Final answer:
For a molecule with the formula AB2, if there are no lone pairs on the central atom, the molecular shape is linear, as in BeH2 or CO2. If one lone pair exists, it creates a bent or V-shaped structure, seen in molecules like SO2. Other geometries like trigonal planar or T-shaped are not possible for AB2.
Explanation:
For a molecule with the formula AB2, there are potentially different shapes that the molecule can have, depending on the presence and arrangement of lone pairs of electrons on the central atom. If there are no lone pairs on the central atom, the molecule would have a linear shape, with the two B atoms and the A atom arranged in a straight line. This can be seen in examples like BeH2 and CO2, where the central atom contains only two electron groups, and they orient themselves as far apart as possible—180° apart.
However, if there is one lone pair on the central atom, the shape will be bent, or V-shaped. This is because the molecule can be thought of as a trigonal planar structure with one vertex missing due to the lone pair. The lone pair takes up additional space, causing the bond angle to be less than 120°, as seen in molecules like SO2.
Lastly, with additional lone pairs, other geometries like trigonal planar can be eliminated. The molecule AB2 could also not exhibit a T-shaped geometry as that would require more than three electron groups on the central atom.
The crystal structure of an ionic compound depends on the
Answer:
The ion's sizes and their radius ratio.
Explanation:
Ionic compounds take the form of three dimentional arrays by alternating anions and cations in order to minimize the potential energy of the system by maximizing the attractive force between opposite charges.
The resultant geometric structures are known as crystal lattices and their arrangements depend on the ion's sizes and, since they are bound though electrostatic attraction, their radius ratio.
I hope you find this information useful and interesting! Good luck!
What are hydrogen bonds? What type of molecules do hydrogen bonds occur in?
What is the volume of the solution produced when enough water is added to 42.0 g of mgcl2 ⋅ 6h2o to yield a solution that has a cl- ion concentration of 0.500m?
Answer:
827 mL
Explanation:
To answer this question we use the definition of Molarity:
Molarity = mol / L
[Cl⁻] = mol Cl⁻ / L
Now we calculate the moles of Cl⁻ present in 42.0 g of MgCl₂⋅6H₂O:
Molar mass of MgCl₂⋅6H₂O = 24.3 + 2*35.45 + 6*18 = 203.2 g/mol
moles of Cl⁻ = 42.0 g MgCl₂⋅6H₂O ÷ 203.2 g/mol * [tex]\frac{2molCl^{-}}{1molMgCl_{2}.6H_{2}O}[/tex] = 0.4134 mol Cl⁻
Finally we use the definition of molarity to calculate the volume:
0.500 M = 0.4134 mol Cl⁻ / xL
xL = 0.827 L = 827 mL
Imagine that one carbon in buckminsterfullerene (C60) is replaced by a silicon atom, yielding SiC59. This molecule can then orient in 60 different ways. What is the entropy of one mole of SiC59 at T = 0 K?
Answer:
The entropy will be 0
Explanation:
Because of the third principle of thermodynamics, the entropy of a pure substance (such as SiC59), with finite density (we have 1 mol in a finite volume), at 0 K is equal to 0.
So, it really dosen't mather the Si atom, if you are analizing it at the absolute zero (0 K).
In which of the following processes is it necessary to break covalent bonds as opposed to simply overcoming intermolecular forces?
A. Melting mothballs
B. Dissolving hydrogen bromide gas in water to form hydrobromic acid
C. Vaporizing ethyl alcohol
D. Changing ozone to oxygen gas
Answer:
D. Changing ozone to oxygen gas
Explanation:
As a rule of thumb, it is always noting that making putting a substance through physical changes like melting or boiling, evaporating involves breaking intermolecular bonds. On the other hand, making a substance undergo chemical changes involves breaking intramolecular bonds like ionic bonds and covalent bonds.
Oxygen being changed from ozone to oxygen is a chemical change and therefore requires breaking of the oxygen-oxygen double bonds
Final answer:
Breaking covalent bonds is necessary in changing ozone to oxygen gas, while the other processes listed involve overcoming intermolecular forces.
Explanation:
In the processes described, breaking covalent bonds is necessary when changing ozone (O3) to oxygen gas (O2). Melting mothballs, dissolving hydrogen bromide gas into water to form hydrobromic acid, and vaporizing ethyl alcohol involve overcoming intermolecular forces rather than breaking covalent bonds. The transition from ozone to oxygen involves an endothermic reaction breaking the O-O covalent bonds within the ozone molecule to form diatomic oxygen molecules.
Neptunium-237 undergoes a series of α-particle and β-particle productions to end up as thallium-205. How many α particles and β particles are produced in the complete decay series? α particles β particles?
8 alpha particles
4 beta particles
Explanation:We are given;
Neptunium-237 Thallium-205 Neptunium-237 undergoes beta and alpha decay to form Thallium-205.We are required to determine the number of beta and alpha particles produced to complete the decay series.
