reactant.
1 mole of the chlorine produces the 1 mole of the C₂H₅Cl
moles of the C₂H₅Cl = 9.15 mol
mass of the C₂H₅Cl = 9.15 × 64.5
= 590.175 g
The percent yield = (experimental yield / theoretical yield ) × 100 %
= ( 490 / 590 .175 ) × 100 %
= 83.0 %
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The sum of three consecutive odd numbers is 69. Find the numbers of P is the largest
number
Answer:
The correct answer is - 25.
Explanation:
Given:
Sum of the 3 consecutive odd numbers = 69
solution:
Let’s assume the initial number - 2X+1
Let's say the second number is -‘2X+3’ and
Let's say the largest number is- ‘2X+5’.
Sum of the numbers = 69
(2X+1) + (2X+3) + (2X+5) = 69
6X+9 = 69
6X = 69–9
6X = 60
X = 60/6
X= 10
So, x value would be 10. Putting value of X in 2X+5
= 2(10)+5
=25
= 25 (Answer)
How many days does it take 16.Og of Gold-198 to decay to 1.0g? (each half-
life = 2.69 days) *
O 10 days
0 2.69 days
O 10.76 days
16 days
PLZ HELP NOW
Answer:
10.8 days (3 sig.figs.)
Explanation:
All radioactive decay is 1st order decay defined by the expression A = A₀e^-kt
which is solved for time of decay (t) => t = ln(A/A₀) / -k
A = final weight = 1.0 gram
A₀ = initial weight = 16.0 grams
k = rate constant = 0.693/t(1/2) = 0.693/2.69 days = 0.258 days⁻¹
t = ln(1/16) / -0.258da⁻¹ = (-2.77/-0.258) days = 10.74646792 days (calculator)
≅ 10 days (1 sig. fig. based on given 1 gram mass)
Are group 1 or group 2 elements more reactive?
The elements belonging to group 1 are more reactive than elements belonging to group 2.
The elements that belongs to s block elements are hydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The nature of alkali metals is soft and shiny in appearance. They have low melting point and are highly reactive in nature and usually tarnish when exposed to air. Sodium (Na) is the most reactive element since it's valence electrons are not tightly held together in the atom. The three elements that are highly reactive are Lithium (Li), Sodium (Na), and potassium (K). The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive.
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A compound with EF CH2 was found to have a Molar mass of 84g. What is the MF of the compound?
Answer:
C6H12
Explanation:
MM = 84g
CH2 = 12+2 =14g
Hence, 84/14 = 6g/mol
CH2 x 6 = C6H12
How do you calculate number of molecules?
Determine the substance's molecular weight in units of one mole, then divide the molar mass value by the molecular mass, and multiply the result by the Avogadro constant to get the required number of molecules.
It is possible to determine the number of molecules by using the relationship between the number of moles and Avogadro's number, which is provided by;
1 mole = Avogadro's constant (NA)
The number of molecules will equal the product of the number of moles and Avogadro's number, which is determined after the number of moles has been determined
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PLEASE ANSWER FAST!!!!!!!!!!!!!!!
What is light?
A. a wave of vibrating electric and magnetic energy
B. a wave that travels by compressions
C. a wave that travels by rarefactions
D. a state of matter
Answer:
The answer is A. a wave of vibrating electric and magnetic energy.
helpp!!
1.) How many protons?
2.) How many neutrons?
3.) How many electrons?
Answer:
1) 33
2)47
3)33
Explanation:
The atomic number 33 is the same for both protrons and electrons.
In a reaction between vinegar and antacid tablets, the antacid is the limiting reagent. At constant pressure and temperature, three tablets produce 600 cm³ of gas.
What volume will six tablets produce?
The volume of gas produced by six tablets would be twice the volume produced by three tablets, or 600 cm³ x 2 = 1200 cm³.
Definition of a gas's volumeUntil they are enclosed in a container, gases lack a definite shape or volume. Gases can expand and contract as they are forced into various container sizes and shapes because of the way their molecules spread out and move randomly.
The volume of the container in which a gas is contained can be used to define the volume of the gas itself.
The volume of a gas reduces as the molecules are crammed closer together when it is compressed. A gas's volume rises when it expands.
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Answer:
1200 cm³.
Explanation:
Explain how the following two processes alter the percentage of carbon dioxide in the
atmosphere
(1) combustion
We burn the things that have previously grown in the sunlight-carbohydrates. Hydrogen in the carbohydrates burns to form water which is very harmless. The carbon can be recycled into many different compounds.
The carbon in this material becomes carbon monoxide carbon dioxide, (Poisonous to us mammals) and the carbon or char which can be a nutrient into the soil. Other things that can be burning in the waste will be toxic. Plants will absorb some worst things that humans will spill out so carelessly like: lead, cadmium, and the other toxic metals—and these toxins are very dangerous in the atmosphere
So we can indeed to alter the composition of our atmosphere by burning things. Once our planet had a carbon dioxide in the atmosphere. It was a hell-hole here. It was very hot and the atmosphere was poisonous to higher life forms. Gradually life on the planet primarily plant life has been changed this atmosphere into something clean and wonderful. But we by our careless behaviour could return it into its original poisonous luckily the huge coniferous forests clean our air of carbon and the other pollution. We are eroding one factor of this margin after the another. Glaciation, wetlands, oceans, coral reefs, wild areas—these are our safeguards and one after another they are being lost.
