Answer:
if it is pure, the substances is either an element or a compound. if a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture. if its composition is uniform throughout, it is a homogeneous.
Calculate the amount of heat needed to melt 160. g of solid octane (C8H18 ) and bring it to a temperature of 99.2 degrees c. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.
Answer: The amount of heat needed to melt the given amount of octane is 84.6 kJ
Explanation:
We know:
Boiling point of Octane = [tex]125.6^oC[/tex]
Few processes involved are:
(1): [tex]C_8H_{18} (s) (-57^oC, 219K) \rightleftharpoons C_8H_{18}(s) (-57^oC, 219K[/tex]
(2): [tex]C_8H_{18}(l) (-57^oC, 219K) \rightleftharpoons C_8H_{18}(l) (99.2^oC,372.2K)[/tex]
Calculating the heat absorbed for the process having same temperature:
[tex]q=n\times \Delta H_{(f)}[/tex] ......(i)
where,
q is the amount of heat absorbed, n is the moles of sample and [tex]\Delta H_{(f)}[/tex] is the enthalpy of fusion
Calculating the heat released for the process having different temperature:
[tex]q=n\times C_{l}\times (T_2-T_1)[/tex] ......(ii)
where,
n = moles of sample
[tex]C_{l}[/tex] = specific heat of liquid
[tex]T_2\text{ and }T_1[/tex] are final and initial temperatures respectively
The number of moles is defined as the ratio of the mass of a substance to its molar mass.
The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(3)
Given mass of octane = 160. g
Molar mass of octane = 114.23 g/mol
Plugging values in equation 3:
[tex]\text{Moles of octane }=\frac{160.g}{114.23g/mol}=1.40 mol[/tex]
For process 1:We are given:
[tex]n=1.40mol\\\Delta H_{fusion}=20.740 kJ/mol[/tex]
Putting values in equation (i), we get:
[tex]q_1=1.40mol\times 20.470kJ/mol\\\\q_1=28.658kJ[/tex]
For process 2:We are given:
[tex]n=1.40mol\\C=255.68J/mol^oC\\T_2=99.2^oC\\T_1=-57^oC[/tex]
Putting values in equation (ii), we get:
[tex]q_2=1.40mol\times 255.68J/mol^oC\times (99.2-(-57))\\\\q_2=55912.10J=55.912kJ[/tex]
Calculating the total amount of heat released:
[tex]Q=q_1+q_2[/tex]
[tex]Q=[(28.658)+(55.912)]kJ=84.6kJ[/tex]
Hence, the amount of heat needed to melt the given amount of octane is 84.6 kJ
g 1. Write a mechanism for the Grignard reaction of benzophenone with phenylmagnesium bromide. Be as complete as possible and show electron flow for all steps.
Answer:
See explanation and image attached
Explanation:
The reaction between benzophenone and phenylmagnesium bromide is a Grignard reaction.
A Grignard reagent is any alkyl magnesium halide compound. In this case, the Grignard reagent is phenylmagnesium bromide.
Reaction of Grignard reagent with a ketone yields all alcohol. Thus, the reaction of benzophenone with phenylmagnesium bromide yields triphenyl methanol.
The mechanism of the reaction and all electron movements are shown in the image attached to this answer.
A hot air balloon has an air vent that keeps the air pressure inside and outside the same. Allen observes that a hot air balloon rises up when the gas molecules inside it are heated. Which
of the following laws is used to understand the behavior of the gas and why?
a) The high temperature brings the gas molecules closer together according to Charles's law because this law describes how a gas will behave at constant pressure
b) The high temperature makes the gas molecules spread apart according to Charles's law because this law describes how a gas will behave at constant pressure.
c) The high temperature lowers volume according to Boyle's law because this law describes how a gas will behave when the number of moles remains constant.
d) The high temperature ralses volume according to Boyle's law because this law describes how a gas will behave when the number of moles remains constant.
Answer:
B - The high temperature makes the gas molecules spread apart according to Charles's law because this law describes how a gas will behave at constant pressure.
Explanation:
Charle's Law describes the relationship between temperature and volume, where increased temperature leads to increased volume. When volume is increased, that means the gas molecules are more spread apart and have more random motion. Therefore, the answer is B.
The high temperature causes the gas molecules to spread apart according to Charles's law because explain how a gas, behave at constant pressure.
