Question 1 What is the pH of a 2.50M solution of NH4CI. The Kb for NH3 is 1.79 E-5. NH4+ + H2O H3O+ NH3 CI-+H20-> No reaction Question 2 A buffer is made by adding 0.500L of a 5.00M solution of Aceti
Answers
The pH of a 2.50 M solution of NH₄Cl is approximately 0.60.
To break the buffer solution made from acetic acid and sodium acetate, approximately 10 ml of a 0.500 M NaOH solution needs to be added.
1: The pH of a 2.50 M solution of NH₄Cl can be determined by considering the hydrolysis of the ammonium ion (NH₄+). The chemical equation for the hydrolysis reaction is:
NH₄+ + H₂O ↔ NH₃ + H₃O+
The Kb (base dissociation constant) for NH₃ (ammonia) is given as 1.79 × 10⁻⁵.
Using the Kb expression, we have:
Kb = [NH₃][OH-] / [NH₄+]
Assuming the concentration of NH₃ formed is negligible compared to the initial concentration of NH₄+, we can simplify the equation:
Kb = [OH-] * x / (2.50 - x)
where x is the concentration of OH- ions produced, and (2.50 - x) is the concentration of NH₄+ ions remaining after hydrolysis.
Given that Kb is small compared to the initial concentration of NH₄Cl, we can approximate x to be negligible compared to 2.50. This leads to the equation:
Kb = x * (2.50 - x) / 2.50
Solving this equation for x, we find x ≈ 0.0182 M.
The resulting concentrations of the species involved in the hydrolysis reaction are approximately:
[NH₄+] = 2.50 - x ≈ 2.50 M
[NH₃] = x ≈ 0.0182 M
Therefore, the pH of the solution can be determined using the concentration of H3O+ ions, which is equal to the concentration of NH₄+ ions:
pH = -log[H₃O+] ≈ -log(2.50) ≈ 0.60
Thus, the pH of the 2.50 M NH₄Cl solution is approximately 0.60.
2: To determine the amount of 0.500 M NaOH needed to break the buffer made from acetic acid (CH₃COOH) and sodium acetate (CH₃COONa), we consider the neutralization reaction between the weak acid and the base:
CH₃COOH + NaOH → CH₃COONa + H₂O
Since the acetic acid is a weak acid, it does not completely dissociate, and the reaction can be represented as the neutralization of the weak acid. The balanced chemical equation for the reaction is:
CH₃COOH + NaOH → CH₃COONa + H₂O
Given that the volumes of the acetic acid and sodium acetate solutions are both 0.500 L and their respective molarities are 5.00 M, we can use the stoichiometry of the balanced equation to calculate the amount of NaOH needed to break the buffer.
Using the molar ratio between CH₃COOH and NaOH from the balanced equation, we find that one mole of CH₃COOH reacts with one mole of NaOH. Therefore, the number of moles of NaOH needed is equal to the number of moles of CH₃COOH in the buffer solution.
The moles of CH₃COOH can be calculated using the volume and molarity:
moles of CH₃COOH = volume of CH₃COOH solution (L) × molarity of CH₃COOH (M)
moles of CH₃COOH = 0.500 L × 5.00 M = 2.50 moles
To break the buffer solution, the pH needs to change by 1 unit, which corresponds to a tenfold change in [H₃O+] concentration. This can be achieved by neutralizing all the acetic acid in
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Question 1 What is the pH of a 2.50M solution of NH4CI. The Kb for NH3 is 1.79 E-5. NH4+ + H2O <-> H3O+ NH3 CI-+H20-> No reaction Question 2 A buffer is made by adding 0.500L of a 5.00M solution of Acetic Acid to 0.500L of a 5.00M solution of Sodium Acetate. The Ka of Acetic acid is 1.8 E-5. How many ml of a 0.500M NaOH needs to be added to this buffer to break it. A buffer is considered broken when the pH of the original solution is changed by 1 pH unit.
Related Questions
The time for one cycle of a periodic process is called the:.
Answers
Answer:
Period
Explanation:
I believe your answer should be period.
I hope it helps! Sorry if it didn’t… Have a great day!
Layla~
A 25.0 mL sample of a solution of an unknown compound is titrated with a 0.115 M NaOH solution. The titration curve above was obtained with pH at equivalence point of around 8. The unknown compound is ________.
Answers
Answer:
Weak acid
Explanation:
A titration curve is a graphical description of the change in pH of the solution in the conical flask as the reagent is added from the burette. A titration curve can be plotted for the different kinds of acid and base titrations. The volume of the titrant is always plotted as the independent variable and the pH of the solution as the dependent variable. The equivalence point is read off from the titration curve. A titration curve is very important because it shows the pH at various points during the titration.
