Answer:
1. NaI Y AgI
2. K2S Y CuS
3. K2CO3 N
Explanation:
1. When we add NaI to the mixture, the reaction that takes place is:
NaI(aq) + Ag⁺(aq) → AgI(s) + Na⁺(aq)Such a reaction does not happen with Cu⁺².
2. When we add K₂S to the mixture, the reaction that takes place is:
K₂S(aq) + Cu⁺²(aq) → CuS(s) + 2K⁺(aq)Such a reaction does not happen with Ag⁺.
3. When we add K₂CO₃ to the mixture, the reactions that take place are:
K₂CO₃(aq) + 2Ag⁺(aq) → Ag₂CO₃(s) + 2K⁺(aq)K₂CO₃(aq) + Cu⁺²(aq) → CuCO₃(s) + 2K⁺(aq)This means both Cu⁺² and Ag⁺ would precipitate, thus they would not be separated.
Consider the following four pairs of molecules. You may use 1H-NMR, 13C-NMR, or IRspectroscopyto differentiate the structures, but you may use a technique only once on this page(i.e. each pair mustuse a different technique).For each pair, pick one of the above forms of spectroscopy and describe the single clearest difference between the two compounds by that analytical technique.
Answer:
The question is incomplete. The structures were not added to the question. Find attached of the structure and the given answer.
Explanation:
See the attached file for explanation
Draw the structure of the major organic product of the following reaction.
NaOCH2CH3
------------------------------→
95% aq. ethanol, 20°
Predict whether the product will be an aldol or an enone.
You do not have to consider stereochemistry.
You do not have to explicitly draw H atoms.
Do not include lone pairs in your answer.
They will not be considered in the grading.
If no reaction occurs, draw the organic starting material.
Answer:
Aldol
Explanation:
The reaction will be an aldol.
The iron content of foods can be determined by dissolving them in acid (forming Fe3+), reducing the iron(III) to iron(II), and titrating with cerium(IV): Fe2+(aq) + Ce4+(aq) → Fe3+(aq) + Ce3+(aq). Identify the two half-reactions in the above reaction. oxidation half-reaction reduction half-reaction
Answer:
Oxidation half-reaction:Fe²⁺(aq) → Fe³⁺(aq) + 1e⁻
Reduction half-reaction:Ce⁴⁺(aq) + 1e⁻ → Ce³⁺(aq)
Explanation:
The reaction that takes place is:
Fe²⁺(aq) + Ce⁴⁺(aq) → Fe³⁺(aq) + Ce³⁺(aq)The oxidation half-reaction is:
Fe²⁺(aq) → Fe³⁺(aq) + 1e⁻It is an oxidation because the oxidation state of Fe increases from 2+ to 3+.
The reduction half-reaction is:
Ce⁴⁺(aq) + 1e⁻ → Ce³⁺(aq)It is a reduction because the oxidation state of Ce decreases from 4+ to 3+.
What is the amount of heat required to raise the temperature of 200.0 g of aluminum by 10°C? (specific heatof aluminum = 0.21 cal/g°C)
4,200 cal
420 cal
42, 00 cal
420,000 cal
Answer:
We need 420 cal of heat
Explanation:
Step 1: Data given
Mass of the aluminium = 200.0 grams
Temperature rises with 10.0 °C
Specific heat of aluminium = 0.21 cal/g°C
Step 2: Calculate the amount of heat required
Q =m * c* ΔT
⇒with Q = the amount of heat required= TO BE DETERMINED
⇒with m = the mass of aluminium = 200.0 grams
⇒with c = the specific heat of aluminium = 0.21 cal/g°C
⇒with ΔT = the change of temperature = 10.0°C
Q = 200.0 grams * 0.21 cal/g°C * 10.0 °C
Q = 420 cal
We need 420 cal of heat (option 2 is correct)
Answer:
420 cal of heat
Explanation:
You carry out a reaction that yields a major product Q (boiling point: 120°C) and side product R (boiling point: 150°C). The ratio of Q to R is 70:30. Both Q and R are liquids. m) You use ethyl acetate (0.902 g/mL) to act as an extraction solvent. What are three main criteria for the liquid/liquid extraction organic solvent based on the lecture notes? (3 pts) What layer will ethyl acetate be at? (upper/lower) (1 pt) n) Q and R will be soluble in the organic layer (ethyl acetate) – any residual inorganic material was removed by water. Provide two ways you remove water from the organic layer. (2 pts) o) After the ethyl acetate is evaporated, Q and R (a mixture of liquids) remain. What criteria does this mixture have to satisfy to be separated by simple or fractional distillation (besides bp difference and composition)? (1 pt) p) What kind of distillation would you carry out (simple or fractional) and why? (3 pts) q) What parts of the microscale kit (seen on page 12 in the textbook) that you use for the distillation you pick that you don’t use for the alternate distillation (the one you didn’t pick)? (3 pts)
Answer:
Here's what I get
Explanation:
1. Requirements for a liquid/liquid extraction solvent
(a) Distribution Coefficient
The solute must be more soluble in the solvent (the extract phase) than in the raffinate phase (the other liquid).
(b) Insolubility
The solvent and the other liquid must be mutually immiscible. This means they will form two layers in the separatory funnel.
