Why is it necessary to run TLC in a closed container and to have the interior vapor saturated with the solvent? What error is introduced into the determination of an Rf value if the top is left off of the developing chamber?

Answers

Answer 1

Answer:

See explanation

Explanation:

Rf value is known as retention factor.The retention factor of a particular material is the ratio of the distance the spot moved above the origin to the distance the solvent front moved above the origin(Harper College).

TLC is carried is out in a closed container and the interior is saturated with the solvent vapor in order to have a maximum resolution between components this prevents solvent from evaporating from the system.

Peradventure the solvent for the separation is partly or wholly  lost due to an open container, the Rf value would be lower than the expected value.


Related Questions

complete the equation C14H30 = ________ + C7H14

Answers

Answer:

C14H30 -----> C7H14 + C2H4 +C5H10

Explanation:

The temperature of an oxyacetylene torch flame can reach as high as 3137 °C. What is this temperature in Fahrenheit and Kelvin? Please show work.

Answers

Answer:

A)3410K

B)5678.6 °F

Explanation:

✓ To convert Celcius to Kelvin expression below can be used

K= °C + 273

We were given T=3137 °C

= 3137 + 273= 3410K

✓To convert Celcius to Fahrenheit, expression below can be used

°F =(°C × 9/5) + 32

We were given T=3137 °C

°F= (3137 × 9/5) + 32

= 5646.6+32

=5678.6 °F

A compound or material formed by a chemical reaction is know as the of the reaction

Answers

Answer:

reactants

Explanation:

please give brainlist

Answer:

Reactant

Explanation:

According to the graph, what is the instantaneous speed of the object at 5 seconds? *

Captionless Image
4 m/s
7 m/s
0.25 m/s
3 m/s

Answers

nooooOoOOOOOɪᴏᴏɪᴡᴏᴏɪʀᴇᴡʜʜʙᴠᴇᴠᴅᴊʜʙsʙʙsʙʙᴊᴊᴊᴊʀvesebhreeje

Answer:4m/s

Explanation:The reason why that the answer is because I am Smart.

plz need help right away !

Answers

Explanation:

1 mole = 6.02 x 10^23 atoms (Avogadro’s number)

Step 1) Determine how many grams of a substance are in the problem

Step 2) Find the amount of grams in 1 mole of the substance

3) Multiply step one by step two

What is the voltage in a circuit is the current is 3 amps and the resistance is 3 ohms

Answers

Answer:

9

Explanation:

V=I*R

3*3

Thats the answer

Describe what an Ionic Substance is....

Answers

Answer:

Ionic Substance is....

Explanation:

In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions.

The average adult heart pumps about 84./mLs of blood at 72 beats per minute. Suppose you need to calculate how long it would take the average heart to circulate 1700.mL of blood. Set the math up.

Answers

Answer:

1700 mL / 84 mLs

Explanation:

Given that:

Volume of blood pumped per minute = 84 /mLs

Time it takes to circulate 1700 mL of blood :

Time taken = Volume of blood circulate / Rate

Hence, to circulate 1700 mL of blood :

Time taken = 1700 mL / 84 mLs

What is the electronegativity and bond polarity like in the "head" vs. the "tail" ends of soap?

Answers

Answer:

gay

Explanation:

very gay

5. Write the two resonance hybrids for the carbocation that would be formed by protonation at C-1 of 2-methyl-1,3-pentadiene. Without doing a calculation, would you expect C-2 or C-4 (the two end carbons of the allylic cation) to have the most positive charge on it

Answers

Answer:

Follows are the solution to this question:

Explanation:

Please find the complete solution in the attached file.

A certain liquid X has a normal boiling point of 129.90°C and a boiling point elevation constant =Kb= 1.67°C·kgmol^−1. Calculate the boiling point of a solution made of 90.g of iron(III) chloride (FeCl3) dissolved in 650.g of X.

Answers

Answer:

Boiling T° of solution = 135.6°C

Explanation:

Formula for elevation boiling point is:

ΔT = Kb . m . i

ΔT =  Boiling point of solution - Boiling point of pure solvent

Kb = Boiling point elevation constant

m = molality →  moles of solute in 1kg of solvent

i = numbers of ions dissolved

FeCl₃ →  Fe³⁺  +  3Cl⁻

In the dissociation of the ionic salt, we determined 4 moles of ions dissolved.