A weak acid/strong base titration leads to an equivalence point above 7. From the question, we were told that the pH at equivalence point lies around 8. Hence the unknown substance must be a weak acid.
4. 6.5a
Which of these have a positive charge and are found in the nucleus of an atom?
Neutrons
Protons
Electrons
Elements
Answers
Answer:
protons
Explanation:
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What would the mass be, in grams, of 0.89 moles of Cl2?
Answers
Answer:
Mass = 63.19 g
Explanation:
Given data:
Number of moles of Cl₂ = 0.89 mol
Mass in gram = ?
Solution:
Formula:
Mass = number of moles × molar mass
Molar mass of Cl₂ = 71 g/mol
by putting values,
Mass = 0.89 mol × 71 g/mol
Mass = 63.19 g
which statement about chemical reactions is true?
A) The reaction rates are always constant
B) The reaction rates can increase
C) The reaction rates cannot change
D) The reaction rates cannot decrease
Answers
The statement about chemical reaction is true is :
B) The reaction rate can increase.
A) The rates are always constant is not true. for a chemical reaction, the rate of chemical reaction does not remains constant because rate depends on the concentration of reactants.
B) The rate of reaction can increase is true . for a chemical reaction , the rate of reaction can be increase by increasing the concentration of reactant.
C) The rate of reaction cannot change is not true.
D) The rate of reaction cannot decreases is not true . reaction rates
decreases with time .
Thus, The statement about chemical reaction is true is :
B) The reaction rate can increase.
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Chlorine has 7 valence electrons. With what group of elements will chlorine most readily bond?.
Answers
The elements that chlorine will most readily bond with are elements found in group one eg sodium, potassium, etc.
What is group of elements?Elements are arranged in groups in the periodic table based on their number of valance electrons.
Elements in the same group of the periodic table has similar characteristics.
Reaction between metals and nonmetalsWhen metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms, forming ions.
The resulting compound is called an ionic compound.
Chlorine is the most reactive non metal and will bond easily with metals. The most reactive metals are found in group one.
Example of chlorine reaction with a group one elementCl⁻ + Na⁺ -------> NaCl
Thus, the elements that chlorine will most readily bond with are elements found in group one eg sodium, potassium, etc.
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The half-life of K-42 is 12. 4 hours. How much of a 750 g sample is left after 62 hours?
Answers
After 62 hours, approximately 23.4375 grams of the 750 gram sample of K-42 is left.
To calculate the amount of K-42 remaining after 62 hours, we need to determine the number of half-lives that have passed and then calculate the remaining amount using the formula:
Remaining amount = Initial amount × (1/2)^(number of half-lives)
Given that the half-life of K-42 is 12.4 hours, we can divide the total time (62 hours) by the half-life to find the number of half-lives:
Number of half-lives = 62 hours / 12.4 hours = 5
Now, we can calculate the remaining amount:
Remaining amount = 750 g × (1/2)^5 = 750 g × (1/32) = 23.4375 g
Therefore, approximately 23.4375 grams of the 750 g sample of K-42 will be left after 62 hours.
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Which is classified as an inner transition element? calcium copper fermium helium
Answers
Answer:
C.) Ferbananallium
Explanation:
do you have any other choice?
An Inner transition element among the following is Fermium. Hence option (C) is correct.
What is Inner Transition Elements ?Inner transition elements are the elements in which the last electron enters in the f-orbital.
They generally belong to group 3 in the periodic table but are mentioned separately as the f block elements. These f- block elements are known as inner transition elements.
Fermium is a synthetic element with the symbol Fm and atomic number 100 belongs to Inner transition element. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements.
Hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared.
Therefore, An inner transition element among the following is Fermium. Hence option (C) is correct.
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round off .00042557 to three significant digits
Answers
Round off .00042557 to three significant digits is = 0.000426
What is round of value ?If 5, 6, 7, 8, or 9 come after the number you are rounding, round it up. For instance, 40 is the result of rounding 38 to the nearest ten.If the numbers 0, 1, 2, 3, or 4 come after the number, round it down. If 33 is rounded to the nearest ten, it becomes 30.To estimate a certain number in a context, rounding is a process. Look at the next digit in the correct position to determine how to round a number; if it is less than 5, round down, and if it is 5 or more, round up.Given
The digit of 00042557
Three significant digits is 0.000426
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In a cell, what is the function of the cell membrane?
A.
It only maintains the cell shape.
B.
It controls the entry and exit of substances.
C.
It generates energy for the cell.
D.
It removes waste and stores ingested food.
Answers
Answer:
b it controls the entry and exit of substances
How many oxygen atoms are there in 3 molecules of CH3FO?
Answers
Answer: There should be 3.
Explanation:
when energy changes from one form to another (for example, chemical energy —> heat —> light) it is known as:
fossil fuel change
energy transformation
energy transfer
light & heat change
Answers
Daniel is conducting an experiment on magnetic objects. He completes more than one trial. Why is it important for Daniel to do this?
