Answer:
The correct answer is 1.68 × 10⁻⁵ Ci
Explanation:
The activity of the uranium is determined by using the formula,
R = 0.693 N/t1/2 -------------- (i)
The number of atoms is, N = nNA
Here, NA is the Avogadro number and n is the number of moles. The value of n is m/M, that is, mass/molecular mass. Now the value of N becomes,
N = (m/M) NA
The m or mass of uranium given is 50.1 grams, and the molecular mass is 238 g/mol, now putting the values we get,
N = (50 g/238 g) (6.023 × 10²³) = 1.26 × 10²³
The half-life of 238U from year to second is,
t1/2 = (4.468 × 10⁸ year) (3.16 × 10⁷ s/ 1 year) = 1.412 × 10¹⁶ s
Substituting the values of t1/2 as 1.412 × 10¹⁶, and 1.26 × 10²³ for N in equation (i) we get,
R = 0.639 (1.26 × 10²³) / 1.412 × 10¹⁶ s
= 6.18 × 10⁶ Bq (2.7027 × 10⁻¹¹ Ci/1 Bq)
= 1.68 × 10⁻⁵ Ci
Hence, the activity of the plate is 1.68 × 10⁻⁵ Ci
The entropy of a substance above absolute zero will always be:
a. Negative
b. Positive
c. Neither Negative nor positive
What is the pOH of a solution at 25.0∘C with [H3O+]=4.8×10−6 M?
Answer:
8.68
Explanation:
pOH = 8.68
all you need is contained in the sheet
Answer:
Approximately [tex]8.68[/tex].
Explanation:
The [tex]\rm pOH[/tex] of a solution can be found from the hydroxide ion concentration [tex]\rm \left[OH^{-}\right][/tex] with the following equation:
[tex]\displaystyle \rm pOH = -\log_{10} \rm \left[OH^{-}\right][/tex].
On the other hand, the ion-product constant of water, [tex]K_{\text{w}}[/tex], relates the hydroxide ion concentration [tex]\rm \left[OH^{-}\right][/tex] of a solution to its hydronium ion concentration [tex]\rm \left[{H_3O}^{+}\right][/tex]:
[tex]K_\text{w} = \rm \left[{H_3O}^{+}\right] \cdot \rm \left[OH^{-}\right][/tex].
At [tex]25 \; ^\circ \rm C[/tex], [tex]K_{\text{w}} \approx 1.0 \times 10^{-14}[/tex]. For this particular [tex]25 \; ^\circ \rm C[/tex] solution, [tex]\rm \left[{H_3O}^{+}\right] = 4.8 \times 10^{-6}\; \rm mol \cdot L^{-1}[/tex].Hence the [tex]\rm \left[OH^{-}\right][/tex] of this solution:
[tex]\begin{aligned}\left[\mathrm{OH}^{-}\right] &= \frac{K_\text{w}}{\rm \left[{H_3O}^{+}\right]} \\ &= \frac{1.0 \times 10^{-14}}{4.8 \times 10^{-6}}\; \rm mol\cdot L^{-1} \approx 2.08333 \times 10^{-9}\; \rm mol\cdot L^{-1}\end{aligned}[/tex].
Therefore, the [tex]\rm pOH[/tex] of this solution would be:
[tex]\begin{aligned}\rm pOH &= -\log_{10} \rm \left[OH^{-}\right] \\ &\approx -\log_{10} \left(4.8 \times 10^{-6}\right) \approx 8.68\end{aligned}[/tex].
Note that by convention, the number of decimal places in [tex]\rm pOH[/tex] should be the same as the number of significant figures in [tex]\rm \left[OH^{-}\right][/tex].
For example, because the [tex]\rm \left[{H_3O}^{+}\right][/tex] from the question has two significant figures, the [tex]\rm \left[OH^{-}\right][/tex] here also has two significant figures. As a result, the [tex]\rm pOH[/tex] in the result should have two decimal places.
During a titration, a known concentration of _____ is added to a _____ of an unknown concentration g
Explanation:
The whole process of titration involves finding the concentration of a solution (usually an acid or base) by adding (titrating) it to a solution(acid or base) with a known concentration.
The solution of unknown concentration (the analyte) is usually placed in an flask, while the solution of known concentration (titrant) is placed in a burette and slowly added to the flask.
The solubility of lead(II) iodide is 0.064 g/100 mL at 20ºC. What is the solubility product for lead(II) iodide?
