Answer:
a spectrum of the electromagnetic radiation emitted by a source.
D
Explanation:
A. The photons emitted when an electron drops down an energy level.
Explanation:When a source emits electromagnetic radiation then the spectrum is called as emission spectrum. It is emitted during the process when an atom makes its transition of energy levels to ground state.
Ground state is the state where atom possesses the lowest energy. When an atom or molecule comes down from higher energy level to lower energy level, it emits the spectrum which is called as emission spectrum.
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Why is chlorine gas a product of NaCl electrolysis?
A. The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
B. The Cl+ ions become reduced at the anode allowing them to form Cl2 molecules.
C. The Na+ ions react to the anode, releasing the Cl- ions with enough energy to change into a gas.
D. The Na- ions react to the cathode, releasing the Cl+ ions with enough energy to change into a gas.
Answer:
A. The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
Explanation:
At the anode in an electrolytic cell oxidation occurs.
In the electrolysis of NaCl, at the anode both Cl⁻ and OH⁻ migrates here.
Cl⁻ is preferentially discharged and it undergoes oxidation as shown below:
2Cl⁻ → Cl₂ + 2e⁻
We see a loss of electron and change in oxidation number of Cl from -1 to 0
Chlorine gas is liberated in this electrode.
Answer:
The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
Explanation:
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3.50 liters of a gas at 727.0 K will occupy how many liters at 153.0 K?
Answer:
0.737 L
Explanation:
Charles law states for a fixed amount of gas, volume of the gas is directly proportional to the absolute temperature of the gas at constant pressure
we can use the following equation
V1/T1 = V2/T2
where V1 is volume and T1 is temperature at first instance
V2 is volume and T2 is temperature at the second instance
substituting the values
3.50 L / 727.0 K = V2 / 153.0 K
V2 = 0.737 L
new volume at 153.0 K is 0.737 L
Final answer:
Using Charles's Law, which states the direct relationship between the volume and temperature of a gas with constant pressure, we can calculate that 3.50 liters of gas at 727.0 K will occupy approximately 0.7366 liters at 153.0 K.
Explanation:
The question asks to determine the volume a gas will occupy at a different temperature, holding pressure and the amount of gas constant. This is a direct application of Charles's Law, which states that the volume of a gas is directly proportional to its temperature when pressure is held constant. To solve this, we can use the formula:
V1/T1 = V2/T2
Where V1 is the initial volume, T1 is the initial temperature, V2 is the final volume, and T2 is the final temperature. Plugging in the values we have:
V1 = 3.50 L
T1 = 727.0 K
T2 = 153.0 K
V2 = ?
First, let's isolate V2:
V2 = V1 * (T2/T1)
Now, substituting the given values:
V2 = 3.50 L * (153.0 K / 727.0 K)
Performing the calculation:
V2 = 3.50 L * 0.21045126...
V2 ≈ 0.7366 L
The gas originally at 727.0 K will occupy approximately 0.7366 liters at 153.0 K.
To determine the ammonia concentration in a sample of lake water, three samples are prepared. In sample A, 10.0 mL of lake water is mixed with 5 mL of phenol solution and 2 mL of sodium hypochlorite solution, and diluted to 25.0 mL in a volumetric flask. In sample B, 10.0 mL of lake water is mixed with 5 mL of phenol solution, 2 mL of sodium hypochlorite solution, and 2.50 mL of a 5.50×10−4 M ammonia solution, and diluted to 25.0 mL. Sample C is a reagent blank. It contains 10.0 mL of distilled water, 5 mL of phenol solution, and 2 mL of sodium hypochlorite solution, diluted to 25.0 mL. The absorbance of the three samples is then measured at 625 nm in a 1.00 cm cuvet. The results are shown in the table.Sample Absorbance (625 nm)A 0.419B 0.666C 0.045What is the molar absorptivity (????) of the indophenol product?????=M−1cm−1What is the concentration of ammonia in the lake water?[NH3]lake water=M
Answer:Sample Absorbance (625 nm)
A 0.536
B 0.783
C 0.045
Therefore, I will use these data to solve your question. If you have other absorbances values, just follow my steps and plug in different numbers.
First, we see 1 mole of NH3 gives 1 mole product.
In B moles of NH3 = moles of NH3 in A + (5.5 x10^-4 x2.5/1000) = 1.375 x10^6 + mA
( mA = moles of NH3 in A) vol of B = 25 = vol of A
now A = el C = eC ( since l = 1cm)
Because, n net absorbance due to complex blank absorbance must be removed.
