A student titrates an unknown weak acid, HA, to a pale pink phenolphthalein endpoint with 25.0 mL of 0.100 M NaOH. The student then titrates in 11.0 mL of 0.100 M HCl to the solution containing the neutralized unknown acid (HCl was delivered from a second buret). The pH of the resulting solution is pH

Answers

Answer 1

Answer:

Hello your question is incomplete the pH of the solution is unknown hence I will take the pH of the solution be = 4.7

answer : Pka = 5   i.e. > 4.7

Explanation:

Student titrates :

Unknown weak acid ( HA ) with 25 mL of 0.100 M of NaOH ( to a pale pink phenolphthalein endpoint )  then titrates with  11.0 mL of 0.100 M HCL to the solution that contains neutralized unknown acid

Assuming pH of solution = 4.7

HA + NaOH --------> H2O + NaA

at equilibrium  point

0.1 * 25 * 1 = n * 1  ∴   [tex]n_{ha}[/tex] = 2.5 mmoles ------ 1

also

[tex]A^-[/tex]  + HCL ---------> HA + C[tex]L^-[/tex]

at equilibrium point

[tex]n_{a}[/tex] = 1.1 mmoles --------- 2

The ratio of reaction 2 to 1

[tex]\frac{n_{a} }{n_{ha} }[/tex] = 1.1 / 2.5 ≈ 1/2   ( this show that when the pH = 4.7 approximately half of the A^-  have been converted to HA )

Determine the pKa value of the solution

Given that

pH = Pka + log ( A^- / hA )

4.7 = Pka + log ( 1/2 )

therefore Pka = 4.7 - ( -0.3 ) = 5


Related Questions

Which of the following MOST influences a major
shift in how the entire nucleotide sequence is
read?
А
base-pair substitutions and point mutations
B
silent mutations and nonfunctioning proteins
С
missense mutations and nonsense mutations
D
base-pair insertions and deletions

Answers

Answer:

Which of the following MOST influences a major

shift in how the entire nucleotide sequence is

read?

А base-pair substitutions and point mutations

B silent mutations and nonfunctioning proteins

С missense mutations and nonsense mutations

D base-pair insertions and deletions

Among the given disorders, missense mutations and nonsense mutations which  mostly  influences the shift in entire nucleotide.

What is mutation?

A nucleotide is made of ribose sugar, phosphate groups and base pairs. Each base have a complementary base to which it pairs. If any disorder occurs in the base pairing or coding in nucleotide it is called the mutation.

A missense mutation is a sort of point mutation or single base mutation that alters the DNA by replacing one nucleotide of the codon with another nucleotide, thus changing the amino acid that is coded for in the protein.

A nonfunctional protein may emerge from the substitution of an amino acid, or the protein may not be impacted at all. Whether the mutational alterations are "conservative" or "nonconservative" will determine the functionality of the resulting protein.

It's interesting to note that the mutation is known as a nonsense mutation when the alteration in the codons nucleotide causes the development of the stop codon. The nonsense mutation causes the premature end of protein synthesis as a result of the creation of the stop codon.

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Which element would be the most suitable to make a spoon that will melt in
your hot drinks?
A) aluminium
melting point: 660°C
boiling point: 2470°C

B) argon
melting point: -189°C
boiling point:-186°C

C) bromine
melting point: -7°C
boiling point: 59°C

D) gallium
melting point: 30°C
boiling point: 2400°C

E) lithium
melting point: 180°C
boiling point: 1330°C

F)mercury
melting point: -39°C
boiling point:357°C​

Answers

Answer:

it's A) or E)

others are not suitable cuz their melting point is weak.

Answer:

Gallium

Explanation:

Because the melting point is low and the drinks are usually around 60-70 degrees Celsius so it wil melt

Given the balanced equation: 4Fe(s) + 30₂(g) → 2Fe₂O₃(s) + 1640 kJ Which phrase best describes this reaction?
A) endothermic with AH = +1640 kJ
B) endothermic with AH =-1640 kJ
C) exothermic with AH= +1640 kJ
D) exothermic with AH = -1640 k

Answers

Answer:

yeah the answer under the explanation

Explanation:

The answer is (4) exothermic with ΔH = -1640 kJ. The 1640 kJ energy is at the right side of equation means that it releases energy. The enthalpy change means the energy of production minus the energy of reactants. If it is exothermic, the ΔH < 0.

