We know, 1 mole of any element/compound contains 6.022 × 10²³ atoms/molecules .
Now, we have to calculate the number of molecules in 0.5 mole of sulfur dioxide, SO₂.
So, number of molecules of SO₂ in 0.5 mole is :
[tex]n = 0.5\times 6.022\times 10^{23}\\\\n = 3.011\times 10^{23}[/tex]
Therefore, number of molecules in 0.5 mole of SO₂ is 3.011 × 10²³.
pls help asap!!
The surface of earth has many impact craters that have been filled in with sediment. these craters were created by
A. moles
B. dinosaurs
C. people
D. meteorites
Answer:
D
Explanation:
Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. The high-speed impact of a large meteorite compresses, or forces downward, a wide area of rock. The pressure pulverizes the rock.
HURRY
Fill in the blank -
metals like to _ electrons to form ionic bonds
Select the correct answer.
Which phrase correctly describes temperature?
A.
average rotational kinetic energy of the particles in an object
B.
average energy of the particles in an object
C.
average translational kinetic energy of the particles in an object
D.
all energy possessed by the particles in an object
Answer:
C. average transnational kinetic energy of the particles in an object.
Explanation:
Temperature measures the average kinetic energy of the particles in a substance. Thermal energy measures the total kinetic energy of the particles in a substance. The greater the motion of particles, the higher a substance's temperature and thermal energy. Therefore we could say that the average kinetic energy of a gas particle is directly proportional to the temperature. Hence an increase in temperature increases the speed in which the gas molecules move. All gases at a given temperature have the same average kinetic energy.Deforestation, intensive agriculture, and drought can result in a condition called
A) urban sprawl
B) land reclamation
C) pollution
D) desertification
Answer:
D
Explanation:
Human activities that contribute to desertification include the expansion and intensive use of agricultural lands, poor irrigation practices, deforestation, and overgrazing. ... Some meteorologists and soil scientists measure the impacts and length of a drought to determine if it is an example of desertification.
Describe how to use a transfer pipet to deliver 10.00 mL of liquid by placing the steps in the correct order.
This question is incomplete, the complete question is;
Describe how to use a transfer pipet to deliver 10.00 mL of liquid by placing the following steps in the correct order;
- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.
- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.
- Transfer the pipette to the receiving vessel.
- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.
- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.
- Suck up a third volume of liquid past the 10.00 ml calibration mark.
- Discard the first two pipette volumes of the liquid to rinse the pipette.
Answer:
- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.
- Discard the first two pipette volumes of the liquid to rinse the pipette.
- Suck up a third volume of liquid past the 10.00 ml calibration mark.
- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.
- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.
- Transfer the pipette to the receiving vessel.
- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.
Explanation:
First of all, We use a suction device to suck up liquid into pipet. Then we will fill the pipet up to the 10 mL marks and will discard the initial two volumes of liquid and will take a final third volume. We will replace the bulb with index finger and will drain it by placing the tip of pipet at the wall of beaker and drain the liquid.
Arranged in the following steps correctly;
- Use a rubber bulb to suck liquid up past the 10.00 ml calibration mark.
- Discard the first two pipette volumes of the liquid to rinse the pipette.
- Suck up a third volume of liquid past the 10.00 ml calibration mark.
- Replace the bulb with your index finger and wipe excess liquid off the outside of the pipette.
- Place the tip of the pipette against the side of the beaker and drain the liquid from the pipette until the bottom of the meniscus reaches the calibration mark.
- Transfer the pipette to the receiving vessel.
- Drain the pipette by gravity while holding the tip against the side of the receiving vessel.
One electron(s) are added to an phosphorus atom. Enter the chemical symbol of the element.
Answer:
S (sulphur)
Explanation:
In a neutral atom, the number of electrons and the number of protons in an element are equal. These numbers are called the ATOMIC NUMBER. That is, in a neutral atom;
proton no. = electron no. = Atomic no.
Hence, in this case where phosphorus atom has an electron number of 15. It means that there are 15 protons and 15 electrons in a phosphorus atom. If one electron is added to these electrons i.e. 15 +1, there will be 16 electrons in the atom, hence, this atom becomes SULPHUR element, which has 16 electrons in its atom, with chemical symbol S.