(c) Removability
It must be easy to separate the solvent from the solutes. This usually means the solvent must have a much lower boiling point than the solutes.
2. Extract layer
The density of ethyl acetate is 0.920 g/mL.
The density of water is 1.00 g g/mL.
The ethyl acetate layer will be on the top.
3. Separability of mixture
Two miscible liquids must have a boiling point difference of at least 40 °C to be separable by simple distillation.
4. Type of distillation
The boiling point difference is only 30°C, so you must use fractional distillation.
5. Apparatus
Your microscale kit must include an air condenser or a fractionating column.
Perhaps it looked like the fractionating head in the kit in Fig. 1.
The alternate distillation (simple distillation) would use a distillation head like that in Fig. 2.
Final answer:
The three main criteria for the liquid/liquid extraction solvent are solvent properties, low boiling point, and chemical inertness. Ethyl acetate will be in the upper layer. Water can be removed from the organic layer using drying agents or azeotropic distillation. The mixture of Q and R should have a significant difference in boiling points and the desired composition to be separated by distillation. Fractional distillation would be carried out in this case, using the distilling flask, condenser, and receiving flask from the microscale kit.
Explanation:
The three main criteria for the liquid/liquid extraction organic solvent are:
Good solvent properties: The solvent should be able to efficiently dissolve the desired solutes while not dissolving other unwanted components.Low boiling point: The solvent should have a lower boiling point than the desired solutes in order to easily evaporate and separate from the solutes.Chemically inert: The solvent should not react with the solutes or other components present in the mixture, to avoid unwanted side reactions.Ethyl acetate will be in the upper layer as it has a lower boiling point than both the major product Q and the side product R.
To remove water from the organic layer, two methods can be used:
Drying agents: Adding a suitable drying agent such as anhydrous sodium sulfate or magnesium sulfate to absorb water from the organic layer.Azeotropic distillation: Utilizing azeotropic distillation by adding another solvent or compound that forms an azeotrope with water, which can then be easily separated from the organic layer by distillation.The mixture of liquids Q and R needs to satisfy the following criteria to be separated by simple or fractional distillation:
Significant difference in boiling points: The boiling points of Q and R should have a noticeable difference to allow for selective vaporization and condensation during distillation.Desired composition: The mixture should have the desired ratio or composition of Q and R for effective separation.In this case, a fractional distillation would be carried out because the boiling points of Q and R are relatively close, and fractional distillation provides better separation of two volatile liquids with similar boiling points.
The parts of the microscale kit that would be used for the chosen fractional distillation would include the distilling flask, condenser, and receiving flask. These are essential components for the distillation process. The parts that would not be used for the alternate distillation method would depend on the specific method chosen but could include components such as the fractionating column or any additional specialized equipment.
When CO2(g) reacts with H2(g) to form C2H2(g) and H2O(g), 23.3 kJ of energy are absorbed for each mole of CO2(g) that reacts. Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation. Note that the answer box for the energy term is case sensitive. Use the SMALLEST INTEGER coefficients possible and put the energy term in the last box on the appropriate side of the equation. If a box is not needed, leave it blank. 2CO2 + 5H2 + C2H2 + 4H2O + -46.6kJ
Final answer:
The balanced thermochemical equation for the endothermic reaction of CO2(g) and H2(g) forming C2H2(g) and H2O(g), with the energy absorption of 23.3 kJ per mole of CO2, is 2CO2(g) + 5H2(g) + 46.6 kJ → 2C2H2(g) + 4H2O(g). The energy term is positive and on the reactant side due to the endothermic nature of the reaction.
Explanation:
The question involves writing a balanced thermochemical equation for the reaction where carbon dioxide (CO2) and hydrogen gas (H2) react to form acetylene (C2H2) and water (H2O), with an energy absorption of 23.3 kJ per mole of CO2 that reacts. Since energy is absorbed, it is an endothermic reaction, and the energy term will appear on the reactant side of the equation with a positive sign.
The balanced thermochemical equation is:
2CO2(g) + 5H2(g) + 46.6 kJ → 2C2H2(g) + 4H2O(g)
Note that we multiply the energy absorbed per mole by the number of moles of CO2, which is 2, resulting in a total energy absorption of 46.6 kJ for the reaction as written.
Assign oxidation states to all of the species in the following redox reaction. For the reactants, identify electron loss or gain, the species oxidized, the species reduced, the oxidizing agent and the reducing agent. Co(s) + F2(g) Co2+(aq) + 2F-(aq) Oxidation state Electron loss or gain Oxidized or reduced Reducing or oxidizing agent
Answer: Co lose two electrons and thus gets oxidized and acts as reducing agent.
[tex]F_2[/tex] gain two electrons and thus gets reduced and acts as oxidizing agent.
Explanation:
Oxidation reaction : When there is an increase in oxidation state number by loss of electrons
Reduction reaction : when there is a decrease in oxidation state number by gain of electrons.
[tex]Co(s)+F_2(g)\rightarrow Co^{2+}(aq)+2F^-(aq)[/tex]
Cobalt metal has undergone oxidation, as its oxidation state is changing from 0 to 2+.
Florine gas has undergone reduction, as its oxidation state is changing from 0 to -1.
The chemical agent which itself get oxidized and reduce others is called reducing agent. Thus Co is a reducing agent.
