The appropriate procedure for preparing a buffer solution with a pH close to 9 is given by Carla C., who suggests mixing [tex]NH_4Cl[/tex] and [tex]NH_3[/tex]solutions.
A buffer solution consists of a weak acid and its conjugate base (or a weak base and its conjugate acid). The buffer's pH is determined by the equilibrium between the weak acid and its conjugate base, which helps maintain the pH stability of the solution. Among the options provided:
Archie A.'s suggestion of mixing acetic acid and sodium acetate solutions is appropriate for preparing a buffer with a pH close to 4.7 (the pKa of acetic acid), but not close to 9. Beula B.'s suggestion of mixing [tex]NH_4Cl[/tex] and HCl solutions would result in an acidic solution due to the addition of HCl. It does not involve a weak acid and its conjugate base and thus cannot create a buffer at pH 9. Dexter D.'s suggestion of mixing [tex]NH_3[/tex] and NaOH solutions would result in an alkaline solution due to the addition of NaOH. It also does not involve a weak acid and its conjugate base, so it cannot create a buffer at pH 9. Carla C.'s suggestion of mixing [tex]NH_4Cl[/tex] and [tex]NH_3[/tex] solutions is appropriate because it involves the weak acid [tex]NH_{4}^+[/tex] (ammonium ion) and its conjugate base [tex]NH_3[/tex] (ammonia). The ammonium/ammonia system can form a buffer solution with a pH close to the pKa of the ammonium ion, which is approximately 9.24 (calculated from the given Ka value of [tex]NH_{4}^+[/tex]).
Therefore, Carla C.'s procedure is the correct one for preparing a buffer solution with a pH close to 9.
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predict the theoretical mass of baco3 that should form
A precipitation reaction occurs when 50. 0 mL of 0. 50 M BaCl₂ is mixed with 75. 0 mL of 0. 75 M Na₂CO₃ (aq). The only precipitate is the BaCO₃ (s) formed. (a) The balanced chemical equation is BaCl₂ + Na₂CO₃ → BaCO₃ + 2NaCl. (b) The limiting reagent is Na₂CO₃.
What is Balanced Chemical Equation ?The balanced chemical equation is the equation in which the number of atoms on the reactant side is equal to the number of atoms on the product side in an equation.
Now we have to write the balanced equation
BaCl₂ + Na₂CO₃ → BaCO₃ + 2NaCl
How to find the number of moles ?To calculate number of moles when molarity and volume are given as:
Number of moles = Molarity × Volume
Now,
Number of moles of BaCl₂ = Molarity × Volume
= 0.50 M × 0.05 L [1 ml = 0.001 L]
= 0.025 moles
Number of moles of Na₂CO₃ = Molarity × Volume
= 0.75 M × 0.075 L [1 ml = 0.001 L]
= 0.05625 moles
The limiting reagent is Na₂CO₃ here.
Thus from the above conclusion we can say that A precipitation reaction occurs when 50. 0 mL of 0. 50 M BaCl₂ is mixed with 75. 0 mL of 0. 75 M Na₂CO₃ (aq). The only precipitate is the BaCO₃ (s) formed. (a) The balanced chemical equation is BaCl₂ + Na₂CO₃ → BaCO₃ + 2NaCl. (b) The limiting reagent is Na₂CO₃.
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Disclaimer: The question was given incomplete on the portal. Here is the complete question.
Question: A precipitation reaction occurs when 50. 0 mL of 0. 50 M BaCl₂ is mixed with 75. 0 mL of 0. 75 M Na₂CO₃ (aq). The only precipitate is the BaCO₃ (s) formed.
a) Write the balanced equation that describes this reaction.
b) Which chemical is the limiting reactant
What is a foram and what is curious about the foram fossils of gubbio’s limestone?
Their fossilized shells formed these limestone rocks, which, like Gubbio's mountains, were once at the bottom of the ocean. Now exposed, they represent over a million years of a geological time period known as the Cretaceous.
Walter Alvarez found that forming a distinct boundary between the limestone of the two periods was a thin layer of red clay. Immediately below this clay boundary, the Cretaceous limestone was heavily populated with a wide mix of the fossils of tiny marine creatures called foraminifera, or “foram” for short.
On the Atlantic Coast, outside the town of Zumaia, Dutch geologist Jan Smit was studying the forams from a different ancient sea. Their fossilized shells formed these limestone rocks, which, like Gubbio's mountains, were once at the bottom of the ocean.