3 for chlorides and 1 for iron. Then i = 4

m → We convert the mass of solute to moles:

90 g . 1mol / 162.2g = 0.555 moles

650 g of solvent = 0.650 kg of solvent

m = 0.555 mol/0.650kg → 0.85

We replace data at formula

Boiling T° of solution - 129.90°C = 1.67°C . kg/mol  .  0.85 mol/kg . 4

Boiling T° of solution = 1.67°C . kg/mol  .  0.85 mol/kg . 4 + 129.90°C

Boiling T° of solution = 135.6°C

Select the option that best represents recycling food waste
O turning food scraps into biogas
O donating unused food to food pantries
O incinerating leftover food
O feeding scraps to livestock

Answers

Answer:

feeding leftover or scraps to livestock

Explanation:

Because feeding leftover healthy food instead of leaving livestock to eat garbage is good for health of the animals and they give good quality of milk, eggs, meat, etc in return

Which of the following statements about steroid hormones is true?
A. They bind with receptor proteins in the plasma membrane.
B. They bind to carrier proteins in order to be transported in the blood to
their target cells.
C. They are synthesized from epinephrine in the adrenal gland.
D. They are mostly derivatives of the amino acid tyrosine.

Answers

Answer:

B. They bind to carrier proteins in order to be transported in the blood to

their target cells.

Explanation:

Steroid hormones are belongs to the class of chemical compound called steroid. Steroid hormones are majorly secreted by three glands - ovaries, testes and adrenal cortex.

Steroid hormones are released in the blood and are allowed to bind to the specific carrier proteins such as corticosteroid-binding globulin and albumin which helps them to carry to the target cells for the functioning.

The steroid hormone binds to receptor proteins in the target cell and not in the plasma membrane

Hence, the correct answer is "B. They bind to carrier proteins in order to be transported in the blood to  their target cells."

Tengo que resolver con procedimiento
1. Un automóvil viaja a una velocidad de 100 Km/h durante dos horas. Calcular la distancia recorrida.



2. Un automóvil viaja a una velocidad de 68 Km/h durante tres horas. Calcular la distancia recorrida.





3. Un auto recorre 154 Km en dos horas. ¿Cuál fue su velocidad?



4. Un auto recorre 1500 Km, si lo hace a una velocidad de 70 Km/h, ¿cuánto tardo en hacerlo?.​

Answers

Answer:

Distance = 200 km

Distance = 204 km

Speed = 77 km/h

Time = 21.42 h

Explanation:

Given:

A.

Speed = 100 km/h , Time = 2 h

Find:

Distance

B.

Speed = 68 km/h , Time = 3 h

Find:

Distance

C.

Distance = 154 km , Time = 2 h

Find:

Speed

D.

Distance = 1500 km speed = 70 km/h

Find:

Time

Computation:

Speed = distance / time

A.

Distance = 100 x 2

Distance = 200 km

B.

Distance = 68 x 3

Distance = 204 km

C.

Speed = 154 / 2

Speed = 77 km/h

D.

Time = 1500 / 70

Time = 21.42 h

which one of the following a compounds a.sugar b.rock salt c.iron d.alloy
which one of the following a
compound ?
a.sugar c.alloy
brock salt d.iron

Answers

Answer:

a

Explanation:

sugar is composed of different elements combined in a manner form

Given this balanced equation:

1 Cu + 1 H2SO4 -> 1 CuSO4 + 1 H2

If you have 22.45 moles of H2SO4 , how many mole of CuSO4 can you make?

Answer value

Answers

Since there is one mole of H2SO4 on the left side of the equation, and that Cu is one mole, 1 mole CuSO4 will be equivalent to that of H2SO4.

22.45 mol H2SO4 means 22.45 mol CuSO4

H.w. balance the following equations:
a) Iron + chlorine → Iron (iii) chloride
b) Nitrogen + hydrogen → Ammonia
c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide
d) Nitrogen dioxide + water + oxygen → Nitric acid

Answers

Answer:

3iron + chlorine=iron3 chloride

nitrogen +3hydrogen

Answer:

a) Iron + chlorine → Iron (iii) chloride

3fe+cl__fe3cl

b) Nitrogen + hydrogen → Ammonia

2N+3h2------2NH3

c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide

2H3PO3+3Na2CO3-----2Na3PO4+3H2O+3CO2

d) Nitrogen dioxide + water + oxygen → Nitric acid

NO2+H2O+O2--NOH

sorry if mistake

Enter the electron configuration for I+ using noble gas shorthand notation.
In the first box enter the noble gas (notice the brackets). In the following boxes enter the number that goes in front of the orbital followed by the superscript.
For example, the electron configuration for sulfur is: [Ne]3s2 3p4
so the first box would have Ne in it followed by 3, then 2, then 3 then 4.
If you do not need an orbital, just enter 0 (zero) in the boxes for the coefficient and superscript.
[ ] s f d p
Find the element in the periodic table and count over
to the right the number of negative charges on your anion.
This element has the same electron configuration as your anion.
Which noble gas precedes the element? Knowing the s, p, d, and f blocks
of elements in the periodic table, deduce the the electron configuration
of the element from the preceding noble gas. Remember that the
1p 1d, 2d, 1f, 2f, and 3f orbitals are forbidden energy levels (they do not exist).

Answers

Answer:

[Kr] 4d10 5s2 5p4

Explanation:

The Symbol I represents Iodine. It has atomic number of 53. The full electronic configuration is given as;

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5

However the question requested for the configuration of I+.

I+ is a cation and it simply refers to an iodine atom that has lost a single electron. The electronic configuration of I+ is given as;

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p4

Using Noble gas shorthand representation, we have;

[Kr] 4d10 5s2 5p4

How are people and the landscape impacted by earthquake?

Answers

they are impacted because people loose their home due to the wreckage that has happend and landscapes are ruined due to landslides

Answer:

Well the landscape is torn up, it goes through quite a bit of damage. the plants, animals, and water are all affected by it. when a earth quake hits it destroyes most everything, houses fall into the ground and are destroyed, people die. Earthquakes destry electrical wires and many other things

Explanation:

Sorry I did not answer it full, but you can look it up online.

No pain no gain . which figure of speech is this​

Answers

Answer:

No pain, no gain is a proverb that means in order to make progress or to be successful, one must suffer. This suffering may be in a physical or mental sense. The phrase no pain, no gain was popularized in the 1980s by the American actress, Jane Fonda.

MnO4 - is a stronger oxidizing agent than ReO4 - . Both ions have charge-transfer (LMCT) bands; however, the charge-transfer band for ReO4 - is in the ultraviolet, whereas the corresponding band for MnO4 - is responsible for its intensely purple color. Are the relative positions of the charge-transfer absorptions consistent with the oxidizing abilities of these ions? Explain

Answers

Answer:

[tex]$MnO^-_4$[/tex]  is a strong oxidizing agent.

Explanation:

The 5d orbitals of Re are higher in energy than 3 d orbitals of Mn. So an LMCT ligand to metal charge transfer excitation requires more energy of [tex]$ReO^-_4$[/tex].

Also, since the molecular orbitals are derived primarily from  3d orbitals of [tex]$MnO^-_4$[/tex] are lower in energy than the corresponding MO's of   [tex]$ReO^-_4$[/tex], [tex]$MnO^-_4$[/tex]  is better able to accept the electrons.

So it is a better oxidizing agent.

The ligand to metal charge transfer band in ReO4- occurs in the near UV region hence ReO4 - appears colorless.

The electron configuration of Re is Xe 4f14 5d5 6s2 and the electron configuration of Mn is [Ar] 3d5 4s2. We can see that Mn^7+ and Re^7+ have empty d orbitals.

The color of MnO4 - must result from ligand to metal charge transfer hence the purple color of MnO4 -. In the case of ReO4 -, the ligand to metal charge transfer occurs at a much higher energy owing to the fact that 5d orbitals are involved. This transition occurs in the near UV region hence ReO4 - appears colorless. The ligand to metal charge transfer in MnO4- involves lower energy 3d orbitals hence it occurs in the visible region of the spectrum.

Learn more: https://brainly.com/question/8646601

The percentage by mass of oxygen in a compound containing potassium, chlorine, and oxygen was determined experimentally. The technique used follows. solid (KClo compound is weighed. Then it is heated in a crucible. The The solid decomposes to produce oxygen gas and a salt. Because the oxygen escaping, mass of the original solid decreases. From the mass of oxygen lost and mass is the the percentage by mass of oxygen in of the original the original compound is determined. KClyo. (s) salt (s) O (g A student performs five trials and determines the following by mass of oxygen in the compound (KCLO) by mass of oxygen Trial in the compound 38.933 38,940 38,892 38.900
a. Determine the average experimental percentage oxygen in the compound. by mass of 30.933
b. If the actual value of the percentage by mass ofoxygen in this compound is 39.13 determine the percentage error.