Answer:
[tex]Ksp=1.07x10^{-8}[/tex]
Explanation:
Hello,
In this case, the dissociation reaction is:
[tex]PbI_2(s)\rightleftharpoons Pb^{2+}(aq)+2I^-(aq)[/tex]
For which the equilibrium expression is:
[tex]Ksp=[Pb^{2+}][I^-]^2[/tex]
Thus, since the saturated solution is 0.064g/100 mL at 20 °C we need to compute the molar solubility by using its molar mass (461.2 g/mol)
[tex]Molar solubility=\frac{0.064g}{100mL}*\frac{1000mL}{1L}*\frac{1mol}{461.2g}=1.39x10^{-3}M[/tex]
In such a way, since the mole ratio between lead (II) iodide to lead (II) and iodide ions is 1:1 and 1:2 respectively, the concentration of each ion turns out:
[tex][Pb^{2+}]=1.39x10^{-3}M[/tex]
[tex][I^-]=1.39x10^{-3}M*2=2.78x10^{-3}M[/tex]
Thereby, the solubility product results:
[tex]Ksp=(1.39x10^{-3}M)(2.78x10^{-3}M)^2\\\\Ksp=1.07x10^{-8}[/tex]
Regards.
Solubility product constant for the product of lead(II) iodide is [tex]\bold { 1.07x 10^-^8}[/tex].
The dissociation reaction for lead (II) iodide
[tex]\bold {Pb I^2 (s) \leftrightharpoons Pb^2^+ + 2I^- }[/tex]
Solubility product constant at equilibrium.
[tex]\bold {Ksp = [Pb^2^++[I^-]^2}[/tex]
The molar solubility of the substance can be calculated by using the molar mass,
[tex]\bold {s = \dfrac {0.064}{100 mL} \times 461.2 g/mol = 1.39x10^-^3}[/tex]
Molar ratio between between PbI to lead and iodide ions is 1:1 and 1:2 respectively.
Thus Ksp will be,
[tex]\bold {Ksp =(1.39x10^-^3)(2.78x10^-^3 )^2}\\\\\bold {Ksp = 1.07x 10^-^8}[/tex]
Therefore, solubility product constant for the product of lead(II) iodide is [tex]\bold { 1.07x 10^-^8}[/tex].
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Consider the following reaction at 298.15 K: Co(s)+Fe2+(aq,1.47 M)⟶Co2+(aq,0.33 M)+Fe(s) If the standard reduction potential for cobalt(II) is −0.28 V and the standard reduction potential for iron(II) is −0.447 V, what is the cell potential in volts for this cell? Report your answer with two significant figures.
Answer:
The correct answer is 0.186 V
Explanation:
The two hemirreactions are:
Reduction: Fe²⁺ + 2 e- → Fe(s)
Oxidation : Co(s) → Co²⁺ + 2 e-
Thus, we calculate the standard cell potential (Eº) from the difference between the reduction potentials of cobalt and iron, respectively, as follows:
Eº = Eº(Fe²⁺/Fe(s)) - Eº(Co²⁺/Co(s)) = -0.28 V - (-0.447 V) = 0.167 V
Then, we use the Nernst equation to calculate the cell potential (E) at 298.15 K:
E= Eº - (0.0592 V/n) x log Q
Where:
n: number of electrons that are transferred in the reaction. In this case, n= 2.
Q: ratio between the concentrations of products over reactants, calculated as follows:
[tex]Q = \frac{ [Co^{2+} ]}{[Fe^{2+} ]} = \frac{0.33 M}{1.47 M} = 0.2244[/tex]
Finally, we introduce Eº= 0.167 V, n= 2, Q=0.2244, to obtain E:
E= 0.167 V - (0.0592 V/2) x log (0.2244) = 0.186 V
A soft drink contains 63 g of sugar in 378 g of H2O. What is the concentration of sugar in the soft drink in mass percent
Answer:
[tex]\% m/m= 14.3\%[/tex]
Explanation:
Hello,
In this case, the by mass percent is computed as shown below:
[tex]\% m/m=\frac{m_{solute}}{m_{solute}+m_{solvent}} *100\%[/tex]
Whereas the solute is the sugar and the solvent the water, therefore, the concentration results:
[tex]\% m/m=\frac{63g}{63g+378g} *100\%\\\\\% m/m= 14.3\%[/tex]
Best regards.
which of the following compounds are polar: CH2Cl2, HBr?