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If the concentration of fluoride anion and aluminum cation was increased to 5 m, by how much would the measured ecell change?.
If the concentration of fluoride anion and aluminum cation was increased to 5M, then there would be decrease in Ecell by 0.055 volts
The standard reduction potential of Fluoride anion and aluminum cation are -
2Al -----> 2Al3+ + 6e- [tex]E^o[/tex]cell = +1.66
6e- + 3F2 -----> 6F- [tex]E^o[/tex]cell = +2.87
The complete reaction is -
2Al + 3F2 ------> 2Al3+ + 6F- [tex]E^o[/tex] = +4.53
Using Nernst Equation :-
E = [tex]E^o[/tex] – 0.0592/n*log[Al3+]^2[F-]^6
n = 6 (n = number of transferred electrons)
E = +4.53 - 0.0592/6*log(5)^2(5)^6
E = +4.53 - 0.00987*log(25)(1.56 x 10^4)
E = +4.53 – 0.00987*log(3.9 x 10^5)
E = + 4.53 -0.00987(5.59)
E = + 4.53 - 0.055
E = +4.47
The change in Ecell = 5 - 4.47 = 0.055V
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To demonstrate the formation of iron (iii) chloride from iron fillings
Iron (iii) chloride is obtained by vapor condensation from the reaction between chlorine gas and iron fillings.
How can iron (iii) chloride be formed from iron fillings?Iron (ii) chloride can be formed from iron fillings in the laboratory as follows:
Iron fillings + Cl₂ → FeCl₃Chlorine gas is introduced into a reaction vessel containing iron fillings and the iron (iii) chloride vapor formed is obtained by condensation.
In conclusion, iron (iii) chloride is formed by the the direct combination of iron fillings and chlorine gas.
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How will designing more efficient stoves help conserve fuel?
Answer:
it would do wonders for the health of those using them and, by extracting energy from the fuel more efficiently, would be more environmentally sustainable too.
A chemist want to prepare a solution containing (soluble) silver ions. Which salt should they use? silver nitrate AgCI AgOH silver carbonate 2 pts
Answer: silver nitrate
Explanation:
it is the only soluble salt listed.
please help with question #2
The Ksp of the solution is 3.2 * 10^-8.
What is Ksp?The Ksp is called the solubility product . We know it to be the equilibrium constant that shows the extent to which a substance is dissolved in solution.
Now given that;
CaF2(s) ⇔ Ca^2+(aq) + 2F^-(aq)
Ksp = [ Ca^2+] [F^-]^2
Ksp = [0.002] [0.004]^2
Ksp = 3.2 * 10^-8
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Write the balanced chemical equation for the reaction of aqueous sodium sulfate
and solid calcium chloride to produce aqueous calcium sulfate and solid sodium
chloride
The equation of the reaction is [tex]Na_2SO_4 (aq) + CaCl_2 (s) --- > CaSO_4 (aq) +2 NaCl (s)[/tex]
What are chemical reactions?They are reactions involving chemical reactants leading to the formation of chemical products.
The chemical formula for sodium sulfate is [tex]Na_2SO_4[/tex]
The chemical formula for calcium chloride is [tex]CaCl_2[/tex]
The two react to produce calcium sulfate ([tex]CaSO_4[/tex]) and sodium chloride (NaCl) according to the following equation:
[tex]Na_2SO_4 (aq) + CaCl_2 (s) --- > CaSO_4 (aq) +2 NaCl (s)[/tex]
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What is the oxidation number for S in the compound SO3? (Recall that O has an oxidation number of –2.)
0
+2
+4
+6
The oxidation number for S in the compound SO3 is +6 (option D). Details about oxidation number can be found below.
What is oxidation number?Oxidation number of an element is the hypothetical charge of an atom within a molecule.
The oxidation number of elements in a compound adds up to the overall charge of that compound.
According to this question, O has an oxidation number of -2 in SO3, the oxidation number of S can be calculated as follows:
x - 2(3) = 0
x - 6 = 0
x = 6
Therefore, the oxidation number for S in the compound SO3 is +6.
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The answer is D: 6+
Worked for me on EDGE 2023
According to the modern periodic law the properties of elements are periodic function of their
Type the correct answer in the box. Use numerals instead of words.
The mechanical advantage shown in the image in ___.
The mechanical advantages of the machine are 3.
The amount that a force is boosted by employing a machine is known as the mechanical advantage. It is determined by dividing the applied force by the machine's force ( force exerted by the machine).