The conclusion is less accurate.
The conclusion is more accurate.
There is a greater chance of error.
The results will be inaccurate.
Answers
Answer:The conclusion is less accurate.
Explanation:
Feb 17, 2021 — He completes more than one trial. Why is it important for Daniel to do this?
Use the Venn Diagram below to identify where the listed characteristics belong.
Answers
The atom's nucleus is composed of neutrons and protons. BOTH: In the nucleus. Contribute to the mass of the atom. Mass equal 1 amu. PROTON. Number is atomic number of element. Determine the identity of the atom. NEUTRON: Neutral charge.
What is a subatomic particle?
Subatomic particles are matter structures that are smaller in size than an atom. Hence, subatomic particles compose the atoms, determining their properties.
Many subatomic particles are unstable and remain unknown. However, three of them are the most stable ones,
protons electronsneutronsSubatomic particles can be either,
compound ⇒ divisible ⇒ protons and neutronelementary ⇒indivisible ⇒ electronsNeutrons and protons compose the nucleus of the atoms, while electrons orbit around them.
These particles differ in their electric charge and their mass.
Protons have a positive charge (+)Neutrons have no charge (0)Electrons have a negative charge (-)
The number of protons in the atom is the atomic number and determines the atom's identity.
The massic number is the addition of the number of protons and the number of neutrons.
Atomic mass is composed of neutrons and protons mass. It is not the same as the massic number or the atomic weight.
When protons, neutrons, and electrons get together to form an atom, they lose part of their mass as energy. This is why the atomic weight is slightly inferior to the sum of masses.
1) BOTH
In the nucleus
Contribute to the mass of the atom
Mass equal 1 amu (1.67377 x 10⁻²⁷ kg or 1.67377 x 10⁻²⁴ g)
2) PROTON
Number is atomic number of element
Determine the identity of the atom
3) NEUTRON
Neutral charge
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Describe the ammonium ion, NH4+, and the sulfate ion, SO42-. What compounds would these ions form with potassium and fluoride ions? Write the formula units for the resulting compounds.
Answers
Explanation:
Ammonium Fluoride and Potassium Sulphate
The name for a positive ion is a ....
Answers
The name for a positive ion is a cation.
hope this helped
What is the control group? What is the independent variable? What is the dependent variable? What should Smithers’ conclusion be?
Answers
Answer:
It says it in the text
Explanation:
What two elements are used to make a laser pen light?
Answers
Answer:
Helium and Neon
Explanation:
Semiconductor diodes are the current elements of laser pointers and are formed by a mixture of Gallium and Arsenic with very small amounts of other elements to obtain different wavelengths.
Laser pointers or pen light are inputs that emit collimated and colored laser radiation, which every day finds more applications in industry, ordinary life and research.
The first pointers were made with Helium and Neon but they were delicate and bulky, today they have been replaced by pointers with solid state diodes, depending on the material they can emit radiation from 1320 nm to 254 nm.
The most common materials for economically priced pointers that emit in the visible range (400 nm to 700 nm) are Gallium and Arsenic, in the GaAs semiconductor compound with 1.4 eV energy gap.
For the emission, a np union is created and depending on the doping, emission is achieved in a wide range of wavelengths.
In conclusion, semiconductor diodes are the current elements of laser pointers and are formed by a mixture of Gallium and Arsenic with very small amounts of other elements to obtain different wavelengths.
Fundamental materials: Gallium and Arsenic
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What might be a possible outcome if you left a soda in a glass bottle in the freezer for a very long time?
A.
The gases in the soda will increase in volume as the soda transitions from liquid to solid. This will cause the bottle to explode.
B.
The gases in the soda will decrease in volume as the soda transitions from liquid to solid. This will cause the bottle to implode or collapse.
C.
H2O will decrease in volume when transitioning from a liquid to solid state. This will cause the bottle to implode or collapse.
D.
H2O will increase in volume when transitioning from a liquid to solid state. This will cause the bottle to explode.
Answers
A the soda will increase in volume
TRUE OR FALSE
- during all chemical reactions, the mass of the products is never equal to the mass of the reactants
- Mass is sometimes lost in chemical reactions
- The Law of Conservation of Mass states that mass is not conserved
Answers
During all chemical reactions, the mass of the products is never equal to the mass of the reactants.
- FALSE
Mass is sometimes lost in chemical reactions.
- FALSE
The Law of Conservation of Mass states that mass is not conserved.
- FALSE
write and balance the equation for the complete combustion of ethane, C2H6.