Answer:
CH2Cl2 is polar
Explanation:
Candle wax melts low temperature, it is not conductive to electricity, it is insoluble in water and partially soluble in solvents nonpolar, like gasoline. Than type of links are present in the candle wax?
A. Electrostatics.
B. Apolar.
C. lónicos.
D. Hydrogen bridges.
electrostatic and ionic are definitely not the answer because they have high melting point
hydrogen bonds are too weak and not permanent.
so the answer is apolar as it is soluble in polar solvents (water)
Answer:
B. Nonpolar
Explanation:
The low melting point tells you the compound is not ionic, metallic, or a network solid.
It is almost certainly a molecular solid.
It does not conduct electricity, so it is not metallic (which we have already ruled out).
It is insoluble in polar solvents (water) and soluble in nonpolar solvents (gasoline).
Since like dissolves like, the molecule is nonpolar.
The type of links must be nonpolar.
What is advertising used for? Check all that apply. influencing consumer tastes tracking product popularity increasing product awareness promoting company branding gathering data about potential consumers
Answer:
influencing consumer tastes
increasing product awareness
promoting company branding
Explanation:
Advertising is basically a form of communication using creative ideas and communicating benefits of the products. Advertising plays a very crucial role in product business and some of the important uses of advertising are as follows:
Creative advertisements, influence customers or consumers to buy the product.Advertisings involve information regarding the product and so increases product awareness.Advertising on social media platforms, TVs, radio and newspapers, promotes company branding.Hence, the correct options are:
influencing consumer tastesincreasing product awarenesspromoting company branding
Answer:
1,3,4
Explanation:
I took the test
Identify a homogeneous catalyst. Identify a homogeneous catalyst. Pd in H2 gas N2 and H2 catalyzed by Fe SO2 over vanadium (V) oxide Pt with methane H2SO4 with concentrated HCl
Answer:
H2SO4 with concentrated HCl
Which of the following types of electromagnetic radiation have higher frequencies than visible light and which have shorter frequencies than visible light? Sort them accordingly. ltems (6 items) (Drag and drop into the appropriate area below)
a. Gamma rays
b. Infrared radiation
c. Ultraviolet liht
d. X-rays
e. Microwaves
f. Radio waves
Answer:
Higher frequency than visible light - Ultraviolet light, X-rays, and Gamma rays
Lower frequency than visible light - Infrared radiation, microwaves, and Radio waves
Explanation:
The frequencies of electromagnetic radiations vary according to their wavelengths. The relationship between the frequency and wavelength of the waves is expressed such that:
λ = c/f, where λ = wavelength, c = speed of light, and f = frequency.
Thus, there is an inverse relationship between the wavelength and the frequency of electromagnetic waves.
The order of the electromagnetic waves based on their frequency from the lowest to the highest is radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma-rays
Hence, electromagnetic waves with higher frequencies than visible light include ultraviolet light, X-rays, and Gamma rays while those with lower frequencies include Infrared radiation, microwaves, and Radio waves.
Answer:
need points
Explanation:
Calculate the molar solubility of CaF2 at 25°C in a solution that is 0.010 M in Ca(NO3)2. The Ksp for CaF2 is 3.9 x 10-11.
Answer:
[tex]Molar \ solubility=3.12x10^{-5}M[/tex]
Explanation:
Hello,
In this case, for the dissociation of calcium fluoride:
[tex]CaF_2(s)\rightleftharpoons Ca^{2+}+2F^-[/tex]
The equilibrium expression is:
[tex]Ksp=[Ca^{2+}][F^-]^2[/tex]
In such a way, via the ICE procedure, including an initial concentration of calcium of 0.01 M (due to the calcium nitrate solution), the reaction extent [tex]x[/tex] is computed as follows:
[tex]3.9x10^{-11}=(0.01+x)(2*x)^2\\\\x=0.0000312M[/tex]
Thus, the molar solubility equals the reaction extent [tex]x[/tex], therefore:
[tex]Molar \ solubility=3.12x10^{-5}M[/tex]
Regards.
The molar solubility of Calcium fluoride has been calculated as [tex]3.12\;\times\;10^-^5\;\rm M[/tex].
The dissociation of calcium fluoride has been given by:
[tex]\rm CaF_2\;\rightarrow\;Ca^2^+\;+\;2\;F^-[/tex]
The solubility constant, ksp has been given as:
[tex]ksp=\rm[Mg^2^+]\;[F^-]^2[/tex]
From the dissociation of Calcium nitrate, the concentration of Ca ion in the solution has been 0.01 M.