We need to know that when a radioisotope emits an alpha particle the mass number reduces by 4 while the atomic number decreases by 2.When a beta particle is emitted the mass number of the radioisotope increases by 1 while the atomic number remains the same.In this case;
Neptunium-237 has an atomic number 93, while,
Thallium-205 has an atomic number 81.
Therefore;
²³⁷₉₃Np → x⁴₂He + y⁰₋₁e + ²⁰⁵₈₁Ti
We can get x and y
237 = 4x + y(0) + 205
237-205 = 4x
4x = 32
x = 8
On the other hand;
93 = 2x + (-y) + 81
but x = 8
93 = 16 -y + 81
y = 4
Therefore, the complete decay equation is;
²³⁷₉₃Np → 8⁴₂He + 4⁰₋₁e + ²⁰⁵₈₁Ti
Thus, Neptunium-237 emits 8 alpha particles and 4 beta particles to become Thallium-205.
What strategy helps to ensure that your home-canned food does not contain the botulinum toxin?
a. Follow proper canning techniques.
b. Freeze the canned food.
c. Test the soil in which the food was grown.
d. Consume the canned food within 12 months.
e. Add an antioxidant before canning.
Answer:
a. Follow proper canning techniques.
Explanation:
Although home canning is a great way to preserve garden goods it can be very risky or even deadly if not done correctly and safely.
Beware! Your canned vegetables and fruits could cause botulism if home canning is not done the correct way!
Botulism is a rare but potentially deadly disease caused by a poison most commonly produced by a germ called Clostridium Botulinum. The germ can be found in soil and can grow, survive and produce a toxin in certain conditions, such as when food is improperly canned. The toxin can damage your nerves, paralyze you, and even cause death.
You cannot smell, see or taste botulinum toxin but putting even a small amount of food containing botulinum into your organism can be fatal.
Botulism is a medical emergency. If you or someone you know has symptoms of foodborne botulism, see your doctor or go to the emergency room immediately.
Some of the symptoms that may occur are: drooping eyelids, double and/or blurred vision, thick-feeling tongue, muscle weakness, dry mouth, difficulty swallowing, slurred speech etc.
Many cases of foodborne botulism have occurred after people ate home-canned, preserved, or fermented foods that were contaminated with this toxin. The food was contaminated because it wasn’t canned or processed correctly.
You can take these steps to protect yourself, your family, and others when it comes to home-canned foods:
1. Use proper canning techniques by carefully following instructions for safe home canning in the USDA Complete Guide to Home Canning. Do not follow recipes and cookbooks that do not follow the steps in the USDA guide, even if you got these items from a trusted friend or family member.
2. Use the right equipment for the kind of foods that you are canning. Pressure canning is the only recommended method for canning low-acid foods. Foods with low acid content are the most common sources of home-canning related botulism cases. Low-acids foods include almost every vegetable, some fruits, milk, all meats, fish, and seafood. Do not use boiling water canners for low-acid foods because they will not protect against botulism.
3. Do not hesitate! If there is any doubt if safe canning guidelines have been followed, do not eat the food. Home-canned and store-bought food might be contaminated with toxin or other harmful germs if the container is leaking, bulging, or swollen; the container looks damaged, cracked, or abnormal; the container spurts liquid or foam when opened; the food is discolored, moldy, or smells bad.
If the container or the food inside has any signs of contamination, throw it out! If any of the food spills, wipe up the spill using a solution of 1/4 cup bleach for each 2 cups of water.
Never taste food to determine if it is safe! Do not taste or eat food that is discolored, moldy, or smells bad. Do not taste or eat food from cans that are leaking, have bulges or are swollen, or look damaged, cracked, or abnormal. Do not taste or eat food from a can that spurted liquid or foam when it was opened.
Final answer:
The best way to avoid botulinum toxin in home-canned foods is to follow proper canning techniques, specifically using a pressure canner to reach the necessary temperature to kill C. botulinum endospores, and boiling the food for 10 minutes before eating. The correct answer is a. Follow proper canning techniques.
Explanation:
The strategy that helps to ensure that your home-canned food does not contain the botulinum toxin is a. Follow proper canning techniques. This involves using a pressure canner to achieve the necessary temperature of 116 °C (240 °F) to kill C. botulinum endospores, as they can survive temperatures above the boiling point of water.
Furthermore, the Centers for Disease Control and Prevention (CDC) recommend boiling home-canned foods for about 10 minutes before consumption to denature any botulinum toxin that may be present.
(a) Name two types of subatomic particles contained in the nucleus of the atom and state the charge associated with each.
(b) Name the subatomic particle found in the region outside the nucleus. What charge is associated with this type of particle?
Answer:
A.) The Proton and the Neutron are the subatomic particles within the nucleus. The Proton has a positive charge, and the Neutron has a neutral charge.
B.) The subatomic particle that is found on the exterior of the atom is the Electron, which has a negative charge.