Here A(A) = 0.536 - 0.045 = 0.491 , A(B) = 0.783 - 0.045 = 0.738
(you can plug in different numbers in this step)
A2/A1 = C2/C1 , A(B)/A(A) = (1.375x10^-6 +mA)/(mA) = 0.738/0.491
So, mA = 2.733 x 10^-6 = moles of NH3 in A (Lake water)
Hence [NH3] water ( 2.733 x10^-6 ) x 1000/25 = 1.093 x 10^-4 M
Lake water vol = 10 ml out of 25,
Concentration of ammonia in lake water = 2.733 x10^-6 x 1000/10 = 2.733 x 10^-4 M
Then, A = 0.491 = e x 1 x 1.093 x10^-4
e = 4492 M-1cm-1
Explanation:
The molar absorptivity (ε) of the indophenol product, as calculated using the Beer-Lambert law and the known concentration and measured absorbance of Sample B, is 12109.09 M^-1 cm^-1. To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank from the absorbance of Sample A, then use the Beer-Lambert law to solve for the concentration. It results in 0.000031 M, or 3.1x10^-5 M.
Explanation:To find the molar absorptivity (ε), we can use the Beer-Lambert law, which states that the absorbance (A) of a solution is directly proportional to its concentration (c) and the path length (l) through which the light passes. The formula is A = εlc. In this case, the path length is a constant 1.00 cm, so we can rearrange the formula to solve for ε: ε = A / (l * c).
Sample B contains a known amount of NH3. From this, we know that the concentration of NH3 in the solution is (2.50 mL * 5.50x10^-4 M) / 25 mL = 0.000055 M. Using the measured absorbance for sample B (0.666), we can solve for ε: ε = 0.666 / (1.00 cm * 0.000055 M) = 12109.09 M^-1 cm^-1.
To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank (C) from the absorbance of sample A, which contains an unknown amount of NH3. This gives us the absorbance due to the NH3 in the lake water: A' = 0.419 - 0.045 = 0.374. We can then use the Beer-Lambert law to solve for the concentration of NH3: [NH3] = A' / (ε * l) = 0.374 / (12109.09 M^-1 cm^-1 * 1.00 cm) = 0.000031 M, or 3.1x10^-5 M.
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How many protons and electrons are present in O²⁻?a) 8 protons and 8 electrons b) 10 protons and 8 electrons c) 8 protons and 10 electrons d) 16 protons and 8 electrons e) none of the above
Answer:
c) 8 protons 10 electrons
Because there would usually be 8 of both, but in this case there has to be 2 more electrons to give it the ²⁻ charge
Consider a galvanic (voltaic) cell that has the generic metals X and Y as electrodes. If X is more reactive than Y (that is, X more readily reacts to form a cation than Y does), classify the following descriptions by whether they apply to the X or Y electrode.
anode
cathode
electrons in the wire flow toward
electrons in the wire flow away
cations from salt bridge flow toward
anions from salt bridge flow toward
gains mass
loses mass
Consider a galvanic (voltaic) cell that has the generic metals X and Y as electrodes. If X is more reactive than Y (that is, X more readily reacts to form a cation than Y does), classify the following descriptions by whether they apply to the X or Y electrode.
Further explanation Anode: XCathode : Y Electrons in the wire flow toward : Y Electrons in the wire flow away : X Cations from salt bridge flow toward : y Anions from salt bridge flow toward : X Gains mass : Y Loses mass: XBecause X is more reactive than Y, So X is oxidized to X²⁺ and Y²⁺ is reduced to Y. Therefore the overall cell reaction is:
X(s) + Y²⁺(aq) → X²⁺(aq) + Y(s)
X electrode: Electrons in the wire flow away from, Anions from the salt bridge flow toward, Anode, Loses mass
Y electrode: Electrons in the wire flow toward, Cations from the salt bridge flow toward, Cathode, Gains mass
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Grade: 9
Subject: chemistry
Chapter: a galvanic (voltaic) cell
Keywords: galvanic (voltaic) cell, the generic metals, cathode, anode, salt bridge
Electrons flow from anode to cathode in a voltaic cell.
A voltaic cell is one in which electrical energy is produced by a redox reaction. Electrons flow from anode to cathode in a voltaic cell and the cell reaction is spontaneous.