The chemical agent which itself get reduced and oxidize others is called oxidizing agent. [tex]F_2[/tex] is an oxidizing agent.
You are examining decomposition of corn leaves following the growing season on a farm. To do this, you place 33 g of corn leaves in a mesh bag and measure decomposition over time. In a literature search, you find that the decay constant of corn leaves is typically 0.04. Given this, use the equation mt =moe−kt to predict the leaf mass remaining in the bag after 30 days.
a. 0.009 g
b. 23.3 g
c. 9.94 g
d. 1.7 g
e. 14.8 g
Answer:
c. 9.94 g
Explanation:
From the question,
Using
mt = m₀e⁻kt.................... Equation 1
Where mt = mass of the leaf remaining in the bag, m₀ = original mass of leave that was placed in the bag, k = decay constant, t = time.
Given: m₀ = 33 g, k = 0.04, t = 30 days.
Substitute into equation 1
mt = 33(e⁻(0.04ˣ30))
mt = 33e⁻¹²/¹⁰
mt = 33/e¹²/¹⁰
mt = 33/3.320
mt = 9.94 g.
Hence the right answer is c. 9.94 g
Calculate the amount of heat needed to convert 50.0 g of liquid water at to steam at 100ºC.
16,700 J
113,000 J
104 J
209 J
Answer:
We need 113000 J of heat (option 2 is correct)
Explanation:
Step 1: Data given
Mass of liquid water = 50.0 grams
ΔHVap = 2260 J/g
Temperature = 100 °C
ΔHVap = The amount of heat released to change phase of a liquid water to steam = 2260 J/g
Step 2: Calculate the heat needed
Q =m* ΔHVap
⇒with Q = the amount of heat needed = TO BE DETERMINED
⇒with m = the mass of water = 50.0 grams
⇒with ΔHVap = 2260 J/g
Q = 50.0 grams * 2260 J
Q = 113000 J
We need 113000 J of heat (option 2 is correct)
1. Determine if the following statements are true or false (each question is worth one point). The rate law for an overall reaction can be written using the coefficients from the overall reaction The rate determining step of the reaction is alwaysthe first step of the reaction A catalyst is a species that is added to the reaction, lowers the activation energy of a reaction, shows up in the rate law (most of the time), and will be in the overall balanced equation Tries 0/45
Answer:
1. F
2. F
3. F
Explanation:
Determine if the following statements are true or false.
The rate law for an overall reaction can be written using the coefficients from the overall reaction. FALSE. The rate law includes the reaction orders, which have to be determined experimentally and may or may not be equal to the coefficients of the overall reaction.The rate-determining step of the reaction is always the first step of the reaction. FALSE. The rate-determining step is always the slowest step.A catalyst is a species that is added to the reaction, lowers the activation energy of a reaction, shows up in the rate law (most of the time), and will be in the overall balanced equation. FALSE. A catalyst does lower the activation energy of the reaction, but it doesn't show up in the rate law nor the overall balanced equation.Final answer:
The statements regarding the rate law being written using coefficients from the overall equation and the rate-determining step always being the first step of the reaction are both false. A catalyst does lower activation energy but is not included in the rate law nor in the overall balanced equation.
Explanation:
Determining the rate law of a chemical reaction and the rate-determining step is a critical part of understanding reaction kinetics in chemistry. The first statement, 'The rate law for an overall reaction can be written using the coefficients from the overall reaction,' is false. The rate law cannot be directly inferred from the stoichiometric coefficients in the balanced chemical equation; it is determined empirically and often depends on the mechanism and the slowest, rate-determining step of the reaction.
The second statement, 'The rate-determining step of the reaction is always the first step of the reaction,' is also false. While the rate-determining step can be the first step, this is not always the case. It is the slowest step with the highest activation energy, and not necessarily the first step in the reaction mechanism.
The third statement about a catalyst being a species that lowers the activation energy and shows up in the rate law (most of the time) is partly correct. A catalyst does lower the activation energy and speeds up the reaction but does not appear in the rate law and is not present in the overall balanced equation because it is not consumed in the reaction; thus, this statement is false in the context given.
Calculate Δ H rxn for the reaction: 5 C ( s ) + 6 H 2 ( g ) → C 5 H 12 ( l ) Use the following reactions and given ΔH’s: C 5 H 12 ( l ) + 8 O 2 ( g ) → 5 CO 2 ( g ) + 6 H 2 O ( g ) Δ H = − 3244.8 kJ C ( s ) + O 2 ( g ) → CO 2 ( g ) Δ H = − 393.5 kJ 2 H 2 ( g ) + O 2 ( g ) → 2 H 2 O ( g ) Δ H = − 483.5 kJ
Answer: The enthalpy of reaction is, -173.2 kJ
Explanation:
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
[tex]5C(s)+6H_2(g)\rightarrow C_5H_{12}(l)[/tex] [tex]\Delta H=?[/tex]
The intermediate balanced chemical reaction will be,
(1) [tex]C_5H_{12}(l)+8O_2(g)\rightarrow 5CO_2(g)+6H_2O(g)[/tex] [tex]\Delta H_1=-3244.8kJ[/tex]
(2) [tex]C(s)+O_2(g)\rightarrow CO_2(g)[/tex] [tex]\Delta H_2=-393.5[/tex]
(3) [tex]2H_2(g)+O_2(g)\rightarrow 2H_2O(g)[/tex] [tex]\Delta H_3=-483.5kJ[/tex]
Reversing (1) , Multiply (2) by 5 , (3) by 3 and add
[tex]\Delta H=\Delta H_1+5\times \Delta H_2+3\times \Delta H_3[/tex]
[tex]\Delta H=(+3244.8)+(5\times -393.5)+(3\times -483.5)[/tex]
[tex]\Delta H=-173.2kJ[/tex]
Therefore, the enthalpy of reaction is, -173.2 kJ
How long does it take to electroplate 0.5 mm of gold on an object with a surface area of 31 cm^^ from an Au3+(aq) solution with a 8 A current? Recall the density of gold is 19.3 g/cm^3.