Explanation:
The atom's nucleus contains protons with a positive charge and neutrons with no charge. The region outside the nucleus, the electron cloud, contains the negatively charged electrons.
Explanation:
The nucleus of an atom contains two types of subatomic particles, protons and neutrons. Protons have a positive charge, represented as +1, while neutrons are neutral and have no charge.
The region outside the nucleus, known as the electron cloud, contains electrons. These subatomic particles carry a negative charge, represented as -1.
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In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat of a solid, or to measure the energy of a solution phase reaction.A student heats 61.68 grams of gold to 99.01 °C and then drops it into a cup containing 79.34 grams of water at 22.14 °C. She measures the final temperature to be 23.98 °C.The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.80 J/°C.Assuming that no heat is lost to the surroundings calculate the specific heat of gold.
Answer:
Specific heat of gold is 0,133J/g°C
Explanation:
In this problem, the heat of the gold is transferred to water and the calorimeter, that means:
[tex]q_{Lost By Metal} = q_{GainedWater} + q_{Gained Calorimeter}[/tex]
The Q lost by metal is:
Q = C×m×ΔT, Where m is mass (61,68g), ΔT is (99,01°C-23,98°C = 75,03°C) and C is sepecific heat of gold
The Q gained by water is:
Q = C×m×ΔT, Where m is mass (79,34g), ΔT is (23,98°C-22,14°C = 1,84°C) and C is sepecific heat of water (4,184J/g°C)
The Q gained by calorimeter is:
Q =Cc×ΔT Where Cc is calorimeter constant (1,80J/°C), and ΔT is (23,98°C-22,14°C = 1,84°C)
Replacing:
C×61,68g×75,03°C = 4,184J/g°C×79,34g×1,84°C + 1,80J/°C×1,84°C
4628g°C×C = 610,8J + 3,3J
4628g°C×C = 614,1J
C = 0,133J/g°C
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The specific heat of gold can be calculated using the equation representing the transfer of heat in the experiment. The sum of the heat absorbed by the water and the calorimeter (each calculated using respective mass, specific heat, and temperature change) equals the heat lost by the gold.
Explanation:The specific heat of a substance is typically calculated using the formula q = mcΔT, where q is the heat absorbed, m is the mass, c is the specific heat, and ΔT is the change in temperature. In this experiment, heat is transferred from the gold to the water and the calorimeter, so we need to set up an equation with the sum of the heat absorbed by the water and the calorimeter equal to the heat lost by the gold.
For the water, we use the specific heat value of water as 4.18 J/g°C, and for the calorimeter, we use the given calorimeter constant. Setting up the equation and solving for the specific heat of gold gives:
(61.68g)(c)[99.01°C-23.98°C] = (79.34g)(4.18 J/g°C)[23.98°C-22.14°C] + (1.80 J/°C)(23.98°C-22.14°C)
Solving the above equation will yield the specific heat of gold.
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When solid KClO3 is heated, it decomposes to give solid KCl and O2 gas. A volume of 262 mL of gas is collected over water at a total pressure 730 mmHg of and 24 ∘C. The vapor pressure of water at 24 ∘C is 22 mmHg:
2KClO3(s)→2KCl(s)+3O2(g)
Part A What was the partial pressure of the O2 gas?
Part B How many moles of O2 gas were in the gas sample?
Answer:
Part A: 708 mmHg
Part B: 0.01 mol O2
Explanation:
Total pressure in a gas mixture = Sum of each partial pressure in the mixture so:
Total pressure = 730mmHg
The mixture has 2 compounds, the O2 and the vapor of water.
730mmHg - 22mmHg = 708 mmHg. Now that we have Pp O2, let's apply the Ideal Gas Law to find the mols
P.V = n . R . T
First of all, covert the mmHg in atm
760 mmHg ____ 1 atm
708 mmHg _____ 708/760 = 0.93 atm
and convert 262mL in L
262/1000 = 0.262L
0.93 atm . 0.262L = n . 0.082 . 297K
(0.93 . 0.262)/ (0.082. 297) = n
0.01 mol = n
The partial pressure of the O2 gas in the reaction of KClO3 decomposing is 708 mmHg, and the number of moles of O2 gas is approximately 0.011 moles.
Explanation:The reaction of potassium chlorate (KClO3) decomposing into solid potassium chloride (KCl) and oxygen (O2) gas when heated is related to the concepts of partial pressure and moles in chemistry.
Part A: The partial pressure of a gas is the pressure contributed by that individual gas in a mixture of gases. If the total pressure is 730 mmHg, and the vapor pressure of water at 24°C is 22 mmHg, the partial pressure of the O2 (oxygen gas) would be the total pressure minus the vapor pressure of water. So, the partial pressure of the O2 gas is 730 mmHg - 22 mmHg = 708 mmHg.
