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
lawyer [7]
3 years ago
5

. Why do you use a pencil and not a pen to mark TLC plates?

Chemistry
1 answer:
KonstantinChe [14]3 years ago
7 0

Answer:

Pencil is always used to mark chromatography paper or TLC plates because ink may run and interfere with the chromatogram. ... As soon as the paper/plate is taken out, mark the solvent front with a pencil before the solvent evaporates and the front becomes impossible to see.

You might be interested in
Consider the cell pt | h2 (1 atm); h+ (? m) || hg2cl2(s); cl− (1 m) | hg 2 h+ + 2 e − → h2 e 0 = 0.00 v hg2cl2 + 2 e − → 2 hg +
Dmitry [639]

Answer:

1.39

Explanation:

[Hg2Cl2]= 1M

[H^+] = ????

E°cell= 0.35V

E= 0.268 V

Therefore E for the reaction must -0.082 V

n= 2 moles of electrons

From Nernst Equation:

E= E°cell- 0.0592/n log [Red]/[Ox]

0.0268= 0.35- 0.0592/2 log 1/[Ox]^2

-0.082= -0.0296 log 1/[Ox]^2

log 1/[Ox]^2= 0.082/0.0296

log 1/[Ox]^2= 2.77

1/[Ox]^2=Antilog (2.77)

[Ox]^2=1.698×10^-3

[Ox] = 0.0412 M

But pH= -log [H^+]= -log(0.0412)= 1.385

3 0
3 years ago
Read 2 more answers
Calculate the mass of aluminum in 500 g of Al(C2H3O2)3
Luden [163]
Answer: 66.2 g

Explanation:

1) The ratio of Al in the molecule is  1 mol to 1 mol .

2) The mass of 1 mol of molecules of Al (CH2H3O2)3 is the molar mass of the compound.

3) You calculate the molar mass of the compound using the atomic masses of each atom, in this way:

Al: 27 g/mol
C: 2 * 3 * 12 g/mol = 72 g/mol
H: 3 * 3 * 1 g/mol = 9 g/mol
O: 2 * 3 * 16 g/mol = 96 g/mol

Molar mass = 27 g/mol + 72 g/mol + 9 g/mol + 96 g/mol = 204 g/mol

4) Set a proportion:

    27 g/mol                x
-------------------- =  ----------
   204 g/mol            500 g

5) Solve for x:

x = 500 g * 27 g/mol / 204 g/mol = 66.2 g
5 0
3 years ago
Calculate the molar solubility of CaF2 in a 0.25 m solution of NaF(aq).
Kipish [7]

Answer:

6.4 × 10^-10 M

Explanation:

The molar solubility of the ions in a compound can be calculated from the Ksp (solubility constant).

CaF2 will dissociate as follows:

CaF2 ⇌Ca2+ + 2F-

1 mole of Calcium ion (x)

2 moles of fluorine ion (2x)

NaF will also dissociate as follows:

NaF ⇌ Na+ + F-

Where Na+ = 0.25M

F- = 0.25M

The total concentration of fluoride ion in the solution is (2x + 0.25M), however, due to common ion effect i.e. 2x<0.25, 2x can be neglected. This means that concentration of fluoride ion will be 0.25M

Ksp = {Ca2+}{F-}^2

Ksp = {x}{0.25}^2

4.0 × 10^-11 = 0.25^2 × x

4.0 × 10^-11 = 0.0625x

x = 4.0 × 10^-11 ÷ 6.25 × 10^-2

x = 4/6.25 × 10^ (-11+2)

x = 0.64 × 10^-9

x = 6.4 × 10^-10

Therefore, the molar solubility of CaF2 in NaF solution is 6.4 × 10^-10M

8 0
3 years ago
4 NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)
Mariulka [41]

Answer:

0.9 moles of water

Explanation:

Use mole ratios:

5 : 6

divide by 5 on both sides

1 : 1.2

multiply by 0.75 on both sides

0.75 : 0.9

So the result is 0.9 moles of water

(Please correct me if I'm wrong)

5 0
2 years ago
What is the osmotic pressure of a 100 ml of toluene solution that contains a total of 0.005 moles of a polymer dissolved in it a
allsm [11]

Osmotic pressure is the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis.

That can be mathematical computed from the expression:

Osmotic pressure=C×R×T

Where,

C= Concentration

R=Gas constant

T=Temperature

Concentration=Number of moles of solute/Volume(L)

=0.005*1000/100

=0.05

R= 0.08206 atm L/mol K

T=25+273

=298

Osmotic pressure= 0.05×0.08206×298

=1.2 atm

4 0
3 years ago
Other questions:
  • What is 85% of 352???????????????????
    6·1 answer
  • Pick the TWO conversions which are exact.
    15·2 answers
  • CHEMISTRY HELP!! can someone please tell me if these metals where oxidized from looking at the table above and also the oxidizin
    13·1 answer
  • What happens when liquid changes to gas?
    15·1 answer
  • Imagine that a new planet was discovered in our solar system. Answer the following questions based on the patterns discovered by
    11·1 answer
  • Please hurry!!! This is a test! I'll mark brainliest! +50
    15·2 answers
  • A DNA sample and a plasmid with the ampR and lacZ(for the enzyme beta-galactosidase) genes are treated with Pstl with the goal o
    14·1 answer
  • 7) Muscles work to lift a bone in your arm by contracts and relaxes to<br><br><br>help please <br>​
    6·1 answer
  • Which layer of the atmosphere is between the mesosphere and the exosphere?
    12·1 answer
  • Potassium carbonate dissolves as follows:
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!