Answer:
It will take 5492 seconds to electroplate 0.5 mm of gold on an object .
Explanation:
Mass of gold = m
Volume of gold = v
Surface area on which gold is plated = [tex]a=31 cm^2[/tex]
Thickness of the gold plating = h = 0.5 mm = 0.05 cm
1 mm = 0.1 cm
[tex]V=a\times h=31 cm^2\times 0.05 cm=1.55 cm^3[/tex]
Density of the gold = [tex]d=19.3 g/cm^3[/tex]
[tex]m=d\times v=19.3 g/cm^3\times 1.55 cm^3=29.915g[/tex]
Moles of gold = [tex]\frac{29.915 g}{197 g/mol}=0.152 mol[/tex]
[tex]Au^{3+}+3e^-\rightarrow Au[/tex]
According to reaction, 1 mole of gold required 3 moles of electrons,then 0.152 moles of gold will require :
[tex]\frac{3}{1}\times 0.152 mol=0.456 mol[/tex] of electrons
Number of electrons = N =[tex]0.456\times \times 6.022\times 10^{23}[/tex]
Charge on single electron = [tex]q=1.6\times 10^{-19} C[/tex]
Total charge required = Q
[tex]Q=N\times q[/tex]
Amount of current passes = I = 8 Ampere
Duration of time = T
[tex]I=\frac{Q}{T}[/tex]
[tex]T=\frac{N\times q}{I}[/tex]
[tex]=\frac{0.456\times \times 6.022\times 10^{23}\times 1.6\times 10^{-19} C}{8 A}=5492 s[/tex]
It will take 5492 seconds to electroplate 0.5 mm of gold on an object .
Kayla owns a food truck that sells tacos and burritos. She sells each taco for $3 and each burrito for $7.25. Yesterday Kayla made a total of $595 in revenue from all burrito and taco sales and there were twice as many burritos sold as there were tacos sold. Write a system of equations that could be used to determine the number of tacos sold and the number of burritos sold. Define the variables that you use to write the system.
The system equations that could be used to determine the number of tacos sold and the number of burritos sold is 17.5x = 595. The variable x is the number of tacos sold.
Let the number of tacos sold = x
Let the number of burritos sold = y
It has been told the revenue for the selling of both taco and burrito = 595 $.
The price of 1 taco = $3
The price of 1 burrito = $7.25
So, 3x + 7.25y = 595. ......(i)
It has been told that the number of burritos sold is twice the number of taco sold.
Since the number of tacos sold = x
Number of burritos sold = 2x
Number of burritos sold = y
y = 2x.
Substituting the value of y in the equation (i).
3x + 7.25 (2x) = 595
3x + 14.5x = 595
17.5x = 595.
For more information about the variable equation, refer to the link:
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You mix 125 mL of 0.170 M with 50.0 mL of 0.425 M in a coffee-cup calorimeter, and the temperature of both solutions rises from 20.20 °C before mixing to 22.17 °C after the reaction. What is the enthalpy of reaction per mole of ? Assume the densities of the solutions are all 1.00 g/mL, and the specific heat capacities of the solutions are 4.2 J/g · K. Enthalpy of reaction = kJ/mol
Here is the correct question
You mix 125 mL of 0.170 M CsOH with 50.0 mL of 0.425 M HF in a coffee-cup calorimeter, and the temperature of both solutions rises from 20.20 °C before mixing to 22.17 °C after the reaction. What is the enthalpy of reaction per mole of ? Assume the densities of the solutions are all 1.00 g/mL, and the specific heat capacities of the solutions are 4.2 J/g · K. Enthalpy of reaction = kJ/mol
Answer:
75.059 kJ/mol
Explanation:
The formula for calculating density is:
[tex]density = \frac{mass}{volume}\\[/tex]
Making mass the subject of the formula; we have :
mass = density × volume
which can be rewritten as:
mass of the solution = density × volume of the solution
= 1.00 g/mL × (125+ 50 ) mL
= 175 g
Specific heat capacity = 4.2 J/g.K
∴ the energy absorbed is = mcΔT
= 175 × 4.2 × (22.17 - 20.00) ° C
= 1594.95 J
= 1.595 J
number of moles of CsOH = [tex]\frac{125}{1000} *100[/tex]
= 0.2125 mole
Therefore; the enthalpy of the reaction = [tex]\frac{Energy \ absorbed }{number \ of \ moles}[/tex]
= [tex]\frac{1.595}{0.02125}[/tex]
= 75.059 kJ/mol
Final answer:
The enthalpy of reaction is calculated by first determining the total heat absorbed or released (∆Q) using the mass of the solutions, specific heat capacity, and temperature change from the calorimetry experiment. Then, by adjusting ∆Q for the amount of reactant, the ∆H per mole is found.