Part B: To find the moles of the O2 gas, the ideal gas law could be used which links pressure, volume, temperature and number of moles in a gas. The law states that (Pressure x Volume) = (number of moles x Ideal Gas Constant x Temperature in Kelvin). We know the volume, partial pressure and absolute temperature, but an appropriate conversion of units is required. Therefore, adjusting to standard SI units, we have the volume 262 mL converted to 0.262 L, the partial pressure 708 mmHg converted to 0.93 atmospheres (1 atmosphere = 760 mmHg), and the temperature 24°C converted to 297 K (Kelvin = Celsius + 273.15). Short calculation later we get around 0.011 moles of O2 gas.
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1. How many negative ones (-1) would you need to balance out one positive 2 (+2)?
Question options:
Two negative ones balance out two positive twos
One negative one balances out one positive two
Two negative ones balance out one positive two
One negative one balances out two positive twos
2. Potassium forms ions with a charge of +1 (Ka+). Iodine forms ions with a charge of -1. Selenium forms ions with a charge of -2 (Se2-).
Imagine that Potassium ions and Selenide ions combine to form Potassium Selenide. What numbers would be in the place of X and Y in:
KXSeY
(Use the number 1 even if it isn't strictly necessary)
X=______ Y =______
3. You are balancing an ionic compound. Let's call it: AB.
Ion A has a charge of +2 and Ion B has a charge of -3.
Therefore, you determine that the ionic compound (AB) will have a ratio of 3 As for every 2 Bs.
How would you modify AB in order to show that they have this 3-to-2 ratio?
Question options:
3A2B
A3B2
A3B2
4. Calcium forms ions with a charge of +2. Iodine forms ions with a charge of -1.
Which of the following would represent an ionic compound composed of Calcium and Iodide ions?
Question options:
CaI2
CaI
Ca2I
Ca2I
2CaI
CaI2
1) The number of negative ones (-1) would you need to balance out one positive 2 (+2) is;
Option C; Two negative ones balance out one positive two
2) The numbers that would be in the place of X and Y in [tex]K_{X}Se_{Y}[/tex] is;
X = 2 and Y = 1
3) AB will be modified in order to show that they have this 3-to-2 ratio as;
Option B; A₃B₂.
4) The formula that will represent an ionic compound composed of Calcium and Iodide ions is; Option A; CaI₂
1) To balance out the ions, it means addition of them should be equal to zero. Thus, to balance out one positive two (+2) with negative 1 (-1), the expression is;
+2 + x(-1) = 0
2 - x = 0
x = 2
Thus, we need 2 negative ones to balance out one positive two.
2) We are told that potassium(K) forms ions with a charge of +1 and selenium (Se) forms ions with a charge of -2.
When two ions combine, the product element will have its' subscript as the absolute value of the ion of its' sharing ion. Thus;
We will have; K₂Se₁
Comparing with [tex]K_{X}Se_{Y}[/tex], then; X = 2 and Y = 1
3) We are told that;
Ion A has a charge of +2 and Ion B has a charge of -3.
From the concept in answer 2 above, it means that the answer will be;
A₃B₂.
4) We are told that;
Calcium forms ions with a charge of +2. Iodine forms ions with a charge of -1. An ionic compound formed by both ions using the concept earlier used would give us; CaI₂
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How many of the following molecules are polar? Brcl3 cs2 sif4 so3
Answer:
BrCl3
Explanation:
BrCl3: This compound has a T- shaped molecular geometry. And the difference in electronegativity is 0.2 to be precise makes is polar covalent compound.
CS2: Carbon sulphide is clearly a non polar compound because of the similar electronegativities of both carbon and sulphur.
SiF4: This molecule has Tetrahedral geometry. So, even though the difference in the electronegativity of Sulphur and Florine is high, the tetrahedral geometry makes it a non polar compound.
SO3: This molecule has trigonal planer geomtry. Hence, again in this molecule the polarity is being equal and opposite is cancelled out.
Answer:
The polarity of the molecule is defined as ability of the molecule to attract water through hydrogen bonding. Polarity of a molecule determines several characteristics of a substance. In the given examples, Bromine trichloride is a polar molecule.
Explanation:
Polarity of the substance or molecule is defined as the ability of a molecule to have electric dipole moment due to distribution of charges. In the given examples:
1. Bromine trichloride has a T-shaped geometry and the difference in electronegativity is 0.2. It has two lone pairs due to which the shape of molecule is bent.
2. Carbon sulphide is a non-polar molecule because of the symmetric shape having no electric dipole moment.
3. The tetrahedral geometry and symmetry of silicon tetrafluoride molecule provides the non-polar characteristic to the molecule. Silicon tetrafluoride have zero net dipole moment.
4. Sulphur trioxide is a non-polar molecule, which have trigonal planar geometry. The polarity of the molecule is cancelled out, which makes it to have zero dipole moment. Thus, it is a non-polar molecule.
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What c5h12 isomer will give only a single monochlorination product?
Answer:
Hence neopentane will give only single monochlorination product.
