Answer:
a. pH = 2.04
b. pH = 3.85
c. pH = 8.06
d. pH = 11.56
Explanation:
The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:
HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)
a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:
Ka = [H⁺] [NO₂⁻] / [HNO₂]
Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):
5.6x10⁻⁴ = X² / 0.15M
8.4x10⁻⁵ = X²
X = [H⁺] = 9.165x10⁻³M
As pH = -log [H⁺]
pH = 2.04b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:
pH = pKa + log [NaNO₂] / [HNO₂]
Where pH is the pH of the buffer,
pKa is -log Ka = 3.25
And [NaNO₂] [HNO₂] could be taken as the moles of each compound.
The initial moles of HNO₂ are:
0.100L * (0.15mol / L) = 0.015moles
The moles of base added are:
0.0800L * (0.15mol / L) = 0.012moles
The moles of base added = Moles of NaNO₂ produced = 0.012moles.
And the moles of HNO₂ that remains are:
0.015moles - 0.012moles = 0.003moles
Replacing in H-H equation:
pH = 3.25 + log [0.012moles] / [0.003moles]
pH = 3.85c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:
0.15M / 2 = 0.075M
The NaNO₂ is in equilibrium with water as follows:
NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺
The equilibrium constant, kb, is:
Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]
Where [OH⁻] = [HNO₂] = x
[NaNO₂] = 0.075M
1.79x10⁻¹¹ = [X] [X] / [0.075M]
1.34x10⁻¹² = X²
X = 1.16x10⁻⁶M = [OH⁻]
pOH = -log [OH-] = 5.94
pH = 14-pOH
pH = 8.06d. At this point, 5mL of NaOH are added in excess, the moles are:
5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH
In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =
3.66x10⁻³M = [OH⁻]
pOH = 2.44
pH = 14 - pOH
pH = 11.56how can a scientist make a solution using salt and water?
Answer:
by boiling water and add the salt
Explanation:
because salt dissolves better if mixed with hot water which makes the process faster and effective
(2pts) Post-lab Questions (1pts) 1. Do you expect the solubility of Borax to increase or decrease as temperature increases? Select the option that best explains why. Solubility will increase, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get larger. Solubility will increase, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get smaller. Solubility will decrease, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get smaller. Solubility will decrease, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get larger. Choose... (1pts) 2. Why was it necessary to make sure that some solid was present in the main solution before taking the samples to measure Ksp? Select the option that best explains why. To make sure no more sodium borate would dissolve in solution. To ensure the dissolution process was at equilibrium. To make sure the solution was saturated with sodium and borate ions. All of the above
Answer:
1. Solubility will increase, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get larger.
2. To ensure the dissolution process was at equilibrium.
Explanation:
Given that;
ΔG°= -RTlnK
and
ΔG° = ΔH° - TΔS°
So;
-RTlnK = ΔH° - TΔS°
lnK = ΔH°/-RT - TΔS°/-RT
lnK = -(ΔH°/RT) + ΔS°/R
K = e^-(ΔH°/RT) + ΔS°/R
Hence, Solubility will increase, because as T increases the − Δ H ∘ R T −ΔH∘RT term becomes smaller therefore K will get larger.
2.
Since solubility is an equilibrium process, it means that some undissolved solute must be present in order to determine the solubility product correctly.
Solubility is the ability of the solute to dissolve in the solution. As temperature increases, the solubility increases, and the presence of solid ensure dissolution.
What is Gibbs energy?The Gibbs free energy is the change in the energy of a system from the energy present in the reactant towards the product formation.
It is given as,
[tex]\rm \Delta G^{\circ}= \rm -RTlnK \\\\\rm \Delta G ^{\circ} = \Delta H ^{\circ} - T\Delta S ^{\circ}[/tex]
Equating both equations we get:
[tex]\begin{aligned} \rm -RTlnK &= \rm \Delta H ^{\circ} - T\Delta S ^{\circ}\\\\\rm lnK &=\rm -(\dfrac{\Delta H ^{\circ}}{RT}) + \dfrac{\Delta S ^{\circ}}{R}\\\\\rm K &=\rm e^{-(\frac{\Delta H ^{\circ}}{RT}) + \frac{\Delta S ^{\circ}}{R}}\end{aligned}[/tex]
Thus, the solubility of the substance increases with an increase in temperature.
