Answer:
[tex]\Delta _rH=17.51\frac{kJ}{mol}[/tex]
Explanation:
Hello!
In this case, since the enthalpy change for any process is computed by subtracting the enthalpy of the final state and the enthalpy of the initial state, for the given phase change, we subtract the enthalpy of the liquid (final state) and the enthalpy of the solid (initial state) considering this a melting process:
[tex]\Delta _rH=-390.76\frac{kJ}{mol} -(-408.27\frac{kJ}{mol} )\\\\\Delta _rH=17.51\frac{kJ}{mol}[/tex]
Which makes sense because this process absorbs energy.
Best regards!
The enthalpy change for the sublimation of LiCl(s) → LiCl(l) is 17.51 kJ/mol.
The enthalpy change for the phase change is given by;
ΔH°fproducts - ΔH°freactants.
From the available information in the question;
ΔH°fLiCl(s) = -408.27 kJ/mol
ΔH°fLiCl(l) = -390.76 kJ/mol
Hence;
ΔH°reaction = (-390.76 kJ/mol) - (-408.27 kJ/mol)
ΔH°reaction = 17.51 kJ/mol
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Determine the best course of action when acid or base is spilled on the skin. Apply base to an acid burn, or acid to a base burn. Remove as much of the acid or base as possible using a towel. None of these actions are appropriate. Rinse the affected area immediately with water.
Answer:
You have to apply the base to an acid burn and vice versa.
Explanation:
If acid or base is spilled on the skin, immediately wash the affected area gently with lukewarm water and get medical attention immediately. Therefore, option (D) is correct.
How to care for acid or base exposure?Exposure to strong acids or bases such as sulphuric acid can take place as skin contact, inhalation of vapors, or ingestion. Each type of exposure can rise serious hazards to health and must be managed quickly and reduce damage and health risks appropriately by medical professionals.
If acid comes into contact with the skin, quickly wash the affected area gently with cold water and seek medical attention immediately. If acid or base gets into your eyes, then flush the eyes with water.
If accidentally ingest strong acid or base, rinse your mouth immediately with water and continually rinse your mouth with water. If you inhale acid or base aerosols, breathe fresh air, and get medical attention immediately.
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Which statement about stars is correct?
A. Star formation begins in a nebula.
B. White dwarfs become main-sequence stars when they gain mass.
C. Supergiants are stars that can absorb black holes.
D. Main-sequence stars are formed by comets.
Answer:
A. star formation begins in a nebula.
Explanation:
How many moles of hydrogen gas would be produced for every mole of magnesium added into the HCl solution?
The wavelength of transmission is 9.7mm. What is the energy of this transition
Answer:
E = 2.05×10⁻²³ J
Explanation:
Given data:
Wavelength of transmission = 9.7 mm (9.7/1000 = 0.0097 m)
Energy of transition = ?
Solution:
9.7 mm (9.7/1000 = 0.0097 m)
9.7×10⁻³ m
Formula:
E = hc/λ
By putting values,
E = 6.63 ×10⁻³⁴ Js × 3×10⁸ m/s / 9.7×10⁻³ m
E = 19.89×10⁻²⁶ J.m / 9.7×10⁻³ m
E = 2.05×10⁻²³ J
Because they have an extended structure, elements that are _____
tend to be in the________
state at room temperature
At a high elevation, there is little chance of... a) flooding b)lack of oxygen c) getting dizzy
Answer:
A. flooding
Explanation:
At high elevations air becomes thinner so a person may not be receiving enough oxygen which can cause dizziness. Flooding typically happens at sea level.
A heater is placed under one corner of a water bed mattress. Warm water moves throughout the mattress because of ____________________________
A. conduction
B. convection
C. Radiation
A heater is placed under one corner of a water bed mattress. Warm water moves throughout the mattress because of convection. The correct option is B.
What is convection?Heat is transferred through convection, which is the large-scale movement of molecules inside gases and liquids.
Conduction is used to move heat from the object to the fluid initially, but fluid motion is responsible for the bulk of the heat transfer.
When heat is transferred from your body by moving air, convection takes place. The air will rise if it absorbs your heat and is cooler than the environment.
Cooler air moves in to take its place and absorb more of your warmth as the warmed air rising around you increases. You feel cooler as this air moves more quickly.
Thus, the correct option is B.
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the element chlorine is a member of which chemical family?
Answer:
is it from bleacH?