Explanation:
see below
The statement of C5H12 isomer will give only a single monochlorination product is "neopentane."
What is monochlorination?Monochlorination is the process of replacing one of the hydrogen atoms in an alkane with a chlorine atom. This is accomplished by chlorinating the alkane in the presence of UV radiation. The chlorine molecule splits into chlorine free radicals under these conditions. A monochlorination product is a chemical with two chlorine atoms in it.
Only one monochloroderivative is produced by the C5H12 isomer, implying that all hydrogen is equal. It's got to be neopentane. As a result, neopentane is the sole chemical that produces only one monochlorination product when chlorinated in the presence of sunlight.
Hence the correct option is neopentane.
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A balloon containing methane gas has a volume of 2.64 L at 31.0 C. What volume will the balloon occupy at 62.0 C?
Answer:
The balloon will occupy the volume of 2.91 L at 62.0 °C .
Explanation:
Using Charle's law
[tex]\frac {V_1}{T_1}=\frac {V_2}{T_2}[/tex]
Given ,
V₁ = 2.64 L
V₂ = ?
T₁ = 31.0 °C
T₂ = 62.0 °C
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T₁ = (31.0 + 273.15) K = 304.15 K
T₂ = (62 + 273.15) K = 335.15 K
Using above equation as:
[tex]\frac{2.64}{304.15}=\frac{V_2}{335.15}[/tex]
[tex]V_2=\frac{2.64\cdot \:335.15}{304.15}[/tex]
New volume = 2.91 L
The balloon will occupy the volume of 2.91 L at 62.0 °C .
When a 3.23 g sample of solid sodium hydroxide was dissolved in a calorimeter in 100.0 g of water, the temperature rose from 23.9 °C to 32.0 °C. Calculate ΔH (in kJ/mol NaOH) for the following solution process: NaOH(s) →Na+(aq)+ OH−(aq)
Answer:
-41,9kJ/mol NaOH
Explanation:
For the solution process:
NaOH(s) →Na⁺(aq) + OH⁻(aq)
The released heat is:
Q = -C×m×ΔT
Where Q is the released heat, C is specific heat of the solution (4,18J/g°C), m is the mass of water (100,0g) and ΔT is (32,0°C-23,9°C)
Replacing:
Q = -3385,8J
This heat is released per 3,23g of NaOH. Now, the heat released (ΔH) per mole of NaOH is:
[tex]\frac{-3385,8J}{3,23gNaOH} *\frac{40g}{1mol}[/tex]= -41929J/molNaOH ≡
-41,9kJ/mol NaOH
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A 275-mL flask contains pure helium at a pressure of 752 torr. A second flask with a volume of 475 mL contains pure argon at a pressure of 722 torr. If the two flasks are connected through a stopcock and the stopcock is opened, what is the partial pressure of each gas and the total pressure?
Answer:
Partial pressure He = 276 torrPartial pressure Ar = 457 torrTotal pressure = 733 torrExplanation:
Assuming temperature remains constant, we can use Boyle's law to solve this problem: P₁V₁=P₂V₂.
Once the two flasks are connected and the stopock opened, the total volume is:
275 + 475 = 750 mLNow we use Boyle's law twice, to calculate the new pressure of each gas:
He ⇒ 752 torr * 275 mL = P₂He * 750 mLP₂He = 276 torr
Ar ⇒ 722 torr * 475 mL = P₂Ar * 750 mLP₂Ar = 457 torr
Finally we calculate the total pressure, adding the partial pressures:
Total pressure = P₂He + P₂Ar = 733 torrWhich of the compounds below is not an example of a molecular solid?
A. CO2(s)
B. C25H52(s)
C. SiO2(s)
D. I2(s)
E. H2O(s)
SiO₂(s) is not an example of a molecular solid
A molecular solid is a of solid in which its molecules are held together by weak intermolecular forces such as van der Waals forces.
Molecular solids are soft, often volatile, have low density, have low melting temperatures, and are electrical insulators.
Example of molecular solid include CO₂(s) (dry ice), iodine (I₂(s)), C₂₅H₅₂(s) (paraffin wax), H₂O(s)
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What is meant by "the energy of an electron is quantized"?
a. The quantity of electron energy can be measured.
b. Each electron around an atom has a discrete measure of energy.
c. The quantity of electron energy changes as it moves around the nucleus.
d. All of the above
Answer:
a and B are correct
Explanation:
The energy of an electron associated with one shell around the nucleus is quantized. And is given by the formula
[tex]E= -\frac{13.6 eV}{n^2}[/tex].
where n= shell number 1,2,3...
It is true that energy of an electron cab be measured and Each electron around an atom has a discrete measure of energy associated with it. Moreover, quantity of electron energy remains constant in a shell and changes only when the electron changes its shell.
hence C is incorrect.
Answer: B: Each electron around an atom has a discrete measure of energy.