Given a generic voltaic cell in which metal X is more reactive than metal Y, it follows that;
X will be the anode and Y will be the cathodeElectrons in the wire will flow away from X and flow towards YAnions in the salt bridge flow towards X while cations in the salt bridge flow towards Y.There will be a gain in mass at Y and a loss in mass at X.Learn more: https://brainly.com/question/1340582
Which of the following data tables correctly shows how temperature affects the reaction between sodium thiosulfate and hydrochloric acid?
a because as temperature increases, reaction rate increases.
Answer:
The correct answer is the table of point A.
Explanation:
An increase in temperature increases the speed of reaction, regardless of whether the reaction is endothermic or exothermic. This is because as the temperature increases, the number of molecules with an energy equal to or greater than the activation energy increases, thus increasing the number of effective shocks.
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A chemistry student weighs out 0.0975 g of acrylic acid (HCH2CHCO2) into a 250. mL volumetric flask and diluted to the mark with distilled water. He plans to titrate the acid with 0.0500 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the equilvalence point. Be sure your answer has the correct number of significant digits.
Answer:
27.06 mL.
Explanation:
Firstly, we need to calculate the molarity of acrylic acid.Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.
M = (no. of moles of acrylic acid)/(V of the solution (L))
M = (mass/molar mass)acrylic acid / (V of the solution (L))
mass of acrylic acid = 0.0975 g, molar mass of acrylic acid = 72.06 g/mol, V of the solution = 250 mL = 0.25 L.
∴ M = (0.0975 g/72.06 g/mol)/(0.25 L) = 0.0054 M.
For the acid-base neutralization, we have the role:The no. of millimoles of acid is equal to that of the base at the neutralization.
∴ (XMV) NaOH = (XMV) acrylic acid.
X is the no. of reproducible H⁺ (for acid) or OH⁻ (for base),
M is the molarity.
V is the volume.
For NaOH:X = 1, M = 0.05 M, V = ??? mL.
For acrylic acid:X = 1, M = 0.0054 M, V = 250.0 mL.
∴ V of NaOH = (XMV) acrylic acid/(XM) NaOH = (1)(0.0054 M)(250.0 mL)/(1)(0.05 M) = 27.06 mL.
To solve the problem, we first calculate the moles of acrylic acid, which is 0.001352 mol. Since it reacts with NaOH in a 1:1 ratio, the same amount of moles is needed for NaOH. Therefore, to find the volume of NaOH solution, we divide the moles of NaOH by its molarity, giving us the result of 27.04 mL.
Explanation:The question given is a standard acid-base titration problem in chemistry. We first need to determine the number of moles of acrylic acid present. The molar mass of acrylic acid (HCH2CHCO2) is approximately 72.06 g/mol. The moles of acrylic acid is given by mass divided by molar mass, so 0.0975g / 72.06g per mol = 0.001352 mol.
Now, since acrylic acid is a monoprotic acid and will react with NaOH in a 1:1 ratio, the moles of NaOH required to reach the equivalence point in titration is also 0.001352 mol.
The volume of NaOH solution can be found using the formula M = mol/L, rearranging to solve for volume gives L = mol/M. So, 0.001352 mol / 0.0500 mol per L = 0.02704 L or 27.04 mL of NaOH solution. Therefore, the student will need approximately 27.04 mL of the NaOH solution to reach the equivalence point in the titration.
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6. Newton's First Law of motion addresses a body at rest or in motion. What is inertia's role in Newton's First Law of Motion? A. It determines how much mass the object retains. B. It's associated with the acceleration of the object. C. It's the tendency for the body to change motion quickly. D. It's the tendency for the body to resist a change in motion
Answer: The correct answer is "It's the tendency for the body to resist a change in motion".
Explanation:
Newton's First Law of motion addresses a body at rest or in motion. This law is also known as "Law of inertia".
Inertia resists any change in the state of the object. Mass is a measure of inertia.
If the object is in motion then it remains in this state or if the object is at rest then it remains in this state unless the external force is applied.
If the object is moving with constant velocity then it will remain moving with this velocity unless it is accelerated.
Suppose, bus driver applies suddenly applies brake. The passenger sitting inside the bus falls forward. It is due to inertia. As the passenger does not want to change its state. It resists this change. The upper part of the body wants to remain in the state of motion. It's the tendency for the body to resist a change in motion
Therefore, the correct option is (D).
