In a thin layer chromatography experiment, a plate of length 9.3 cm was used and a horizontal line was made at 1.45 cm above the bottom of the plate. After running the experiment (developing and drying), a spot was observed at 5.6 cm from the bottom of the plate, and the solvent front was 7.7 cm from the bottom of the plate. What is the Rf value
Answer: The [tex]R_f[/tex] value is 0.664
Explanation:
Distance travelled by solvent front = (7.7-1.45)cm = 6.25 cm
Distance travelled by unknown = (5.6-1.45) cm = 4.15 cm
The retention factor or the [tex]R_f[/tex] value is defined as the ratio of distance traveled by the unknown to the distance traveled by the solvent front.
[tex]R_f=\frac{\text {distance travelled by unknown}}{\text {distance travelled by solvent}}[/tex]
[tex]R_f=\frac{4.15}{6.25}=0.664[/tex]
Thus the [tex]R_f[/tex] value is 0.664
In order for heat to flow there must be... *
A. identical tempatures
B. a difference in tempatures
C. a difference in altitude
D. an electrical current present
Answer:
B. a difference in temperatures.
Explanation:
Conduction involves the transfer of electric charge or thermal energy due to the movement of particles. When the conduction relates to electric charge, it is known as electrical conduction while when it relates to thermal energy, it is known as heat conduction.
In the process of heat conduction, thermal energy is usually transferred from fast moving particles to slow moving particles during the collision of these particles.
Also, thermal energy is typically transferred between objects that has different degrees of temperature and materials (particles) that are directly in contact with each other but differ in their ability to accept or give up electrons.
In order for heat to flow there must be a difference in temperatures.
This ultimately implies that, the driving force responsible for heat to flow is a difference in temperature between the points from which heat originates and where heat is received.
Additionally, the higher the temperature difference, the greater would be the heat flow; which is usually from a high temperature level to a low temperature level.
when a small amount of hydrogen gas mixes with nitrogen gas, hydrogen is the
Answer:
solvent
Explanation:
How many grams do 4.5 moles of oxygen atoms weigh
Answer:
71.99100
Explanation:
The mass of oxygen equal to one mole of oxygen is 15.998 grams and the mass of one mole of hydrogen is 1.008 g. 15.998*4.5 = 71.99100
What are two things that interact that determine if there is a phase change or not HELP
Answer:
phase change always has two phases in contact during the change. melting => solid & liquid; evaporation (boiling) => liquid & vapor. If only one phase is present, then phase change is not occurring. Also, when two phases are in contact, no temperature changes occur. Only the pure phase demonstrates temperature change when measured. Example, when ice is added to water, at thermal equilibrium (temp = 0°C) the water temp will not continue to change. Only when all the ice has melted will the water temperature demonstrate a measured temperature change.
Explanation:
2) A common "rule of thumb" -- for many reactions around room temperature is that the
rate will double for each ten degree increase in temperature. Does the reaction you hav
studied seem to obey this rule.
The question is incomplete. The complete question is :
A common "rule of thumb" for many reactions around room temperature is that the rate will double for each ten degree increase in temperature. Does the reaction you have studied seem to obey this rule? (Hint: Use your activation energy to calculate the ratio of rate constants at 300 and 310 Kelvin.)
Solutions :
If we consider the activation energy to be constant for the increase in 10 K temperature. (i.e. 300 K → 310 K), then the rate of the reaction will increase. This happens because of the change in the rate constant that leads to the change in overall rate of reaction.
Let's take :
[tex]$T_1=300 \ K$[/tex]
[tex]$T_2=310 \ K$[/tex]
The rate constant = [tex]$K_1 \text{ and } K_2$[/tex] respectively.
The activation energy and the Arhenius factor is same.
So by the arhenius equation,
[tex]$K_1 = Ae^{-\frac{E_a}{RT_1}}$[/tex] and [tex]$K_2 = Ae^{-\frac{E_a}{RT_2}}$[/tex]
[tex]$\Rightarrow \frac{K_1}{K_2}= \frac{e^{-\frac{E_a}{RT_1}}}{e^{-\frac{E_a}{RT_2}}} $[/tex]
[tex]$\Rightarrow \frac{K_1}{K_2}= e^{-\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)}$[/tex]
[tex]$\Rightarrow \ln \frac{K_1}{K_2}= - \frac{E_a}{R} \left(\frac{1}{T_1} -\frac{1}{T_2} \right)$[/tex]
[tex]$\Rightarrow \ln \frac{K_2}{K_1}= \frac{E_a}{R} \left(\frac{1}{T_1} -\frac{1}{T_2} \right)$[/tex]
Given, [tex]$E_a = 0.269$[/tex] J/mol
R = 8.314 J/mol/K
[tex]$\Rightarrow \ln \frac{K_2}{K_1}= \frac{0.269}{8.314} \left(\frac{1}{300} -\frac{1}{310} \right)$[/tex]
[tex]$\Rightarrow \ln \frac{K_2}{K_1}= \frac{0.269}{8.314} \times \frac{10}{300 \times 310}$[/tex]
[tex]$\Rightarrow \ln \frac{K_2}{K_1}= 3.479 \times 10^{-6}$[/tex]
[tex]$\Rightarrow \frac{K_2}{K_1}= e^{3.479 \times 10^{-6}}$[/tex]
[tex]$\Rightarrow \frac{K_2}{K_1}= 1$[/tex]
∴ [tex]$K_2=K_1$[/tex]
So, no this reaction does not seem to follow the thumb rule as its activation energy is very low.
