Answer:
Bromine (Br)
Explanation:
A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter? A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of Ccal for the calorimeter? 99 J/K 21 J/K 76 J/K 28 J/K 19 J/K
Answer:
First choice: 99 J/KExplanation:
1) First law of thermodynamic (energy balance)
Heat released by the the hot water (345K ) = Heat absorbedby the cold water (298 K) + Heat absorbed by the calorimeter2) Energy change of each substance:
General formula:
Heat released or absorbed = mass × Specific heat × change in temperature
density of water: you may take 0.997 g/ ml as an average density for the water.mass of water: mass = density × volume = 50.0 ml × 0.997 g/ml = 49.9 gSpecif heat of water: 1 cal / g°CHeat released by the hot water:Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)
Heat absorbed by the cold water:Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)
Heat absorbed by the calorimeterHeat₃ = Ccal × (317 K - 298 K) = Ccal × (19K)
4) Balance
Heat₁ = Heat₂ + Heat₃49.9 g × 1 cal / g°C × (28 K) = 49.9 g × 1 cal / g°C × (19 K) + Ccal × (19 K)
Solve for CcalCcal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K
Ccal = 23.6 cal/ K
Convert to cal / K to Joule / K1 cal = 4.18 Joule23.6 cal / K × 4.18 J / cal = 98.6 J/K
Which rounded to 2 signficant figures leads to 99 J/k, which is the first choice.
Calorimetry is the measurement technique, in which heat of the chemical reactions and heat capacity is measured. The value of Ccal for the calorimeter is 99 J/K.
According to the first law of thermodynamics, the energy cannot be created nor be destroyed. It can be transferred from one form to another.
Such as:
Heat released by the the hot water at 345K = Heat absorbed by the cold water at 298 K + Heat absorbed by the calorimeterAlso, from the formula, it can be calculated as:
Heat or H = mass × Specific heat × change in temperatureGiven that,
Density of water = 0.997 g/ mlMass of water = density × volume = 50.0 ml × 0.997 g/ml = 49.9 gSpecific heat = 1 cal/ g CelciusNow, substituting the values, heat released by the water will be:
Heat₁ = 49.9 g × 1 cal / g°C × (345 K - 317 K) = 49.9 g × 1 cal / g°C × (28K)Similarly, heat absorbed by the cold water will be:
Heat₂ = 49.9 g × 1 cal / g°C × (317 K - 298 K) = 49.9 g × 1 cal / g°C × (19K)Now, the overall heat absorbed by the calorimeter will be equal to:
Heat₃ = Ccal × (317 K - 298 K) = Ccal × (19K),The value of Ccal will be:
Ccal = [49.9 g × 1 cal / g°C × (28 K) - 49.9 g × 1 cal / g°C × (19 K) ] / 19K Ccal = 23.6 cal/ K or 98.6 J/K (in Joules)Therefore, the Ccal for the calorimeter will be equal to approximately 99 J/K.
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Units used to measure the rate of electron flow
Several bird species feed is a certain species of tree. Each bird species feeds in a different part of the tree. Which statement is true of these birds species
Answer:
They have adapted to different niches.
Explanation:
due to competition
Answer:
B.they have adapted to different niches due to competiton.
Explanation:
apexs
which of the following would the kinetic theory address
The Kinetic Theory of gases states that the gases are made of small particles (atoms or molecules) which are in random motion.
Postulates of Kinetic Molecular Theory of gases:
1. All gases are made up of a large number of minute particles of molecules.
2. The molecules are separated from one another by large distances, called as intermolecular spaces.
3. The molecules are in the state of rapid motion in all directions. They collide with each other and the walls of the container, and thus change their directions.
4. There is no loss of energy when the molecules collide among themselves and the wall of the container.
5. The molecules are independent of each other as the molecules has no forces of interaction (repulsive or attractive) between molecules.
6. The pressure exerted by the gas is due to the collision of the molecules with the walls of the container per unit area.