Which segments represent changes in potential energy of the molecules in the substance?
Check all that apply.
A-B
B-C
C-D
D-E
E-F
The segments A-B, C-D, and E -F in the graph represents the changes in potential energy of the molecules in the substance.
What is potential energy?The potential energy of a substance is the energy generated by virtue of its position at a height from the surface. The energy generated by virtue of the motion of the substance is called the kinetic energy.
The average kinetic energy of the substance is called its thermal energy. Hence, as the temperature of the substance increases, kinetic energy increases, potential energy decreases.
In the given graph, the segments, that indicates an increase in temperature indicates a decrease in potential energy. Hence, the segments A-B, C-D, and E -F in the graph represents the changes in potential energy of the molecules in the substance.
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The segments A-B, C-D, and E -F in the graph represents the changes in potential energy of the molecules in the substance.
The potential energy of a substance is the energy generated by virtue of its position at a height from the surface. The energy generated by virtue of the motion of the substance is called the kinetic energy.
The average kinetic energy of the substance is called its thermal energy. Hence, as the temperature of the substance increases, kinetic energy increases, potential energy decreases.
In the given graph, the segments, that indicates an increase in temperature indicates a decrease in potential energy. Hence, the segments A-B, C-D, and E -F in the graph represents the changes in potential energy of the molecules in the substance.
A certain radioactive element has a half-life of one hour. If you start with 20.0 grams of the element at noon, how much of the radioactive element will be left at 3 p.m.?
a. 10.0 grams b. 5.0 grams c. 2.5 grams d. 1.25 grams
your answer should be C.
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Answer: The correct answer is Option c.
Explanation:
All the radioactive reactions follows first order kinetics.
The equation used to calculate half life for first order kinetics:
[tex]t_{1/2}=\frac{0.693}{k}[/tex]
We are given:
[tex]t_{1/2}=1hr[/tex]
Putting values in above equation, we get:
[tex]k=\frac{0.693}{1}=0.693hr^{-1}[/tex]
Rate law expression for first order kinetics is given by the equation:
[tex]k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}[/tex]
where,
k = rate constant = [tex]0.693hr^{-1}[/tex]
t = time taken for decay process = 3.00 pm - 12.00 pm = 3 hour
[tex][A_o][/tex] = initial amount of the reactant = 20 g
[A] = amount left after decay process = ?
Putting values in above equation, we get:
[tex]0.693hr^{-1}=\frac{2.303}{3hr}\log\frac{20}{[A]}[/tex]
[tex][A]=2.5g[/tex]
Hence, the correct answer is Option c.
If a neutral atom becomes positively charged, it has undergone _________.
A. oxidation
B. catalyzation
C. None of these
D. redox
If a neutral atom becomes negatively charged, it has undergone reduction.
Reduction is the process through which a neutral atom gain an electron (thus reducing its oxidation number) and turns into a negative ion (also known as : anion)
So basically none of the above
If a neutral atom becomes negatively charged, it has undergone reduction. Hence, option C is correct.
What are atoms?An atom contains a central nucleus surrounded by one or more electrons.
Protons are bound in the nucleus and can be neither gained nor lost. So any change in the charge of an atom is due to changes in its electron count. If a neutral atom gains electrons, then it will become negatively charged. If a neutral atom loses electrons, then it becomes positively charged.
The loss of electrons is the corresponding increase in the oxidation state of a given reactant is called oxidation. The gain of electrons and the decrease in the oxidation state of a reactant is called reduction.
Reduction is the process through which a neutral atom gains an electron (thus reducing its oxidation number) and turns into a negative ion (also known as an anion).
Hence, option C is correct.
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In full detail, explain what happens during the electrolysis of a NaCl brine? Be sure to identify what is being oxidized and what is being reduced (2). Identify where in the cell the reactions are taking place (2).
Answer:
Explanation:
Electrolysis of aqeous sodium chloride(NaCl)
Electrolysis is a process that converts electrical energy into chemical energy.
Electrolytic processes involves three major steps:
1. Ionization of electrolyte and water
2. Migration of ions to electrodes
3. Discharge of ions at the electrodes.
For the Electrolysis of brine, we follow these three steps:
1. Ionization of the aqeous brine solution:
NaCl → Na⁺ + Cl⁻
H₂O ⇄H⁺ + OH⁻
2. Migration of ions to the electrodes
The positive charges Na⁺ and H⁺ would both go to the cathode which is the negatively charged electrode
The negative charges Cl⁻ and OH⁻ migrates to the anode which are the positively charged electrodes. The anode is positively charged electrode.
