Answer:
12,742 km
Explanation:
Therefore, its radius is 6,371 km.
Answer:
12,742 km
Explanation:
radius is 6,371 km.
What does the atomic number represent?
O
A. The number of neutrons in the nucleus
O
B. The number of protons and neutrons in the nucleus
c. The number of protons in the atom's nucleus
O
O
D. The number of electrons orbiting the nucleus
SU
Answer:
B
Explanation:
The tarnish that forms on objects made of silver is solid silver sulphide. This can be removed by reacting it with aluminium metal to produce silver metal and solid aluminium sulphide. How many moles of the excess reactant remain unreacted after the reaction between 3.4 moles of silver sulphide with 8.1 moles of aluminium metal is finished?
Answer:
5.83 mol.
Explanation:
From the balanced reaction:2Al + 3Ag₂S → 6Ag + Al₂S₃,
It is clear that 2 mol of Al react with 3 mol of Ag₂S to produce 1 mol of Ag and 1 mol of Al₂S₃.
Al reacts with Ag₂S with (2: 3) molar ratio.
So, 2.27 mol of Al reacts completely with 3.4 mol of Ag₂S with (2: 3) molar ratio.
The limiting reactant is Ag₂S.The excess "left over" reactant is Al.
The reamining moles of excess reactant "Al" = 8.1 mol - 2.27 mol = 5.83 mol.
What is the total energy change for the following reaction: CO + H2O -> CO2 + H2?
Given:
C-O bond: 358 kJ/mol
H-O bond: 463 kJ/mol
H-H bond: 436 kJ/mol
A. +132 kJ/mol
B. +1152 kJ/mol
C. +27 kJ/mol
D. -541 kJ/mol
1)Delta H=(Delta H of reactants)-(Delta H of products)
2)And we know CO have 3 bond CO and CO2 have 2 bond that each of them are 2 bond, please see the picture!
so lets answer it:
[tex](3 \times 358) + (2 \times 463) - (4 \times 358) - 436 = 132[/tex]
The total energy change for the given chemical reaction, CO + H2O -> CO2 + H2, is +132 kJ/mol. This is calculated by subtracting the total energy released when the product bonds are formed from the total energy required to break the reactant bonds.
To determine the total energy change for the given reaction: CO + H2O -> CO2 + H2, you first need to calculate the total energy required to break the reactant bonds (C-O and H-O), and then subtract from this the total energy released when the product bonds are formed (C=O and H-H). The given energies are:
C-O bond: 358 kJ/mol; H-O bond: 463 kJ/mol; H-H bond: 436 kJ/mol.
Calculating Energy ChangeEnergy required to break reactant bonds: (1 x C-O bond) + (2 x H-O bonds) = (1 x 358 kJ/mol) + (2 x 463 kJ/mol) = 1284 kJ/mol Energy released when the product bonds form: (2 x C=O bonds) + (1 x H-H bond) = (2 x 358 kJ/mol) + (1 x 436 kJ/mol) = 1152 kJ/mol
Total energy change = Energy required - Energy released = 1284 kJ/mol - 1152 kJ/mol = 132 kJ/mol.
So, the total energy change for the reaction is +132 kJ/mol, which corresponds to option A.
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A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.00°C and the temperature of the resulting solution was recorded as 37.00°C, determine the ΔH°rxn (in units of kJ/mol NaNO3) for the neutralization reaction between aqueous NaOH and HNO3
Answer:
Qm = -55.8Kj/mole
Explanation:
NaOH(aq) + HNO₃(aq) => NaNO₃(aq) + H₂O(l)
Qm = (mc∆T)water /moles acid
Given => 100ml(0.300M) NaOH(aq) + 100ml(0.300M)HNO₃(aq)
=> 0.03mole NaOH(aq) + 0.03mole HNO₃(aq)
=> 0.03mole NaNO₃(aq) + 0.03mole H₂O(l)
ΔH⁰rxn = [(200ml)(1.00cal/g∙°C)(37 – 35)°C]water / 0.03mole HNO₃
= 13,333 cal/mole x 4.184J/cal = 55,787J/mol = 55.8Kj/mole (exothermic)*
Heat of reactions comes from formation of H-Oxy bonds on formation of water of reaction and heats the 200ml of solvent water from 35⁰C to 37⁰C.
Answer:
-55.8 kJ/mol
Explanation:
There is a part missing from the question.
Assume no heat is lost to the calorimeter or the surroundings, and the density and heat capacity of the resulting solution are the same as water.
The initial moles of NaOH and HNO₃ are:
0.1000 L × 0.300 mol/L = 3.00 × 10⁻² mol
The neutralization reaction is:
NaOH + HNO₃ → NaNO₃ + H₂O
When 3.00 × 10⁻² moles of NaOH react with 3.00 × 10⁻² moles of HNO₃, they produce 3.00 × 10⁻² moles of NaNO₃ and 3.00 × 10⁻² moles of H₂O.
According to the law of conservation of energy, the sum of the heat released by the reaction and the heat absorbed by the solution is equal to zero.
ΔH°rxn + ΔH°sol = 0
ΔH°rxn = -ΔH°sol [1]
The volume of the solution is 100.0 mL + 100.0 mL = 200.0 mL. Since the density is 1.00 g/mL, the mass of the solution is 200.0 g.
We can calculate the heat absorbed by the solution using the following expression.
ΔH°sol = c × m × ΔT = (4.184 × 10⁻³ kJ/g.°C) × 200.0 g × (37.00°C - 35.00°C) = 1.674 kJ
where,
c: specific heat capacity of the solution
m: mass of the solution
ΔT: change in the temperature
From [1],
ΔH°rxn = -1.674 kJ
We can express the enthalpy of reaction per mole of NaNO₃.