In Universe L, recently discovered by an intrepid team of chemists who also happen to have studied interdimensional travel, quantum mechanics works just as it does in our universe, except that there are three d orbitals instead of the usual number we observe here. Use these facts to write the ground-state electron configurations of the second and third elements in the first transition series in Universe.
Answer:
Second element(Titanium); [Ar] 3d2 4s2
Third element(Vanadium):Ar 3d3 4s2
Explanation:
Given that there are only three d orbitals in universe L instead of five, the electronic configuration of the second and third elements in the first transition series will now look thus;
Second element(Titanium); [Ar] 3d2 4s2
Third transition element(Vanadium):Ar 3d3 4s2
Hence, the electronic configuration of Titanium and Vanadium in universe L is just the same as what it is on earth.
Which of the following is a true statement about wind erosion?
Most wind erosion happens in the Arctic.
Most wind erosion happens in deserts, beaches, and plowed fields.
Most wind erosion happens only on top of mountains.
Most wind erosion happens in areas with tropical climate.
Answer :
B. Most wind erosion happens in deserts, beaches, and plowed fields.
Determine the Oxidation number of the indicated element in each of the following substances: Mn in KMnO4 S in SO2 C in COCl2 P in PF4 O in K2O2
Answer:
1. Mn = +7
2. S = +4
3. C = +4
4. P = +4
5. O = -1
Explanation:
The oxidation number of each element in a compound is as follows:
1. Mn in KMnO4
KMnO4 = 0
Where; K = +1, O = -2, Mn = x
+1 + x -2(4) = 0
1 + x - 8 = 0
x - 7 = 0
x = +7
2. S in SO2
SO2 = 0
Where; S = x, O = -2
x + -2(2) = 0
x - 4 = 0
x = +4
3. C in COCl2
COCl2 = 0
Where; C = x, O = -2, Cl = -1
x + -2 + -1(2) = 0
x + -2 + -2 = 0
x -2 - 2 = 0
x - 4 = 0
x = +4
4. P in PF4
PF4 = 0
Where; P = x, F = -1
x + -1 (4) = 0
x - 4 = 0
x = +4
5. O in K2O2
K2O2 = 0
Where; K = +1, O = x
+1(2) + x(2) = 0
2 + 2x = 0
-2x = 2
x = -1
What is the name for a particle that has a mass about 1/1835 of a proton, but with a negative charge
Answer:
Electron
Explanation:
It is a hot summer day. Your dog, Spot, is lying in the shade, panting. The water content in the dog's blood gets low. Spot gets up
to find________ because he is responding to the internal stimulus of_______
A)
food; hunger
B)
water; thirst
C)
his bed; sleepiness
D)
shade; high temperatures
Using standard heats of formation, calculate the standard enthalpy change for the following reaction. 2NH3(g) 3N2O(g)4N2(g) 3H2O(g) ANSWER: kJ Submit Answer
Answer: [tex]\Delta H^{0} = -879.15 kJ/mol[/tex]
Explanation: Heats of formation is the amount of heat necessary to create 1 mol of a compound from its molecular constituents. The basic conditions the substance is formed is at standard conditions: 1 atm and 25°C. Each compound has its own heat of formation per mol of compound (kJ/mol), but to an element is assigned a value of zero.
Standard Enthalpy Change is defined as the heat absorbed or released when a reaction takes place. It can be positive or negative, which means reaction is endothermic or exothermic, respectively.
Enthalpy change is calculated as the difference between the sum of heat formation of products and the sum of heat formation of the reactants:
[tex]\Delta H^{0}=\Sigma H^{0}_{f}_{(products)}-\Sigma H^{0}_{f}_{(reactants)}[/tex]
For the reaction
2NH₃ + 3N₂O → 4N₂ + 3H₂O
2(-46.2) + 3(82.05) 4(0) + 3(-241.8)
[tex]\Delta H^{0}=3(-241.8)-[ 2(-46.2)+3(82.05)][/tex]
[tex]\Delta H^{0}=-725.4-153.75[/tex]
[tex]\Delta H^{0}=-879.15[/tex]
The standard enthalpy change for the reaction is [tex]\Delta H^{0}=-879.15[/tex] kJ
what does the suffix -ine mean in the word heroine?
example :
the silent movie heroine faced danger from an evil villain.
a. female
b. many
c. young
d. great
Answer:
Female
Explanation:
Answer: A. Female.