3. Discharge of ions at the electrodes.
The preferential discharge of ions is based on the activity series and concentration of the ions.
On the activity series H is lower and it discharges preferentially to Na in the cathode:
2H⁺ + 2e⁻ → H₂
At this electrode, the cathode, reduction occurs and H⁺ ions are reduced.
At the anode Cl⁻ and OH⁻ migrates. But Cl⁻ is discharged preferentially due to its higher concentration.
2Cl⁻ ⇄ Cl₂ + 2e⁻
This is the oxidation half and Cl is oxidized
What is the net ionic equation for the reaction that is represented by the following total ionic equation? 6Na+ + 2Ca^2+ + 6CI- → 6Na+ + 6CI- + Ca3(PO4)2
The net ionic equation for the given reaction simplifies the total ionic equation by removing spectator ions, focusing on the ions directly participating in the reaction.
Net Ionic Equation:
3 Ba²+ (aq) + 2 PO₄³¯ (aq) → Ba₃(PO₄)₂ (s)
For the given total ionic equation, spectator ions are removed to obtain the net ionic equation. In this case, the net ionic equation highlights the essential ions involved in the reaction.
All man-made and most carbon-based compunds are___ . 1. organic 2.inorganic
Answer:
2. Inorganic
Explanation:
All man-made and most carbon-based compounds are inorganic
Answer:
inorganic
Explanation:
If a reaction involves gases and the pressure is decreased, how will the equilibrium change?
A. Towards the side with the fewest molecules.
B. It will not be affected.
C. Towards the products.
D. Towards the side with the most molecules.
Answer:
A towards the sode with the fewest molecules
Answer:
Towards the side with the most molecules.
Explanation:
According to Le Chatelier’s Principle when stress is applied to a system in equilibrium, the equilibrium will shift in such a way to minimize the effect of the applied stress. In a reaction involving gases when pressure of the gas is decreased there are fewer gas molecules so to compensate for this the equilibrium will shift towards more moles of the gas or towards the side with the most molecules.
Use the following equation to determine the charge on iron when it dissociates from oxygen and determine whether it is being oxidized or reduced:
Fe2O3 + 3CO -> 2Fe + 3CO2
A. It starts with a charge of +3 and is reduced.
B. It starts with a charge of +2 and is reduced.
C. It starts with a charge of -2 and is oxidized.
D. It starts with a charge of -3 and is oxidized.
The correct answer is A. Brainliest would be much appreciated.
The oxidation state of [tex]Fe_2O_3[/tex] is +3. The bond formation between oxygen and iron depends on the difference in electronegativity between these two atoms. It starts with a charge of +3 and is reduced. Hence, option A is correct.
What is the oxidation number?The total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
Oxygen in nearly all cases has a charge of 2−, so the total ionic charge the O atoms exhibit is 3(−2)=−6 .
If two Fe atoms equalize this charge and make it neutral, the charge (oxidation state) of Fe in this compound must be 3+.
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What is a nonpolar covalent bond?
A.
a bond between two nonmetal atoms
B.
a bond in which electrons are shared unequally
C.
a bond with ΔEN greater than 0.5
D.
a bond between two atoms that have equal electronegativities
Reset
Answer: The correct answer is Option D.
Explanation:
A non-polar covalent bond is defined as the bond which is formed between the atoms having no difference in electronegativity values. For Example: [tex]Cl_2,H_2[/tex] etc..
In this bond, the electrons are shared equally and [tex]\Delta EN[/tex] value is equal to 0.
Hence, the correct answer is Option D.
The correct answer is D. A nonpolar covalent bond is a type of covalent bond where electrons are shared equally between two atoms due to equal electronegativities.
The equal sharing occurs because the atoms have identical or nearly identical electronegativity values, meaning neither atom attracts the shared electrons more than the other. An example of a nonpolar covalent bond can be found in a molecule of chlorine, where both chlorine atoms share the electrons equally.
A total of 2.00 mol of a compound is allowed to react with water in a foam coffee cup and the reaction produces 114 g of solution. The reaction caused the temperature of the solution to rise from 21.00 to 24.70 ∘C. What is the enthalpy of this reaction? Assume that no heat is lost to the surroundings or to the coffee cup itself and that the specific heat of the solution is the same as that of pure water. Enter your answer in kilojoules per mole of compound to three significant figures.