Which of the following is equal to one molecule of calcium atoms?

6.022x10^23 molecules of Ca

6.022x10^23 atoms of Ca

6.022x10^20 molecules of Ca

6.022x10^22 atoms of Ca

Answers

Answer:

https://download.cnet.com/1-Click-Answers/3000-2378_4-10060189.html

Explanation:

Answer:

6.022x10^23 atoms of Ca

Explanation:

Which of the nine substances are made of three elements?

Answers

Answer: You are made of mostly 6 elements: Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, and Phosphorus. Some of these elements combine to form compounds in your body.

Explanation:

Oxygen, Carbon, Hydrogen, Nitrogen, Calcium and Phosphorus

Which type of solute would have the greatest impact on a colligative property?

A. C6H12O6

B. NaCl

Answers

It would be A

Correct me if I’m wrong

Using the rules of electron configurations is this a valid orbital diagram?

Answers

The first three quantum numbers of an electron are n=1, l=0, ml=0. Only two electrons can correspond to these, which would be either ms = -1/2 or ms = +1/2. As we already know from our studies of quantum numbers and electron orbitals, we can conclude that these four quantum numbers refer to the 1s subshell. If only one of the ms values are given then we would have 1s1 (denoting hydrogen) if both are given we would have 1s2 (denoting helium). Visually, this is be represented as

Which element is used in the treatment of patients with respiratory diseases in hospitals?

Answers

Answer:

I think the oxygen.

Answer:

Oxygen (O2)

Explanation:

The fundamental importance of oxygen to life on this planet ensures its place in the care of patients with respiratory disorders. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease.

Which is the correct complete ionic equation for the reaction of
2HCl(aq) + Zn(s) + H2(g) + ZnCl2(aq)?

a) H+(aq) + CI-(aq) + Zn(s) →
H2(g) + Zn2+(aq) + Cl-(aq)

b) 2H+(aq) + 2C1-(aq) + Zn(s) → H2(g) + Zn2+(aq) + 2Cl-(aq)

c) H+(aq) + Zn(s) → H2(g) + Zn2+(aq)

d) 2H+(aq) + Zn(s) → H2(g) + Zn2+(aq)

Answers

Answer:

b) 2H+(aq) + 2C1-(aq) + Zn(s) → H2(g) + Zn2+(aq) + 2Cl-(aq)

Explanation:

The equation is given as;

2HCl(aq) + Zn(s) + H2(g) + ZnCl2(aq)

In writing an ionic equation, only the aqueous compounds dissociates into ions. This means HCl and ZnCl2 would dissociate to form ions.

This is given as;

2H+  +  2Cl-  + Zn(s) --> H2(g) + Zn2+  + 2Cl-

The correct option is;

b) 2H+(aq) + 2C1-(aq) + Zn(s) → H2(g) + Zn2+(aq) + 2Cl-(aq)

A forecaster studying the climate of an area would find which of the following most helpful?

A. average yearly precipitation

B. today's barometric pressure

C. temperature changes in one month

D. how often natural disasters occur

Answers

The answer should be A

A forecaster studying the climate of an area would find average yearly precipitation most helpful.

What is forecaster studying of climate?

Forecaster studying of climate tells about the changes which will occur in the atmosphere in the upcoming future time.

Forecasting is done by measuring various environmental factors for the prediction of atmosphere. As it will given information about the percent of rainfall in the upcoming days, amount of precipitation, snowfall and so on.

Hence, option (A) is correct.

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How many molecules are found in 3.4 moles of carbon dioxide?

Please help me asap! :0

Thank you!

Answers

Answer:

One mole of anything has 6.023 x 10^23 molecules.

That would mean 3.4moles of CO2 have 6.023x 10^23 times 3.0.

So that would be2.04782×10^24 molecules in 3.0 moles of C02.

Mole measure the number of elementary entities of a given substance that are present in a given sample. 2.047×10²⁴ molecules are found in 3.4 moles of carbon dioxide.

What is mole?

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number.