Explanation: The word 'heroine' means a female or a woman that is admired and looked upon for her courage, bravery, and noble qualities.
The diagram shows salt dissolved in water. What does it show about water molecules
and chloride ions?
+
Chloride
Oxygen
Hydrogen 4
Sodium
Answer:
that they all dissolved went on watef
Chemical bonds between atoms in molecules such as H2, CH4, NH3, and
many large biological molecules are:
lonic Bonds
Hydrogen Bonds
Covalent Bonds
Metallic Bonds
Answer:In ionic compounds, electrons are transferred between atoms of different elements to form ions. But this is not the only way that compounds can be formed. Atoms can also make chemical bonds by sharing electrons equally between each other. Such bonds are called covalent bonds. Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves (i.e., when both atoms have identical or fairly similar ionization energies and electron affinities). For example, two hydrogen atoms bond covalently to form an H2 molecule; each hydrogen atom in the H2 molecule has two electrons stabilizing it, giving each atom the same number of valence electrons as the noble gas He.
Compounds that contain covalent bonds exhibit different physical properties than ionic compounds. Because the attraction between molecules, which are electrically neutral, is weaker than that between electrically charged ions, covalent compounds generally have much lower melting and boiling points than ionic compounds. In fact, many covalent compounds are liquids or gases at room temperature, and, in their solid states, they are typically much softer than ionic solids. Furthermore, whereas ionic compounds are good conductors of electricity when dissolved in water, most covalent compounds are insoluble in water; since they are electrically neutral, they are poor conductors of electricity in any state.
Arrange the following substances from the lowest to highest normal boiling point: CaO, O2, H2, H2CO, H2O.
Answer:
The answer is CH4<CH3OCH3<CH4O<CaCO3
Explanation:
The order of the lowest to highest normal boiling point:
H₂ < O₂ < H₂CO₃ < H₂O < CaO
What is the boiling point?The boiling point is the temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure. At this temperature, the liquid phase is changed into a vapor phase.
The boiling point is the temperature point at which the material transforms into the gas phase in the liquid phase. The Celsius scale was created on the basis of the ice or water melting point and the liquid water or vapor boiling point. Each substance consists its own boiling point.
The boiling point of Calcium oxide is 2850° C as it has a strong force of attraction between the ions. The boiling point of water as we already know is equal to 100° C.
The boiling point of the oxygen gas is -183°C and the boiling point of the hydrogen gas is - 252.8°C. The boiling point of carbonic acid is 333.6°C.
Therefore, CaO has the highest, and hydrogen gas has the lowest normal boiling point among the given compounds.
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How many moles are in 1.5 x 10^23 atoms of fluorine?
Answer: 0.125 moles F2
Explanation: 1.5x1023 atoms of F = 0.75x10^23 molecules F2
moles F2 = 0.75x10^23/avogadro number = 0.125 moles
There are 0.25 moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
Given,
How many moles are in one atom?
In one mole we have,
6.02 x [tex]10^{23}[/tex] atoms.
1 mole = 6.02 x [tex]10^{23}[/tex] atoms
Find the number of moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
We have,
1 mole = 6.02 x [tex]10^{23}[/tex] atoms
Multiply 1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] on both sides
1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 1 mole = 1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 6.02 x [tex]10^{23}[/tex] atoms
1.5/6.02 mole = 1.5 x [tex]10^{23}[/tex] atoms
0.25 moles = 1.5 x [tex]10^{23}[/tex] atoms.
Thus there are 0.25 moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
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CHEMISTRY HELP!! due in 10 minutes! :(
Answer:
Yes, because it match the octet rule!!
It is double bond lewis structure of ch2s!!