7. The average Kinetic energy of the gas molecules is directly propotional to the absolute temperature.
Answer: vibrating molecules
Explanation:
a p e x
What is heat of vaporization?
A.
It is the heat required to change a substance’s temperature by 1°C.
B.
It is the heat required to change a gram of substance from a solid to a liquid.
C.
It is the heat required to change a substance from a solid directly to a gas.
D.
It is the heat required to change a gram of substance from a liquid to a gas.
E.
It is the heat required to separate one substance into two substances.
Answer:
D.
Explanation:
The heat of evaporation, is the amount of energy that must be added to a liquid substance, to transform a quantity of that substance into a gas. The heat of vaporization is a function of the pressure at which that transformation takes place.
The nucleus of an atom holds 4 neutrons and 4 protons, how many electrons does it have
What is the name of the functional group that is attached to this hydrocarbon?
A. alkyl halide
B. alcohol
C. carbonyl
D. ketone
The correct answer is D. Ketone, given that the functional group described is the carbonyl group within the carbon chain, not at the end.
Explanation:The functional group being described is the carbonyl group. However, the type of compound it forms depends on the location of the carbonyl group within the hydrocarbon chain. An aldehyde contains the carbonyl group at the end of a carbon chain, represented as -CHO, whereas a ketone contains the carbonyl group within the carbon chain, represented as -CO-. Since the information mentions an OH group on a carbon atom attached to two other carbon atoms, and oxidation of this results in a ketone, the correct answer to the question is a ketone. Aldehydes and ketones are both commonly named by identifying the longest chain that includes the carbonyl carbon and changing the suffix of the hydrocarbon name appropriately to -al for aldehydes and -one for ketones.
The correct option is B(alcohol).
The functional group attached to the hydrocarbon can be identified by specific groups bonded to carbons in the chain. In this case, the correct functional group is an alcohol, indicated by the presence of a hydroxyl (OH) group.
To determine the functional group attached to a hydrocarbon, we need to identify specific atoms or groups of atoms bonded to the carbon atoms in the hydrocarbon chain.
Step 1: Identify the functional group
If the group attached is a hydroxyl group (OH), the compound is classified as an alcohol. If we see a carbonyl group (C=O) bonded to two alkyl groups, it is a ketone. A carbonyl group at the end of the hydrocarbon chain forms an aldehyde.
For the answer choices given:
A. Alkyl halide: This includes halogens like chlorine, bromine, etc., bonded to carbon.
B. Alcohol: Indicates the presence of an OH group bonded to carbon. C.Carbonyl: Indicates the presence of a C=O group.
D. Ketone: A specific type of carbonyl group between two carbon atoms.
Thus, the correct functional group attached to the hydrocarbon is, most likely, an alcohol (answer B).
The density of an object with a volume of 5.0mL and a mass of 20.0g is ____________.
15.0g/mL
0.25g/mL
100.0g/mL
4.0g/mL
whenn you have sublimation
Answer: The density of the object will be 4 g/ml.
Explanation:
Density is defined as the mass contained per unit volume.
[tex]Density=\frac{mass}{Volume}[/tex]
Given : Mass of object = 20.0 grams
Volume of object= [tex]5ml[/tex]
Putting in the values we get:
[tex]Density=\frac{20.0g}{5ml}=4g/ml[/tex]
Thus density of the object will be 4 g/ml.
Chemistry question! Please help!
When a solid (solute) comes in contact with the liquid (solvent), the solute goes about C) dissolution, in which the solid dissolves into the liquid.
~
As this is with regards to solute and solvent, the solid will eventually dissolve in the liquid. The answer is C. dissolution.