Explanation:
hazardous
Answer:
halogen family
Explanation:
if a horse gallops 1 meter per second, how far can it travel in 1 minute?
pls help
Answer:
60 meters
Explanation:
What mass of sucrose, C12H22O11, should you dissolve in 100.0 g of water to obtain a solution in which the mole fraction of C12H22O11 is 0.124?
Answer:
the sucrose mass is 264.g
Explanation:
The computation of the sucrose mass is shown below;
The Molar mass of [tex]C_{12}H_{22}O_{11}[/tex] is 342.3 g/mol
And, the molar mass of [tex]H_2O[/tex] is 18g/mol
The mass of [tex]C_{12}H_{22}O_{11}[/tex] be Y
Now
The moles of [tex]C_{12}H_{22}O_{11}[/tex] is
= Mass of [tex]C_{12}H_{22}O_{11}[/tex] ÷ molar mass of [tex]C_{12}H_{22}O_{11}[/tex]
= Y ÷ 342.3 mol
And,
The moles of [tex]H_2O[/tex] is
= Mass of [tex]H_2O[/tex] ÷ molar mass of [tex]H_2O[/tex]
= 100.0 ÷ 18
= 5.56mol
Now
The molar fraction of [tex]C_{12}H_{22}O_{11}[/tex] is
= Moles of [tex]C_{12}H_{22}O_{11}[/tex] ÷ (moles of[tex]C_{12}H_{22}O_{11}[/tex] + moles of [tex]H_2O[/tex]) = 0.124
= (Y ÷ 342.3) ÷ [(Y ÷ 342.3) + 5.56] = 0.124
Y ÷ 342.3 = 0.124 × [(Y ÷ 342.3 + 5.56]
Y = 0.124 × Y + (0.124 × 5.56 × 342.3)
Y = 269.4 g
hence, the sucrose mass is 264.g
Which of these steps is most likely to be part of an investigation about friction?
A.
putting different kinds of batteries in a toy car
B.
measuring how long it takes one full cup of water to evaporate
C.
testing which surface is easier to slide a wooden block across
D.
counting how many paper clips stick to a magnet in a chain
Answer:
I want to say option C: Testing which surfa e is easier to slide a wooden block across.
Explanation:
I'm not 100 % sure though with my answer. I'm truly so very sorry if my answer is wrong. I tried my best.
In physics, friction is said to be the opposing force that resists any object. Testing which surface is more effortless to slide a block across can be used to investigate friction. Thus, option c is correct.
What is friction?Friction has been defined as the resisting force that opposes the movement of objects across the surface. It can also be said as a force that opposes the relative motion of an object.
The friction can be rolling, sliding, fluid, or static depending on the surface and type of object. The frictional force is present only when the object has been in contact of the surface body.
When a surface is tested for sliding the wooden block, then the sliding friction has been used. It is possible as the resistant force of the surface with respect to the block is taken into the consideration.
Therefore, option C. the surface testing for sliding wooden blocks involves friction.
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How many grams of hydrogen are in 6.0g of sucrose?
Answer:
The formula for sucrose is
C12H22O11
moles sucrose = mass / molar mass
= 6.0 g / 342.30 g/mol
= 0.017528 mol
the formula shows that each sucrose molecule has 22 H atoms
so moles H = 22 x moles sucrose
= 0.3856 mol
mass H = molar mass x moles
= 1.008 g/mol x 0.3856 mol
= 0.3887 g
= 0.39 g ( 2 sig figs)
Corrosive means having the tendency to erode or eat away at something. Strong acids and bases are both corrosive.
A. True
B. False
Answer:
true
Explanation:
A mid-ocean ridge occurs at what boundary?
Answer:
Divergent boundary plate
Explanation:
I hope this helps but this question has its answer at the top of google when you search it
Question:
A mid-ocean ridge occurs at what boundary?
1. Convergent Boundary Plate
2. Divergent Boundary Plate
3. Transform Boundary Plate
Answer:
2. Divergent Boundary Plate
An atom can be called a particle, but a molecule is never called a particle. True or false. Thanks everyone for your help
What coefficients would balance the following equation?
__C2H6 + __O2 → __CO2 + __H2O
Determine the molar mass of iron(II) chloride hexahydrate. Provide an answer to two decimal places.
Answer:
FeCl₂ · 6H₂O = 234.75 g/mol
Explanation:
Iron (II) = Fe²⁺
Number between () indicates the oxidation state
Chloride = Cl⁻
Iron (II) chloride = FeCl₂
If we say hexahydrate, it means that our salt is hydrated by 6 molecules of water.