The solubility product is estimated correctly by the equilibrium process that ensures the presence of the undissolved solute particles.
Therefore, 1. option A. solubility increases and 2. option B. to ensure the equilibrium process are the correct options.
Learn more about solubility here:
https://brainly.com/question/14092287
Which action would not help a person stay safe during a tornado? O A. Moving away from outside walls B. Going into a storm shelter or basement O C. Driving to get supplies OD. Staying away from windows
Answer:
Driving to get supplies
Explanation:
HI PLEASE HELP!!!!
7) As you move left to right across Period 3 from Sc to Zn, the energy needed to remove an electron from an atom —
A. generally increases
B. generally decreases
C. does not change
D. varies unpredictably
As we move left to right across Period 3 from Sc to Zn, the energy needed to remove an electron from an atom generally increases.
What is Periodic Table?Periodic table is the arrangement of chemical elements according to their atomic number in the tabular form. It is arranged from the lowest atomic number to highest atomic number i.e. the total number of protons in the atomic nucleus are in the increasing order.
In this type of recurring pattern which is called as periodic law in their properties in which elements in the same column (group) have similar properties.
The horizontal rows which goes from left to right is called as periods (7 in numbers) where the vertical columns which goes from up to down are called groups (18 in numbers). There is a square for each element includes a number and letters. These letter are the chemical name for the element like Hydrogen is H but for silver it is Ag. The number present is the atomic number. There are total 118 elements but only 94 is naturally exist on Earth.
So, as we move left to right across Period 3 from Sc to Zn, the energy needed to remove an electron from an atom generally increases.
Learn more about Periodic table, here:
https://brainly.com/question/11155928
#SPJ2
if a sample is 0.5g but has an impurity of 70% what is the real mass of the sample(pure)?
Answer:
0.15
Explanation:
0.5 is100% of the total mass if 70% is impure .find the mass of 70%
which is 0.35g take 0.5 -0.35 =0.15
0.15 is the mass of the pure sample
Please help me outttt
Answer:
4.) 9, 1, and 4 5.) 4, 1, and 4
Explanation:
I am not quite sure about this because I cannot remember if the coefficient (the number before the elements) is applied to every element in the compound. If it is then your number of atoms are as follows: CORRECTION: you do not have to apply the coefficient to every element only the one that is after it. So when you back and fix the error your number of atoms will be as follows:
number 4
H: 9
P: 1
O: 4
number 5:
H: 4
S: 1
O: 4
you can calculate the number of atoms present in this compound by multiplying the coefficient and the subscripts of each atom.
hope this helped you :)
What does the esophagus connect?
the intestine to the colon
the intestine to the mouth
The stomach to the intestine
the mouth to the stomach
Answer: it think it would be last one. the mouth to the stomach is the answer.
Explanation:
Answer:
The correct answer is D! The esophagus connects the mouth to the stomach.
Explanation:
The mouth is connected to the esophagus, which in turn is connected to the throat. The throat, in turn, connects the mouth to the stomach.
I had this on a science test and I got it right :D
I hope this helps! ;)
Why is Potassium hydroxide considered a strong base?
Answer:
KOH is a strong base, and therefore dissociates completely into negative and positive ions in water solution. pH 8.35 is a high pH (> 7), therefore this is a basic solution. 4.
Explanation:
HELP plis !
Find the molar masses of the following compounds: SHOW ALL WORK!!!
1) LiI. Li. 7 + I 127
134g/mol
2) PbCO4
Pb =. 1 x 207 =207
C = 1 X 12 = 12
O = 4 x 16 = 64
283 g/mol
3) Mg(OH)2
Mg= 1x 12 = 12
O= 2 x16 =32
H= 2x1= 2
46 g/mol
4) K3PO4
5) (NH4)3PO4
6) C12H22O11
7) Fe2(SO4)3
8) Na3P
9) AgF
10) NH4C2H3O2
After balancing this equation, how many oxygen atoms are present on the product side of the following equation:
C3H8 + 02 --> CO2 + H20
A.10
B.42
C.2
D.3
Answer:
B
Explanation:
A student performed an experiment in which 10 mL of a strong acid was placed on a sample of limestone. Bubbles formed where the acid touched the limestone. After 20 minutes, the bubbling stopped and the surface of the limestone appeared unchanged. What is an observation that suggests a chemical reaction did in fact take place between the acid and the limestone?
a) The limestone appeared to be unchanged.
b) The acid had to be prepared beforehand.
c) Bubbles formed where the acid and limestone touched.
d) None of the above
Answer:
Answer is D, None of the above :)
Explanation:
Which of the following astronomical bodies would most likely be the largest?