ΔH°rxn = -1.674 kJ / 3.00 × 10⁻² mol = -55.8 kJ/mol
Which explains how burning a magnesium ribbon highlights a toolmark?
A.)The shimmering light provides shadows that show the relief of the mark.
B.) It burns brightly to provide light for photography.
C.) It forms a fine, white powder within the mark.
D.) It forms a material to cast the toolmark.
The magnesium ribbon, D. It forms a material to cast the tool mark.
Explanation:When a magnesium ribbon is burnt in the presence of oxygen it gives out strong light and heat is produced. Apart from it, it leads to the production of substance called as magnesium oxide which is formed as the product due to the reaction of magnesium with the oxygen present in the air.
Tool marks are the mark which is created by tools while using them. In order to identify or locate them castes made up of magnesium oxide is utilized. When this is pasted on the suspected area, the tool mark of the suspected tool gets pasted on it.
The correct answer is option (C). Burning a magnesium ribbon highlights a toolmark is: It forms a fine, white powder within the mark.
When a magnesium ribbon is burned, it produces a very bright light, which is useful for illuminating scenes in low-light conditions, especially in forensic photography. However, the specific reason it is used to highlight toolmarks is due to the properties of the residue it leaves behind.
As the magnesium burns, it oxidizes and produces magnesium oxide, which is a fine, white powder. This powder adheres to the surfaces and edges of the toolmark, effectively filling in the grooves and ridges. When the excess powder is brushed away, the magnesium oxide remains within the indentations of the toolmark, thereby highlighting it.
This makes the toolmark more visible and easier to photograph and analyze. The white powder contrasts sharply with the surrounding material, which is particularly useful when the toolmark is on a dark or non-reflective surface.
The other options do not accurately describe the process:
A.) The shimmering light provides shadows that show the relief of the mark. - While the bright light from the burning magnesium can create shadows, the primary method by which it highlights a toolmark is by leaving behind the white powder, not just by casting shadows.
B.) It burns brightly to provide light for photography. - While this is true and is one of the reasons magnesium is used, it is not the direct method of highlighting the toolmark. The light helps in seeing the toolmark after the powder has been applied and excess removed.
D.) It forms a material to cast the toolmark. - This option is incorrect because magnesium does not form a material to cast the toolmark. Instead, it leaves behind a powder that fills the toolmark, making it more visible. Casting implies creating a three-dimensional copy, which is not the case here.
Iron (III) oxide, also known as rust can be removed from iron by reacting it with hydrochloric acid to produce iron (III) chloride and water. Fe2O3 (s) + 6HCl (aq) ---> 2FeCl3 + 3H2O (l) What mass of hydrogen chloride is required to react with 100 g of rust? a. 371g HCl b. 137g HCl c. 130g HCl d. 147g HCl
Answer:
b. 137 g.
Explanation:
The balanced equation for the mentioned reaction is:Fe₂O₃(s) + 6HCl(aq) → 2FeCl₃(s) + 3H₂O(l),
It is clear that 1.0 mole of Fe₂O₃ react with 6.0 mol of HCl to produce 2.0 moles of FeCl₃ and 3.0 moles of H₂O.
We need to calculate the no. of moles of rust (100.0 g):n = mass/molar mass = (100.0 g)/(159.69 g/mol) = 0.6262 mol.
Using cross multiplication:
1.0 mol of Fe₂O₃ react completely with → 6.0 mol of HCl, from stichiometry.
0.6262 mol of Fe₂O₃ produced with → ??? mol of HCl.
∴ The no. of moles of HCl = (6.0 mol)(0.6262 mol)/(1.0 mol) = 3.757 mol.
∴ The mass of HCl needed = no. of moles x molar mass = (3.757 mol)(36.46 g/mol) = 137.0 g.
So, the right choice is: b. 137 g.
To find the required mass of HCl to react with 100 g of rust, calculate the moles of rust, use the stoichiometry of the reaction to find moles of HCl needed, and then convert those moles to grams. The answer is approximately 137 g of HCl.
Explanation:To determine the mass of hydrochloric acid (HCl) required to react with 100 g of rust (iron (III) oxide, Fe₂O₃), we use stoichiometry based on the balanced chemical equation: Fe₂O₃ (s) + 6HCl (aq) → 2FeCl₃ (aq) + 3H₂O (l).
First, calculate the molar mass of Fe₂O₃ (55.85 g/mol for Fe and 16.00 g/mol for O):
2(55.85) + 3(16.00) = 159.70 g/mol.
Next, calculate the moles of Fe₂O₃ in 100 g:
100 g ÷ 159.70 g/mol = 0.626 moles of Fe₂O₃.
According to the equation, 1 mole of Fe₂O₃ reacts with 6 moles of HCl. Therefore, 0.626 moles of Fe₂O₃3 will react with 0.626 * 6 = 3.756 moles of HCl.
Molar mass of HCl = 36.46 g/mol, so the mass of HCl needed is:
3.756 moles * 36.46 g/mol = 136.93 g, or approximately 137 g.
Thus, option (b) 137 g HCl is the correct answer for the mass of HCl required to react with 100 g of rust.
What is the total pressure of a mixture that contains 50% nitrogen at 1.7 atm, 23% oxygen at 1.1 atm, 12% argon at 0.7atm, 10% methane at 0.5 atm, and 5% water vapor at 0.2 atm?
A. 0.13 atm
B. 1.247 atm
C. 0.85 atm
D. 4.2 atm
I think so 4.2, we get the answer when we add together the pressure of each of the gases.