Mathematically,

number of molecules of carbon dioxide = number of moles of carbon dioxide ×6.022×10²³ molecules

Number of moles of carbon dioxide=3.4moles

Substituting the values in the above equation we get

number of molecules of carbon dioxide =3.4moles×6.022×10²³ molecules

number of molecules of carbon dioxide =2.047×10²⁴

Therefore, 2.047×10²⁴ molecules are found in 3.4 moles of carbon dioxide.

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weeks and how much money, in dollars, Jamal deposits into the savings account.
Week
Deposit (dollars)
0
10
1
15
2
20
3
25
4
30
Let f ()represent the amount of money Jamal deposits into his savings account at the end of 2 weeks. Based on the table,
what is f(10)?
E
A
50
0
С
D
60
B
10
2.
3
4
5
6
7
8
9
10 11
Next
Activat
Go to Setto
1002A
3/19/20
CH
O
BH
Type here to search

Answers

An

196 becase we all rice

Explanation:

Which of the following is an example of kinetic energy?
O B. a stretched rubber band
O C. a piece of coal
O A. a battery
O D. a rolling ball

Answers

I would think a rolling ball because kinetic energy is what is released in the moment while potential energy has the potential to be released. Hope this makes sense!
I think it will be D

Correct me if I’m wrong

A 500-gram block of solid cheese is melted in a pot. Which is most likely be the mass of the cheese after it is melted?


pleaseeeeeeeeee answer

Answers

Answer:

due to the law of conservation of mass, the mass would stay the same.

What is a cone of depression and how is it caused?

Answers

Answer:

Depression can be caused by many things, like being neglected, abused, or even trauma. Even thoughts that might trigger sadness, or anxiety it's caused by alot of problems of your life or others around you

Explanation:

hope this helps a bit :)

A cone of depression occurs in an aquifer when groundwater is pumped from a well. In an unconfined aquifer (water table), this is an actual depression of the water levels. In confined aquifers (artesian), the cone of depression is a reduction in the pressure head surrounding the pumped well.

When a well is pumped, the water level in the well is lowered. By lowering this water level, a gradient occurs between the water in the surrounding aquifer and the water in the well. Because water flows from high to low water levels or pressure, this gradient produces a flow from the surrounding aquifer into the well.

As the water flows into the well, the water levels or pressure in the aquifer around the well decrease. The amount of this decline becomes less with distance from the well, resulting in a cone-shaped depression radiating away from the well. This, in appearance, is similar to the effect one sees when the plug is pulled from a bathtub. This conical-shaped feature is the cone of depression.

Molar Mass:
Find the molar masses of the following compounds. Also report the number of atoms in the compound:
1) NaBr
2) PbSO4
3) Ca(OH)2
4) Na3PO4
5) (NH4)2CO3
6) C6H12O6
7) Fe3(PO4)2
8) (NH4)2S
9) Zn(C2H3O2)2
10) AgF

Answers

Answer:

Atomic models are important because, they help us visualize the interior of atoms and molecules, and thereby predicting properties of matter.

Explanation:

We study the various atomic models in our course of study because, it is important for us to know, how did people come to the present concept of an atom. How did physics evolve from classical to quantum physics.

All these are important for us to know and thus, knowledge about various atomic models, their discoveries and drawbacks and finally improvements based on scientific evidence present at that time is important for us to understand the underlying theory very well.

Explanation:

A DAY IN THE LIFE OF METIS JOURNAL. I WROTE IT HOPE U LIKE IT XD

We, who live in the west, were Nomadic. So we always moved from place to place to hunt buffalo and other fur-bearing animals. And now again we have to shift everything we collected , like, all the essential needs we collected. It’s really hard to shift stuff, But when you move to a new place you get to see new beautiful places. They are just so satisfying to see! It’s like all my work(like the shifting work) is paid off. I love it! We always meet the Hudson’s bay company employees, and give them furs which we took from the bissons and other furry animals we hunted. And in exchange they give us their (Hudson’s Bay company) goods. Which is good! Because then we or I won't be able to enjoy that delicious pemmican!