Answers
Answer:
C2H6 + 7/2O2 ....... 2CO2 + 3H2O
Which one is a single replacement reaction? (Whoever gets it correct first I’ll mark)
Answers
The equation that represents a single replacement reaction given the various options is 2Al(s) + 6HCl -> 2AlCl₃(aq) + 3H₂O(g) (option 2)
What is a single replacement reaction?A single replacement reaction, also known as single displacement reaction is a reaction in which elements higher in the electro-chemical series displace or replace elements lower in the electro-chemical series displace from a solution.
The following example illustrates single replacement reaction:
A + BC -> AC + B
From the above reaction, we can see that A has replace/displace B to from AC.
With the above information, we can determine the equation that represents single replacement reaction. Details below:
Equation from the questions:
2Al + 3Cl₂ -> 2AlCl₃2Al(s) + 6HCl -> 2AlCl₃(aq) + 3H₂O(g)2AlCl₃(aq) -> 2Al + 3Cl₂ AlCl₃ + 3KOH -> Al(OH)₃ + 3KClFrom the above, we can see that only 2Al(s) + 6HCl -> 2AlCl₃(aq) + 3H₂O(g) conform to single replacement reaction.
Thus, the correct answer to the question is: 2Al(s) + 6HCl -> 2AlCl₃(aq) + 3H₂O(g) (option 2)
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How does increasing the surface area affect the motions of the molecules?
Answers
Increasing the surface area of a reactant increases the rate of collisions which also increases the reaction rate.
Why increasing the surface area affect the movement of molecules?Because increasing the surface area of an incentive increases the frequency of collisions and increases the reaction rate. some smaller molecules have more surface area than one large particle. further, the surface area that is available for particles to collide, a speedy reaction will occur. The rate of a chemical reaction can be elevated by increasing the surface area of a solid reactant. Molecular movement is affected by heat and temperature. because the temperature is the computation of the average kinetic energy of the molecules and acts for the motion of molecules. grow surface area is the most favored trend for better performance of gas sensor materials.
So we can conclude that So the larger the surface area of the solid, the faster the reaction will be.
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NAME: Madsen Binette
CLASS: Blue 4
Percent yield practice
1. Consider the following balanced equation
2 Al + 6 HBr - →2 AlBr3 + 3 H₂
A) If 86.88 grams of Aluminum (Al) reacts with 401.31 grams of
Hydrogen Bromide (HBr) how many grams of H₂ will be produced?
B) which is the limiting reactant?
C) what is the percent yield
Answers
Answer:
I dont understand nd also i need to message u privately
Which of the following is one way creativity can help scientists?
Answers
Answer:
One way creativity is helpful to scientists is when they need to come up with a experiment or cure for something their imaginastion is very helpful. The reason for that is with creativity they could get answers much quicker!
Explanation:
Answer:
I agree with that answer
if you were given an unknown sample, how would you determine if it was a suspension, colloid or homogeneous solution?
Answers
The Tyndall effect can be used to detect whether an unknown sample is a suspension, colloid, or homogeneous solution.
Light can always travel through a solution, and there is never any general light scattering. Between solutions and suspensions, a colloid exists. By diffusing the incoming light, it produces the Tyndall effect. A suspension is hazy and contains visible suspended particles. The suspensions obstruct the passage of light.
A combination that is heterogeneous and has some of its particles settle out as it stands is called a suspension. Therefore, if a beam of light is passed through your sample and it scatters, it is either a suspension or a colloid. It is a solution if it doesn't scatter.
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How is it determined the highest energy level an atom has
A. By the group number
B. By the period number
C. By the atomic number
D. By the mass number
Answers
Answer:
C. Atomic mass
Explanation:
i just did the quiz and got 100 :) i hope I get brainiest answer
atoms or molecules that have gained or lost electrons are called:
Answers
Atoms or molecules that have gained or lost electrons are called ions.
Atoms or molecules that have gained or lost electrons are called ions. When an atom or molecule gains electrons, it becomes a negatively charged ion called an anion. Anions have an excess of electrons compared to the number of protons, resulting in a negative charge.
Conversely, when an atom or molecule loses electrons, it becomes a positively charged ion called a cation. Cations have fewer electrons compared to the number of protons, resulting in a positive charge.
The process of gaining or losing electrons is known as ionization.
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Which surface has the most friction
Answers
Answer: Rougher surfaces have more friction between them than smoother surfaces. That's why we put sand on icy sidewalks and roads. You can't slide as far across ice with shoes as you can on the blades of skates. The rougher surface of the soles of the shoes causes more friction and slows you down. There are four types of friction: static, sliding, rolling, and fluid friction. Static, sliding, and rolling friction occur between solid surfaces. Static friction is strongest, followed by sliding friction, and then rolling friction, which is weakest.
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Ocean currents bring warm from the equator towards earth?
Answers
Answer:Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics.
Explanation:
Answer:
Explanation:
Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics.
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