1. A dwarf star from a nearby solar system
2. A comet
3. One of the gas giants in our solar system
4. Ganymede, the largest moon of Jupiter
Answer:
1
because a dwarf star will seemlarge because of the in ability of any human being to see d sun
24. A wave has a speed of 50 m/sec. If its frequency is 100 Hz,
what is its wavelength?
Answer:
I guess
Wave speed= Frequency x Wavelength
-> Wavelength= Wave speed divide Frequency
-> 50m/s divide 100Hz= 0.5m
I hope it help! :)
An electron confined in a one-dimensional box is observed, at different times, to have energies of 12 eV, 27 eV, and 48 eV. What is the length of the box? 45. | The nucleus of a typical atom
Answer:
[tex]l=3.5*10^{-10}m[/tex]
Explanation:
From the question we are told that:
1st Energy [tex]E_1=12eV=4(3eV)[/tex]
2nd Energy [tex]E_2=27eV=9(3eV)[/tex]
3rd Energy [tex]E_3=48eV=16(3eV)[/tex]
Generally the equation for Energy E for electron in one dimensional box at ground state [tex]E_0[/tex] is mathematically given by
[tex]E_0=\frac{h}{8ml^2}[/tex]
[tex]E_0=\frac{h}{8ml^2}[/tex]
Therefore Length a is mathematically given as
[tex]l=\sqrt{\frac{h^2}{8mE_0} }[/tex]
[tex]l=\sqrt{\frac{(6.625*10^{-34})^2}{8(9.1*19^{-31}{(3eV(1.6*10^{-19}))}}[/tex]
[tex]l=3.5*10^{-10}m[/tex]
Which compound contains a bond with the least ionic character? A. CO B. CaO C. K2O D. Li2O
Answer:
A. CO
Explanation:
This is the answer I believe based on that it has the least amount of elements leading me to think that it would have the least ionic character.
The compound that contains a bond with the least ionic character is CO.
Ionic bonding involves transfer of valency electrons. Usually from a metal to a non metal.
The ionic character or nature of a bond is determined by the relative
electronegativity of the atoms involved.
So, the bigger the difference between the electronegativity of two atoms, the more likely it is to be ionic.
This simply implies that if the electronegativity differences of the atoms
involved are smaller, the ionic character will be small.
Therefore, the compound that contain a bond with the least ionic character is CO.
The difference in negativity of the carbon and oxygen atoms are small, this is
why the compound CO among the options possess the least ionic character.
learn more: https://brainly.com/question/19523724?referrer=searchResults
how many energy levels are known about Bohr's atomic model?
What is the charge that a Phosphorus atom would likely form?
+1
+2
+3
-1
-2
-3
Answer:(b) By referring to a periodic table or table of elements, we see that phosphorus (symbol P) has an atomic number of 15. Thus, each atom has 15 protons. The mass number of the ion is 15 + 16 = 31. Because the ion has 15 protons and 18 electrons (three more electrons than protons), its net charge is 3-
Groups of organs that work together to complete a series of takes are called..
A: Skeletal System
B: Organ System
C: Muscular System
can someone help me???
Answer:
Waning Crescent
Explanation:
Hope iT Help
Brainliest please
A 50.0 mL sample of an aqueous H2SO4 solution is titrated with a 0.375 M NaOH solution. The equivalence point is reached with 62.5 mL of the base. The concentration of H2SO4 is ________ M. A 50.0 mL sample of an aqueous H2SO4 solution is titrated with a 0.375 M NaOH solution. The equivalence point is reached with 62.5 mL of the base. The concentration of H2SO4 is ________ M. 0.150 0.234 0.300 0.469 0.938
Answer: The concentration of [tex]H_2SO_4[/tex] is 0.234 M
Explanation:
According to the neutralization law,
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1[/tex] = basicity [tex]H_2SO_4[/tex] = 2
[tex]M_1[/tex] = molarity of [tex]H_2SO_4[/tex] solution = ?