The dissociation of Calcium fluoride x M has been resulted in x M Ca and 2x M F ions.
The concentration of Ca in the solution has been resulted as x + 0.01 M.
The solubility product can be given as:
[tex]3.9\;\times\;10^-^1^1=[x+0.01]\;[2x]^2\\3.9\;\times\;10^-^1^1=[x+0.01]\;4x^2\\x=3.12\;\times\;10^-^5[/tex]
The molar solubility of Calcium fluoride has been calculated as [tex]3.12\;\times\;10^-^5\;\rm M[/tex].
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If you had a cup full of methanol and a pool full of methanol, would the mass change?
Answer:
the mass does not change
Explanation:
Increasing which factor will cause the gravitational force between two objects to decrease?
weights of the objects
distance between the objects
acceleration of the objects
masses of the objects
Answer:
B
Explanation:
Increasing distance between the objects factor will cause the gravitational force between two objects to decrease. Therefore, option B is correct.
What causes gravitational force to decrease?The gravitational force grows in proportion to the size of the masses . The gravitational force weakens rapidly as the distance between masses grows. Unless at least one of the objects has a lot of mass, detecting gravitational force is extremely difficult.
Gravity is affected by object size and distance between objects. Mass is a unit of measurement for the amount of matter in an object.
The force of gravity is proportional to the masses of the two objects and inversely proportional to the square of the distance between them. This means that the force of gravity increases with mass but decreases as the distance between objects increases.
Thus, option B is correct.
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The direction of the functional group is called?
Explanation:
they are called hydrocarbyls
pls mark me brainliest
Answer:
The first carbon atom that attaches to the functional group is referred to as the alpha carbon.
A variation of the acetamidomalonate synthesis can be used to synthesize threonine. The process involves the following steps: Ethoxide ion deprotonates diethyl acetamidomalonate, forming enolate anion 1; Enolate anion 1 makes a nucleophilic attack on acetaldehyde, forming tetrahedral intermediate 2; Protonation of the oxyanion forms alcohol 3; Acid hydrolysis yields dicarboxyamino alcohol 4; Decarboxylation leads to the final amino acid. Write out the mechanism on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 2.
Answer:
See figure 1
Explanation:
For this reaction, we have the production of a carbanion as the first step. The base "ethoxide" can remove a hydrogen-producing a negative charge in the carbon (enolate anion 1). Then this negative charge can attack the carbon of the carbonyl group in the molecule acetaldehyde and the tetrahedral intermediate 2 is form. In the next step, we have the protonation of the oxygen to produce alcohol 3. A continuation we have the hydrolysis of the ester groups to produce the Dicarboxyamino alcohol and finally, we have a decarboxylation reaction we will produce the amino acid Threonine.
To further explanations see figure 1
I hope it helps!
Why will the conjugate base of a weak acid affect pH? Select the correct answer below: it will react with hydroxide
Answer:
It will react with water
Explanation:
I know this is an older question, but I just wanted to provide the correct answer.
Since we are dealing with a weak base, and the acid is somewhat stronger, it will react with the water molecules to produce hydronium, which will affect the pH of the solution.
The conjugate base of a weak acid affect pH because it will react with hydronium ion.
A weak acid is an acid that does not dissociate completely in water. On the other hand, a strong acid achieves almost 100% dissociation in water.
Acids dissociate in water to yield the hydronium ion and a conjugate base. For instance, the weak acid, acetic acid is dissociated as follows;
CH3COOH(aq) + H2O(l) ⇄ CH3COO-(aq) + H3O+(aq)
We can see that the conjugate base( CH3COO-) could react with the hydronium ions thereby moving the equilibrium position to the left hand side and affecting the pH by decreasing the hydronium ion concentration.
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Missing parts;
Why will the conjugate base of a weak acid affect pH? Select the correct answer below: O it will react with hydroxide O it will react with water O it will react with hydronium O none of the above
A galvanic cell is powered by the following redox reaction:
2Zn2+(aq) + N2H4(aq) 4OH-zn2+ right arrow(aq) 2Zn(s) + N2(g) + 4H2O(I)
1. Write a balanced equation for the half-reaction that takes place at the cathode.
2. Write a balanced equation for the half-reaction that takes place at the anode.
3. Calculate the cell voltage under standard conditions.
If we want to change a gas to its liquid state, should we add or remove energy from the gas?