Answer: The total pressure of a mixture is 1.247 atm.
Explanation:
To calculate the total pressure of the mixture of the gases, we use the equation given by Raoult's law, which is:
[tex]p_T=\sum_{i=1}^n(\chi_{i}\times p_i)[/tex]
where,
[tex]p_T[/tex] = total pressure of the mixture
[tex]\chi_{i}[/tex] = mole fraction of i-th species
[tex]p_i[/tex] = partial pressure of i-th species
We are given:
For nitrogen:Mole fraction of nitrogen = 0.5
Partial pressure of nitrogen = 1.7 atm
For oxygen:Mole fraction of oxygen = 0.23
Partial pressure of oxygen = 1.1 atm
For argon:Mole fraction of argon = 0.12
Partial pressure of argon = 0.7 atm
For methane:Mole fraction of methane = 0.10
Partial pressure of methane = 0.5 atm
For water vapor:Mole fraction of water vapor = 0.05
Partial pressure of water vapor = 0.2 atm
Putting values in above equation, we get:
[tex]p_T=[(0.5\times 1.7)+(0.23\times 1.1)+(0.12\times 0.7)+(0.10\times 0.5)+(0.05\times 0.2)][/tex]
[tex]p_T=1.247atm[/tex]
Hence, the total pressure of a mixture is 1.247 atm.
Mercury and oxygen react to form mercury(II) oxide, like this: 2Hg (l) + O2 (g) → 2HgO (s) At a certain temperature, a chemist finds that a 5.2L reaction vessel containing a mixture of mercury, oxygen, and mercury(II) oxide at equilibrium has the following composition: compound amount Hg 14.7g O2 13.4g HgO 17.8g calculate Kc for this reaction
Answer:
Kc = 12.4 M⁻¹
Explanation:
1) Chemical equilibrium
2Hg (l) + O₂ (g) ⇄ 2HgO (s) (the double arrow indicates an equilibrium reaction)2) Equilibrium constant, Kc:
The equilibrium constant, Kc, is equal to product of the concentrations of each product,each raised to its stoichiometric coefficient / product of the concentrations of each reactant each raised to its stoichiometric coefficient.Since the concentrations of liquid and solid substances remain practically constant, their value is incorporated into the constant Kc, and the equation only uses the concentrations of the aqueous or gaseous substances.Thus, the equation to use is:
Kc = 1 / [O₂(g) ]3) Determine the concentration of O₂ (g)
M = number of moles / volume in litersNumber of moles = mass in grams / molar massNumber of moles of O₂ (g) = 13.4 g / 32.00 g/mol = 0.419 mol M = 0.419 mol / 5.2 liter = 0.0806 mol / liter = 0.0806 M4) Compute Kc
Kc = 1 / 0.0 806 M = 12.4 M⁻¹ ← answerIn a closed system, how will a decrease in pressure affect the following reaction: N2O4(g) ⇌ 2NO2(g)?
A. More nitrogen dioxide will be produced.
B. No change will occur.
C. The dinitrogen tetroxide will condense into a liquid.
D. More dinitrogen tetroxide will be produced.
Answer:
Answer 'A'
Explanation:
In general, if the Σmolar volumes(g) reactants ≠ Σmolar volumes(g) products, a change in atmospheric pressure will shift the reaction equilibrium. If the pressure is increased, the rxn will shift toward the LOWER molar volume side of the rxn or if the pressure is decreased the rxn will shift toward the HIGHER molar volume side. For the reaction N₂O₄(g) ⇄ 2NO₂(g), Vm(N₂O₄(g)) < Vm(NO₂(g)) so, a decrease in atmospheric pressure would shift rxn toward the NO₂(g) side of the equation increasing the moles of NO₂(g). Also, note that if the Σmolar volumes(g) reactants = Σmolar volumes(g) products, no shift in equilibrium will occur regardless of changes in atmospheric pressure.
According to Le Chatelier's principle, a pressure decrease in a closed system will make the system compensate by producing more gas molecules. In the given reaction N2O4(g) ⇌ 2NO2(g), it will move to increase the production of nitrogen dioxide (NO2) to balance the reduced pressure.
Explanation:In a closed system, if the pressure is decreased, the equilibrium will be shifted in the direction of the reaction that produces more gas molecules. This is according to Le Chatelier's principle. The given chemical reaction N2O4(g) ⇌ 2NO2(g) shows that one molecule of N2O4 dissociates into two molecules of NO2.
Therefore, if the pressure is decreased, the reaction will shift to the right to produce more nitrogen dioxide (NO2), thus increasing the number of gas molecules to counter the decrease in pressure. So, more nitrogen dioxide will be produced when the pressure decreases in this closed system.
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In a constant‑pressure calorimeter, 60.0 mL of 0.300 M Ba(OH)2 was added to 60.0 mL of 0.600 M HCl. The reaction caused the temperature of the solution to rise from 23.65 ∘C to 27.74 ∘C. If the solution has the same density and specific heat as water ( 1.00 g/mL and 4.184J/g⋅K,) respectively), what is Δ???? for this reaction (per mole H2O produced)? Assume that the total volume is the sum of the individual volumes.