What does Charles law state?The physical principle called Charles' law which states that the volume of a gas equals a constant value many by its temperature as measured on the Kelvin scale.
Volume regaled by a clinched amount of gas is directly proportional to its temperature and pressure if remains steady.
Thus, option "B" is correct, the volume of a gas equals a constant value.
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Why would iron filings rust faster than an iron nail?
Answer:
Rust forms on iron filings faster than on a large iron block
Explanation:
Because the surface area exposed to air in the refrigerator is greater than its area by mass, the rust-forming reaction occurs faster.
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explain how you would find the solubility of a solute
Answer:
Solubility indicates the maximum amount of a substance that can be dissolved in a solvent at a given temperature. Such a solution is called saturated. Divide the mass of the compound by the mass of the solvent and then multiply by 100 g to calculate the solubility in g/100g .
Solubility of solute:
Solubility is the ability of a solid, liquid, or gaseous chemical substance (referred to as the solute) to dissolve in solvent (usually a liquid) and form a solution.The solubility of a given solute in a given solvent typically depends on temperature. For many solids dissolved in liquid water, solubility tends to correspond with increasing temperature.To calculate the solubility in g/100g:
Divide the mass of the compound by the mass of the solvent and then multiply by 100 g.For example:Solubility of NaNO₃=[tex]\frac{21.9g*100g}{25 g} =87.6[/tex]
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Answer:
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Explanation:
Which of the following relations is correct for exothermic and endothermic reactions?
Answer:
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Explanation:
pleseee need answerrrr
The correct relations for exothermic and endothermic reactions from the given relations is H Products > H Reactants in exothermic reactions. Hence, Option (D) is Correct.
What is Exothermic Reaction ?
In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change ΔH⚬ is negative." Exothermic reactions usually release heat.
Therefore, The correct relations for exothermic and endothermic reactions from the given relations is H Products > H Reactants in exothermic reactions. Hence, Option (D) is Correct.
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calculate the maximum theoretical percent recovery from the recrystallization of 1.00g of benzoic acid
Answer:
The maximum theoretical percent recovery from the recrystallization of 1.00 g of benzoic acid from 15 mL of water = 94.9%
Note: The question is incomplete. A similar but complete question is given below:
The solubility of benzoic acid in water is 6.80g per 100mL at 100 degrees C and 0.34 g per 100mL at 25 degrees C.
Calculate the maximum theoretical percent recovery from the recrystallization of 1.00 g of benzoic acid from 15 mL of water, assuming the solution is filtered at 25 degrees C.
Explanation:
Solubility of benzoic acid in water at 100 degrees C = 6.80g per 100mL
Solubility of benzoic acid in water at 25 degrees C = 0.34 g per 100mL
Mass of benzoic acid to be theoretically recovered from 100 mL of water = 6.80 g - 0.34 g = 6.46 g
At 25 degrees;
0.34 g of benzoic acid is present in 100 mL of water
x g of benzoic acid will be present in 15 mL of water
x = 0.34 × 15 / 100 = 0.051 g
Mass of benzoic acid to be theoretically recovered from 25 mL of water = 1.00 g - 0.051 g = 0.949 g
Maximum theoretical percent recovery = (mass recovered / original mass dissolved) x 100%
Maximum theoretical percent recovery = (0.949 / 1.00) × 100% = 94.9 %
Therefore, the maximum theoretical percent recovery from the recrystallization of 1.00 g of benzoic acid from 15 mL of water = 94.9%
(iii) Give areason why the nitrogen gas obtained is not pure
Answer:
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Explanation:
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What will be the mass of 2 moles of propane gas?
a 20 grams
b 44 grams
c88 grams
d 30 grams
Answer: 88 grams
Explanation:
Hypochlorous acid decays in the presence of ultraviolet radiation. Assume that degradation occurs accord- ing to first-order kinetics and the rate of degradation was measured to be 0.12 day−1 (at a particular sun- light intensity and temperature). Given this, how long does it take for the concentration of hypochlorous acid to reach nondetectable levels (0.05 mg · L−1) if the initial concentration were 3.65 mg · L−1?