Which of the following elements is in the same group as Sulfur (S)?
Answer:
PLEASE SHOW ME THE ELEMENTS OR I WOULD ENLIST ALL THE ELEMENTS.
Explanation:
Group 6A (or VIA) of the periodic table are the chalcogens: the nonmetals oxygen (O), sulfur (S), and selenium (Se), the metalloid tellurium (Te), and the metal polonium (Po)
We discussed the different types of intermolecular forces in this lesson, which can affect the boiling point of a substance.
1. Which of these has the highest boiling point?
A) Ar
B) Kr
C) Xe
D) Ne
2. Which substance has the highest boiling point?
A) CH4
B) He
C) HF
D) Cl2
Answer:
1, C, Xe 2, B,He
Explanation:
1, cause as u go down a group the boiling point increases.
2, boiling point of single element is greater than a compound
According to periodic trends in periodic table boiling point increases down the group and hence Xe has highest boiling point and more amount of heat is required to boil an element hence He has highest boiling point.
What is periodic table?
Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.
It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.
Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.
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I add a 50. g piece of Al (c = 0.88 J/g-deg) that is at 225°C to 100. mL of water at 20°C. What is the final temperature of the water in °C? The density of water is approximately 1g/mL.
Answer:
THE FINAL TEMPERATURE OF WATER IS -4.117 °C
Explanation:
Mass of the aluminium = 50 g
c = 0.88 J/g C
Initial temperature of aluminium = 225 °C
Volume of water = 100 ml
Density of water = 1 g/ml
Mass of water = density * volume of water
Mass of water = 1 * 100 = 100 g of water
Initial temperature of water = 20 C
It is worthy to note that the heat of a system is constant and conserved as no heat is lost or gained by a closed system,
So therefore,
heat lost by aluminium = heat gained by water
H = mass * specific heat capacity * temeprature change
So:
m c ( T2- T1) = m c (T2-T1)
50 * 0.88 * ( T2 - 225) = 100 * 4.18 *( T2 - 20)
44 ( T2 - 225 ) = 418 ( T2 - 20)
44 T2 - 9900 = 418 T2 - 8360
-9900 + 8360 = 418 T2 - 44 T2
-1540 = 374 T2
T2 = - 4.117
So therefore the final temperature of water is -4.117 °C
A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the solution before the addition of any HNO3. The Kb of NH3 is 1.8 × 10-5.
Answer:
[tex]pH=11.12[/tex]
Explanation:
Hello,
In this case, ammonia dissociation is:
[tex]NH_3(aq)+H_2O(l)\rightleftharpoons NH_4^+(aq)+OH^-(aq)[/tex]
So the equilibrium expression:
[tex]Kb=\frac{[NH_4^+][OH^-]}{[NH_3]}[/tex]
That in terms of the reaction extent and the initial concentration of ammonia is written as:
[tex]1.8x10^{-5}=\frac{x*x}{0.10M-x}[/tex]
Thus, solving by using solver or quadratic equation we find:
[tex]x=0.00133M[/tex]
Which actually equals the concentration of hydroxyl ion, therefore the pOH is computed:
[tex]pOH=-log([OH^-])=-log(0.00133)=2.88[/tex]
And the pH from the pOH is:
[tex]pH=14-pOH=14-2.88\\\\pH=11.12[/tex]
Best regards.
i) Briefly discuss the strengths and weaknesses of the four spectroscopy techniques listed below. Include in your answer the specific structural information you get from each method.
IR
UV-VIS
NMR
Mass Spec
delete please .....................................
A sample of ammonia gas was allowed to come to equilibrium at 400 K. 2NH3(g) <----> N2(g) 3H2(g) At equilibrium, it was found that the concentration of H2 was 0.0484 M, the concentration of N2 was 0.0161 M, and the concentration of NH3 was 0.295 M. What was the initial concentration of ammonia
Answer:
0.327 M
Explanation:
Step 1: Write the balanced equation
2 NH₃(g) ⇄ N₂(g) + 3H₂(g)
Step 2: Make an ICE chart
2 NH₃(g) ⇄ N₂(g) + 3 H₂(g)
I x 0 0
C -2y +y +3y
E x-2y y 3y
Step 3: Find the value of y
The concentration of N₂ at equilibrium is 0.0161 M. Then,
y = 0.0161
Step 4: Find the value of x
The concentration of NH₃ at equilibrium is 0.295 M. Then,
x-2y = 0.295
x-2(0.0161) = 0.295
x = 0.327
If the dissolution of borax in water is spontaneous, is the change in enthalpy positive or negative - or are both signs possible?