FeCl₂ · 6H₂O = Iron(II) chloride hexahydrate
Molar mass is = 55.85 g/mol + 35.45 g/mol . 2 + 6 . 18g/mol = 234.75 g/mol
We have just summed molar mass of Fe, plus Cl (x2), plus 6 H₂O
A large ice sculpture of a swan has a greater temperature than a lit match.
O True
O False
HURRY PLEASE
Which are functions of the stomata in the leaves of seed plants? Check all that apply.
reduce water loss
make glucose
absorb sunlight
take in carbon dioxide
produce oxygen
Answer:
reduce water loss
absorb sunlight
take in carbon dioxide
produce oxygen
Explanation:
i think
Answer:
A, D, and E
Reduces water loss, take in carbon dioxide, and produce oxygen.
Explanation:
if a snail crawls 12 centimeters per hour, how long will it take for the snail to travel 1 meter?
answer NOW
Answer:
8 hours 20 minutes
Explanation:
A chemical equation is shown: C2H4 + O2 → CO2 + H2O According to the law of conservation of mass, how many atoms of oxygen exist in the products of this reaction? (3 points) 2 4 6 8
Answer:
6 oxygens on the product side
Explanation:
1) balance the equation:
C2H4 + 3O2 → 2CO2 + 2H2O
2) calculate the number of oxygens on the product side
2CO2=4
2H2O=2
According to the law of conservation of mass, there are 6 atoms of oxygen in the product of this reaction.
What is law of conservation of mass?According to law of conservation of mass, it is evident that mass is neither created nor destroyed rather it is restored at the end of a chemical reaction .
Law of conservation of mass and energy are related as mass and energy are directly proportional which is indicated by the equation E=mc².Concept of conservation of mass is widely used in field of chemistry, fluid dynamics.
Law needs to be modified in accordance with laws of quantum mechanics under the principle of mass and energy equivalence.This law was proposed by Antoine Lavoisier in the year 1789.
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How would the number 3475.32 in be expressed in scientific notation? *
Explanation:
i think 3x10^5
hope this helps if not sorry
A solution of 0.0027 M K2CrO4 was diluted from 3.00 mL to 100. mL. What is the molarity of the new solution?
Answer:
[K₂CrO₄] → 8.1×10⁻⁵ M
Explanation:
First of all, you may know that if you dilute, molarity must decrease.
In the first solution we need to calculate the mmoles:
M = mmol/mL
mL . M = mmol
0.0027 mmol/mL . 3mL = 0.0081 mmoles
These mmoles of potassium chromate are in 3 mL but, it stays in 100 mL too.
New molarity is:
0.0081 mmoles / 100mL = 8.1×10⁻⁵ M
What is the most significant chemical difference between triacylglycerols and glycerophospholipids that leads to their different functions?
Answer:
Triacylglycerols (triglycerides) are non-polar or hydrophobic molecules
Glycerophospholipids (phosphoglycerides) are polar or hydrophilic
Explanation:
Triacylglycerides (TGs) are esters synthesized by the esterification of three molecules of glycerol and fatty acid, and this is essentially by the replacement of the three hydroxyl groups on glycerol with three fatty acids. This removes the hydrophilic property from the glycerol molecule hence TGs are only soluble in non-polar solvents like alcohol and benzene, and TGs are therefore the storage forms of fats in adipose tissues.
Glycerophospholipids are formed by the addition of two hydrophobic fatty acid groups and one phosphoric acid (phosphate group) to glycerol (alcohol) leaving a hydrophilic head (phosphate end) and a hydrophobic tail (fatty acid ends). This amphipathic property of this molecule makes it a suitable molecule for membrane structures, especially of cells (lipid bi-layer), with an arrangement where the hydrophilic side interacts with the aqueous environment, while the hydrophobic side makes contact with the non-aqueous environment.
Triacylglycerols-
They are nonpolar, hydrophobic, and insoluble in water. This is due to the ester linked bond between the polar hydroxyls of glycerol and the polar carboxylates of the fatty acids.Glycerophospholipids-
Glycerol-based phospholipids. The alcohol here is glycerol, to which two fatty acids and phosphoric acid are attached as esters. The two fatty acid chains attached to the molecule of glycerol are nonpolar hence hydrophobic While the polar heads which mainly consists of the phosphate group attached to the third carbon of the glycerol molecule is hydrophilic.Learn more:
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What would be the matching DNA strand for the code below?:
A A T G C G G T C C
A. TTGTACCTCC
B. GGCATAACTT
C. TTTGGCATT
D. TTACGCCAGG
Answer:
D. TTACGCCAGG. that would be your answer.
Answer:
i think its either A TTGTACCTCC or D TTACGCCAGG
Explanation:
What ingredients are used to make chloroform.