Answer:
35.75 days
Explanation:
From the given information:
For first-order kinetics, the rate law can be expressed as:
[tex]\mathsf{In \dfrac{C}{C_o} = -kt}[/tex]
Given that:
the rate degradation constant = 0.12 / day
current concentration C = 0.05 mg/L
initial concentration C₀ = 3.65 mg/L
[tex]\mathsf{In( \dfrac{0.05}{3.65})= -(0.12) t}[/tex]
㏑(0.01369863014) = -(0.12) t
-4.29 = -(0.12)
t = -4.29/-0.12
t = 35.75 days
The [OH-] of a solution is 7.89 10^-12 M. What is the pH of the solution? it acidic or basic? *
Answer: pH = 2,897 , basic[tex][H+][OH-] = 10^{-14} ==> [H+] = \frac{10^{-14}}{7,89*10^{-12} } =\frac{1}{789} \\pH= -lg([H+]) = 2,897 \\pH<7 ==> basic[/tex]
Explanation:
Describe the buffer capacity of the acetic acid buffer solution in relation to the addition of both concentrated and dilute acids and bases. Reference the results in Data Tables 1,2,3, and 4 in your answer.
Answer:
The more concentrated acetic acid buffer has a better buffer capacity because requires more moles of acid or base to change the pH than a more diluted acetic acid buffer.
Explanation:
Buffer capacity is defined as the moles of an acid or base that are needed to change the pH of a buffer in 1 unit.
A more concentrated solution of acetic buffer contains more moles of the acid per liter of solution. A solution that contains more moles of the acetic ion or the acetic acid requires more moles of base or acid to change the pH, that means:
The more concentrated acetic acid buffer has a better buffer capacity because requires more moles of acid or base to change the pH than a more diluted acetic acid buffer.
Classify these bonds as ionic, polar covalent, or nonpolar covalent. You are currently in a sorting module. Turn off browse mode or quick nav, Tab to items, Space or Enter to pick up, Tab to move, Space or Enter to drop. Ionic Polar covalent Nonpolar covalent C-O , Mg-F , Cl-Cl
Answer: The bond present in given compounds is as follows-
Ionic - MgFPolar covalent - CONon-polar covalent - Cl-ClExplanation:
A bond formed due to transfer of electrons from one atom to another is called ionic bond.An ionic bond is always formed between a metal and a non-metal atom.
For example, MgF has metal magnesium and non-metal fluorine. So, an ionic bond is there in the compound MgF.
A compound in which valence electrons are shared between two atoms is called a covalent bond. A covalent bond is always formed between two or more non-metal atoms.When sharing of electrons occur between atoms of different electronegativity then the bond formed is called a polar covalent bond.
For example, C-O has a polar covalent bond.
When sharing of electrons occur between atoms of same element then bond formed is called non-polar covalent bond.For example, Cl-Cl is a non-polar covalent bond.
A company manufacturing KMnO4 wants to obtain the highest yield possible. Two of their research scientists are working on a technique to increase the yield.
Both scientists started with 50.0 g of manganese oxide (MnO2).
What is the theoretical yield of potassium permanganate when starting with this 50.0 g MnO2?
The equation for the production of potassium permanganate is as follows:
2 MnO2 + 2 KOH + O2 → 2 KMnO4 + H2
You must show all work to receive full credit.
Answer:
[tex]m_{KMnO_4}=90.9gKMnO_4[/tex]
Explanation:
Hello there!
In this case, according to the given chemical equation for the reaction for the production of potassium permanganate, we can see a 2:2 mole ratio of this product to the starting manganese (II) oxide, which means, we can calculate the theoretical yield of the former via stoichiometry:
[tex]m_{KMnO_4}=50.0gMnO_2*\frac{1molMnO_2}{86.94gMnO_2}*\frac{2molKMnO_4}{2molMnO_2} *\frac{158.034gKMnO_4}{1molKMnO_4} \\\\m_{KMnO_4}=90.9gKMnO_4[/tex]
Regards!
Sound travels through the air in
Answer:
Sound travels through the air in approximately 332 metres per second?
Explanation:
is this what you are looking for>
(answer is a period table element!) When apprehending a suspect, try not to put your ____ on him.