 The one reason that makes me proud of my parents is that because of them I am like a translator for both sides in the fur trade! Anyways coming back to the present. As I said before, we were moving today to another place, But on the way some people along with my father will ride the famous York boats carrying supplies to fur posts. I begged my father to take me with him! And as usual he gave me some silly reason for me to stay. And now since I don’t have anything to do I will-..Nevermind, My mom’s calling me. Okay after helping my mom keep the fur posts into the York boats me , my mom, and the others are just relaxing and enjoying nature just to take a break. Since, I am so obsessed with my Journal notebook today I’m just going to sit here and right what comes to my mind. I’m not like the others who always seem to be talking with someone. I like my own space! 

I kind of miss my dad already, but he and his fellow members need to travel the waterways from the red river further west and north to hudson bay. These red river carts also travel the trek back and forth over land to St. Paul, Minnesota and to posts in saskatchewan.  Speaking about the red river, the only large settlement in the region is the red colony. About 12000 people lived in this colony around Fort Garry. Some were the original Selkirk settlers or their descendents. They had come from Scotland with lord Selkirk when he established the colony in 1811. Many of these original settlers were poor farmers who had been displaced  from their lands in scotland. They had endured many hardships in the early years of settlement, including foods, hunger, and sickness. I love studying about other colonies, cultures , history etc.

What is the molarity of a solution when 2.75 g of NaCl is dissolved in 1100 mL of solution?
0.043 M
0.25 M
0.43 M
4.27 M​

Answers

Answer:

Explanation:

0.25 M

The molarity of a solution will be 4.27M .

What is molarity?

Molarity (M), often known as molar concentration, is the concentration of a solution expressed in moles of solute per liter of solution.

What is solution?

Solution can be considered as a mixture of more than one component. It may be homogeneous solution as well as heterogeneous solution.

Gram to mole conversion:

[tex]=\;2.75\;g.\;\frac{1\;mol}{58.44g} \\=\;0.0470 \;mol[/tex]

Molarity of the solution can be calculated by using the following formula:

It is calculated that, moles of solute = 0.0470 mol, volume of the solution = 1100 mL.

Now, put the value of given data in molarity formula:

[tex]Molarity=\frac{Moles\;of\;the\;solute}{Volume \;of\; the\; solution} \\=\frac{0.0470\;mol}{1100 \;mL} \\=\;4.27\;mol/mL\\=\;4.27\; M[/tex]

Therefore,  the molarity of a solution will be 4.27M.

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True or False? You can observe physical properties of matter without changing the identity of the substance

Answers

True it is true a

true
True And im typing this for charater limit

I need help with this for an assignment

Answers

Answer:
hydrochloric acid reacts with sodium hydroxide to form sodium chloride (the salt) and water.

Explanation:
Sodium chloride is made up of Na+ cations from the base (NaOH) and CI-anions from the acid (HCI).

Hope this helped!

explain how rain gauge measures the amount of rainfall​

Answers

A rain gauge is really just a cylinder that catches rain. If an inch collects in the cylinder, it means an inch of rain has fallen. It's that simple. Most standard rain gauges have a wide funnel leading into the cylinder and are calibrated so that one-tenth of an inch of rain measures one inch when it collects inside.

A student draws the model shown below. Which of these best compares the conditions at Location X and Location Y?

Answers

Answer:

Explanation:

You have to use formula b to your answer

Question 3
5 pts
The diagram shows a 21.7kg ball located on a shelf 1.6m above the ground. Which best describes the energy
of the ball?
o C. It has mechanical energy in the form of potential energy
O A. Its energy is lost once it falls off the shelf.
O B. Its energy depends upon the speed the ball will travel.
O D. It has mechanical energy in the form of kinetic energy.

Answers

Answer:

c

Explanation:

The ball of 21.7 kg which is located on a shelf 1.6 m above ground is having a mechanical energy in the form of potential energy. Hence, C best describes the energy of the ball.

What is potential  energy ?

Potential energy is the energy stored on it when the object is at rest. Kinetic energy of an object is generated by virtue of its motion. When a body starts moving its potential energy starts converts to kinetic energy.

The sum of kinetic and potential energy of an object is called its mechanical energy. An object has mechanical energy in the form of kinetic energy when it is at rest. When it starts to move its potential energy converts to kinetic energy.

Therefore, the ball of 21.7 kg placed in the shelf of height 1.6 m has a potential energy as long as it stays there on the shelf. Its potential energy = mgh

p = 21.7 kg × 9.8 m/s² × 1.6 m = 340.25 J

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Where have you seen evidence of viscosity?