Explanation:
Rank the following compounds in order of decreasing boiling point: potassium fluoride (KF), acetylene (C2H2), and formaldehyde (CH2O)
Answer: [tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]
Explanation:
The order of boiling point depends upon the type of interactions present between the molecules.
Potassium fluoride (KF) is an ionic compound and the opposite ions are held together by strong electrostatic forces.
[tex]C_2H_2[/tex] is a covalent compound and the molecules are held together by weak van der Waals' forces.
Formaldehyde is a polar compound due to presence of polar carbonyl group. Hence dipole-dipole force is present between formaldehyde molecules.
Thus the decreasing order of boiling point is:
[tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]
which element is the least reactive? Neon, Chlorine, Gallium or Tin
blank is the total disappearance of all members of a species.
Answer:
Extinction
Explanation:
When a species becomes extinct, every last specimen has died out
When an endothermic chemical reaction (the system) occurs inside a calorimeter containing water (the surroundings) and no heat escapes from the calorimeter, which of the following statements is true?
a. Heat flows from the system to the surroundings and the temperature of the water increases.
b. Heat flows from the surroundings to the system and the temperature of the water decreases.
c. Heat flows from the system to the surroundings and the temperature of the water decreases.
d. Heat flows from the surroundings to the system and the temperature of the water increases.
Answer:
b. Heat flows from the surroundings to the system and the temperature of the water decreases.
Explanation:
The laws of thermodynamics lets us know that energy is neither created nor destroyed but can be converted from one form to another. Also, energy transfer does accompany chemical reactions in the form of heat.
For an endothermic reaction, heat is absorbed by the system from the surroundings. This leads to a drop in the temperature of the surroundings as energy is removed.
This implies that the water temperature decreases.
How many liters of oxygen are necessary for the combustion of 425 g of sulfur, assuming that the reaction occurs at STP
Answer:
V = 296.6 liters of oxygen.
Explanation:
The reaction of combustion of sulfur is:
O₂(g) + S(s) → SO₂(g) (1)
To find the volume of the oxygen we need to use the Ideal Gas Law:
[tex] V = \frac{n_{O}RT}{P} [/tex] (2)
Where:
V: is the volume
[tex]n_{O}[/tex]: is the number of moles of oxygen
R: is the gas constant = 0.082 L*atm/(K*mol)
T: is the temperature = 273 K (at STP)
P: is the pressure = 1 atm (at STP)
So we need to find the number of moles of oxygen that reacts with sulfur:
[tex]n_{S} = \frac{m}{M}[/tex]
Where:
[tex]n_{S}[/tex]: is the number of moles of sulfur
m: is the mass of sulfur = 425 g
M: is the molar mass of sulfur = 32.065 g/mol
[tex]n_{S}=\frac{m}{M} =\frac{425 g}{32.065 g/mol} = 13.25 moles[/tex]
From reaction (1) we have that 1 mol of O₂ reacts with 1 mol of S, hence the number of moles of oxygen is:
[tex] n_{S} = n_{O} = 13.25 moles [/tex]
Finally, the volume of oxygen is (equation (2)):
[tex]V = \frac{13.25 moles*0.082 L*atm/(K*mol)*273 K}{1 atm} = 296.6 L[/tex]
Therefore, are necessary 296.6 liters of oxygen for the combustion of sulfur.
I hope it helps you!
A friend is calculating the energy of reaction for a combustion reaction using bond energies, and the calculations are returning a positive for ?H. What, if anything, has your friend done incorrectly?
A. He or She used the wrong table of bond energies
B. Nothing, a combustion reaction should have a positive ?H
C. He or she may have subtracted the reactants from the products
D. Bond energies don’t apply to combustion reactants and should not be used.
Answer:
He or She used the wrong table of bond energies
Explanation:
We know that we obtain the energy of a reaction also known as the enthalpy of reaction from the formula; ΔHo(reaction) = sum of the bond energies of bonds being broken - sum of the bond energies of the bonds being formed.
Combustion is an exothermic reaction for which the value of ΔH is expected to the negative. If ΔH is not negative, then the calculation was not properly done and the wrong values of bond energy were probably used.
Answer:
He or she may have subtracted the bond energies for the reactants from the products.