Answers

Answer:

See explanation

Explanation:

The percentage by mass of oxygen is defined as;

Mass of oxygen/ molar mass of the compound * 100/1

The average percentage by mass of oxygen = 38.933 + 38.940 + 38.871 + 38.892 + 38.900/5

The average percentage by mass of oxygen = 38.907

Percentage Error  = (|accepted value – experimental value| \ accepted value) x 100%

Percentage Error  = 39.13 - 38.907 / 39.13 * 100

Percentage Error  = 0.57%

Billy and Susie heat a 78.9 g sample of Unobtanium at 18.0C. Using a lab burner, they burn propane and the unobtanium absorbs 13,240 J of heat untill the temperature reaches the melting point 109C. what is the specific heat of unobtanium

Answers

Answer:

1.8 J/g·°C (2 sig.figs. per ΔT)

Explanation:

Given:

mass (m) = 78.9 grams

specific heat (c) = ?

Temp. Change (ΔT) = 109°C - 18°C = 91°C

Heat flow (q) = 13,240 Joules

q = m·c·ΔT => c = q/m·ΔT

∴c = 13,240J / 78.9g·91°C = 1.844 J/g·°C ≅ 1.8 J/g·°C (2 sig.figs. per ΔT)

When a baseball bat hits a baseball, what happens to the energy?
completo ancur

Answers

Answer: the baseball bat transfor its energy in the ball.

Explanation: you hit it with one and find out and tell me what you think what happen.

If 25.00 mL of 6.00 M HCl is transferred by pipet into a volumetric flask and diluted to 5.00 L, what is the molarity of the diluted HCl?

Answers

Answer:

0.03 M

Explanation:

The computation of the molarity of the diluted HCI is given below:

As we know that

(M1) × (V1) = (M2) × (V2)

Now

(M2) = {(M1) × (V1)} ÷ (V2)

or

Molarity of the diluted HCl,(M2) is

= {6 × 25} ÷ 5000

= 0.03 M

4. What is the maximum no. of electrons that can be associated with the following set of
quantum numbers?
n=4, l=1, m=-1
a) 10
b) 6
d) 2
c) 4​

Answers

Answer:

d) 2

Explanation:

We are given;

n = 4, l = 1, m = -1

We can tell that is is an orbital with sub shell as 3P.

Now, from Paul's exclusion principle, each orbital will have maximum of 2 electrons of each π with a spin of +½ and -½.

Since the maximum is seen to be 2, then option D is correct.

The pain reliever morphine contains 17.900 g C, 1.680 g H, 4.225 g O, and 1.228 g N. Determine the empirical Formula.

Answers

Answer: The empirical formula is [tex]C_{17}H_{19}O_3N[/tex]

Explanation:

Mass of C= 17.900 g

Mass of H = 1.680 g

Mass of O = 4.225 g

Mass of N = 1.228 g

Step 1 : convert given masses into moles.

Moles of C =[tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{17.990g}{12g/mole}=1.5moles[/tex]

Moles of H =[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{1.680g}{1g/mole}=1.680moles[/tex]

Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{4.225g}{16g/mole}=0.264moles[/tex]

Moles of N =[tex]\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{1.228g}{14g/mole}=0.087moles[/tex]

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = [tex]\frac{1.5}{0.087}=17[/tex]

For H = [tex]\frac{1.680}{0.087}=19[/tex]

For O =[tex]\frac{0.264}{0.087}=3[/tex]

For N = [tex]\frac{0.087}{0.087}=1[/tex]

The ratio of C : H: O: N = 17: 19: 3: 1

Hence the empirical formula is [tex]C_{17}H_{19}O_3N[/tex]

What is the vapor pressure of a solution in which the mole fraction of the solute is 0.200 and the vapor pressure of the pure solvent is 100.0 torr? (Assume a single nonvolatile, nonelectrolyte solute).
a. 0 torr
b. 80.0 torr
c. 100.0 torr
d. 120.0 torr
e. 20.0 torr