Atoms with an electric charge come charged by gaining or losing
Is the atoms of electric
In each case tell which sn2 reaction will proceed faster. 1. the displacement on 2-bromopropane by (a) ch3ch2o- or (b) cn-. 2. the displacement by oh- on (a) h2c=chbr or (b) h2c=chch2br. submit answertry another version2 item attempts remaining
The displacement on 2-bromopropane will likely proceed faster with CH3CH2O- because of the degree of nucleophilicity; this group is likely more nucleophilic than a CN group, as even though the triple bond would make it more reactive it is still relying heavily on the effects of induction in justifying its reactivity.
The displacement for number 2 would occur SIGNIFICANTLY quicker on the H2C=CHCH2Br due to its position. The alternative has Bromine in a vinylic position to the double bond making an SN2 reaction nearly impossible (sp2 hybridized centers don’t react well with SN2 and have a poor intermediate while allylic SN2s are stabilized by resonance).
Hope this helps!
For a reaction system at equlibrium, le chateliers principle can be used to predict the
According to Le Chatelier's principle, adding additional reactant to a system will shift the equilibrium to the right, towards the side of the products. ... By Le Chatelier's principle, we can predict that the amount of methanol will increase, thereby decreasing the total change in CO.
What weight of oxalic acid dihydate must be measured to prepare 1 litre of 0.01 oxalic acid solution
The weight of oxegon
What is the kinetic theory
The body of theory which explains the physical properties of matter in terms of motion so I think it’s A
The kinetic molecular theory is an atomic description of gaseous, liquid, and solid matter. It states that these molecules are in constant, random motion with kinetic energy dependent on temperature. This theory is fundamental in explaining properties of matter including the ideal gas law.
Explanation:The kinetic molecular theory is a scientific model that explains the behavior of gases. According to this theory, gases are comprised of a large number of tiny molecules, which are widely separated and in constant, random motion. These molecules engage in elastic collisions with each other and the walls of their container. The speed of these molecules, and consequently their kinetic energy, is determined by their absolute temperatures.
This theory is also extended to explain the properties of solids and liquids in terms of continuous random motion of atoms and molecules. In other words, the kinetic molecular theory is essentially an atomic description of matter, providing detailed explanations for various phenomena such as temperature, pressure, and heat transfer, among others.
Moreover, the ideal gas law ties in closely with the kinetic molecular theory. It can be expressed in terms of the mass of the gas's molecules and the average of the molecular speeds squared.
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Which of the following is true for a heating curve?
A. It shows how the pressure of a substance changes when heated.
B. It shows how the temperature of a substance changes when heated.
C. It shows how the volume of a substance changes when heated.
D. It shows how the mass of a substance changes when heated.
the answer is b: it shows how temperature of a substance changes when heated.
According to the forces of attraction, the statement which is true for a heating curve is that it shows how the temperature of a substance changes when heated.
What are forces of attraction?Forces of attraction is a force by which atoms in a molecule combine. it is basically an attractive force in nature. It can act between an ion and an atom as well.It varies for different states of matter that is solids, liquids and gases.
The forces of attraction are maximum in solids as the molecules present in solid are tightly held while it is minimum in gases as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.
The physical properties such as melting point, boiling point, density are all dependent on forces of attraction which exists in the substances.
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When 1,4-dimethylcyclohepta-1,3-diene is treated with hbr at elevated temperature, the 1,2-adduct predominates, rather than the 1,4-adduct. choose the correct explanation from below?
Most likely, the production of the 1,4-adduct yields a less-substituted alkene in this situation. Following the 1,2-adduct pathway ensures that the remaining double bond is stabilized by the peripheral methyl group (trisubstituted), rather than making the new double bond disubstitited.
Hope this helps!
What does each variable stand for in PV=nRT?
Thank you.
Hello there!
Let's explain to you the different variables in the PV=nRT equation:
PV=nRT:
P = Pressure
V = Volume
n = Moles (number of moles)
R = Gas Constant (universal)
T = Temperature
This is the ideal use of the gas law.
When calculating these different variables, its units are:
P = ATM (atmospheres)
V = L (liters)
n = mol (Moles)
R = J (Joule)
T= K (Kelvin)
Please explain, I don't understand.
