1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
german
2 years ago
11

You will need to prepare 12 mL of 25% Sodium Phosphate Buffer (pH 4) solution for Activity 2. What volume of the stock Sodium Ph

osphate Buffer and Water will you need to measure out
Chemistry
1 answer:
zhuklara [117]2 years ago
6 0

Assuming the concentration of stock solution is 50% sodium phosphate buffer solution, the volume of stock solution required is 6 mL and the volume of water required is 6 mL.

<h3>What volume of a stock Sodium phosphate buffer and water is needed to 12 mL of 25% sodium phosphate buffer of pH 4?</h3>

The process of preparing solutions from stock solutions of higher concentration is known as dilution.

Dilution is done with the aid of the dilution formula given below:

  • C1V1 = C2V2

where

  • C1 is the concentration of stock solution
  • V1 is the volume of stock solution required to prepare a diluted solution
  • C2 is the concentration of the diluted solution prepared
  • V2 is the final volume of the diluted solution

From the data provided:

C1 is not given

V1 is unknown

C2 = 25%

V2 = 12 mL

  • Assuming C1 is 50% solution

Volume of stock, V1, required is calculated as follows:

V1 = C2V2/C1

V1 = 25 × 12 /50

V1 = 6 mL

Therefore, the volume of stock solution required is 6 mL and the volume of water required is 6 mL.

Learn more about dilution formula at: brainly.com/question/7208546

You might be interested in
Suppose a laboratory wants to identify an unknown pure substance. The valence electrons of the substance's atoms feel an effecti
zalisa [80]

Answer:

  • The answer is the third option in the list:<em> It would have smaller atomic radii than Si and higher ionization energies than Si.</em>

Explanation:

The<em> effective nuclear charge</em> is that portion of the total nuclear charge that a given electron in an atom feels.

Since, the inner electrons repel the outer electrons, t<em>he effective nuclear charg</em>e of a determined electron is the sum of the positive charge (number of protons or atomic number) that it feels from the nucleus less the number of electrons that are in the shells that are are closer to the nucleus than the own shell of such (determined) electron.

Mathematically, <em>the effective nuclear charge (Zeff)</em> is equal to the atomic number (Z) minus the amount (S) that other electrons in the atom shield the given (determined) atom from the nucleus.

  • Zeff = Z - S.

Since, the valence electrons are the electrons in the outermost shell of the atom, you can find certain trend for the value Zeff.

Let's look at the group to which Si belongs, which is the group 14. This table summarizes the relevant data:

Element   Z   Group   # valence electrons     S                      Zeff = Z - S

C              6      14                      4                     6 - 4 = 2             6 -  2 = +4

Si             14     14                      4                     14 - 4 = 10         14 - 10 = +4

Ge           32     14                     4                     32 - 4 = 28       32 -28 = +4

Sn           50     14                     4                     50 - 4 = 46       50 - 46 = +4

Pb           82     14                     4                     82 - 4 = 78        82 - 78 = +4  

With that, you have shown that the valence electrons of the unknown substance's atoms feel an effective nuclear charge of +4 and you have a short list of 4 elements which can be the unknown element: C, Ge, Sn or Pb.

The second known characteristic of the unknown substance's atoms is that it has a <em>higher electronegativity than silicon (Si)</em><em>.</em>

So, you must use the known trend of the electronegativity in a group of the periodic table: the electronegativity decreases as you go down in a group. So, three of the elements (Ge, Sn, and Pb) have lower electronegativity than Si, which has left us with only one possibility: the element C. The valence electrons of carbon (C) atoms feel an effective nuclear charge of +4 and it carbon has a higher electronegativity than silicon.

Other two periodic trends attending the group number are the <em>atomic radii and the ionization energy</em>.

The atomic radii generally increases as you go from top to bottom in a group. This is because you are adding electrons to new higher main energy levels. So, you can conclude that the originally unknwon substance (carbon) has a smaller atomic radii, than Si.