The enthalpy of this reaction is 0.882 kJ/mol.
Given the following data:
Initial temperature = 21.0°C Final temperature = 24.70°C Mass of solution = 114 grams.Number of moles = 2.00 molWe know that the specific heat capacity of water is 4.184 J/g°C.
To find the enthalpy of this reaction:
First of all, we would determine the quantity of heat energy that was used during this chemical reaction by using the formula;
[tex]Q = mc\theta[/tex]
Where:
Q represents the quantity of heat. m represents the mass of an object. c represents the specific heat capacity. ∅ represents the change in temperature.[tex]\theta = T_2 - T_1\\\\\theta = 24.70 - 21.00\\\\\theta = 3.70[/tex]
Substituting the values into the formula, we have:
[tex]Q = 114[/tex] × [tex]4.184[/tex] × [tex]3.70[/tex]
Quantity of heat, Q = 1764.81 Joules
Now, we can find the enthalpy of this reaction by using the formula;
[tex]Enthalpy = \frac{Energy}{Number\; of\; moles}[/tex]
Substituting the parameters into the formula, we have:
[tex]Enthalpy = \frac{1764.81}{2.00}[/tex]
Enthalpy = 882.405 J/mol.
In Kilojoules per mole of compound to three significant figures:
Note: 1 Kilojoules = 1000 Joules
[tex]Enthalpy = \frac{882.405}{1000}[/tex]
Enthalpy = 0.882 kJ/mol.
Therefore, the enthalpy of this reaction is 0.882 kJ/mol.
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To find the enthalpy of the reaction, we first calculate heat change with the equation q = msΔT, where m is mass, s is the specific heat, and ΔT is the change in temperature. The calculated heat energy is then divided by the number of moles of the compound to find the enthalpy. Thus, the enthalpy for the reaction described is approximately 0.886 kJ/mol.
Explanation:To calculate the enthalpy of the reaction, we first need to calculate the heat change, noted as q. The equation for q in a reaction is q = msΔT where m is mass, s is the specific heat, and ΔT is the change in temperature.
First, transform the 114 grams of solution into mL since the density of water is approximately 1.0 g/mL. So the mass of the solution is 114 mL.
The change in temperature (ΔT) is 24.70°C - 21.00°C = 3.70°C. The specific heat (s) of water is 4.18 J/g°C. Using these figures, the calculation becomes: q = (114 g)(4.18 J/g°C)(3.70°C) = 1772.428 J or 1.772 kJ (keep in mind 1 kJ = 1000 J).
To find the enthalpy, which is expressed as kJ/mol, we divide the heat energy change by moles. So, the enthalpy = q (in kJ) / moles = 1.772 kJ / 2.00 mol = 0.886 kJ/mol.
Therefore, the enthalpy of this reaction is approximately 0.886 kJ/mol.
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Quick chemistry question (photo attached)
Answer:
18,8 kJ
Explanation:
Heat=(ΔH)*ν, where ν=m(CH₃OH)/M(CH₃OH). Then
[tex]Heat=\frac{m(CH_3OH)*H}{M(CH_3OH))}=\frac{15.8*38.0}{32} =18.76(kJ).[/tex]
To what temperature must propane be cooled to remain a liquid at standard sea level?
any temperature below 40°C
any temperature above -42°C
at or below -42°C
below 20°C
Boils at -40 C (or F, same same) so colder than that it would be a clear stable liquid.
Answer:
At or below -42°C
Explanation:
Hello,
As propane is gaseous at the standard sea level wherein the atmospheric pressure is 1 atm and the environmental temperature roughly 25°C, in order to condense it, say convert it from gas to liquid, one must cool it down at least until its boiling temperature which is -42°C. In such manner, to remain as a liquid, it must be cooled down at or below 42°C.
Best regards.
Which of the following would have the greatest reaction speed?
A. A reaction with solid reactants under low pressure and with high surface area.
B. A reaction in cold temperature and high surface area with gaseous reactants.
C. A reaction with liquids under high pressure and high surface area.
D. A reaction with solids at high temperature and high surface area.
Letter D is the answer
The correct answer is D. Brainliest would be much appreciated.
True or False. Mixing of baking soda with vinegar is a chemical change.