An endothermic reaction has An endothermic reaction has a positive ΔH, absorbs heat from the surroundings, and feels cold to the touch. a positive ΔH, absorbs heat from the surroundings, and feels warm to the touch. a positive ΔH, gives off heat to the surroundings, and feels warm to the touch. a negative ΔH, absorbs heat from the surroundings, and feels cold to the touch. a negative ΔH, gives off heat to the surroundings, and feels warm to the touch.
Answer:
An endothermic reaction has a positive ΔH, absorbs heat from the surroundings, and feels cold to the touch.
Explanation:
The enthalpy of reaction, ΔH, is the difference between the enthalpies of the products and the enthalpies of the reactants:
[tex]ΔH = H(products) - H(reactants)[/tex]
The enthalpy of reaction can be positive or negative, depending on the process.
For an endothermic process (heat absorbed by the system from the surroundings), ΔH is positive (that is, ΔH > 0).
For an exothermic process (heat released by the system to the surroundings), ΔH is negative (that is, ΔH < 0).
An endothermic reaction absorbs heat from its environment, has a positive ΔH, and feels cold to touch. It occurs when more energy is required to break bonds in reactants than the energy released when new bonds form in products. In contrast, an exothermic reaction releases heat, thus feels warm, and has a negative ΔH.
Explanation:An endothermic reaction is a type of chemical reaction that absorbs heat energy from the surroundings, hence it has a positive ΔH (enthalpy change). In simpler words, it requires more energy to break the bonds in the reactants than is released when new bonds form in the products. As a result, the reaction feels cold to the touch because heat is being drawn in from the environment. On the other hand, an exothermic reaction gives off heat to the surroundings, has a negative ΔH, and feels warm to the touch as it releases energy.
The enthalpy (ΔH), is a measure of the total energy of a thermodynamic system. It consists of the internal energy of the system plus the product of pressure and volume. The sign of ΔH can predict whether a reaction would be exothermic or endothermic.
For instance, the decomposition of dinitrogen tetroxide (N₂O4 (g) → 2NO₂ (g)) is an endothermic process, which means the reaction will absorb 57.20 kJ of heat from its surroundings. In contrast, the combustion reaction in an oxyacetylene torch is exothermic and releases energy in the form of heat and light.
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The Earth’s atmosphere contains about 0.04% (or 400 parts per million) carbon dioxide. Although most of the carbon dioxide is in the form 12CO2, which is not radioactive, a specific fraction of the total is made up of radioactive 14CO2.
A) True
B) False
Answer:
True
Explanation:
Yes the given statement is true
Most of the carbon dioxide preset in the atmosphere is C12 isotope and a very small fraction of The atmosphere is made up by C14 isotope which is radioactive in nature
C14 makes about 1 to 1.5 atoms per [tex]10^{12}[/tex] atoms of carbon in the atmosphere.
450g of chromium (III) sulfate reacts with excess potassium phosphate. How many grams of potassium sulfate will be produced? (ANS: 6.0x10˄2 g K2SO4)
Answer:
599.26 grams of potassium sulfate will be produced.
Explanation:
[tex]Cr_2(SO_4)_3(aq)+2K_3PO_4(aq)\rightarrow 2CrPO_4(s)+3K_2SO_4(aq)[/tex]
Moles of chromium (III) sulfate = [tex]\frac{450 g}{392 g/mol}=1.1480 mol[/tex]
According to reaction, 1 mole of chromium (III) sulfate gives 3 moles of potassium sulfate.
Then 1.1480 moles of chromium (III) sulfate will give:
[tex]\frac{3}{1}\times 1.1480 mol=3.4440 mol[/tex]
Mass of 3.4440 moles of potassium sulfate:
= 3.4440 mol × 174 g/mol = 599.26 g
599.26 grams of potassium sulfate will be produced.
Which element has the same oxidation number in all of its compounds?
Answer:
Sodium, potassium, calcium , magnesium etc
Explanation:
To determine the species which is being oxidized or reduced in a reaction, we make use of oxidation number. While oxidation involves electron loss, reduction involves electron gain. The specie which gain electrons is being reduced and thus experience a decrease in oxidation number and thus said to be the oxidizing agent. The species which lose electrons experience and increase in oxidation number and thus is the reducing agent.
There are some elements however which never get oxidized or reduced in the course of a chemical reaction. What we mean by this is that they neither get oxidized nor reduced but maintain the same original oxidation number.
Examples of these kind of elements include the groups 1 and 2 metals.
A sample of 97 g of NaCl is dissolved to make 2 L of solution. What is the molarity of the solution?
Molarity = Moles of solute/liters of solution
Hint: You need to calculate the moles from the grams given first
A. 1.66 M
B. 0.83 M
C. 48.5 M
D. 97 M
Answer:
Option B is the right one 0.83M
Explanation:
Molarity = Moles of solute/liters of solution
You should calculate the molar mass of NaCl firstly.