Answer:
ΔH = 57.04 Kj/mole H₂O
Explanation:
60ml(0.300M Ba(OH)₂(aq) + 60ml(0.600M HCl(aq)
=> 0.06(0.3)mole Ba(OH)₂(aq) + 0.60(0.6)mole HCl(aq)
=> 0.018mole Ba(OH)₂(aq) + 0.036mole HCl(aq)
=> 100% conversion of reactants => 0.018mole BaCl₂(aq) + 0.036mole H₂O(l) + Heat
ΔH = mcΔT/moles H₂O <==> Heat Transfer / mole H₂O
=(120g)(4.0184j/g°C)(27.74°C - 23.65°C)/(0.036mole H₂O)
ΔH = 57,042 j/mole H₂O = 57.04 Kj/mole H₂O
ΔH = 57.04 Kj/mole H₂O
The symbol "Δ" stands for the change in enthalpy; (Hproducts -Hreactants). A positive value suggests an endothermic reaction or that the products have a higher enthalpy (heat is required) If the value is negative, the reaction is exothermic or the reactants have a higher enthalpy (heat is produced).
ΔH = 57,042 j/mole
H₂O = 57.04 Kj/mole
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What was one main point of Dalton's atomic theory?
O
A. That atoms were made up of positive and negative charges
B. That atoms had a nucleus at the center
C. That atoms made up the smallest form of matter
O
D. That atoms changed as they formed compounds
Answer:
C. That atoms made up the smallest form of matter
Explanation:
The crux of the Dalton's atomic theory is that atoms are the smallest form of matter. He propositioned that atoms is an indivisible particle and beyond an atom, no form of matter exists.
Series of discoveries through time have greatly shaped the Dalton's atomic theory. The discovery of cathode rays by J.J Thomson in 1897 opened up the atom. Atoms were now seen to be made up of some negatively charged particles. Ernest Rutherford through his gold foil experiment proposed the nuclear model of the atom.
What is the pressure of 1.9 mols of nitrogen gas in a 9.45 L tank and at a temperature of 228 K
Answer:
P = 3.8 Atm = 2900 mmHg (2 sig.figs.)
Explanation:
PV = nRT => P = nRT/V = (1.9 moles)(0.08206LAtm/molK)(228K)/9.45L = 3.76 ~ 3.8 Atm x 760mmHg/Atm =2888 mmHg ~ 2900 mmHg (2 sig.figs.)
2900 mmHg is the pressure of 1.9 mols of nitrogen gas in a 9.45 L tank and at a temperature of 228 K.
What is pressure?"Pressure" is defined as the thrust (force) applied to a surface per area. The force to area ratio is another way to describe it (over which the force is acting). The height of a mercury column that precisely balanced the mass of the columns of atmosphere above the barometer is used to measure atmospheric pressure, which is also referred to as barometric pressure.
It can be stated using a number of various measurement methods, including millimeters (or inches) of mercury, pounds every square inch (psi), dynes per square centimeter (dyn/sq cm), millibars (mb), standard atmospheres, as well as kilopascals.
PV = nRT
P = nRT/V
(1.9 moles)(0.08206LAtm/molK)(228K)/9.45L = 3.76
3.8 Atm x 760mmHg/Atm =2888 mmHg
=2900 mmHg
Therefore, the pressure is 2900 mmHg.
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a common concentration unit used commercially is percent weight per volume (%w/v) which is the number of gram of solute in 100 ml of solution. a bottle of hydrogen peroxide contains 2.5 %w/v hydrogen peroxide (h2o2). what is the molar concentration of hydrogen peroxide in the solution?
Answer:
The molar concentraion is 0.74 MExplanation:
1) Data:
a) % w/v = 2.5%
b) compound: H₂O₂ (from a table molar mass = 34.0147 g/mol)
c) M = ?
2) Formulae:
a) % w/v = (mass of soulte / volume of solution) × 100
b) numer of moles, n = mass in grams / molar mass
c) M = number of moles of solute / liters of solution
3) Solution:
a) Take a base of 100 ml of solution (0.100 liter):
%w/v = 2.5% = 2.5 g solute / 100 ml solutionmass of solute = 2.5 g / 100 ml × 100 ml = 2.5 gb) Calculate the number of moles of solute, n:
n = mass in grams / molar mass = 2.5 g / 34.0147 g/mol = 0.0735 molc) Calculate the molarity, M:
M = n / V in liter = 0.0735 mol / 0.100 liter = 0.735 MRound to two significant figures: 0.74 M ← answer
Calculate the entropy change for the reaction: N2(g) + 3H2(g) -> 2NH3(g)
Entropy data:
NH3 = 192.5 J/mol K
H2 = 130.6 J/mol K
N2 = 191.5 J/mol K
Answer:
ΔS⁰ = -198.3 J/K
Explanation:
N₂(g) + 3H₂(g) → 2NH₃(g)
S⁰: N₂(g) = 1mole(191.5J/mole·K) = 191.5J/K
S⁰: 3H₂(g) = 3moles(130.6J/mole·K) = 391.8J/K
S⁰: 2NH₃(g) = 2moles(192.5J/mole·K) = 385J/K
ΔS⁰ = ∑n·S⁰(Products) - ∑n·S⁰(Reactants
=[385J/K] - [191.5J/K + 391.8J/K]
= (385 - 191.5 - 391.8)J/K
= -198.3J/K
Answer: The [tex]\Delta S^o[/tex] of the reaction is [tex]-198.3Jmol^{-1}K^{-1}[/tex]
Explanation:
Entropy change of the reaction is defined as the difference between the total entropy change of the products and the total entropy change of the reactants.