Answer:
H
Explanation:
try not to put your hands on him
This reaction was at equilibrium when 0.2 atm of iodine gas was pumped into the container, what happened to the equilibrium and the partial pressures of the gases
Answer:
Q was < K. Partial pressure of hydrogen decreased, iodine increased
Explanation:
After iodine was added the Q was [Select] K so the reaction shifted toward the Products [Select] ,The partial pressure of hydrogen [Select], Iodine [Select] |,and hydrogen iodide Decreased
Based on the equilibrium:
H2(g) + I2(g) ⇄ 2HI(g)
K of equilibrium is:
K = [HI]² / [H2] [I2]
Where [] are concentrations at equilibrium
And Q is:
Q = [HI]² / [H2] [I2]
Where [] are actual concentrations of the reactants.
When the reaction is in equilibrium, K=Q.
But as [I2] is increased, Q decreases and Q was < K
The only concentration that increases is [I2], doing partial pressure of hydrogen decreased, iodine increased
Given the data you collected for the volume of water displaced by 25.000 g of aluminum, what is the density of aluminum?
A. 3.38 g/cm
B. 13.5 g/mL
C. 2.70 g/cm
D. 0.637 g/mL
Answer:
C. 2.70 g/mL
Explanation:
Density is the ratio between the mass of a substance and the volume it occupies. Based on Archimedes' volume, the displaced volume of the aluminium is the volume it occupies. To solve this question we must find the difference in volume between initial volume of water = 30mL and final volume of water + aluminium = 39.26mL. This difference is the volume of the aluminium. With its mass we can find density:
39.26mL - 30mL = 9.26mL
Density = 25.00g / 9.26mL =
2.70g/mL
Right answer is:
C. 2.70 g/mLWhat’s the answers to the answers
Part B Identify the sets of quantum numbers that describe all the electrons in the ground state of a neutral beryllium atom, Be. Each set is ordered (n, l, me, ms). Drag the appropriate items to their respective bins. View Available Hint(s) Reset Help 2,0,0,1/2 2,1,-1,1/2 2,1,0,1/2 1,0,0,-1/2 2,1,-1,-12 1,0,0,1/2 2,1,0,-1/2 2,0,0,-1/2 Electrons in Be Electrons not in Be Submit
Answer: The set of quantum numbers for the electrons in Be atom are (2, 1, -1, 1/2), (1, 0, 0, 1/2), (1, 0, 0, -1/2) and (2, 0, 0, -1/2)
Explanation:
There are 4 quantum numbers:
Principal Quantum number (n) specifies the energy of the electron in a shell.Azimuthal Quantum number (l) specifies the shape of an orbital. The value of it lies in the range of 0 to (n-1)Magnetic Quantum number (m) specifies the orientation of the orbital in space. The value of it lies in the range of -l to +lSpin Quantum number (s) specifies the spin of an electron in an orbital. It can either have a value of [tex]+\frac{1}{2}[/tex] or [tex]-\frac{1}{2}[/tex]Berylium (Be) is the 4th element of periodic table having electronic configuration of [tex]1s^22s^2[/tex]
For electrons in 1s-orbital, the quantum numbers can be:For first electron:
[tex]n=1\\l=0\text{ (for s-subshell)}\\m=0\\s=+\frac{1}{2}[/tex]
For second electron:
[tex]n=1\\l=0\\m=0\\s=-\frac{1}{2}[/tex]
For electrons in 2s-orbital, the quantum numbers can be:For first electron:
[tex]n=2\\l=0\text{ (for s-subshell)}\\m=0\\s=+\frac{1}{2}[/tex]
For second electron:
[tex]n=2\\l=0\text{ (for s-subshell)}\\m=0\\s=-\frac{1}{2}[/tex]
Hence, the set of quantum numbers for the electrons in Be atom are (2, 1, -1, 1/2), (1, 0, 0, 1/2), (1, 0, 0, -1/2) and (2, 0, 0, -1/2)
Which statement best describes the formula equation Cl2(g) + 2KBr(aq) Right arrow. 2KCl(aq)+ Br2(l)?
Carbon iodide reacts with potassium bromide to form potassium carbon iodide and bromine.
Bromine gas reacts with a solution of potassium chloride to form potassium bromide and chlorine gas.
Potassium bromine gas reacts with liquid chlorine to form potassium chloride in solution and bromine gas.
Chlorine gas reacts with potassium bromide to form potassium chloride in solution and liquid bromine.