The ionization energies generally decreases as you go from top to bottom in a group. This os due to the shielding effect: as seen, the effective nuclear charge of the atom's valence electrons remains constant, while the distance of the electrons from the nucleus increases (the valence electrons are farther away from the nucleus), which means the upper the element in a given group, the larger the ionization energy of the atoms.

With this, our conclusions about the unnkown substance are:

  • Since it has a higher electronegativity value than silicon (Si), it is right up of Si, and there is on only element possible element than can be (C).

  • Since, it is upper than silicon (Si), it would have smaller atomic radii.

  • Due to the shielding effect, it would have larger ionization energies.

  • The answer is the third option in the list: It would have smaller atomic radii than Si and higher ionization energies than Si.

6 0
3 years ago
Two substances are combined and react. After 10 minutes, the chemical reaction has reached equilibrium. Which values would be eq
galina1969 [7]

The extra conversion of concentration of reactant and product should be zero in order to attaining equlibrium state.

<h3>What is equilibrium?</h3>

Chemical equilibrium refers to the state in which both the reactants and products are present in equal concentrations or amount. In equlibrium, same amount of reactant is converted into product and product into reactant.

So we can conclude that the extra conversion of concentration of reactant and product should be zero in order to attaining equlibrium state.

Learn more about equilibrium here: brainly.com/question/517289

7 0
2 years ago
The Bohr model of the atom suggest that the protons and neutrons are found in the nucleus and the electrons orbit the nucleus mu
kondaur [170]

Answer:

The Bohr model suggested that electrons orbited the nucleus in circular paths where as the modern model views the atom to consist of positively charged nucleus surrounded by electrons.

Explanation:

In the modern model, the nucleus contains two sub-atomic particles, the protons which are positively charged and the neutrons which are not charged.According to Bohr's model,the electron in a hydrogen atom travel around the nucleus in a circular orbit. In the modern model, electrons do not move around nucleus around circular obits.

4 0
3 years ago
Any method of determining whether an event or object is older or younger than others
Inga [223]
The answer is relative dating, btw

6 0
3 years ago
Read 2 more answers
Complete the balanced neutralization equation
lbvjy [14]

Answer:

2 HC₂H₃O₂(aq) + Sr(OH)₂(aq) ⇒ Sr(C₂H₃O₂)₂(aq) + 2 H₂O

Explanation:

Let's consider the reaction between acetic acid and strontium hydroxide. This is a neutralization reaction, in which an acid reacts with a base to form salt and water. The unbalanced equation is:

HC₂H₃O₂(aq) + Sr(OH)₂(aq) ⇒ Sr(C₂H₃O₂)₂(aq) + H₂O

We have 1 acetate ion to the left and 2 to the right, so we will multiply HC₂H₃O₂(aq) by 2.

2 HC₂H₃O₂(aq) + Sr(OH)₂(aq) ⇒ Sr(C₂H₃O₂)₂(aq) + H₂O

Finally, we multiply water by 2 to get the balanced equation.

2 HC₂H₃O₂(aq) + Sr(OH)₂(aq) ⇒ Sr(C₂H₃O₂)₂(aq) + 2 H₂O

8 0
3 years ago
Other questions:
  • A buffer is prepared by adding 100 mL of 0.50 M sodium hydroxide to 100 mL of 0.75 M propanoic acid. Is this a buffer solution,
    9·1 answer
  • The _________ indicates that 70% of the Sun's radiation is contained on Earth and 30% is reflected back into space.
    15·2 answers
  • C(s) + S8(s) → CS2(l)
    15·1 answer
  • What happens to reactants molecules when forming product molecules?
    5·1 answer
  • Which material typically make up the A horizon in soil
    7·1 answer
  • How many moles are there in 125 grams of water?
    6·1 answer
  • 1. What are some similarities between the dogs pictured? What are some differences?
    5·1 answer
  • Why do you think they stilk proruxe bright flowers to attract bees?
    13·2 answers
  • Using the reactivity series shown in the handbook, tell whether the following reactions
    7·1 answer
  • What kind of radioactive element is useful for dating an object?
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!