Molar mass NaCl = Molar mass Na + Molar mass Cl
Molar mass NaCl = 23 g/m + 35.45 g/m
Molar mass NaCl = 58.45 g/m
To know the moles we should divide grams / molar mass
97 g/ 58.45 g/m = 1.66 moles
This moles are in 2L of solution.
Molarity = mol/L
1.66 moles/2L = 0.83M
What volume is represented by each small tick
Answer:
there
Explanation:
Tick Volume Definition Tick volume is measuring every trade whether up or down and the volume that accompanies those trades for a given time period. If you are a day trader or a short term swing trader, tick volume analysis will assist you in sizing up the market on an intraday basis.
The volume by each small tick on a burette represents 0.05 mL.
What is a burette?A burette is a long, graduated tube with a stopcock at the bottom. It is used to measure small volumes of liquids, such as in titrations. The graduations on a burette are typically in milliliters (mL), and each small tick represents 0.05 mL.
This means that if you want to dispense 0.1 mL of liquid from a burette, you would need to dispense 2 small ticks.
The volume represented by each small tick may vary depending on the burette. It is always best to check the burette's calibration before using it to ensure that you are dispensing the correct volume of liquid.
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A steel container with a movable piston contains 2.00 g of helium which was held at a constant temperature of 25 °C. Additional helium was pumped into the container and the piston adjusted so that the gas pressure remained constant. How many grams of helium were added to the cylinder if the volume was changed from 2.00 L to 3.00 L?A) 0.700 gB) 2.00 gC) 1.8 gD) 1.00 gE) 9.7 gF) 5.63 gG) 4.63 g
Answer: D) 1.00 g
Explanation:
According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,
[tex]V\propto n[/tex]
or,
[tex]\frac{V_1}{V_2}=\frac{n_1}{n_2}[/tex]
where,
[tex]V_1[/tex] = initial volume of gas = 2.00 L
[tex]V_2[/tex] = final volume of gas = 3.00 L
[tex]n_1[/tex] = initial moles of gas =[tex]\frac{\text {Given mass of helium}}{\text {molar mass of helium}}=\frac{2.00g}{4g/mol}=0.500mol[/tex]
[tex]n_2[/tex] = final moles of gas = ?
Now we put all the given values in this formula, we get
[tex]\frac{2.00L}{3.00L}=\frac{0.500mol}{n_2}[/tex]
[tex]n_2=0.75mole[/tex]
Mass of helium =[tex]moles\times {\text {molar mass}}=0.75\times 4=3.00g[/tex]
Thus mass of helium added = (3.00-2.00) g = 1.00 g
Ne, Ar, and Kr have which properties in common? Group of answer choices
They are gases at STP, unreactive, and are generally monatomic.
They are gases at STP, unreactive, and are generally diatomic.
They are gases at STP, reactive, and are generally monatomic.
They are gases at STP, reactive, and are generally diatomic.
Answer:
Ne, Ar, and Kr are gases at STP, unreactive, and are generally monatomic.
Explanation:
they are unreactive and monoatomic and thats why have a very low boiling point.
The correct answer is: They are gases at STP, unreactive, and are generally monatomic.
Neon (Ne), Argon (Ar), and Krypton (Kr) are all noble gases, which are elements in Group 18 of the periodic table. The properties of noble gases are well-known and include the following:
1. State at STP (Standard Temperature and Pressure): At STP, all noble gases are in the gaseous state. This is because they have relatively low boiling points and exist as gases under normal conditions.
2. Reactivity: Noble gases are known for their lack of reactivity. They have a full valence shell, which means they do not readily form chemical bonds with other elements. This makes them very stable and unreactive under most conditions.
3. Atomicity: Noble gases are generally monatomic, meaning they consist of single atoms rather than molecules made up of two or more atoms. This is due to their stable electron configurations, which do not require sharing or transferring electrons to achieve stability.
Given these properties, the only option that accurately describes Ne, Ar, and Kr is that they are gases at STP, unreactive, and generally monatomic. The other options incorrectly describe either their state at STP, their reactivity, or their atomicity.
A student listed the characteristics of chemical and nuclear reactions.
Chemical and Nuclear Reactions
A -->Total mass remains unchanged
B --> Small change in mass takes place
Which of these statements best explains the identity of Reaction A?
A. It is a nuclear reaction because the total mass remains the same when there is a change in the number of protons and neutrons.
B. It is a chemical reaction because the total mass remains the same when the nuclei of the atoms reacting split.
C. It is a nuclear reaction because the total mass remains the same when there is a change in the overall energy of the system.
D. It is a chemical reaction because the total mass remains the same when new substances are formed.
Answer:
D. It is a chemical reaction because the total mass remains the same when new substances are formed.
Explanation:
A chemical reaction is represented by a chemical equation which show the reactant and products. Reactants are written on left side of arrow while products are written on right side. The number of atoms are remain same however arrangement of atoms is different on both side.