Answer:
Chlorine gas reacts with potassium bromide to form potassium chloride in solution and liquid bromine.
Answer:
DDDDD
Explanation:
how old was the oldest animal fossil
help thx
Answer:
the Rhyniognatha hirsti
Explanation:
at age 400 million years old
What is a chemical reaction that absorbs heat called?
A. A thermal energy reaction
B. A thermodynamic reaction
C. An endothermic reaction
D. An exothermic reaction
Answer:
maybe it's c. An endothermic reaction
An endothermic reaction is a chemical reaction that absorbs heat. Therefore, the correct option is option C.
An endothermic reaction in thermochemistry would be any thermodynamic process that results in a rise in the system's enthalpy H (or heat capacity U). A closed system typically helps to absorb thermal energy from the surroundings during such a process, which causes heat transfer through into system.
It could be a physical process, like the melting of ice cubes, or a chemical process, like the dissolution of ammonium nitrate (NH[tex]_4[/tex]NO[tex]_3[/tex]) throughout water (H[tex]_2[/tex]O). An endothermic reaction is a chemical reaction that absorbs heat.
Therefore, the correct option is option C.
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Which statement is not true for an electrochemical cell?
Electrons must flow through a separate path from the reaction solutions.
The metals that form the electrodes must be identical.
Nonparticipating ions must flow to keep the electrons electrically neutral.
An oxidation-reduction reaction must occur.
Answer:
B
Explanation:
C and D is correct
To be clear that electrochemical is science that study the exchange conversion of chemical energy and electric energy through redox reaction
As c is salt bridge
And d is electrochemical define
A is correct as the electricity transfer in electric wire not in solution so its B) un correct
The statement which is not true about the electrochemical cell is option B, the metals that form the electrodes cannot be identical.
What is an electrochemical cell ?In an electrochemical cell, two different metals or metal ions are typically used as the electrodes. These electrodes are placed in separate compartments, which contain the reaction solutions and are connected by a salt bridge or porous membrane.
During the cell's operation, electrons flow through an external wire or circuit, from the anode (where oxidation occurs) to the cathode (where reduction occurs), and nonparticipating ions flow through the salt bridge or porous membrane to maintain charge neutrality.
An oxidation-reduction reaction must occur to generate an electrical potential difference between the two electrodes, driving the flow of electrons through the external circuit. Therefore, options A, C, and D are true for an electrochemical cell. Hence, B is incorrect.
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what is electron configuration of oxygen in its excited state
Answer:
[tex]1 {s}^{2} 2 {s}^{2} 2 {p}^{4} [/tex]
OR
[tex]2 : 6[/tex]
Answer:
If we look at the ground state (electrons in the energetically lowest available orbital) of oxygen, the electron configuration is [tex]1s^{2} 2s^{2} 2p^{4}[/tex] . If the element were to become excited, the electron could occupy an infinite number of orbitals. However, in most texts, the example will be the next available one. So for oxygen, it might look like this: [tex]1s^{2} 2s^{2} 2p^{3}3s^{1}[/tex] - where the valence electron now occupies the 3s orbital in an excited (i.e. not ground) state.
So, the electron configuration of oxygen in its excited state is [tex]1s^{2} 2s^{2} 2p^{3}3s^{1}[/tex].
Which of the following substances did Robert Brown observed upon forming the concept of Brownian motion?
A. Talc powder suspended in water
B. Talc powder suspended in air
C. Pollen grains suspended in water
D. Pollen grains suspended in air
Answer:
Talc powder suspended in air
Ammonia fumes is found to permanently fog soft contact lenses. Students wearing soft contact lenses should be particularly careful when doing this experiment. Will wearing goggles or other eye protection remove the risk or danger for these students?
Answer:
Wearing goggles or other eye protection will remove the risk or danger for these students
Explanation:
Soft contact lenses are usually worn in the eyes and Ammonia compound may fog the lens thereby retaining the particles of ammonia which could spread to the eye and cause a lot of damage to it.
Using a goggle is usually more effective in dealing with the risks involved as they prevent the Ammonia from having any contact at all with the eyes due to the far proximity to the eyes when compared to contact lenses.
Copper sulfate is made of one copper (Cu) atom, one sulfur (S) atom, and four oxygen (O) atoms. Write the chemical formula correctly.