Mathematically,
[tex]\Delta S_{rxn}=\sum [n\times \Delta S^o_{products}]-\sum [n\times \Delta S^o_{reactants}][/tex]
For the given chemical equation:
[tex]N_2(g)+3H_2(g)\rightarrow 2NH_3(g)[/tex]
We are given:
[tex]\Delta S^o_{NH_3}=192.5Jmol^{-1}K^{-1}\\\Delta S^o_{H_2}=130.6Jmol^{-1}K^{-1}\\\Delta S^o_{N_2}=191.5Jmol^{-1}K^{-1}[/tex]
Putting values in above equation, we get:
[tex]\Delta S^o_{rxn}=[(2\times \Delta S^o_{NH_3})]-[(1\times \Delta S^o_{N_2})+(3\times \Delta S^o_{H_2})][/tex]
[tex]\Delta S^o=[(2\times 192.5)]-[(1\times 191.5)+(3\times 130.6)]=-198.3Jmol^{-1}K^{-1}[/tex]
Hence, the [tex]\Delta S^o[/tex] of the reaction is [tex]-198.3Jmol^{-1}K^{-1}[/tex]
Determine what is missing from this neutralization reaction: HBr+KOH→H2O+−−−−
A. KBr
B. BrOH
C. HBr
D. KOH
Answer:
KBr
Explanation:
HBr+KOH=H2O+KBr
neutralization reaction
Answer:
The answer is KBr
Explanation:
By making a balance of the elements in the reaction you can determine the missing compound.
In the left side of the reaction we have:
- 2 of H
- 1 of Br
- 1 of K
- 1 of O
In the right side we have:
- 2 of H
- 1 of O
Doing the subtraction we have missing:
- 1 of Br
- 1 of K
So the answer is KBr
Given the reaction: H2O2(l) ⇌ H2(g) + O2(g) The forward reaction is endothermic. Determine which of the following changes would result in equilibrium shifting towards the reactants.
I. Increase H2
II. Decrease O2
III. Add a catalyst
IV. Decrease the temperature
V. Increase H2O2
Answer:
I and IV
Explanation:
Increasing the number of particles at one side of the reaction (H2 in this case) results in the shifting of the equilibrium to the side with lesser number of particles, so in this case the equilibrium will shift to the left (towards the reactants)
A decrease in temperature will always function to favor the exothermic reaction, and since the backwards reaction is exothermic, the equilibrium will shift to the left (towards the reactants).
Option II and V will shift the equilibrium to the products, and adding a catalyst has no effect on the equilibrium.
Hope this helps!Answer: all I know it’s not I and II
Explanation:
The rate of a chemical reaction will be affected more by which?
entropy
enthalpy
both enthalpy and entropy
neither enthalpy nor entropy
Answer:
Enthalpy => Heat Effects => changes in temperature
Explanation:
Rate of Rxn is affected by changes in 5 issues ...
C => Concentration
A => Surface Area
N => Nature (Chemical Structure)
T => Temperature (Enthalpy = Heat of Rxn)
C => Catalyst
The rate of a chemical reaction is generally more directly impacted by factors like concentration of reactants, temperature, presence of a catalyst, and surface area of reactants rather than enthalpy and entropy. While enthalpy and entropy can determine whether a reaction is feasible or not, they usually do not directly affect the rate of the reaction.
Explanation:The rate of a chemical reaction can be affected by both enthalpy and entropy, but these factors usually do not impact the rate of the reaction directly. They are part of the factors that determine the feasibility of a reaction, not the speed. The factors that directly impact the rate of a reaction include concentration of reactants, temperature, presence of a catalyst, and surface area of reactants.
Enthalpy pertains to the heat content of the reaction, while entropy pertains to the degree of disorder or randomness in the system. However, while they can determine whether a reaction is spontaneous or not, they do not directly influence the rate of the reaction.
To conclude, the rate of a chemical reaction is typically affected more directly by factors other than enthalpy and entropy, such as the concentration of reactants, temperature, presence of a catalyst, and surface area of reactants.
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Which of the following combinations represents an element with a net charge of +1 with a mass number of 75?a) 35 (o), 35 (+), 34 (-)b) 40 (o), 40 (+), 39 (-)c) 40 (o), 35 (+), 34 (-)d) 37 (o), 38 (+), 34 (-)e) 40 (o), 35 (+), 35 (-)
Answer:
c) 40 (o), 35 (+), 34 (-)
Explanation:
Let us represent the element with P
Given information about the element:
Charge on P = +1
Mass number of P = 75
We can express the atom as ⁴⁵P¹⁺
The positive charge on the atom denotes that the atom has lost an electron. Electrons are negatively charge elementary particles in an atom. Therefore, the number of protons, positively charged particles are now more. This charge imbalance is what leaves atom P with a charge of +1. The difference between the proton number and number of electrons is just 1 and it represents a loss of an electron. Atoms that are not charged have their proton and electron number to be the same. Those that are negatively charge signifies that an electron has been gained and the number of electrons are greater than those of the protons.
The mass number 75 is the number of protons plus neutrons.
Option C gives the following information:
Neutron = 40
Protons = 35
Electrons = 34
Here Protons > Electrons with a difference of 1+.
Mass number = Protons + Neutrons =35 + 40 = 75
For each row in the table below, decide whether the pair of elements will form a molecular or ionic compound. If they will, then enter the chemical formula of the compound. If the elements will form more than one compound, enter the compound with the fewest total number of atoms You may assume all chemical bonds are single bonds, not double or triple bonds element #1 | element #2 | compound formed? | chemical formula ionic O molecular O neither argon xenon ionic O molecular O neither fluorine cesiumm ionic O molecular O neither nitrogen bromine
The pairs potassium and fluorine, and nitrogen and bromine, form ionic and molecular compounds respectively with chemical formulas KF and NBr3. However, lithium and beryllium, both being metals, would not typically form a compound.
Explanation:The question asks to decide whether the pairs of elements given would form a molecular or ionic compound, and if so, to provide the chemical formula of the compound. In general, a compound that includes a metal and a nonmetal forms an ionic compound, while a compound that includes two nonmetals forms a molecular compound. Of course, there are significant exceptions.