That is the mechanical advantage of any machine is equal to the ratio between the output force and the input force.
Mechanical advantages M.A. = Input force / Output force
We have,
Input force: 52 N
Output force: 156 N
Therefore,
Mechanical advantage = Input force / Output force.
52/156 = 3
Hence, the mechanical advantages of the machine are 3.
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Four students all do the same experiment for the science fair. They test reaction times for pushing a button when a specific color is shown. Their data is as follows: ⎡⎣⎢⎢⎢⎢⎢⎢⎢⎢⎢⎢Student 1Student 2Student 3Student 4Reaction Time (seconds)Trial 10.440.350.410.42Trial 20.410.430.520.43Trial 30.470.380.570.41Trial 40.390.390.460.42Trial 50.460.420.550.41Trial 60.420.440.490.42⎤⎦⎥⎥⎥⎥⎥⎥⎥⎥⎥⎥ Put the students in order from most to least reliable data. A. Student 3, Student 2, Student 1, Student 4 B. Student 2, Student 1, Student 4, Student 3 C. Student 4, Student 1, Student 2, Student 3 D. Student 1, Student 2, Student 3, Student 4
The order of the students from the most reliable to the least reliable is C. Student 4, Student 1, Student 2, Student 3.
what student has the most reliable data?the student with the most reliable data is the one that has the least variation in their data in the various trials.
this student is therefore student 4.
the next student would be student 1 and student 2 would be the third most reliable.
student 3 has large variations in their trials which makes their data the least reliable.
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Grant plans to evaporate enough water from 22 gallons of a 16 mmonia solution to make a 24 mmonia solution. Which equation can he use to find n, the number of gallons of water he should remove?
He can use 3.52/22-n = 24/100 equation to find n, where n is the number of gallons of water.
Calculation of amount of ammonia in 22 gallon of 16% ammonia solution.
amount of ammonia = 16%×22 gallon = 3.53 gallon
The amount of ammonia remains the same after evaporation of water but the total amount of solution is reduced because solution contain ammonia as well as water . So, if water is evaporate then solution reduced.
Amount of water remains = 22 - n
Desired concentration, 24% = 24/100
Therefore the final equation becomes,
3.52/22-n = 24/100
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Nuclear decay occurs according to first-order kinetics. What is the half-life of zinc-65 if a sample decays from 65.0 g to 2.90 g in 3.0 years
Answer:
Explanation:
244 days
will you brainlyest?
The half life of the Zn-65 sample if it decays from 65 g to 2.9 g in 3 years is 1.53 years. This can be obtained using the first order kinetic of nuclear decay.
What is nuclear decay?Nuclear decay is the process by which unstable isotopes of an atom decays by the emission of alpha or beta particles to form stable nuclei. Nuclear decay is a first order reaction and the decay constant k can be written as:
k = 1/t log [no]/[nt]
Where, no and nt be the initial and final amount of the sample.
Given that the initial mass of Zn was 65 g and after 3 years it is 2.90 gram. Thus, decay constant is calculated as :
k = 1/3 yrs log (65/2.9)
= 0.45 yr⁻¹.
Now, the half life of Zn-65 can be calculated as:
t1/2 = 0.693/ k
= 0.693/0.45 yr⁻¹
= 1.53 yrs.
Therefore, the half life of Zn-65 will be 1.53 years.
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see the attached photo*** can someone please explain how to do this for me? I really need help on my summer school thank you !
Answer:
See attached image.
Explanation:
See attached image.
Remember to use the units in deciding steps to take. Find the moles needed or delivered by using:
Molarity x Volume = moles [(moles/L)*(L) = moles]
Molarity, M, is dedined as 1 mole/liter. When working with a unit such as 6M, rewite it as 6 moles/liter, and then use unit conversions to guide how to find the solution, so to speak.
The book value of a machine, as shown on the balance sheet, is not relevant in a decision concerning the replacement of that machine by another machine. (Ignore taxes.) Group starts
The book value of a machine, as shown on the balance sheet, is not relevant in a decision concerning the replacement of that machine by another machine: TRUE
What is the book value?Book value is the worth of an asset based on its balance sheet account balance in accounting. The value of an asset is determined by subtracting the asset's original cost from any depreciation, amortization, or impairment expenses. Traditionally, a company's book value is equal to its total assets minus intangible assets and liabilities. In practice, however, depending on the source of the computation, book value may include either goodwill or intangible assets, or both. The value inherent in its employees, which is part of a company's intellectual capital, is always overlooked. When intangible assets and goodwill are specifically omitted, the indicator is frequently defined as "tangible book value."Therefore, the statement "the book value of a machine, as shown on the balance sheet, is not relevant in a decision concerning the replacement of that machine by another machine" is TRUE.