7. For the combustion of ethyl alcohol as described in the above equation, which of the following is true?
8. The total volume of hydrogen gas is needed to fill the Hindenburg was 2.00 × 10^8 at 1.00 atm and 25.1°C. How much energy was evolved when it burned?
Answer:
7. A) I, II ; 8. D) 2.34e9 kJ
Step-by-step explanation:
7. Combustion of ethanol
I. The negative sign for ΔH shows that the reaction is exothermic.
II. The enthalpy change would be different if gaseous water were produced.
That's because it takes energy to convert liquid water to gaseous water, and this energy is included in the value of ΔH.
III. The reaction is a redox reaction, because
Oxygen is reacting with a compound The oxidation number of C increases The oxidation number of O decreases.IV. The products of the reaction occupy a smaller volume than the reactants, because 3 mol of gaseous reactant are forming 2 mol of gaseous product.
Therefore, only I and II are correct.
7. Hindenburg
Data:
V = 2.00 × 10⁸ L
p = 1.00 atm
T = 25.1 °C
ΔH = -286 kJ·mol⁻¹
Calculations:
(a) Convert temperature to kelvins
T = (25.1 + 273.15) K = 298.25 K
(b) Moles of hydrogen
Use the Ideal Gas Law:
pV = nRT
n = (pV)/(RT)
n = (1.00 × 2.00 × 10⁸)/(0.082 06 × 298.25) = 8.172 × 10⁶ mol
(c) Heat evolved
q = nΔH = 8.172 × 10⁶ × (-286) = -2.34 × 10⁹ kJ
The hydrogen in the Hindenburg released 2.34e9 kJ .
What is the ph of pure water at 40.0°c if the kw at this temperature is 2.92 × 10-14?
Answer: pH = 6.77
Explanation:
1) Chemical equilibrium
2 H₂O (l) ⇄ H₃O⁺ (aq) + OH⁻ (aq)2) Equilibrium constant, Kw
Kw = [H₃O⁺] × [OH⁻]By stoichiometry [H₃O⁺] = [OH⁻]. Call it xKw = x²x² = 2.92 × 10⁻¹⁴ M²x = √ (2.92 × 10⁻¹⁴) = 1.709 × 10⁻⁷ M = [H₃O⁺]3) pH
pH = - log [H₃O⁺] = - log (1.709 × 10⁻⁷) = 6.77The pH of pure water at 40.0°C, given an autoionization constant (Kw) of 2.92 × 10-14, would be approximately 6.768. This value is derived from using the equations Kw=[H+][OH-] for the autoionization of water and pH = -log[H+] to calculate the pH.
Explanation:The question asks about the pH of pure water at 40.0°C if the autoionization constant (Kw) at this temperature is 2.92 × 10-14. Kw is the product of the molar concentrations of H+ ions and OH- ions in water. At any given temperature, Kw remains constant. In pure water (or any neutral solution), [H+] = [OH-] and therefore, pH = pOH.
As mentioned, Kw = [H+][OH-] , so in neutral water [H+] = [OH-] = sqrt(Kw). Given that Kw is 2.92 *10^-14, we can calculate [H+] = sqrt(2.92 *10^-14) = 1.708 *10^-7 M.
The formula to find the pH is pH = -log[H+]. Substituting in, pH = -log(1.708 *10^-7) = 6.768 which is slightly on the acidic side because the ideal neutral pH in standard conditions (25°C) is 7.
This demonstrates that the pH of pure water decreases (becomes more acidic) as the temperature increases.
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Need asap! 25 pts! Magnetic iron oxide has 72.4% iron and 27.6% oxygen. What is the empirical formula?
Hi!