[tex]V_1[/tex] = volume of [tex]H_2SO_4[/tex] solution = 50.0 ml
[tex]n_2[/tex] = acidity of [tex]NaOH[/tex] = 1
[tex]M_1[/tex] = molarity of [tex]NaOH[/tex] solution = 0.375 M
[tex]V_1[/tex] = volume of [tex]NaOH[/tex] solution = 62.5 ml
Putting in the values we get:
[tex]2\times M_1\times 50.0=1\times 0.375\times 62.5[/tex]
[tex]M_1=0.234M[/tex]
Therefore concentration of [tex]H_2SO_4[/tex] is 0.234 M
Another name for a single-celled organism is
A. uni-cellular
B. one cellular
C. multi-cellular
D. eukaryotic
Answer:
A. Uni-cellular
How is the molar mass of an element determined?
O A. The atomic mass unit times Avogadro's number is the molar
mass.
B. The number of moles in grams is the molar mass of the element.
C. The atomic mass in g/mol is the molar mass of the element.
D. The atomic number in g/mol is the molar mass of the element.
Obsidian _____.
is formed from sand and quartz
cools very quickly
has large mineral crystals
cools very slowly
Answer:
Cools Very Quickly
Explanation:
This is the right answer!
Use the drop-down menus to match the name and structure for the following cycloalkanes. A five-sided polygon. A square. A five-sided polygon with one line extending from a point. A 6-sided polygon with a line extending from one point to a C H 3.
Answer:
A five-sided polygon.- cyclopentane
A square.- cyclobutane
A five-sided polygon with one line extending from a point.- methylcyclopentane
A 6-sided polygon with a line extending from one point to a C H 3.- methlcyclohexane
Explanation:
The correct options are :
The 5 sided polygon is cyclopentane.The square is a cyclobutane.The 5 sided polygon extends from a point.- methyl cyclopentane.The six-sided polygon CH3 is methylcyclohexane.What are cycloalkanes?Cycloalkane is a cyclic hydrocarbon meaning that the carbon of the molecules is arranged in the form of a ring. These are also saturated and all of the carbon stems make up a ring.
These are monocyclic and made from hydrogen and carbon. One ring structure is named after cyclo. Cyclobutane is columns gases and is available in liquefied gas.
Find out more information about the cycloalkanes.
brainly.com/question/10189586
Answer that pls will give brainlist
Answer:
1. went on the first manned launch during the Apollo mission
2. responsible for all spacecraft systems
3. 4500 hour
4. published All-American Boys
5. Joined back in space organization as a consultant to inspire next generation for mars
Using the Lewis dot system, show the formation of a covalent bond between
A. Two Br atoms
B. A Br atom and a Cl atom
C. A N atom and three H atoms
D. A C atom and 4 Cl atoms
E. An S atom and 2 H atoms
Which of these affects the motion of an object
A. the position of nearby objects
B. the force acting on the object
C the object's length
D. the age of the object
Answer:
B
Explanation:
If an object is acted upon by another force this will cause it to change the direction and velocity of where it is going.
Trojans are _____.
a. asteroids which fall to the Earth
b. long-period comets
c. planets with ring systems
d. asteroids affected by Jupiter's gravity
Answer:
d. asteroids affected by Jupiter's gravity
Explanation:
A Trojan horse or Trojan is a type of malware that is often disguised as legitimate software. Trojans can be employed by cyber-thieves and hackers trying to gain access to users' systems. Users are typically tricked by some form of social engineering into loading and executing Trojans on their systems.
Answer:
D
Explanation:
D is the correct answer, they are planets that are close to the center star
Material use make car tyres and chewing gum?
Answer:
Rubber
Rubber
Make me brainlyist
What volume is occupied by 22.1 g of O2 at 52°C and a pressure of 1.63 atm?