Explanation:
The question concerns the calculation of the enthalpy of reaction from a mixing experiment in a coffee-cup calorimeter. Given are volumes and molarities of two solutions mixed, along with the temperature change upon mixing. The enthalpy of reaction (∆H) is calculated using the concept that the heat absorbed or released by the solution (∆Q) during the reaction, adjusted for the amount of reactant, is equivalent to the enthalpy change.
To find ∆H, first, the mass of the solution needs to be calculated assuming the density is 1.00 g/mL. Then ∆Q can be determined using the specific heat capacity (4.2 J/g·K), the mass of the solution, and the temperature change. Finally, ∆H per mole of reactant can be calculated by dividing ∆Q by the moles of the limiting reactant. This approach illustrates how calorimetry experiments can provide valuable insights into the thermochemical properties of reactions.
Group the following electronic configurations of neutral elements in sets according to those you would expect to show similar chemical properties.
a. 1s^22s^22p^63s^23p^3
b. 1s^22s^22p^63s^23p^63d^104s^24p^5
c. 1s^22s^22p^63s^23p^6
d. 1s^22s^22p^3
Answer:
Option A and D
Explanation:
The element with electronic configuration 1s^22s^22p^63s^23p^3 and the element with electronic configuration 1s^22s^22p^3 will show similar chemical properties as they both have the same valence electrons of 5 each. The valence electron of the two elements shows that they both belong to the same group. Elements in the same group naturally have the same chemical properties because they have the same combining power i.e valence electron.
The pair of elements that tend to show the same chemical properties are a and d.
The elements belonging to the same group tend to show the same chemical properties. Based on the electronic configuration, the element having the same number of valence electrons belongs to the same group.
The valence electrons in the given configurations are:
a. [tex]\rm 1s^2\;2s^2\;2p^6\;3s^2\;3p^3[/tex] = 5
b. [tex]\rm 1s^2\;2s^2\;2p^6\;3s^2\;3p^6\;3d^1^0\;4s^2\;4p^5[/tex] = 7
c. [tex]\rm 1s^2\;2s^2\;2p^6\;3s^2\;3p^6[/tex] = 8
d. [tex]\rm 1s^2\;2s^2\;2p^3[/tex] = 5
The element a and d tend to show the same number of valence electrons. Thus both the elements will show the same chemical properties.
The pair of elements that tend to show the same chemical properties are a and d.
For more information about electronic configuration, refer to the link:
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A catalyst increases the reaction rate of a reaction by (3 points)
Answer:
A catalyst increases the rate of reaction by decreasing activation energy. ... Enzymes are highly substrate specific and catalyze reactions by providing an alternate pathway of lower activation energy.
Explanation:
I hope this helps :)
A solution has a 3.5*10^-3 M of OH^- .Calculate the HO3^+ and pH of this solution, Is it Acidic, Basic or neutral
Answer:
[H3O+]= 2.88×10^-12M
pH= 11.54
Explanation:
pOH= -log[OH] = -log[3.5*10^-3]= 2.46
pH= 14- pOH= 14-2.46= 11.54
High pH means that a solution is basic while high pOH means that a solution is acidic,
Hence the solution is basic
40 POINTS COLLEGE CHEMISTRY
Determine the concentration of a solution prepared by diluting 20.0 mL of 2.00 M NaCl to 250.0 mL. Please show your work.
Answer:
C2= 0.16M
Explanation:
C1= 2M, V1= 20ml, C2= ?, V2= 250ml
Applying dilution formula
C1V1= C2V2
2×20 =C2×250
C2= 0.16M
Three buffers are prepared using equal concentrations offormic acid (HCOOH) and sodium formate, hydrofluoric acid (HF) andsodium fluoride, and acetic acid (CH3COOH)and sodium acetate. Rank the three buffers from highest to lowest pH.
The question given is incomplete because the Ka of the acids were not provided. I got the complete question from google as below:
Three buffers are prepared using equal concentrations offormic acid (HCOOH) and sodium formate, hydrofluoric acid (HF) andsodium fluoride, and acetic acid (CH3COOH)and sodium acetate. Rank the three buffers from highest to lowest pH.
According to the text, the Ka of the acids are as follows:
HCOOH: 1.77 × 10–4
HF: 6.8 × 10–4
CH3COOH: 1.76 × 10–5
Answer:
Based on the Ka values of the acids given, the arrangement of the acids given from the highest to lowest pH is as below:
HF > HCOOH > CH3COOH
Explanation:
For acids, the higher the pH, the higher the pK , also, the lower the pH, the lower the pK.
then
pKa = -log(Ka)
So,
The acid with the highest pH will have the highest Ka value , while the acid with the lowest pH will have the lowest Ka value.
Thus, based on the Ka values of the acids given, the arrangement of the acids given from the highest to lowest pH is as below:
HF > HCOOH > CH3COOH
The buffers are ranked from highest to lowest pH based on the pKa values of the weak acids: acetic acid (highest pH), formic acid, and hydrofluoric acid (lowest pH).