1. Assume that these percentages are the mass.
2. For each of Fe and O, divide the mass by the Ar (relative atomic mass).
Fe: 72.4/55.8 = 1.297 moles
O: 27.6/16 = 1.725 moles
3. Work out which mole value is smallest, then divide the bigger mole value by the smaller one.
1.297 is smaller than 1.725, so your empirical formula is 1.1297/1.1297 = 1 atom of iron, and 1.725/1.297 = 1.33 atoms of oxygen.
4. Ensure your atom values are whole numbers.
1.33 is not a whole number, so multiply both 1 and 1.33 by 3.
5. Write out your empirical formula.
Fe3O4
Hope that helps!
The empirical formula for magnetic iron oxide, given that it has 72.4% iron and 27.6% oxygen by mass, is Fe3O4.
Explanation:The problem asks us to find the empirical formula for magnetic iron oxide. Given the percentage composition of iron and oxygen in the compound, we can look at it as if we had 100g of the substance. This would give us 72.4g of iron (Fe) and 27.6g of oxygen (O).
First, we convert these amounts to moles. The atomic mass of iron is approximately 55.845 g/mol and for oxygen is approximately 16.00 g/mol. Therefore, we have 1.3 mol Fe and 1.72 mol O.
To find the empirical formula, we divide each of these by the smallest number of moles to get a ratio. So, we have Fe1O1.3. However, an empirical formula should consist of whole numbers. Therefore, if we multiply both by the same factor, in this case, a factor of 3 will give us whole numbers, we get Fe3O4. Therefore, the empirical formula for magnetic iron oxide is Fe3O4.
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Where does electromagnetic radiation come from
Electromagnetic radiation is made when an atom absorbs energy.
Question 2(Multiple Choice Worth 3 points)
(07.05 MC)
The table shows the concentration of a reactant in the reaction mixture over a period of time.
Reactant Concentration
Time Concentration
0 s 1.8 M
210 s 1.2 M
450 s 0.8 M
580 s 0.6 M
720 s 0.4 M
What is the average rate of the reaction over the first 580 seconds?
1.6 × 10−3
1.9 × 10−3
2.0 × 10−3
2.2 × 10−3
Answer:
2.0 × 10−3
Explanation:
this is the correct answer, i don't know why people gave the other answer 3/5 stars because that answer and work was correct.
The average rate of reaction for the first 580 seconds is 2.0 × 10−3 M/s.
What is average rate of reaction?The average rate is defined as the ratio of the change in concentration to the time taken. We are required here to find the average rate of the reaction over the first 580 seconds.
Hence, we have;
average rate = 1.8 M - 0.6 M/580 s - 0 s = 1.2 M/580 s = 2.0 × 10−3 M/s
Hence, the average rate of reaction for the first 580 seconds is 2.0 × 10−3 M/s.
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What is the freezing point of a solution of 0.5 mol of LiBr in 500 mL of water? (Kf = 1.86°C/m) –1.86°C –7.44°C –5.58°C –3.72°C
Answer:
Last choice: - 3.72°CExplanation:
The freezing point depression in a solvent is a colligative property: it depends on the number of solute particles.
The equation to predict the freezing point depression in a solvent is:
ΔTf = Kf × m × iWhere,
ΔTf is the freezing point depression of the solvent,m is the molality,Kf is the cryoscopic molal constant of the solvent, and i is the Van'f Hoff factor, which is the number of ions produced by each unit formula of the ionic compound.The calcualtions are in the attached pdf file. Please, open it by clicking on the image of the file.
Answer: -1.86
Explanation: Got it right on edg
How are science and technology related? A. Science is a branch of technology. B. Science is the application of technological knowledge. C. Technology is the application of the knowledge gained by science.
The answer should be C. Technology is the application of the knowledge gained by science.
Answer:
C. Technology is the application of the knowledge gained by science.
Explanation:
Science is about the discovery of some novel compounds such as cancer curing drugs or understanding the kinetics of reaction mechanisms. Technology takes the discovery made by science and upscales the process and makes it more efficient. Technology involves stem cell engineering to create clones or making pesticide resistant plants.