Answers

Answer: The vapor pressure of a solution in which the mole fraction of the solute is 0.200 is 80.0 torr

Explanation:

As the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The formula for relative lowering of vapor pressure will be,

[tex]\frac{p^o-p_s}{p^o}=i\times x_2[/tex]

where,

[tex]p^0[/tex]= vapor pressure of pure solvent = 100.0 torr

[tex]p_s[/tex] = vapor pressure of solution = ?

i = Van'T Hoff factor = 1 for nonvolatile, nonelectrolyte solute

[tex]x_2[/tex] = mole fraction of solute  = 0.200  

[tex]\frac{100.0-p_s}{100.0}=1\times 0.200[/tex]

[tex]p_s=80.0torr[/tex]

The vapor pressure of a solution in which the mole fraction of the solute is 0.200 is 80.0 torr

A chemistry graduate student is studying the rate of this reaction:
NH4OH(aq)→NH3(aq)+H2O(aq)

She fills a reaction vessel with and measures its concentration as the reaction proceeds:

Time (minutes) NH4OH
0 0.200M
1.0 0.0895M
2.0 0.577M
3.0 0.0426M
4.0 0.0337M

Use this data to answer the following questions.

a. Write the rate law for this reaction.
b. Calculate the value of the rate constant.

Answers

Answer:

Rate = k[NH₄OH]²

k = 6.17

Explanation:

We have concentrations of NH₄OH along with the given times. To determine the rate law of the reaction we need to determine first the order of reaction. This reaction can be order zero, first or second order. The expressions for each are the following:

Zero order:

k = [A₀] - [A] / t

First order:

k = 1/t * ln([A₀]/[A])

Second order:

k = (1/t) * (1/[A₀] - 1/[A])

And from here, the next part is easier. We just need to determine hat order is, calculating the value of k at two different times. If the value of k is constant, then we can say that the reaction is of that order.

Let's suppose its order zero (t = 1 and t = 2, [A₀] = 0.200 M):

k1 = 0.2 - 0.0895 / 1 = 0.1105

k2 = 0.2 - 0.577 / 2 = -0.1885

From this results we can conclude it's not zero order.

Let's suppose its order 1:

k1 = ln(0.2/0.0895) / 1 = 0.8041

k2 = ln(0.2/0.577) / 2 = 0.1733

It's not first order either, so we can conclude that this reaction is of 2nd order and the rate law would be:

Rate = k[NH₄OH]²

Now that we know it's a second order reaction, we can determine the value of k using its expression:

k = (1/t) (1/[A] - 1/[A₀])

k = ln(1/0.0895 - 1/0.2) (1/1)

k = 6.17

And to confirm this value, let's calculate k for t = 2 s

k = (1/2) (1/0.0577 - 1/0.2)

k = 6.17

The value is constant, so this is the true value of k.

Hope this helps

Attempt 2
Four marbles are made of different metals. Each marble has the same mass, but a different volume. The density of each
metal is given in the table.
Metal
Density (g/mL)
aluminum
2.70
silver
10.5
rhenium
20.8
nickel
8.90
Place the marbles in order from largest to smallest.
Largest

Answers

Lets let our mass equal 3 on alletals and solve using d=m/v equation

Aluminum
V=3/2.70=1.11
Silver
V=3/10.5=.286
Rhenium
V=3/20.8=.144
Nickel
V=3/8.90=.337
This gives us the following list from largest to smallest Aluminum, Nickel, Silver, and Rhenium

The order of marbles can be Aluminum, Nickel, Silver, and Rhenium.

What is volume?

If volume is the amount of three-dimensional space contained by a closed surface, such as the amount of space within a given cube, cylinder, or other three-dimensional shape.

Liquid volume is a way to measure an amount of liquid by describing how much three-dimensional space it occupies.

The mass of something is the amount of stuff it is made of. The volume of an object is the amount of space it usually takes up.

Density provides an easy way to calculate a body's mass from its volume or vice versa.

The mass is equal to the volume multiplied by the density (M = Vd), and the volume is equal to the mass divided by the density (V = M/d).

As per the density given, the volume of aluminum can be 1.11mL, Silver is 0.286mL, Rhenium is 0.144mL, Nickel is 0.337mL.

Thus, the order from largest to smallest will be Aluminum, Nickel, Silver, and Rhenium.

For more details regarding volume, visit:

https://brainly.com/question/1578538

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