For example:
6H₂O + 6CO₂ + energy → C₆H₁₂O₆ + 6O₂
it is known from balanced chemical equation that 6 moles of carbon dioxide react with the six moles of water and created one mole of glucose and six mole of oxygen. The number of atoms are same on both side however arrangement of atoms is different.
While in case of nuclear reaction small change in mass take place.
Answer: D
Explanation: Just took the test
Assuming that an acetic acid solution is 12% by mass and that the density of the solution is 1.00 g/mL, what volume of 1 M NaOH is needed to fully neutralize a 10 mL aliquot of the acetic acid solution
Explanation:
Let us assume that total mass of the solution is 100 g. And, as it is given that acetic acid solution is 12% by mass which means that mass of acetic acid is 12 g and 88 g is the water.
Now, calculate the number of moles of acetic acid as its molar mass is 60 g/mol.
No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]
= [tex]\frac{12 g}{60 g/mol}[/tex]
= 0.2 mol
Molarity of acetic acid is calculated as follows.
Density = [tex]\frac{mass}{volume}[/tex]
1 g/ml = [tex]\frac{100 g}{volume}[/tex]
volume = 100 ml
Hence, molarity = [tex]\frac{\text{no. of moles}}{volume}[/tex]
= [tex]\frac{0.2 mol}{0.1 L}[/tex]
= 2 mol/l
As reaction equation for the given reaction is as follows.
[tex]NaOH + CH_{3}COOH \rightarrow CH_{3}COONa + H_{2}O[/tex]
So, moles of NaOH = moles of acetic acid
Let us suppose that moles of NaOH are "x".
[tex]x \times 1 M = 10 mL \times 2 M[/tex] (as 1 L = 1000 ml)
x = 20 L
Thus, we can conclude that volume of NaOH required is 20 ml.
Whats the formula for selenium pentaoxide, iodine trichloride, zinc (1) nitride, chromium (III) bicarbonate, and there molar mass
Answer one of them plz and thx
Answer:
1) Se2O5
2) I2O6
3)Zn3n2
4) Cr(HCO3)3
Explanation:
selenium pentaoxide (= also called diselenium pentoxide)
= Se2O5
⇒ Se = 78.97 g/mol
⇒ O = 16 g/mol
⇒ 2*78.97 + 5*16 = 237.94 g/mol
iodine trichloride
= I2O6
⇒ I = 126.9 g/mol
⇒ Cl = 35.45 g/mol
⇒ 2* 126.9 + 6 * 35.45 = 466.5 g/mol
zinc (1) nitride does not exist (it's Zinc(ii)nitride
The oxidation number for zinc is always 2
Zn3n2
⇒ Zn = 65.38 g/mol
⇒ N = 14 g/mol
⇒3*65.38 + 2* 14 = 224.14 g/mol
chromium (III) bicarbonate
Cr(HCO3)3
⇒ Cr = 52 g/mol
⇒ H = 1.01 g/mol
⇒ C = 12 g/mol
⇒ O = 16 g/mol
52 + 3*1.01 + 3*12 + 6*16 = 235.03 g/mol
A cell was prepared by dipping a Cu wire and a saturated calomel electrode into 0.10 M CuSO4 solution. The Cu wire was attached to the positive terminal of a potentiometer and the calomel electrode was attached to the negative terminal.(a) Write a half-reaction for the Cu electrode. (Use the lowest possible coefficients. Omit states-of-matter.)
(c) Calculate the cell voltage.
Answer:
a) cu2+ + 1Hg (l) 1Cl- equilibrium cu (s) + Hg2Cl2 (s)
b) 0.068 V.
Explanation:
A) Cu2+ + 2e- euilibrium cu (s)
Hg2Cl2 + 2e- equilibrium 2Hg (l) + 1cl-
Cell Reaction: cu2+ + 1Hg (l) 1Cl- equilibrium cu (s) + Hg2Cl2 (s)
B) To calculate the cell voltage
E = E_o Cu2+/Cu - (0.05916 V / 2) log 1/Cu2+
putting values we get
= 0.339V + (90.05916V/2)log(0.100) = 0.309V
E_cell = E Cu2+/Cu - E SCE = 0.309 V - 0.241 V = 0.068V.
The half-reaction for the copper electrode in a copper sulfate solution is Cu(s) -> Cu2+(aq) + 2e-. However, you cannot calculate the cell voltage without additional information about the Calomel electrode's standard reduction potential.
Explanation:The subject of this question is electrochemistry, which involves redox reactions and measurements of electrode potential.
(a) The half-reaction for the Cu electrode in your scenario, when the Cu wire is dipped into the CuSO4 solution, can be represented as follows: Cu (s) -> Cu2+ (aq) + 2e-. This reaction shows that copper metal (Copper in zero oxidation state) is being oxidized to Copper(II)(in +2 oxidation state) ions by losing 2 electrons.
For the cell voltage, we do not have sufficient information to calculate. To perform this calculation, we would also need the standard reduction potential for the Calomel electrode, or some other point of comparison.
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