Answers

Answer:

Lubrication in vehicles. When you put oil into your car or truck, you should be aware of its viscosity

Cooking. Viscosity plays a significant role in the preparation and serving of food.

Manufacturing. Manufacturing equipment requires appropriate lubrication to run smoothly.

oh, and medicine

o
Plants rely heavily on _______
in the nitrogen cycle to incorporate nitrogen into organic come pounds
1 oxygen
2 viruses
3 bacteria
4 fungi

Answers

Answer:

3. Bacteria

Explanation:

If you don't trust me, search it up!

Suppose Rutherford's lab was 10 meters (m) long and the speed of an alpha particle is 3.0x10^8 meters per second (m/s). How much time would he plan on the alpha particles taking to move from the alpha particle source to the gold foil target? Write it in a mathematical equation

Answers

Answer:

t = d/v , 33.3 ns

Explanation:

Since distance, d = vt where v = speed and t = time taken to cover the distance.

Since the distance, d covered by the alpha particle is the length of Rutherford's lab which is 10 m long and the speed of the alpha particle is v = 3 × 10⁸ m/s, the time, t it takes the alpha particle to move from the alpha particle source to the gold foil target is thus

t = d/v

= 10 m/3 × 10⁸ m/s

= 10/3 × 10⁻⁸ s

= 3.33 × 10⁻⁸ s

= 33.3 × 10⁻⁹ s

= 33.3 ns

For the balanced equation shown below, how many moles of N2 reacted, if 155 moles of NH3 are produced?
3H2 + N2 => 2NH3

Answers

Answer: 1 mole nitrogen produces 2 moles ammonia

How many moles you need for 155 mol ammonia?

155/2 moles

Explanation:

What kind of data does doppler radar provide?

Answers

ANSWER: flooding and tsunamis i believe

EXPLANATION: the doppler radar uses the doppler effect to provide data about the velocity of objects at a distance

Answer:

the one above is not right

Explanation:

Which of the following pairs of elements will combine to produce a covalent bond?
1-Hydrogen and chlorine
2-Magnesium and oxygen
3-Lithium and bromine

Answers

Answer:

Hydrogen and Chlorine

ie HCL

The pairs of chemical elements that will combine to produce a covalent bond is: 1. Hydrogen and chlorine.

In Chemistry, the three (3) main types of chemical bonds include:

Ionic bonds: Lithium and bromineHydrogen bonds: Hydrogen and oxygen.Covalent bonds: Hydrogen and chlorine.

A covalent bond can be defined as a type of bond that typically involves the sharing of electrons between the atoms of a chemical element.

For example, the type of bond that is produced (formed) between hydrogen atoms and a chlorine atom is a covalent bond.

The hydrogen atom shares it single electron with a chlorine atom that is having seven (7) valence electrons to produce an inert gas such as hydrochloric acid (HCL).

In conclusion, the pairs of chemical elements that will combine to produce a covalent bond is hydrogen and chlorine.

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I went for a walk the other day. I went four blocks east, then seven blocks south, then one block west and finally
eight blocks north
a.What distance did I travel?
b. What's my displacement?

Answers

Answer:

a) distance is 4+7+1+8=20 blocks

b) displacement is 10 blocks

Explanation:

find displacement: x and y

x axis displacement = 4-1 = 3 blocks

y axis displacement = -7+8= 1 block

displacement = the square root of 3^2 + 1^2

= 9+1 = 10 blocks.

You can find the angle of displacement with respect to the initial position using trig identities, if you wish.

Which of these is a behavioral adaptation?

An anteater has a very long tongue to help it eat catch and eat ants.
An artic fox has white fur which helps it blend into the snow.
A mouse has 3–14 offspring at a time to increase the number that survive.
A brown bear hibernates and becomes inactive during winter.

Answers

Answer: Your answer would be  D

Explanation: Sorry if i get it wrong ! (but good luck and make sure to rate)

Answer:

D

Explanation:

because when it is winter

a bear hibernates in a cave

and eats lots of food so it

dosent starve after sleeping

for such a while.

Hope this helps

plz mark brainliest

if you would be so kind!

bye!

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