Which of the following cell organelles is NOT found in BOTH plant and animal cells?
O cells membrane
O cell wall
O ribosomes
O cytoplasm
What is the mass of 2 moles of nitrogen gas, N2?
Answer:
28g
Solution. Hence, 2 moles of nitrogen atoms weigh 28g.
What volume in
L
of a 0.724 M Nal solution contains 0.405 mol of Nal ?
Answer:
[tex]0.5594\ \text{L}[/tex]
Explanation:
Mol of NaI = 0.405 mol
Molarity of solution = 0.724 M
Molarity is given by
[tex]M=\dfrac{\text{mol}}{\text{Volume of solution in }NaI}\\\Rightarrow \text{Volume of solution in }NaI=\dfrac{0.405}{0.724}\\\Rightarrow \text{Volume of solution in }NaI=0.5594\ \text{L}[/tex]
The required volume is [tex]0.5594\ \text{L}[/tex].
CuCl2(aq) + Na3PO4(aq) =>?
Net ionic equation
What are the coefficients that would correctly balance this equation?
____Zn + ____K2CrO4 → ____K + ____ZnCrO4
1, 2, 1, 2
2, 1, 2, 1
1, 1, 2, 1
1, 2, 3, 1
Answer:
Explanation:
1,2,1,2
Answer:
b
Explanation:
How many atoms are in a 591 g sample of gold?
116,000 atoms
1.81 × 1024 atoms
3.00 atoms
3.60 × 1025 atoms
The number of atoms present in 591 g of gold is 1.81×10²⁴ atoms
Avogadro's hypothesisFrom Avogadro's hypothesis,
1 mole of Gold = 6.02×10²³ atoms
But
1 mole of gold = 197 g
Thus,
197 g of gold = 6.02×10²³ atoms
How to determine the atoms in 591 g of gold197 g of gold = 6.02×10²³ atoms
Therefore,
591 g of gold = (591 × 6.02×10²³) / 197
591 g of gold = 1.81×10²⁴ atoms
Thus, 1.81×10²⁴ atoms is present in 591 g of gold.
Learn more about Avogadro's number:
https://brainly.com/question/26141731
What is depicted in a molecule formula
Answer:
Molecular formulas describe the exact number and type of atoms in a single molecule of a compound. The constituent elements are represented by their chemical symbols, and the number of atoms of each element present in each molecule is shown as a subscript following that element's symbol
A key process common to all organisms is the ability to reproduce. Where do all cells come from?
A. from ova
B. from atoms
C. from gametes
D. from pre-existing cells
Answer:
It’s d
Explanation:
It’s d 100%
Why wouldn’t you use Avogadro’s number to change 32.4 grams of Lithium into moles of Lithium?
What is the income effect?
Answer:
Explanation:
the income effect is the change in demand for a good or service caused by a change in a consumer's purchasing power resulting from a change in real income. This change can be the result of a rise in wages etc., or because existing income is freed up by a decrease or increase in the price of a good that money is being spent on.
Answer: a proportional change in quantity demanded based on income
Explanation:
As a raindrop falls from a cloud to the surface of Earth,
A. its speed increases due to gravity.
B. its speed increases due to air resistance,
C. it moves at a constant speed,
<
OD. it moves at a constant velocity
Answer:
The answer is C!
Explanation:
Hope it helps
Answer D
Explanation: did the quiz ψ(｀∇´)ψ
Which of the following statements would be an argument against multiculturalism?
(Click all that apply.)
A) Canadians are a mixture of people from various cultural, religious, racial, and ethnic origins. This mixture helps in relations with other countries.
B) Many cultural and ethnic groups have helped build Canada. We should encourage people to preserve their heritage; their traditions are part of Canadian history.
C) Canadians will learn tolerance through being in contact with other cultures. Multiculturalism can help to eliminate discrimination and prejudice.