To rank the buffers from highest to lowest pH, we can refer to the pKa values of the corresponding weak acids, since the buffers are prepared using equal concentrations of the weak acids and their conjugate bases. The higher the pKa, the weaker the acid, and therefore the higher the pH of its buffer when the concentrations of the acid and its conjugate base are equal.
The pKa of acetic acid (CH₃COOH) is approximately 4.76.
The pKa of formic acid (HCOOH) is approximately 3.75.
The pKa of hydrofluoric acid (HF) is approximately 3.17.
Therefore, the acetic acid and sodium acetate buffer will have the highest pH, followed by the formic acid and sodium formate buffer, with the hydrofluoric acid and sodium fluoride buffer having the lowest pH.
What is stoichiometry used for?
A. To determine the shape of a molecule
B. To determine the amount of a substance
C. To determine the molar mass of a molecule
D. To determine the atoms in a formula
Answer:
b
Explanation:
A chemist prepares a solution of sodium bromide by measuring out of into a volumetric flask and filling to the mark with distilled water.Calculate the molarity of anions in the chemist's solution.Be sure your answer is rounded to significant digits.
Answer:
The molarity of the Br anion is 0.00136 M = 0.0014 M to 2 s.f
Explanation:
Complete full question
A chemist prepares a solution of sodium bromide (NaBr) by measuring out 14. mg of NaBr into a 100 mL volumetric flask and filling to the mark with distilled water. Calculate the molarity of Br anions in the chemist's solution. Be sure your answer is rounded to 2 significant digits.
To do this, we first calculate the molarity of the aqueous solution of NaBr.
Molarity = (Concentration in g/L) ÷ (Molar Mass)
(Concentration in g/L)
= (Mass of solute in g) ÷ (Volume of solution in L)
Mass of solute = 14 mg = 0.014 g
Volume = 100 mL = 0.10 L
(Concentration in g/L)
= (Mass of solute in g) ÷ (Volume of solution in L)
(Concentration in g/L) = (0.014/0.1) = 0.14 g/L
Molarity = (Concentration in g/L) ÷ (Molar Mass)
Molar Mass = 102.894 g/mol
Molarity = (0.14/102.894) = 0.0013606236 M = 0.00136 M
Assuming complete dissociation, NaBr dissociates into
NaBr → Na⁺ + Br⁻
1 mole of NaBr gives 1 mole of Br⁻
0.00136 M of NaBr will give 0.00136 M of Br⁻
So, the molarity of the Br anion is 0.00136 M = 0.0014 M to 2 s.f
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From the lists of available reagents select the one(s) you would use to in a preparation of acetophenone (phenyl methyl ketone) from methyl benzoate. (In no case are more than three steps necessary.) Reagents Available a. CH COCI, AICI, d. CH CHO g. Mg 1. SOCI b. (CH3),Culi e. Hg(OC), H,Othen NaBH4 h. NaOH, H2O C. CH, MgBr, then H30* . KMnO4 H20 i. Dess-Martin periodinane List reagents by letter in the order that they are used; example:
Reagents used: ______
Answer:
Step 1) hydrolysis using NaOH/H2O to form benzylalcohol
Step2) oxidation to Carboxylic acid using KMnO4 followed by decarboxylation to form benzene
3) friedel craft acylation using CH3COCl/AlCl3
Explanation:
The above 3 steps will yield acetophenone from methylbenzoate
You are using a pressure cooker to make rice. After 10 minutes, you hear a loud “BANG.” You walk into the kitchen to find that the pressure cooker has exploded. Which gas law explains this?
(Keep in mind that you set the temperature of the cooker one time and you do not change it again)
A) Avogadro’s Law (relationship between number of moles of a gas and volume) B) Boyle’s Law (relationship between pressure and volume)
C) Charles Law (relationship between temperature and volume)
D) Dalton’s Law (looks age partial pressures of gases in a container)
E) Gay-Lussac’s Law (relationship between pressure and volume)
An explosion in a pressure cooker can be explained by Boyle's Law, which states that pressure and volume are inversely related at constant temperature.So,option B is correct.
The explosion of a pressure cooker while making rice can be explained by Boyle's Law, which relates the volume and pressure of a gas under conditions of constant temperature. According to Boyle's Law, if a gas is compressed to a smaller volume without changing the temperature, the pressure of the gas increases. In a pressure cooker, when the steam cannot escape, the pressure continues to rise, and if the volume is constricted, the cooker may not be able to withstand the increased pressure, leading to an explosion. Therefore, the correct answer to the question is B) Boyle’s Law (relationship between pressure and volume).
Use the standard half-cell potentials listed below to calculate the standard cell potential for the following reaction occurring in an electrochemical cell at 2 5°C. (The equation is balanced.) Pb(s) + Br2(l) → Pb2+(aq) + 2 Br-(aq) Pb2+(aq) + 2 e- → Pb(s) E° = -0.13 V Br2(l) + 2 e- → 2 Br-(aq) E° = +1.07 V
Answer:
1.20 V
Explanation:
The standard cell potential is calculated from the expression
ε⁰ cell = ε⁰ oxidation + ε⁰ reduction
The species that will be reduced is the one with the higher standard reduction potential and the species that will be oxidized will be the one with the more negative reduction potential.