For potassium (group 1, a metal) and fluorine (group 17, a nonmetal), they would form an ionic compound with the chemical formula KF.
For nitrogen (group 15, a nonmetal) and bromine (group 17, also a nonmetal), they would form a molecular compound with the chemical formula NBr3.
For lithium (group 1, a metal) and beryllium (group 2, also a metal), they would not typically form a compound because compounds usually consist of metals and nonmetals or two nonmetals.
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The complete question is given below:
For each row in the table below, decide whether the pair of elements will form a molecular or ionic compound. If they will, then enter the chemical formula of the compound. If the elements will form more than one compound, enter the compound with the fewest total number of atoms You may assume all chemical bonds are single bonds, not double or triple bonds. The pair element 1 and element 2 pairs are given below.
1. potassium and fluorine
2. nitrogen and bromine
3. lithium and beryllium
How does the addition of salt to solid ice affect the melting transition from solid to liquid?
A. The amount of energy absorbed would not change during the plateau.
B. It would need to absorb less energy during the plateau in order to melt.
C. It would need to absorb more energy during the plateau in order to melt.
D. There would be no plateau, the salt would cause the solid to immediately melt.
The water would need to B. absorb less energy during the plateau in order to melt.
Explanation:Salt when added to ice lowers the freezing point of the ice. So, if ice is added to the solid ice it doesn't let it to freeze rather the temperature of water may fall but it won't freeze.
For melting, it needs less energy after adding salt because salt itself absorbs the energy from the surroundings to help the phase transition of water from solid to liquid.
Answer: C. It would need to absorb more energy during the plateau in order to melt.
Explanation:
adding salt lowers the freezing point, meaning it needs to absorb more energy from its surrounding in order to melt.
What was Ernest Rutherford's experiment?
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A. He measured the electricity produced when light hit metal.
B. He measured the bending of a cathode ray caused by electricity.
) C. He shot tiny alpha particles through a piece of gold foil.
D. He suspended tiny drops of charged oil in an electric field.
Answer:
C. He shot tiny alpha particles through a piece of gold foil.
Explanation:
In the year 1911, Ernest Rutherford performed the gold foil experiment which gave a deeper perspective to the structure of an atom.
He simply collided a thin gold foil with an alpha particle which he generated from a radioactive source. He discovered that most of the alpha particles passed through the thin gold foil but a few were deflected back. His discovery led to the proposition of the nuclear model of the atom.
shot tiny alpha particles
a.pex
How would you classify weather?
Answer:
Weather can have many classification, how hot how windy how cold how humid. There are however different classifications for different types of weather. Hope this helps :)
What are the only things that can change in a valid experiment?
A. Independent variable and Hypothesis
B. Control variable and Range
C. Control variable and Dependent variable
D. Dependent and Independent Variable
Answer:
D. Dependent and Independent Variable
Explanation:
Since the independent variable is already the variable being changed, that is one of the things that can be changed and fromt the independent variable being changed, that changes the dependent variable.
The only things that can change in a valid experiment are dependent and independent variables.
Independent variables and independent variables:when someone is conducting an experiment, the independent variable is what they change, and the dependent variable is what changes comes because of independent variables, like the independent variable as the cause and the dependent variable as the effect.
so when one is changing the independent variable and dependent varible automatically being changed.
Therefore the correct answer is Dependent and Independent Variable (option D)
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About 40 different substances called organophosphorus compounds are registered in the United States as insecticides. They are considered less damaging to the environment than some other insecticides because they breakdown relatively rapidly in the environment. The first of these organophosphorus insecticides to be produced was tetraethyl pyrophosphate, TEPP, which is 33.11% carbon, 6.95% hydrogen, 38.59% oxygen, and 21.35% phosphorus. It has a molecular mass of 290.190. What is the molecular formula for TEPP?
The molecular formula for TEPP, or tetraethyl pyrophosphate, is approximately C4H10O6P2. This is calculated from the given element percentages and the given molecular mass.
Explanation:The process of figuring out the molecular formula of TEPP, which stands for tetraethyl pyrophosphate, involves several steps. First, given the percentage composition of each element, we need to calculate the number of moles of each element in a 100g sample of the compound. For example, the 33.11% carbon equals 33.11g in a 100g sample. When divided by the molar mass of carbon (12.01 g/mole), this gives us approximately 2.76 moles. We do the same calculation for hydrogen, oxygen, and phosphorus to end up with a 'base' empirical formula of C2.76H6.96O3.86P1.36.
The next step is to figure out how to get the simplest whole number ratio. This can be done by dividing all the numbers by the smallest one, 1.36. This gives us C2.03H5.12O2.84: these are approximately 2, 5, 3, and 1, respectively, so the empirical formula of TEPP is approximately C2H5O3P.
We need to compare the empirical mass to the given molecular mass of 290.19 g/mol to determine whether the molecular formula is a multiple of the empirical. The empirical formula mass is about 144.99 g/mol. Therefore, the molecular formula of TEPP is approximately C4H10O6P2, as the molecular weight is approximately twice that of the empirical formula weight.
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Both scientists are working together to develop a model of Earth's layers in order to test their theories. They are using a Bunsen burner to represent Earth's core and vegetable oil within a large glass container to represent the asthenosphere. Given their experimental setup thus far, which of the following would be the best representation of the lithosphere
A.Water
B.Solid block of clay
C.Sand
D.Cardboard pieces
Answer:
D.Cardboard pieces
Explanation:
Cardboard pieces would a good representation of the crust.
The crust of just a thin layer in terms of thickness. We can picture the crust as an apple skin or an orange peel. It's thickness is averages about 5-10km for thinner oceanic crusts and about 30-50km for thicker continental crust.