Which of the following best describes what happens in radioactive decay?The nucleus emits particles and/or energy. The electron cloud emits particles and/or energy. The nucleus transfers particles and/or energy to the electron cloud. The electron cloud transfers energy to the nucleus.
Answer:
The nucleus emits particles and/or energy
Explanation:
In nuclear decay, the nucleus of an unstable atom (usually with a high neutron number over protons) splits into lighter more stable atoms. The process involves the release of energy particles such as neutrons or beta particles and energy. The released particles bombard with the other unstable atoms in the vicinity and split them producing a chain reaction.
Answer:
The nucleus emits particles and/or energy.
Explanation:
proving the answer is right on the bottom
Based on the kinetic molecular theory, which of the following statements is correct about the particles in a sample of gas? They have negligible kinetic energy. There is negligible force of attraction between them. The space between them decreases with increase in temperature. Their average kinetic energy decreases with increase in temperature.
Answer:
There is negligible force of attraction between them.
Explanation:
According to kinetic molecular theory of gases:
a) They have high kinetic energy so the molecules show random motion.
b) The space between them increases with increase in temperature. With increase in temperature, the kinetic energy increases and the molecules move farther from each other, volume increases.
c) the average kinetic energy increases with increase in temperature
Thus only true statement is:
There is negligible force of attraction between them.
Based on the kinetic molecular theory, there is a negligible force of attraction between the particles in the sample of gas.
The correct statement is option B.
What kinetic molecular theory?Kinetic molecular theory state that the particles of gas are large spherical and are in constant motion and have a perfectly elastic collision.
This theory can explain both Boyle's law and Charles's law.
Thus, the correct option is B, There is a negligible force of attraction between them.
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Which of the following is a part of the geocentric model?
a. All objects in the universe are perfect spheres.
b. All objects in the universe move around the sun.
c. All objects in the universe revolve around Earth.
d. All objects in the universe move in random patterns.
Answer:The correct answer is all the planets revolve around earth.
Explanation:This model was made a long time before technolige when they looked at the stars they would always move across the sky in the same pattern so they assumed that the stars were revolving around earth but come to find out everything was revolving around the sun.
Answer:
I think d
Explanation:
Draw the structural formula for all the alkenes with the indicated molecular formula that, without undergoing a rearrangement, produce the compound shown as a major product g
ya got to go get sum to eat then get it
Which of the following units is used to express electrical charge? Question 2 options: Newton Coulomb Joule
The coulomb whose symbol is (C), is used to express charge. It is the SI unit of electric charge.
1 C is equivalent to charge carried by 6.24×10¹⁸ electrons. Although electrons are negatively charged, the Coulomb expresses both positive and negative charges.
Answer: Coulomb
Explanation:
[tex]Q=I\times t[/tex]
where Q= quantity of electricity
I = current in amperes
t= time in seconds
Thus charge is in coulomb. 1 coloumb of charge appears whe 1 ampere current is passed for 1 second.
Newton is the unit of force.
[tex]1kgms^{-2}=1Newton(N)[/tex]
Joule is the unit of energy.
[tex]1kgm^2s^{-2}=1 Joule[/tex]
Explain how the height of a liquid can be used to measure temperature
One of the most common devices for measuring temperature is the glass thermometer. This consists of a glass tube filled with mercury or some other liquid, which acts as the working fluid. Temperature increase causes the fluid to expand, so the temperature can be determined by measuring the volume of the fluid.
Liquid-in-glass thermometers depend on change in the volume of a liquid as temperature changes.
Every thermometer makes use of a thermometric property. The thermometric property is the property of the substance that changes with change in temperature.
In the case of liquid-in-glass thermometers, the thermometric property is the change in the volume of a liquid with change in temperature.
The liquid used must have high expansivity and must expand and contract uniformly as temperature changes.
Hence, as the liquid expands and contracts with temperature, the height of the liquid can be used to measure temperature.
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