Thus for our question we will have
oxidation:
Pb(s) → Pb2+(aq) + 2 e- ε⁰ oxidation = - ε⁰ reduction
= - ( - 0.13 V ) = + 0.13 V
reduction
Br2(l) + 2 e- → 2 Br-(aq) ε⁰ reduction = +1.07 V
ε⁰ cell = ε⁰ oxidation + ε⁰ reduction = + 0.13 V + 1.07 V = 1.20 V
Explain how the atom is a part of the electrical current process.
When an area has a net flow of electric charge, an electric current is considered to be present. Electrons traveling via a wire in electric circuits frequently carry this charge.
What is electric current?
One or more of the electrons from each atom are only weakly connected to the atom in metals, allowing them to move around freely inside the metal. Electric current is a term used to describe how much electricity flows across a circuit and how it flows in an electronic circuit. Amperes are used to measure it (A). The more electricity flowing across the circuit, the higher the ampere value.
If you imagine electricity as the flow of water in a river, it will be simple to understand. When the electrons collide, the current is the number of electrons flowing per second.
Like current, voltage is a word that is frequently used in relation to electrical circuits. Volts are used to measure voltage (V). Voltage and the movement of electrons in a circuit are connected, just like current and current are. Voltage is the amount of force driving the flowing electrons, whereas the current is the flow of electrons.
Therefore, when there is a net flow of electric charge through an area, an electric current is said to exist. In electrical circuits, electrons traveling over a wire frequently carry this charge.
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A chemist fills a reaction vessel with 0.750 M lead (II) (Pb2+) aqueous solution, 0.232 M bromide (Br) aqueous solution, and 0.956 g lead (II) bromide (PbBr2 solid at a temperature of 25.0°C. Under these conditions, calculate the reaction free energy AG for the following chemical reaction: Pb2+ (aq) + 2Br (aq) = PbBr2 (s) Use the thermodynamic information in the ALEKS Data tab. Round your answer to the nearest kilojoule.
To calculate the reaction free energy ΔG for this reaction, we need to use the standard free energy of formation values given in a data tab, the stoichiometry of the reaction, and the specific conditions of the reaction, including the concentrations of Pb2+ and Br−. After a series of calculations, we will get the ΔG value in joules, which can be converted to kilojoules.
Explanation:The task here is to calculate the reaction free energy ΔG for the Pb2+(aq) + 2Br−(aq) = PbBr2(s) reaction at 25.0°C. From the given information, we can start by calculating the number of moles of PbBr2 from its mass. Then, referring to the thermodynamic data tab of the ALEKS, we find the standard free energy of formation (ΔGf°) values for Pb2+(aq), Br−(aq), and PbBr2(s). Now, we can use these values and the definition of ΔG for a reaction in terms of ΔGf° values and stoichiometry.
ΔG = ΣΔGf°(products) - ΣΔGf°(reactants).
Note that the equation must be balanced so each ΔGf° value is multiplied by the stoichiometric coefficient of that substance in the reaction. It is also important to remember to convert the answer to kilojoules if the ΔGf° values are given in joules/mole. Lastly, the concentrations of Pb2+ and Br− are included in the reaction quotient Q to show the reaction's non-standard conditions.
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The reaction free energy under the given conditions[tex]\Delta G \approx -472 \text{ kJ/mol}[/tex].
The reaction free energy for the given chemical reaction can be calculated using the standard free energy of formation for each substance involved in the reaction. The reaction is as follows:
[tex]\[ \text{Pb}^{2+} (aq) + 2\text{Br}^- (aq) \rightarrow \text{PbBr}_2 (s) \][/tex]
The standard free energy change \( \Delta G^\circ \) for the reaction is given by:
[tex]\[ \Delta G^\circ = \Delta G^\circ_f (\text{PbBr}_2) - \left( \Delta G^\circ_f (\text{Pb}^{2+}) + 2 \cdot \Delta G^\circ_f (\text{Br}^-) \right) \][/tex]
Using the thermodynamic data provided in the ALEKS Data tab, we have:
[tex]- \( \Delta G^\circ_f (\text{PbBr}_2) = -260.8 \text{ kJ/mol} \)\\ - \( \Delta G^\circ_f (\text{Pb}^{2+}) = -24.4 \text{ kJ/mol} \)\\ - \( \Delta G^\circ_f (\text{Br}^-) = -121.5 \text{ kJ/mol} \)[/tex]
Plugging in these values, we get:
[tex]\[ \Delta G^\circ = -260.8 \text{ kJ/mol} - \left( -24.4 \text{ kJ/mol} + 2 \cdot (-121.5 \text{ kJ/mol}) \right) \] \[ \Delta G^\circ = -260.8 \text{ kJ/mol} + 24.4 \text{ kJ/mol} - 2 \cdot 121.5 \text{ kJ/mol} \] \[ \Delta G^\circ = -260.8 \text{ kJ/mol} + 24.4 \text{ kJ/mol} - 243.0 \text{ kJ/mol} \] \[ \Delta G^\circ = -260.8 \text{ kJ/mol} - 218.6 \text{ kJ/mol} \] \[ \Delta G^\circ = -479.4 \text{ kJ/mol} \][/tex]
Relationship:
[tex]\[ \Delta G = \Delta G^\circ + RT \ln(Q) \][/tex]
This reaction is:
[tex]\[ Q = \frac{[\text{PbBr}_2]}{[\text{Pb}^{2+}][\text{Br}^-]^2} \][/tex]
Simplifies to:
[tex]\[ Q = \frac{1}{[\text{Pb}^{2+}][\text{Br}^-]^2} \][/tex]