Explanation:
can u pls help me with this question
A-potassium
B-lead
C-iron
D-magnesium
E-zinc
The unknown substance : Lead
Further explanationGiven
Density of element
mass of unknown substance = 40 g
volume = 3.5 cm³
Required
The density of unknown substance
Solution
Density is the ratio of mass per unit volume
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:
[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]
Input the value to find the density of an unknown substance :
ρ = 40 g : 3.5 cm³
ρ = 11.43 g/cm³
If we look at the table, the substance which has a density of 11.43 is Lead
25.
Chemical equations should be balanced so that they demonstrate the Law of Conservation of Mass. Which statement about balanced chemical equations is correct?
A
The products must contain the same number and types of atoms as the reactants.
B. The products must contain the same arrangement of atoms as found in the reactants,
C. The products must contain the same number but not the same types of atoms as the reactants.
D. The products must contain the same types but not the same numbers of atoms as the reactants,
Answer:
a
Explanation:
they have to have the same numbers on each side.
According to the law of conservation of mass, the total mass in the product side is equal to the mass in the reactant side of a reaction. Thus, option A that is The products must contain the same number and same types of atoms as the reactants is correct.
What is mass conservation?Mass conservation is similar to law of energy conservation. That is mass can neither be created nor be destroyed. Thus The total mass in a system is conserved. Therefore,in reaction the mass of product have to be equal to the mass of reactant.
A balanced reaction represent all reactants in their state and in perfect stoichiometry. Hence, each elements have to be equal in number on both side. No new atoms is created here and no atom is lost.Same number and same type will be in both side.
During a chemical reaction, the regrouping of atoms occurs to form the new product. Hence, no new atoms are added . Therefore The products must contain the same number and same types of atoms as the reactants and satisfies the mass conservation.
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assume you mix 0.71g of chlorine with 1.00g of fluorine in a 258 ml flask at 23 . what is the partial pressure of each gas
Answer:
See explanation
Explanation:
Number of moles of Cl2 = 0.71g/71g/mol = 0.01 moles
Number of moles = 1.0 g/38g/mol = 0.02 moles
Total = 0.01 + 0.02 = 0.03 moles
From the ideal gas equation;
PV=nRT
P=?
V= 258 ml
n= 0.03 moles
T= 296 K
P= nRT/ V
P= 0.03 × 0.082 × 296/258
P= 0.003 atm
Partial pressure Cl2 = 0.01/0.03 × 0.003 atm = 0.001 atm
Partial pressure = F2 = 0.02/0.03 × 0.003atm = 0.002 atm
Suppose 128 radioactive atoms have a half-life of 15 seconds. Approximately how many radioactive atoms will be left after 60 seconds
Answer:
8 electrons
Explanation:
Number of atoms = 128
Half life = 15 s
After each half life, the number of atoms reduces by half. So we need to determine how many half lives are in 60s.
Number of half lives = 60s / 15s = 4
After the first life;
Number of electrons left = 128 / 2 = 64
After the second life;
Number of electrons left = 64 / 2 = 32
After the third half life;
Number of electrons left = 32 / 2 = 16
After the fourth half life;
Number of electrons left = 16 / 2 = 8
Answer:
C. 8
Explanation:
correct on gizmo; After one half-life (15 seconds), about 64 radioactive atoms will remain, half of the original 128. After a second half-life passes (30 seconds total), about 32 radioactive atoms will remain, half of 64. After a third half-life passes (45 seconds), about 16 radioactive atoms will remain. A time of 60 seconds represents four half-lives, so about 8 radioactive atoms will remain.
A student fails to insert the cuvette into the colorimeter or spectrophotometer correctly. What effect will this have on the measured absorbance
Answer:
It would cause scattering of light and absorbance measurement is going to be reported as too large
Explanation:
The curvette was not inserted correctly into the spectrometer. The effect that this would have on measured absorbance is that it would cause scattering of light.
Failing to line the curvette correctly would cause light to scatter, the light reaching the photodetector would be less. This less light would then be interpreted as more light being absorbed. This would end up making the absorbance value to be read as too large.