True- it is a chemical change
True, the mixing of baking soda with vinegar is a chemical change.
Mixing of baking soda with vinegar is indeed a chemical change. This reaction occurs when the acetic acid in vinegar reacts with sodium bicarbonate (baking soda) to produce carbon dioxide gas, water, and sodium acetate. The formula for this reaction is:
NaHCO3 + CH3COOH → CO2 + H2O + CH3COONa. The bubbling and fizzing observed when these two substances are mixed is due to the release of carbon dioxide gas. Additionally, since vinegar is an acid and baking soda is a base, mixing the two results in a reaction that neutralizes the pH of the solution.
Sodium and chlorine combine to form table salt, also called sodium chloride. Sodium chloride is a(n) A. atom. B. element. C. compound. D. mixture
Answer:
C. Compound
Explanation:
NaCl is a combination of two elements. This is specifically an ionic compound.
Sodium chloride is a compound.
What is a compound?A chemical compound exists as a chemical substance comprised of many identical molecules composed of atoms from more than one component held together by chemical bonds. Compounds exist as chemical substances made up of two or more elements that exist chemically bound together in a fixed ratio. All the subject in the universe is composed of atoms of more than 100 various chemical elements, which exist found both in pure form and incorporated into chemical compounds. Chemical compounds exist formed by elements that bond together. These bonds stand generally covalent, ionic, or metallic bonds.
The correct solution is option C.
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How many grams of ammonium chloride (NH4Cl) do you have if you have 0.436 moles?
Answer:
23.33 g
Explanation:
molar mass is the mass of 1 mol of atom/compound
molar mass of a compound can be calculated by taking the sum of the products of the molar mass of each element by the number of molecules of that element in the compound
molar mass of NH₄Cl
molar mass of N - 14 g/mol
molar mass of H - 1 g/mol
molar mass of Cl - 35.5 g/mol
molar mass of NH₄Cl - (14 g/mol x 1) + (1 g/mol x 4) + (35.5 g/mol x 1) = 53.5 g/mol
therefore mass of 1 mol of NH₄Cl - 53.5 g
mass of 0.436 mol = 53.5 g/mol x 0.436 mol = 23.33 g
mass of NH₄Cl is 23.33 g
Answer:
0.436 moles of ammonium chloride (NH4Cl) has a mass of 23.3 grams
Explanation:
Step 1: Data given
Number of moles of NH4Cl = 0.436 moles
Molar mass of NH4Cl = 53.49 g/mol
Step 2: Calculate mass of ammonium chloride
Mass = moles * molar mass
Mass NH4Cl = moles NH4Cl * molar mass NH4Cl
Mass NH4Cl = 0.436 moles * 53.49 g/mol
Mass NH4Cl = 23.3 grams
0.436 moles of ammonium chloride (NH4Cl) has a mass of 23.3 grams
Which of the following ions is in the lowest oxidation state?
A. P in H2PO−4
B. Cr in Cr2O2−7
C. Fe in Fe2O3
D. None of these
Final answer:
Iron (Fe) in Fe2O3 has the lowest oxidation state (+3) among the given options, making Option C the correct answer.
Explanation:
To determine which of the following ions is in the lowest oxidation state, we can calculate the oxidation states of the central atoms in the given compounds:
For H2PO−4, phosphorus (P) has an oxidation state of +5.For Cr2O72−, each chromium (Cr) has an oxidation state of +6.For Fe2O3, iron (Fe) has an oxidation state of +3.Considering the calculated oxidation states, the lowest oxidation state among the options is for iron (Fe) in Fe2O3. Therefore, the correct answer is C. Fe in Fe2O3.
You are experimenting on the effect of temperature on the rate of reaction between hydrochloric acid (HCl) and potassium iodide (KI). When the reaction is completed at 400K there are approximately 250,000 collisions per mole of reactant. You run the experiment again at 150K. Which of the following would you expect to be the number of collisions recorded at 150K
A. 0
B. 400,000
C. 250,000
D. 15,000
Answer:
D. 15,000.
Explanation:
Kinetic energy of the molecules (of the reactants) is directly proportional to its temperature according to the relation:KE = (3/2)KT
Where, KE is the kinetic energy of the molecules (J),
K is the Boltzmann constant (1.381 × 10⁻²³ J/K),
T is the temperature (K)
The KE (energy of motion of the molecules) can be expressed as the collisions per mole of reactant.When temperature increases, the collisions per mole of reactant and then the kinetic energy increases.In this problem, at 400 K there are approximately 250,000 collisions per mole of reactant. So, at 150 K, the KE will decrease and also the collisions per mole of reactant will decrease. It is also impossible, for the collisions per mole of reactant, to be zero at this T (150 K).So, the right choice is: D. 15,000
Answer: D. 15,000.