:p
Answer: i dont no
Explanation:
ddd
A chemist titrates 60.0 mL of a 0.1935 M benzoic acid (HC (H5CO2) solution with 0.2088 M KOH solution at 25 °C. Calculate the pH at equivalence. The pKg of benzoic acid is 4.20.
Answer:
pH at the equivalence point is 8.6
Explanation:
A titulation between a weak acid and a strong base, gives a basic pH at the equivalence point. In the equivalence point, we need to know the volume of base we added, so:
mmoles acid = mmoles of base
60 mL . 0.1935M = 0.2088 M . volume
(60 mL . 0.1935M) /0.2088 M = 55.6 mL of KOH
The neutralization is:
HBz + KOH ⇄ KBz + H₂O
In the equilibrum:
HBz + OH⁻ ⇄ Bz⁻ + H₂O
mmoles of acid are: 11.61 and mmoles of base are: 11.61
So in the equilibrium we have, 11.61 mmoles of benzoate.
[Bz⁻] = 11.61 mmoles / (volume acid + volume base)
[Bz⁻] = 11.61 mmoles / 60 mL + 55.6 mL = 0.100 M
The conjugate strong base reacts:
Bz⁻ + H₂O ⇄ HBz + OH⁻ Kb
0.1 - x x x
(We don't have pKb, but we can calculate it from pKa)
14 - 4.2 = 9.80 → pKb → 10⁻⁹'⁸ = 1.58×10⁻¹⁰ → Kb
Kb = [HBz] . [OH⁻] / [Bz⁻]
Kb = x² / (0.1 - x)
As Kb is so small, we can avoid the quadratic equation
Kb = x² / 0.1 → Kb . 0.1 = x²
√ 1.58×10⁻¹¹ = [OH⁻] = 3.98 ×10⁻⁶ M
From this value, we calculate pOH and afterwards, pH (14 - pOH)
- log [OH⁻] = pOH → - log 3.98 ×10⁻⁶ = 5.4
pH = 8.6
NEED HELP WILL MARK U AS BRAINLIEST .
Answer:
C.
Explanation:
What is the major cause of the greenhouse effect?
soot from coal plants in the water
carbon dioxide in the water
carbon dioxide in the atmosphere
soot from coal plants in the atmosphere
Answer:
carbon dioxide in the atmosphere
Explanation:
Carbon dioxide in the atmosphere is the major cause of greenhouse effect.
Greenhouse effect is the main cause of global warming.
This effect is produced as a result of some certain gases called greenhouse gases. These gases are carbon dioxide, water vapor, methane etc. They prevent short wave radiations from leaving the earth. This causes the increase in temperature of the surface.A 7.417 gram sample of an organic compound containing C, H and O is analyzed by combustion analysis and 10.52 grams of CO2 and 6.460 grams of H2O are produced. In a separate experiment, the molar mass is found to be 62.07 g/mol. Determine the empirical formula and the molecular formula of the organic compound.
Answer:
Empirical formula: CH₃O
Molecular formula: C₂H₆O₂
Explanation:
All carbon is converted in CO2 and all hydrogen in H2O. Thus, we can find mass of each element and, by subtracting, the mass of Oxygen:
Mass C:
10.52g CO2 * (1mol / 44g) = 0.239 moles CO2 = Moles C * (12.01g / mol) =
2.87g C
Mass H:
6.460g H2O * (1mol / 18g) = 0.359 moles H2O * 2 = 0.718 moles H * (1g / mol) =
0.718g H
Mass O:
7.417g Sample - 2.87g C - 0.718g H =
3.829g O
Now, we can determine empirical formula defined as the simples whole number ratio of atoms present in a compound with moles of each atom:
Moles C: 0.239 moles C
Moles H: 0.718 moles H
Moles O: 3.829g * (1mol / 16g) = 0.239 moles O
The ratio of moles of each atom divided in moles of oxygen:
C: 0.239 mol / 0.239 mol = 1
H: 0.718 mol / 0.239 mol = 3
C: 0.239 mol / 0.239 mol = 1
Empirical formula: CH₃OThe molar mass of CH3O is:
12.01g/mol + 1g/mol*3 + 16g/mol =
31.01g/mol
That means molecular formula is twice empirical formula because its molecular mass is 31.01g/mol * 2 = 62.02g/mol ≈ 62.07g/mol
Molecular formula: C₂H₆O₂