The crust is the thinnest layer of the earth.
Below the crust is the region of the mantle. The mantle is made of the upper mantle, asthenosphere and mesosphere. The asthenosphere is in a weak plastic form and it is very thick. It averages a thickness of about 190km,about 100 times the oceanic crust and 4 times the continental crust. The mantle is the thickest region of the earth.
The core is the innermosr layer of the earth. It is about 2300km thick.
It would be very ideal to relatively represent the crust as pieces of cardboard floating on an oily asthenosphere.
All of the following statements about different elements are true EXCEPT:a) barium is an alkali earth metalb) manganese is a transition metal c) sulfur is considered a metalloid d) krypton is one of the noble gasses e) iodine is a halogen
Answer:
The statement that is not true is: c) Sulfur is considered a metalloidExplanation:
To answer this kind of questions your best tool is a periodic table.
The periodic table shows the elements ordered by increasing atomic number (number of protons), in an arragement of rows and columns. In such arrangement, the elements appear classified as metals, non-metals, and metaloids.
Roughly metals are on the left side of the table, nonmetals are on the right side, and metalloids are a reduced group that are in a kind of step ladder dividing the metals and nonmetals.
With that, you can follow this procedure for each of the answer choices:
a) Barium is an alkali earth metal:
TRUE. Barium, Ba, has atomic number 56, is in the column (group) number 2, which is the group of the alkali earth metals.
b) Manganese is a transition metal:
TRUE. Manganese, Mn, has atomic number 25 and is in the column 7. The columns 3 through 12 enclose the transition metals. So, manganese is a transition metal.
c) Sulfur is considered a metalloid.
FALSE. Sulfur, S, has atomic number 16, is in the column 16, (right below oxygen) and is classified as a nonmetal.
d) Krypton is one of the noble gasses
TRUE. Krypton, Kr, has atomic number 36, and is in the column 18. This column includes all the noble gases, which are elements whose valence shells are complete (2 electrons in the case of He and 8 electrons in all the other cases).
This group is named noble gases because the elements have very low reactivity, so they are almos inert.
e) Iodine is a halogen
TRUE. Iodine, I, is the element with atomic number 53, and is in the column 17. This column includes all the halogens (F, Cl, Br, I, At, and the most recently discovered Ts).
The false statement is that sulfur is considered a metalloid; sulfur is actually a nonmetal. Barium is an alkali earth metal, manganese is a transition metal, krypton is a noble gas, and iodine is a halogen.So,option c is correct.
The statement that sulfur is considered a metalloid is false; sulfur is actually a nonmetal. Below is a clarification of each element's classification:
Barium is an alkali earth metal and is in Group 2 of the periodic table.
Manganese is indeed a transition metal, found in Group 7 of the transition metals.
Sulfur is a nonmetal and is part of the chalcogens family, also known as the oxygen family.
Krypton is one of the noble gases, which are known for having their outer energy levels full, making them very unreactive.
Iodine is a halogen, part of Group 17 on the periodic table, which is known for being highly reactive.
A sample of argon fills a volume of 5 m3 at 425 K with a pressure of 3.9 atm. The argon is cooled to 240 K and shrinks to a volume of 3.1 m3. After cooling it is added to a tank of helium with a pressure of 1.87 atm. What is the total pressure of the gas mixture?
A. 3.55 atm
B. 2.89 atm
C. 13.0 atm
D. 5.42 atm
Answer:
D. 5.42 atm.
Explanation:
The total pressure of the gas mixture = P of He + P of Ar after cooling.
P of He = 1.87 atm.
Firstly, we need to find the P of Ar after cooling:We can use the general law of ideal gas: PV = nRT.
where, P is the pressure of the gas in atm.
V is the volume of the gas in L.
n is the no. of moles of the gas in mol.
R is the general gas constant,
T is the temperature of the gas in K.
If n is constant, and have different values of P, V and T:(P₁V₁T₂) = (P₂V₂T₁)
Knowing that:
P₁ = 3.9 atm, V₁ = 5.0 m³, T₁ = 425.0 K,
P₂ = ??? atm, V₂ = 3.1 m³, T₂ = 240.0 K,
Applying in the above equation(P₁V₁T₂) = (P₂V₂T₁)
∴ P₂ = (P₁V₁T₂)/(V₂T₁) = (3.9 atm)(5.0 m³)(240 K)/(3.1 m³)(425.0 K) = 3.552 atm.
∴ The total pressure of the gas mixture = P of He + P of Ar after cooling.
P of He = 1.87 atm & P of Ar after cooling = 3.552 atm.
∴ The total pressure of the gas mixture = 1.87 atm + 3.552 atm = 5.422 atm ≅ 5.42 atm.
So, the right choice is: D. 5.42 atm.
How many molecules of sodium oxide will be created if 187 grams of oxygen reacts with excess sodium? 4Na + O2 -> 2Na2O A. 11.69 x 1023 molecules of Na2O
To determine the number of molecules of sodium oxide created, we can use the given balanced chemical equation, molar mass, and Avogadro's number. The reaction equation tells us that for every 4 moles of sodium, 2 moles of sodium oxide are formed. From the given mass of oxygen, we can calculate the number of moles of sodium oxide and then convert that to molecules using Avogadro's number.
Explanation:To determine the number of molecules of sodium oxide created, we need to use the given balanced chemical equation and the molar mass of sodium oxide (Na2O). From the balanced equation, we can see that 4 moles of sodium (Na) react with 1 mole of oxygen (O2) to form 2 moles of sodium oxide (Na2O). Thus, the stoichiometry of the reaction tells us that for every 4 moles of sodium, 2 moles of sodium oxide are formed.