--The given question is incomplete, the complete question is
"Explain how the following two processes alter the percentage of carbon dioxide in the atmosphere. I. Combustion (3) II. Respiration (3)".
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magine a population of rabbits in the woods.
What would happen if the rabbit population continued to decrease?
CHOOSE ALL THAT APPLY
Lesson 5.06
Question 17 options:
Animals that prey on rabbits would begin to prey on other organisms.
none of the choices
Animals that prey on rabbits would starve.
Animals that prey on rabbits would leave the area in search of more rabbits.
Answer:
A.) They would have to prey on other organisms
Explanation:
The answers are.....
Animals that prey on rabbits would begin to prey on other organisms.
And...
Animals that prey on rabbits would starve.
And...
Animals that prey on rabbits would leave the area in search of more rabbits.
My son attends K12 and had this question on his unit 5 test. These were his answer choices and they were correct.
A seismograph measures the size of a volcano eruption.
O True
O False
(This is for Science btw)
Answer:
This is true. A seismograph measures the size of a volcano eruption by detecting the vibrations that are produced by the volcanic activity. The vibrations can then be converted into a numerical value that represents the magnitude of the eruption.
Explanation:
What is the molarity of a solution in which 0.23 moles of NaCl are dissolved in enough water to make 395.6 mL of solution
The molarity of NaCl in enough water is 0.582[tex]\frac{mol}{mL}[/tex]
The moles of NaCl is given which is 0.23 and NaCl is dissolved in enough water which makes the solution of 395.6 mL.
The total number of moles of solute present in a given solution per litre is known as its molarity. In contrast to mass, which varies as the system's physical circumstances vary, the volume of a solution changes as a function of changes in the system's physical qualities, such as pressure and temperature. This has an impact on the molality of the solution. The symbol M, sometimes known as a molar, denotes molarity. A solution is considered to be one molar when one gram of the solute dissolves in one litre of the solution.
So, the molarity= [tex]\frac{totalnumber of moles}{total volume }[/tex]
molarity=[tex]\frac{0.23}{0.395}[/tex]
molarity=0.582[tex]\frac{mol}{mL}[/tex]
Hence, the molarity is 0.582.
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Calculate the final pressure in the cylinder of a car engine if the original volume was 450
mL at a pressure of 0.80 aim, and the final volume is 120 mL. Assume no change in the
number of molecules or ternperature.
According to the Boyle's law, the final pressure of gas in cylinder is 3 atmospheres.
What is Boyle's law?Boyle's law is defined as an experimental gas law which describes how the pressure of the gas decreases as the volume increases. It's statement can be stated as, the absolute pressure which is exerted by a given mass of an ideal gas is inversely proportional to its volume provided temperature and amount of gas remains unchanged.
Mathematically, it can be stated as,
P∝1/V or PV=K. The equation states that the product of pressure and volume is constant for a given mass or amount of gas and the equation holds true as long as temperature is maintained constant or does not change.
According to the equation the unknown pressure and volume of any one gas can be determined if two gases are to taken in consideration.That is,
P₁V₁=P₂V₂
∴P₂=0.8×450/120=3 L.
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Use Le Châtelier’s principle to predict what will happen to the following equilibrium if the volume is decreased.
2NH3(g) ↔ N2(g) + 3H2(g)
Answer:
The reverse reaction is favoured
Explanation:
According to the principle; when a constraint such as a change in concentration, pressure, temperature etc is imposed on a reaction system in equilibrium, the equilibrium position will shift in such a direction as to annul the constraint.
In this case, the constraint is a change in volume. If the volume is decreased, the reverse reaction (leading to less total volume) is favoured.
The forward reaction leads to four volumes while the reverse reaction leads to only two volumes. Decrease in volume favours the direction in which the total volume is lower.
If a bond forms between calcium and chlorine, the bond is covalent.
True or False
Answer:
False
Explanation:
there should be sharing of electrons between two of the atoms to be a covalent bonding. but there is no linkage of electron between them
is the specific heat capacity of gaseous ethanl greater than. less thean or equal to the speciifc heat captity of liquid ethanol
The specific heat capacity of the gaseous ethanol is less than the specific heat capacity liquid ethanol.
The specific heat capacity is given as :
Q = mc ΔT
where ,
Q = heat
m = mass
c = specific heat capacity
ΔT = temperature change
The heating curve represented the temperature , T in the y axis and the heat added at the x - axis. the slope is given as :
T / Q = 1 / C
T is the temperature and the c is the specific heat capacity.
Thus, the heat capacity of the gaseous ethanol is low as compared to the liquid ethanol.
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The filtration technique is used to separate
O two solids
O two liquids
o all of the above
O liquid from a solid
Answer:
Liquid from a solid
Explanation:
ill mark u brainlest if u answer me wit no links!
