Answer:
15.2mL of the 0.10M sodium formate solution and 4.8mL of the 0.10M formic acid solution.
Explanation:
To find the pH of a buffer based on the concentration of the acid and conjugate base we must use Henderson-Hasselbalch equation:
pH = pKa + log [A⁻] / [HA]
<em>Where [A⁻] could be taken as moles of the sodium formate and [HA] moles of the formic acid</em>
<em />
4.25 = 3.75 + log [A⁻] / [HA]
0.5 = log [A⁻] / [HA]
3.162 = [A⁻] / [HA] <em>(1)</em>
<em></em>
As both solutions are 0.10M and you want to create 20mL of the buffer, the moles are:
0.10M * 20x10⁻³L =
2x10⁻³moles = [A⁻] + [HA] <em>(2)</em>
Replacing (2) in (1):
3.162 = 2x10⁻³moles - [HA] / [HA]
3.162 [HA] = 2x10⁻³moles - [HA]
4.162[HA] = 2x10⁻³moles
[HA] = 4.805x10⁻⁴ moles
[A⁻] = 2x10⁻³moles - 4.805x10⁻⁴ moles = 1.5195x10⁻³moles
That means, to create the buffer you must add:
[A⁻] = 1.5195x10⁻³moles * (1L / 0.10mol) = 0.0152L =
<h3>15.2mL of the 0.10M sodium formate solution</h3>
[HA] = 4.805x10⁻⁴ moles * (1L / 0.10mol) = 0.0048L =
<h3>4.8mL of the 0.10M formic acid solution</h3>
Answer:
Charge the balloon, hold it near an electroscope, and determine if the electroscope leaves move.
Explanation:
The gold leaf electroscope is an instrument used to detect if a body is charged. It has two gold leafs suspended from a brass stem in a vacuumed glass jar and connected to a metal cap(Toppr).
When the test body is allowed to touch the metal cap, a change in the size of the leaves shows whether the body is charged or not.
Since we are suspecting the balloon to be made up of a metal; metals can be charged. We can test if there is really a charge on the balloon by bringing it near an electroscope to see if the electroscope moves.
Answer:
First start with the ones we know
Explanation:
1. small - gene
2.chromosome - chromosomes contain genes so they must be bigger
3.dna- is all the chromosomes (genetic material)
A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell
a pair - so must be bigger than one chromosome
1. small - gene
2.chromosome - chromosomes contain genes so they must be bigger
3. homologus pair
4.dna- is all the chromosomes (genetic material)
now 5.
A gene consists of enough DNA to code for one protein, and a genome is simply the sum total of an organism's DNA. DNA is long and skinny, capable of contorting like a circus performer when it winds into chromosomes.
1. small - gene
2.chromosome - chromosomes contain genes so they must be bigger
3. homologus pair
4.dna- is all the chromosomes (genetic material)
5. genome - all the DNA
Cell
Nucleus
DNA
Chromosome
Gene
<>"Refraction is the bending of the path of a light wave as it passes from one material into another material. The refraction occurs at the boundary and is caused by a change in the speed of the light wave upon crossing the boundary. The tendency of a ray of light to bend one direction or another is dependent upon whether the light wave speeds up or slows down upon crossing the boundary. The speed of a light wave is dependent upon the optical density of the material through which it moves. For this reason, the direction that the path of a light wave bends depends on whether the light wave is traveling from a more dense (slow) medium to a less dense (fast) medium or from a less dense medium to a more dense medium. In this part of Lesson 1, we will investigate this topic of the direction of bending of a light wave.
Predicting the Direction of Bending
Recall the Marching Soldiers analogy discussed earlier in this lesson. The analogy served as a model for understanding the boundary behavior of light waves. As discussed, the analogy is often illustrated in a Physics classroom by a student demonstration. In the demonstration, a line of students (representing a light wave) marches towards a masking tape (representing the boundary) and slows down upon crossing the boundary (representative of entering a new medium). The direction of the line of students changes upon crossing the boundary. The diagram below depicts this change in direction for a line of students who slow down upon crossing the boundary.
On the diagram, the direction of the students is represented by two arrows known as rays. The direction of the students as they approach the boundary is represented by an incident ray (drawn in blue). And the direction of the students after they cross the boundary is represented by a refracted ray (drawn in red). Since the students change direction (i.e., refract), the incident ray and the refracted ray do not point in the same direction. Also, note that a perpendicular line is drawn to the boundary at the point where the incident ray strikes the boundary (i.e., masking tape). A line drawn perpendicular to the boundary at the point of incidence is known as a normal line. Observe that the refracted ray lies closer to the normal line than the incident ray does. In such an instance as this, we would say that the path of the students has bent towards the normal. We can extend this analogy to light and conclude that:
Light Traveling from a Fast to a Slow Medium
If a ray of light passes across the boundary from a material in which it travels fast into a material in which travels slower, then the light ray will bend towards the normal line.
The above principle applies to light passing from a material in which it travels fast across a boundary and into a material in which it travels slowly. But what if light wave does the opposite? What if a light wave passes from a material in which it travels slowly across a boundary and into a material in which it travels fast? The answer to this question can be answered if we reconsider the Marching Soldier analogy. Now suppose that the each individual student in the train of students speeds up once they cross the masking tape. The first student to reach the boundary will speed up and pull ahead of the other students. When the second student reaches the boundary, he/she will also speed up and pull ahead of the other students who have not yet reached the boundary. This continues for each consecutive student, causing the line of students to now be traveling in a direction further from the normal. This is depicted in the diagram below.
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Answer:
C.
Fusion reactions require a lot of heat and pressure
Explanation:
nuclear fusion takes place only at extremely high temperatures. That's because a great deal of energy is needed to overcome the force of repulsion between the positively charged nuclei. ... A: Nuclear fusion doesn't occur naturally on Earth because it requires temperatures far higher than Earth temperatures.