Using the molar mass of sodium oxide, which is 61.98 grams/mol, we can calculate the number of moles of sodium oxide formed from the given mass of oxygen. First, convert the mass of oxygen to moles by dividing it by the molar mass of oxygen, which is 32.0 grams/mol. So, 187 grams of oxygen is equal to 5.84 moles. Based on the stoichiometry of the reaction, for every 1 mole of oxygen, 2 moles of sodium oxide are formed. Therefore, 5.84 moles of oxygen will form 11.68 moles of sodium oxide.
Finally, to determine the number of molecules of sodium oxide, we can use Avogadro's number, which states that 1 mole of any substance contains 6.02 x 10^23 particles (atoms or molecules). So, multiplying the number of moles of sodium oxide by Avogadro's number, we get:
11.68 moles x 6.02 x 10^23 molecules/mol = 7.03 x 10^24 molecules of Na2O
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Which of the following set of quantum numbers (ordered n, ℓ, mℓ, ms) are possible for an electron in an atom? Check all that apply. View Available Hint(s) Hint 1. How to approach the problem Hint 2. Identify issues with an example set of quantum numbers opened hint Check all that apply. 4, 2, 3, -1/2 2, 1, 0, 1 3, 1, 0, -1/2 4, 3, -2, 1/2 -3, 2, 2, -1/2 4, 2, -1, -1/2 2, 2, 2, 1/2 3, 2, -3, 1/2
Each of the four quantum numbers for an electron in an atom represents a specific characteristic and has specific rules regarding which values are allowed. The principal quantum number n can be any positive integer, the azimuthal quantum number l ranges from 0 to n - 1, the magnetic quantum number ml ranges from -l to +l, and the spin quantum number ms can either be +1/2 or -1/2. The quantum numbers 2, 1, 0, 1; 3, 1, 0, -1/2; 4, 2, -1, -1/2 from the provided list are valid.
Explanation:To evaluate the possible set of quantum numbers, it is important to understand the rules that govern the values for each quantum number. The quantum numbers are expressed in the form (n, ℓ, mℓ, ms). Each one of these represents a certain feature of a given electron in an atom.
The first quantum number n, known as the principal quantum number, denotes the electron's energy level and can be any positive integer starting from 1.
The second quantum number ℓ, known as the azimuthal or angular momentum quantum number, is responsible for the shape of the electron's orbital and can have values ranging from 0 to n - 1.
The third quantum number, mℓ, known as the magnetic quantum number, describes the orientation of the electron's orbital. It can have values between -ℓ and +ℓ including 0.
Lastly, the fourth quantum number ms, the electron spin quantum number, can have one of two values: +1/2 or -1/2, denoting the two possible spin states of an electron.
Using these rules, we can verify the following quantum numbers: 4, 2, 3, -1/2, 2, 1, 0, 1, 3, 1, 0, -1/2, 4, 3, -2, 1/2, -3, 2, 2, -1/2, 4, 2, -1, -1/2, 2, 2, 2, 1/2, 3, 2, -3, 1/2. It is evident the following quantum numbers are valid: 2, 1, 0, 1; 3, 1, 0, -1/2; 4, 2, -1, -1/2.
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Classify each of these reactions with respect to the following categories: combination reaction, decomposition reaction, combustion reaction, and single‑displacement reaction. a. Fe2(CO3)2(s) Fe2O3(s) 2CO2(g) ∆ b. 2C6H11OH(l ) 17O2(g) → 12CO2(g) 12H2O(l ) c. P4O10(s) 6H2O(l ) → 4H3PO4(aq) d. 2C(s) MnO2(s) Mn(s) 2CO(g) ∆ e. 2NaClO3(s) 2NaCl(s) 3O2(g)
Answer:
a. decomposition reaction
b. Combustion reaction
c. Combination reaction
d. Single displacement reaction
e. Decomposition reaction
Explanation:
Here's a tip that might help you get through categorizing chemical reactions like this:
A combination reaction is when two or more reactants COMBINE to form a single product. This is also known as synthesis reaction. If you look a the chemical equation, it will have a form somewhat like this:
Reactant/s Product
A + B → AB
Taking your problem into consideration, letter c is a combination reaction because it started out as two reactants and combined to form one product.
P₄O₁₀ + 6H₂O → 4H₃PO₄
Reactants Product
A decomposition reaction is when one reactant DECOMPOSES or breaks down into two or more products.
Reactant Product
AB → A + B
Your problem has 2 decomposition reactions, which are letters, a and e because if you notice, you have one reactant and it split into two products.
Fe₂(CO₃) → Fe₂O₃ + 2CO₂
Reactant Product
2NaClO₃ → 2NaCl + 3O₂
Reactant Product
A single displacement reaction is when one element or compound is displaced by another element or compound.
Reactants Product
AB + C → AC + B
or
A + BC → AC + B
Your problem has letter d as your example of single-displacement.
2C + MnO₂ → Mn + 2CO₂
A + BC → B + AC
Reactant Product
A combustion reaction on the other hand occurs when hydrocarbons react with oxygen and heat. The product of a combustion reaction is ALWAYS carbon dioxide (CO₂) and water (H₂O).
Reactants Product
Hydrocarbon + O₂ → CO₂ + H₂O
Lastly, your problem has letter b as an example of a combustion reaction. Notice that the product of the reaction is CO₂ and H₂O.
2C₆H₁₁OH + 17O₂ → 12CO₂ + 6H₂O
Hydrocarbon + O₂ → CO₂ + H₂O
These clues might help you next time.