D) The Canadian government should not spend citizens' tax dollars on multiculturalism. Our taxes are already too high.
Answer:
D
Explanation:
In which atmospheric layer is the ozone layer? O stratosphere o thermosphere O mesosphere troposphere
Answer:
The stratosphere
Explanation:
What is the formula for the ionic compound made up of the ions Cd+3 and SO4-2?
Answer: since the sodium ion is Na+, and sulfate is SO4(2-), you'll need 2 sodiums for a sulfate, making sodium sulfate Na2SO4.
Explanation:
MULTIPLE CHOICE QUESTION
When the frequency increases, the waves
become?
Shorter
Longer
Answer:
Shorter
Explanation:
As a wavelength increases in size, its frequency, and energy (E) decrease. From these equations, you may realize that as the frequency increases, the wavelength gets shorter. As the frequency decreases, the wavelength gets longer. There are two basic types of waves: mechanical and electromagnetic.
Rubbing alcohol is 70.% (v/v) isopropyl alcohol by volume. How many mL of isopropyl alcohol are in a 1 pint (473 mL) container? Rubbing alcohol is 70.% (v/v) isopropyl alcohol by volume. How many mL of isopropyl alcohol are in a 1 pint (473 mL) container? 330 mL 470 mL 70. mL 680 mL 0.15 mL
Answer:
helped
The number of ml of isopropyl alcohol that are 1 pint (473 Ml) is 331.1 Ml
calculation
assume that the 1 pint is in a container
This implies that the 1 pint (473 ml) is in 100 % M/V
what about 70 %(M/V)
that is 473 Ml = 100 %
? = 70 %
by cross multiplication
= 473 x70/100 = 331.1 Ml
Explanation:
2. A spider builds his web in the horns of a deer. What is the symbiotic
relationship?
I point
O MUTUALISM
COMMENSALISM
PARASITISM
O Other
Answer:
COMMENSALISM
Explanation:
Commensalism refers to the relationship that exists between two different organism that belong to different species. In this relationship neither of the organisms are harmed while either of them is benefitted. The web made by the spider between the horns of the deer increases the probability of the spider to catch its prey. The random movement of the deer helps the spider and at the same time it do not harm the deer.
8) All of the following statements are true except ________. A) Internal energy is a state function. B) The enthalpy change for a reaction is equal in magnitude, but opposite in sign, to the enthalpy change for the reverse reaction. C) The enthalpy change for a reaction depends on the state of the reactants and products. D) The enthalpy of a reaction is equal to the heat of the reaction. E) Enthalpy is an intensive property.
Answer:
E. Enthalpy is an intensive property Is false.
Explanation:
The false or wrong option in this question is that Enthalpy is an intensive property.
To explain this, I would first explain an intensive property. An intensive property is one that does not depend on the quantity or the mass of matter. Examples are temperature and pressure.
But an extensive property is a property which depends on the mass and the quantity of the system. Enthalpy, volume are all extensive.
Rank the following species in order of increasing basicity. NH3, NH4 , NH2-, Cl-,H2O.
a. NH3
b. NH4
c. NH2
d. Cl-
e. H2O
Answer:
D, E, A, B, C
Explanation:
The weakest base would be Cl- because HCl is a stronger acid than that of H3O+ from which the water is formed.
Also, for NH3 is a stronger acid than +NH4. Reason is that oxygen is more electronegative than nitrogen and thus NH3 is a stronger acid than NH4+.
The stronger, the acid, the weaker its conjugate base. Thus, NH3 is a weaker base than NH4.
NH2- has the highest basicity because nitrogen is less of an electronegative element than is oxygen. Therefore, it will not want a negative charge.
Hence, the final order in terms of increasing basicity is;
Cl-, H20, NH3, NH4, NH2-
Which of the following statements is NOT true?
An element and a compound are pure substances.
A homogeneous mixture can be called a solution.
An element and a compound are mixtures.
A homogeneous mixture and a heterogeneous mixture can both be classified as mixtures.
Answer:
An element and a compound are mixtures.What does purified water and fluorine make?
Answer:
Adding fluoride to the water supply reduces the incidence of tooth decay. Fluoride protects teeth from decay by demineralization and remineralization. Too much fluoride can lead to dental fluorosis or skeletal fluorosis, which can damage bones and joints.
Explanation:
N/A
Answer this express as a chemical equation
Answer:
Pb(No3)2+2Nacl_PbCl2+2NaNO3
name this structure
Answer:
where is the structure the picture
Explanation:
???
Which of these is a common base?
a. orange juice
b. water
c. ammonia
d. milk of magnesia
Answer:
ammonia is a common base