The initial concentrations are:
[tex]- \( [\text{Pb}^{2+}] = 0.750 \text{ M} \) - \( [\text{Br}^-] = 0.232 \text{ M} \)[/tex]
So:
[tex]\[ Q = \frac{1}{(0.750 \text{ M})(0.232 \text{ M})^2} \] \[ Q = \frac{1}{0.750 \cdot 0.053824 \text{ M}^3} \] \[ Q = \frac{1}{0.040368 \text{ M}^3} \] \[ Q \approx 24.77 \][/tex]
Calculation:
[tex]\[ \Delta G = -479.4 \text{ kJ/mol} + (8.314 \text{ J/(mol·K)} \cdot 298.15 \text{ K}) \cdot \ln(24.77) \] \[ \Delta G = -479.4 \text{ kJ/mol} + (2477.57 \text{ J/mol}) \cdot \ln(24.77) \] \[ \Delta G = -479.4 \text{ kJ/mol} + (2477.57 \text{ J/mol}) \cdot 3.183 \] \[ \Delta G = -479.4 \text{ kJ/mol} + 7896.5 \text{ J/mol} \] \[ \Delta G = -479.4 \text{ kJ/mol} + 7.8965 \text{ kJ/mol} \] \[ \Delta G \approx -471.5 \text{ kJ/mol} \][/tex]
Rounding to the nearest kilojoule:
[tex]\[ \boxed{\Delta G \approx -472 \text{ kJ/mol}} \][/tex]
This is the reaction free energy under the given conditions.
The answer is: [tex]\Delta G \approx -472 \text{ kJ/mol}[/tex].
Which of the following chemical formulas represents a molecule?
H2 CO2 SiO2 NH3
CO2 is a chemical formula that is representing a molecule.
Explanation:
A chemical formula is used to represent molecules in a particular element. Molecules are basically shown by the symbols present in the periodic table. As we know that CO2 is a chemical formula that is representing a molecule because , there are two elements one is carbon whose symbol is C and another element is oxygen whose symbol is O. So in the chemical formula there one carbon atoms and two oxygen atoms.All the given chemical formulas represent molecules as they are made up of two or more than two atoms .
What is chemical formula?
Chemical formula is a way of representing the number of atoms present in a compound or molecule.It is written with the help of symbols of elements. It also makes use of brackets and subscripts.
Subscripts are used to denote number of atoms of each element and brackets indicate presence of group of atoms. Chemical formula does not contain words. Chemical formula in the simplest form is called empirical formula.
It is not the same as structural formula and does not have any information regarding structure.It does not provide any information regarding structure of molecule as obtained in structural formula.
There are four types of chemical formula:
1)empirical formula
2) structural formula
3)condensed formula
4)molecular formula
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In the laboratory, a general chemistry student measured the pH of a 0.583M solution of HClO_3 to be 3.862.
What is the experimentally determined value of K_a for HClO_3?
A. 1.37 times 10^-4
B. 2.35 times 10^-4
C. 3.11 times 10^-7
D. 1.89 times 10^-8
E. 3.24 times 10^-8
The law of conservation of mass states that
Select the definition of diffusion. The gradual dispersal of one substance through another substance. The movement of a gas particle from one area to another. The escape of a gas through a small opening in a barrier into a region of lower pressure. The random motion of gas particles. Select the definition of effusion. The random motion of gas particles. The gradual dispersal of one substance through another substance. The escape of a gas through a small opening in a barrier into a region of lower pressure. The movement of a gas particle from one area to another.
The following are the definition for the following terms:
Explanation:
1. Kinetic molecular theory:
(a) The particles that the compose a gas are so small compared to the distances between them that the volume of the individual particles can be assumed to be neglisible.
2. The definition of a Diffusion:
(a) The movement of a gas particle from one area to another.
3. The definition of Effusion:
(c) The escape of a gas thorugh a small opening in a barrier in to a region of lower pressure.
Diffusion is the process of gaseous molecules moving from regions of high concentration to low concentration until a uniform concentration is achieved. Effusion, similar to diffusion, involves gas escaping from a container to a vacuum through a small opening, often from high pressure to low pressure.
Explanation:In the realm of physics, Diffusion can be defined as the process whereby gaseous atoms and molecules move from regions of relatively higher concentration to regions of lower concentration. The molecules, moving freely and randomly, are transferred due to their inherent kinetic energy. This movement continues until there is a uniform concentration of the molecules throughout, achieving a state of dynamic equilibrium.
On the other hand, Effusion is a similar process, with the key difference being that the gaseous species escape from a container to a vacuum through very small openings or orifices. This escape often occurs from regions of high pressure to regions of low pressure. Just like in diffusion, the rates of effusion are influenced by factors such as the molar mass of the gas involved; however, the rates are not equal.
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