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Complete question:
The book value of a machine, as shown on the balance sheet, is not relevant in a decision concerning the replacement of that machine by another machine. (Ignore taxes.) TRUE or FALSE
What three letters are always added to the end of nonmetals in naming ionic compounds?
Answer:
-ide
Explanation:
Ionic compounds are made up of two parts: a cation and an anion. The cation is positively charged (less electrons) and the anion is negatively charged (more electrons). When naming these compounds, if the anions are nonmetals, they have their endings dropped in order to add the new ending: -ide.
Examples,
CaCl₂ ----> calcium chloride
BaF₂ -----> barium fluoride
MgO -----> magnesium oxide
A compound's molar mass is 240g/mol. its percentage composition is 75% carbon, 5.05% hydrogen and 19.95% oxygen, what is the molecular formula?
explanation please
The molecular formula of the compound is C15H12O3.
What is the molecular formula of the compound?The molecular formula of the compound is determined from the mole ratio of the elements in the compound.
Carbon = 0.75 × 240/12 = 15
Hydrogen = 0.0505 × 240/1 = 12
Oxygen = 0.1995 × 240/16 = 3
Therefore, the molecular formula of the compound is C15H12O3
In conclusion, the molecular formula of the compound is determined from the mole ratio of the elements and their percentage composition.
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Please help me i really need it!
The average atomic mass of sulfur = 32.33 u
What is the average atomic mass of sulfur?The average atomic mass of sulfur is determined as follows:
Average atomic mass = (31.977 × 0.818) + (32.97 × 0.008) + (33.97 × 0.174)
Average atomic mass = 32.33
In conclusion, the average atomic mass of sulfur is determined from the sum of the isotopic masses and their relative abundance.
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What two basic geologic processes contributed to the formation of folded mountain ranges like in Glacier National Park?
The two basic geologic processes which contributed to the formation of folded mountain ranges like in Glacier National Park include:
Folding and breaking of sedimentary rocks.Erosion.What is Erosion?This is a geologic process which involve materials in the earth being washed away and transported to other parts by water, wind etc.
In the case of Glacier National Park, ice erodes the mountain thereby resulting in the folding of the sedimentary rocks.
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What is a molecular dipole moment?
What is acceptable as eye protection when working with one gallon of hydrochloric acid?
The Protective Equipment is a Face Shield.
Hydrochloric acid is a dangerous chemical, it can be handled with proper care. As we know Hydrochloric acid is corrosive. If acid touches the skin, eyes, and internal organs then the damage can not be treated, or even in some cases it is fatal.
If hydrochloric acid is used in the workplace, then there is a need for access to an eye-flush station.
If acid is used at home, then need to follow some safety instructions. If acid is diluted with water, still there is a need for protection. For example: wear protective clothes and gloves.
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Consider the reaction and its equilibrium constant at 25.0 ∘C :
CO(g)+2H2(g)⇌CH3OH(g) , Kp=6.09×10−3
A reaction mixture contains P(CO)=0.265atm , P(H2)=0.265atm , and P(CH3OH)=0.265atm .
Is the reaction mixture at equilibrium?
Since Qp>Kp , the reaction is not at equilibrium
Since Qp
Since Qp=Kp , the reaction is at equilibrium
Since Qp=Kp , the reaction is not at equilibrium
Since Qp>Kp , the reaction is not at equilibrium.
What is the equilibrium constant?The equilibrium constant shows the extent to which reactants are converted into products.
Now we have to obtain the Qp as follows;
Qp =[CH3OH]/[CO] [H2]^2
Qp = 0.265/(0.265) (0.265)^2
Qp = 14.2
Now we know that Kp = 6.09×10−3, Since Qp>Kp , the reaction is not at equilibrium.
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Consider the chemical equation in equilibrium. CH4(g) H2O(g) CO(g) 3H2(g) What will happen to the equilibrium of this reaction if the pressure is increased
The equilibrium of this reaction will shift to the left to favor the reverse reaction if the pressure is increased.
Balanced chemical equation
CH₄(g) + H₂O(g) → CO(g) + 3H₂(g)
The principle suggests
The equilibrium will move to the side of the reaction where there are fewer moles of gas as pressure increases.