Answer:
"Both signs are possible" is the correct choice.
Explanation:
The indication including its change in enthalpy depends on the concentration.As when the enthalpy seems to be negative besides purposeful unexpected temperatures lower, as well as successful for necessary response at extremely high temperatures.As such that when both signals could have been the enthalpy change.
If the dissolution of borax in water is spontaneous, so the change in enthalpy should be negative.
What is enthalpy?Enthalpy of the reaction tells about the total amount of energy released or absorbed during any chemical reaction.
And for the spontaneous reaction, value of standard Gibb's free energy change of the reaction should be negative and formula will be represented as:
ΔG = ΔH - TΔS, where
ΔH = change in enthalpy
For the spontaneous reaction, value of enthalpy should be negative so that we get the negative value of ΔG.
Hence change in enthalpy should be negative.
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From the graph of Density vs. Concentration, created in Graph 1, what was the relationship between the concentration of the sugar solution and the density of the sugar solution?
The graph is not given in the question, so, the required graph is attached below:
Answer:
According to the graph, the relationship between the density of the sugar solution and the concentration of the sugar solution is directly proportional to each other as they both are increasing exponentially.
The graph shows that, the density of sugar solution will increase with the increase in concentration of sugar in the solution.
Which are the chemical properties of water?
Answer:
See explanation.
Explanation:
Hello,
In this case, we can realize that water has a very simple atomic structure which consists of two hydrogen atoms bonded to one oxygen atom. The nature of the atomic structure of water causes its molecules to have unique electrochemical properties. The hydrogen side of the water molecule has a slight positive charge whereas at the other side of the molecule a negative charge exists. This molecular polarity causes water to be a powerful solvent and is responsible for its strong surface tension.
Moreover, water is involved in several both inorganic and organic chemical reactions leading to hydration, for example, the conversion of alkenes to alcohols, the hydrolysis of acyl halides, anhydrides, esters and amides to carboxylic acids and the hydration of a raft of inorganic salts that exist as hydrates only, such as copper (II) sulfate pentahydrate and so.
Best regards.
105/22 • (1.251 - 0.620)=
Answer:
105/22*(1.251-0.620)
105/22*0.631
4.772*0.631
3.011132
Hope it helps
Answer:
3.0
Explanation:
First, complete the operations inside the parenthesis according to the normal rules for significant figures. Because there are subsequent calculations, keep at least one extra significant figure when possible: (4.7727) × (0.631).
The final product will be rounded to two significant figures because it can’t be more precise than the least precise number in the problem, 22. The final product is 3.0.
In the laboratory, a general chemistry student measured the pH of a 0.425 M aqueous solution of benzoic acid, C6H5COOH to be 2.270.
Use the information she obtained to determine the Ka for this acid.
Ka(experiment) = _____
Answer:
Ka = 6.87x10⁻⁵
Explanation:
The equilibrium of benzoic acid in water is:
C₆H₅COOH(aq) + H₂O(l) ⇄ C₆H₅COO⁻(aq) + H₃O⁺(aq)
The equilibrium constant, Ka, is:
Ka = [C₆H₅COO⁻] [H₃O⁺] / [C₆H₅COOH]
The initial concentration of benzoic acid is 0.425M. In equilibrium its concentration is 0.425M - X and [C₆H₅COO⁻] [H₃O⁺] = X.
X is the reaction coordinate. How many acid produce C₆H₅COO⁻ and H₃O⁺ until reach equilibrium.
Concentrations in equilibrium are:
[C₆H₅COOH] = 0.425M - X[C₆H₅COO⁻] = X [H₃O⁺] = XpH is defined as -log [H₃O⁺]. As pH = 2.270
2.270 = -log [H₃O⁺]
10^-2.270 = [H₃O⁺]
5.37x10⁻³M = [H₃O⁺] = X.
Replacing, concentrations in equilibrium are:
[C₆H₅COOH] = 0.425M - 5.37x10⁻³M = 0.4196M
[C₆H₅COO⁻] = 5.37x10⁻³M
[H₃O⁺] = 5.37x10⁻³M
Ka = [5.37x10⁻³M] [5.37x10⁻³M] / [0.4196M]
Ka = 6.87x10⁻⁵