Which of these best describes the brainstorming stage of the engineering design process?
identifying a need to be addressed
gathering feedback about prototypes
collecting information from a variety of background sources
using group input to discuss and prepare preliminary designs
Answer: I believe it would be using group input to discuss and prepare preliminary designs
Explanation:
13. The equation used to find acceleration is a =
1. vf- vilt
b. v/t
a.
C. Vi - vlt
d. vit vflt
Acceleration represented by the equation = Δv/Δt.
like tobacco smoke, the aerosol given off by an e-cigarette can contain dangerous chemicals.
The title "e-cigarettes," sometimes known as "electronic nicotine delivery systems" (ENDS) and infrequently "electronic non-nicotine delivery systems," refers to a wide range of distinct products (ENNDS).
By heating the liquid, these systems can produce aerosols that the user inhales. These so-called e-liquids typically contain additives, flavours, and chemicals that can be harmful to people's health, alongside nicotine (but no tobacco), which could or may not been present.
The deadly mixture of 7,000 hazardous substances in cigarette smoke is generally lower prevalent in e-cigarette aerosol than it is. 3 Aerosol produced e-cigarettes is not risk-free, though.
It may include toxic or carcinogenic drugs include tobacco, contaminants like lead, volatile compounds, and melanoma agents.
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consider three identical flasks with different gases. in which flask will the molecules have the greatest average velocity
The flask A, flask B, flask C, all have equal average kinetic energy at 0°C.
What is the average kinetic energy?The average kinetic energy of the particles in a gas is inversely related to its temperature. These particles must move more quickly as the gas warms because their mass is constant.
KE avg = 3/2RT
As a result, it is possible to state that average kinetic energy depends on temperature. As a result, as the temperature rises, the gas molecules become more energetic and move at a faster rate.
The average kinetic energy also stays the same because, in accordance with the question, the temperature is constant across all flasks.
Therefore, the average kinetic energy of flasks A, B, and C at 0°C is the same.
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Complete question is " Consider three identical flasks with different gases:
Flask A: CO at 760 torr and 273 K
Flask B: N₂ at 250 torr and 273 K
Flask C: H₂ at 100 torr and 273 K
In which flask will the molecules have the greatest average kinetic energy per mole?
The rate of effusion of a particular gas was measured and found to be 21.0 mL/min. Under the same conditions, the rate of effusion of pure methane (CH4) gas is 47.0 mL/min. What is the molar mass of the unknown gas
the particular gas effusion was 21.0. and the methane effusion rate is 47.0 The molar mass of the unknown gas is approximately 28.6 g/mol
The process through which a gas manages to escape through with a small hole or highly permeable barrier is known as effusion. A gas's rate of effusion is inversely proportional to its molar mass squared. The following equation describes this relationship: rate1 / rate2 = (sqrt(molar mass2) / sqrt(molar mass1)). where rate1 and rate2 are the rates of effusion of the two gases and molar mass1 and molar mass2 are the molar masses of the two gases.Given the rate of effusion of the unknown gas is 21.0 mL/min, and the rate of effusion of pure methane (CH4) is 47.0 mL/min, we can use the above equation to find the molar mass of the unknown gas:
(21.0 mL/min) / (47.0 mL/min) = sqrt(molar mass unknown) / sqrt(16.04 g/mol)
Squaring both sides of the equation, we get:
(21.0 mL/min)^2 / (47.0 mL/min)^2 = (molar mass unknown) / (16.04 g/mol)
Solving for molar mass unknown we get:
molar mass unknown = (16.04 g/mol) * (21.0 mL/min)^2 / (47.0 mL/min)^2
The molar mass of the unknown gas is approximately 28.6 g/mol
Please note that the above calculation is based on the assumption that the temperature and pressure are the same for both gases and that the gases are ideal
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why was the bohr model replaced
Answer:
The Bohr model of the atom was replaced by the quantum mechanical model because it was unable to explain the behavior of electrons in atoms. The quantum mechanical model was able to explain the behavior of electrons in atoms more accurately.
Explanation:
Which isotope, when bombarded with nitrogen-15, yields the artificial isotope dubnium-260 plus 4 neutrons
The isotope that when bombarded with nitrogen-15 yields the artificial isotope dubnium-260 plus 4 neutrons is californium-249.
Californium-249 is a heavy element and when bombarded with nitrogen-15, which is a light element, undergoes a nuclear reaction known as a "cold" fusion reaction. This reaction results in the formation of the artificial isotope dubnium-260, which has a higher atomic number than the starting element and the release of 4 neutrons.This process is known as a Nuclear Transmutation, which is a process in which one element is converted into another element by bombarding it with a beam of particles such as protons, neutrons, or other ions.
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J.J Thomson's experiments provided what evidence about atoms?
a) atoms are the smallest particles of matter
b) atoms contain negatively charged particles
c) atoms have a negative charge
d) atoms have a positive charge
Which of these are involved in creating
new technologies?
A. engineering only
B. science only
C. math only
D. science, engineering, and math