Explanation: Founders Educere answer. And whatever that dude said^
What can be said about an endothermic reaction with a negative entropy change? spontaneous at all temperatures. spontaneous at high temperatures. spontaneous at low temperatures. spontaneous in the reverse direction at all temperatures. nonspontaneous in either direction at all temperatures. Submit
Answer:
spontaneous in the reverse direction at all temperaturesExplanation:
The parameter to predict the spontaneity of a reduction is the change in the free energy, ΔG.
This is how it works:
If ΔG = 0, the system is in equilibriumIf ΔG > 0, the reaction is non-spontaneous.If ΔG < 0, the reaction is spontaneous.In brief, free energy's decrease tells that a reaction is spontaneous, while free energy's increase tells a reaction is nonspontaneous.
Now, take the definition of the free energy:
G = H - TSΔG = ΔH - TΔSThe conditions given in the statement are:
An endothermic reaction ⇒ ΔH > 0 (positive)A negative entropy change ⇒ ΔS < 0 ⇒ TΔS < 0 (negative)Replacing in the equation ΔG = ΔH - TΔS, you get:
ΔG = positive - (negative) = positive + positive = positive.Then, you conclude that for an endothermic reaction with a negative entropy change, the change in the free energy is positive, and so the reaction is nonspontaneous (at all temperatures) in the forward direction.
Since, the change in the reverse direction has opposite sign, you also conclude that the reaction is spontaneous in the reverse direction at all temperatures.
Question 1.
An isotope has a half-life of 6 hours. If the original sample had a mass of 500 grams, how much of the sample would be left after 30 hours. Be sure to identify the number of 1/2 life that occurred and to explain how you obtained this answer.
Question 2.
Calculate the percent by mass of water in Copper (II) Fluoride tetra hydrate. You must show all of your work to earn credit. Atomic masses of each element: Cu = 64, F = 19, O = 16, H= 1
Question 3.
If the percent (mass/mass) for a solute is 16% and the mass of the solution is 400 g, what is the mass of solute in solution?
A.6400 grams
B. 25 grams
C.64 grams
D. 0.04 grams
Answer:
Question 1. → The amount remained is 15.625 g after 5 half-lives (30 hours).
Question 2. → mass % of water =41.4 %
Question 3. → C. 64 grams.
Explanation:
Question 1.
It is known that the decay of isotopes and radioactive material obeys first order kinetics.
Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
Thus, 30 hours represent (30/6) 5 half-lives.
500 g →(first 1/2 life) 250 g →(second 1/2 life) 125 g →(third 1/2 life) 62.5 g →(fourth 1/2 life) 31.25 g →(fifth 1/2 life) 15.625 g
So, The amount remained is 15.625 g after 5 half-lives (30 hours).
Question 2.
The formula of Copper (II) Fluoride tetra hydrate is CuF₂.4H₂O.the molar mass of Copper (II) Fluoride tetra hydrate is the sum of the atomic masses o each element.molar mass of 1 mol of CuF₂.4H₂O = 64 + 2*(19) + 8* (1) + 4*(16) = 174 g/mol.molar mass of 4 mol of H₂O = 8*(1) + 4*(16) = 72 g/mol 1 mol of Copper (II) Fluoride tetra hydrate → 4 mol H₂Omass % of water = (mass of 4 mol of H₂O) / (mass of 1 mol of CuF₂.4H₂O ) *100 = (72 /174) *100 = 41.4 %
Question 3.
Mass percentage is defined as the mass of a solute divided by the total mass of the solution, multiplied by 100
mass percent = ( mass of solute / mass of solution) *100∴ 16 = ( mass of solute / 400 g) *100
mass of solute = (16* 400)/ 100 = 64 g.
So the right choice is C. 64 grams.
Which is not a physical property?
A) hardness
B) boiling point
C) ability to conduct electricity
D) ability to combine with oxygen
Boiling point is the only answer that doesn’t have to do with their physical property
Answer:
D) ability to combine with oxygen
Explanation:
D because oxygen is not visible so that is not a physical property