And the equilibrium will move toward the side of the reaction where there are more gas molecules when the pressure is reduced.
In the given chemical equation
The no. of moles of reactant = 2
The no of moles of the product = 4
Total moles of reactant is less than that of total moles of product
Therefore, If the pressure is increased the equilibrium of this reaction will shift to the left to favor the reverse reaction.
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The table shows the amount of radioactive element remaining in a sample over a period of time. radioactive decay rate amount of radioactive sample (grams) time (years) 56.0 0 47.1 400 39.6 800 33.3 1,200 28 1,600 part 1: what is the half-life of the element? explain how you determined this. part 2: how long would it take 312 g of the sample to decay to 9.75 grams? show your work or explain your answer.
1. The half life of the element, given the data from the question is 1600 years
2. The time taken for 312 g of the sample to decay to 9.75 grams is 8000 years
1. How to determine the half life of the elementHalf-life is the time taken for half a material to decay.
To determine the half life of the given element, do the following:
Original amount = 56 gHalf the original amount = 56 / 2 = 28 gTime for 28 g = 1600 yearHalf life of element = 1600 yearsHow to determine the timeWe'll begin by determining the number of half-lives that has elapsed. This can be obtained as follow:
Original amount (N₀) = 312 gAmount remaining (N) = 9.75 gNumber of half-lives (n) =?2ⁿ = N₀ / N
2ⁿ = 312 / 9.75
2ⁿ = 32
2ⁿ = 2⁵
n = 5
Finally, we shall determine the time. This can be obtained as follow:
Half-life (t½) = 1600 yearsNumber of half-lives (n) = 5Time (t) =?t = n × t½
t = 5 × 1600
t = 8000 years
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If a car travels 300 kilometers in 3 hours, its average speed is 100 km/hr.
true or false
Answer:
speed=distance/time taken
=300km/3hr
=100km/hr
So it is true.
please give brainlest and like
Phosphorus reacts with oxygen gas to produce solid diphosphorus pentoxide. What type of reaction is represented
It is a combination reaction.
P + O₂ → P₂O₅
What is a combination reaction?Combination reactions are those in which two or more reactants combine to create a single product.
A synthesis reaction is another name for a combination reaction. The overall form of the reaction is as follows:
X + Y → XY
There can be a combination reaction between two elements, two compounds, or a compound and an element.
Examples:
H₂ + Cl₂ → 2HCl
P + O₂ → P₂O₅
C + O₂ → CO₂
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In the lab, you looked at speed-time graphs to determine the acceleration of the cart for each of the three fan speeds. what was the acceleration of the cart with low fan speed? cm/s2 what was the acceleration of the cart with medium fan speed? cm/s2 what was the acceleration of the cart with high fan speed? cm/s2
Answer:
See below.
Explanation:
Acceleration is the change in velocity over a period of time.
Let vi be the initial velocity.
Let vf be the final velocity.
t is the time it took to go from vi to vf.
Acceleration is (vf-vi)/t
If the initial velocity was 2 cm/s and the final velocity was 10 cm/s, the object would have incresed it's velocity by (10 - 2) or 8 cm/s. If iit took 10 seconds to reach vf, the acceleration would be:
(8 cm/s)/(10 s) = 0.8 cm/s^2
Please help!! Balancing Nuclear Equations
The missing part of the equation is found to be 4/2He. Option A
What are nuclear equations?The term nuclear equations have to do with the type of equation in which one type of nucleus is transformed into another sometimes by the bombardment or loss of a particle.
Now the full equation ought to be written as 7/3Li + 1/1H -----> 4/2He + 4/2He. This is because the total mass on the left is 8 and the total charge on the left is 4.
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Magnesium and calcium have similar chemical properties because their atoms in the ground state have.
Magnesium and calcium have similar chemical properties because they have the same number of electrons in their valence shells.
What does magnesium and calcium have in common?
The valence/outermost shell of magnesium and calcium both has two electrons. An element's chemical characteristics are dictated by how its electrons are arranged in their orbits around the nucleus. The same number of protons and electrons means that an element's chemical behavior is fundamentally determined by its atomic number, which explains why Mg and Ca share the same chemical properties.
On the periodic table, magnesium and calcium are both located in the second vertical column. Magnesium and calcium are alkaline earth metals, just like all Group 2 elements. Both of them are salt-forming soft, silver-colored metals that respond fast to halogen gases like fluorine, chlorine, and bromine.
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