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lina2011 [118]
2 years ago
12

A new student is planning to use thin layer chromatography (TLC) for his research project. After setting up the apparatus the st

udent forgets to place a lid on the TLC jar. He obtains poor results after running the TLC experiment. Which of the following can best explain his bad results?
A. The open system evaporates the solvent on the TLC plate
B. The open system prevents the evaporation of the solvent in the solution
C. The open system prevents the evaporation of the solvent on the TLC plate
D. The open system evaporates the solvent in the solution
Chemistry
1 answer:
tamaranim1 [39]2 years ago
7 0

Answer:

The open system evaporates the solvent in the solution

Explanation:

An open system is a system in which exchange of materials and energy can occur. If a TLC set up is left open, then the set up constitutes an open system.

During TLC, the sample is dotted on the plate and inserted into a suitable solvent. The solvent moves up the plate and achieves the required separation of the mixture.

Most of these solvents used used TLC are volatile organic compounds. Therefore, if the TLC set up is left open, the solvent will evaporate leading to poor results after running the TLC experiment.

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Rubbing alcohol contains 615g of isopropanol (C3H7OH) per liter (aqueous solution). Calculate the molality of this solution. Giv
faltersainse [42]

Answer:

Solution of isopropanol is 10.25 molal

Explanation:

615 g of isopropanol (C3H7OH) per liter

We gave the information that 615 g of solute (isopropanol) are contained in 1L of water. We need to find out the mass of solvent, so we use density.

Density of water 1g/mL → Density = Mass of water / 1000 mL of water

Notice we converted the L to mL

Mass of water = 1000 g (which is the same to say 1kg)

Molality are the moles of solute in 1kg of solvent, so let's convert the moles of isopropanol  → 615 g . 1mol / 60g = 10.25 moles

Molality (mol/kg) = 10.25 moles / 1kg = 10.25 m

4 0
2 years ago
When metals combine with nonmetals, the metallic atoms tend to 1. lose electrons and become positive ions 2. lose electrons and
Vika [28.1K]
The correct answer is 1. Lose electrons and become positive ions.


I hope my answer was beneficial to you! c:
5 0
2 years ago
Read 2 more answers
If 3.18 x 10^23 atoms of iron react with 67.2 L of chlorine gas at STP, what is the maximum
spin [16.1K]

84.34 grams of grams of iron (III) chloride that can be produced is maximum because Fe is the limiting reagent in this reaction and chlorine gas is excess reagent.

Explanation:

Balanced chemical equation:

2 Fe + 3 Cl2 → 2 FeCl3​

DATA GIVEN:

iron =  atoms

mass of chlorine gas = 67.2 liters

mass of FeCl3 = ?

number of moles of iron will be calculated as

number of moles = \frac{total number of atoms}{Avagaro's number}

number of moles = \frac{3.18 x 10^23}{6.022x 10^23}

number of moles = 0.52 moles of iron

moles of chlorine gas

number of moles = \frac{mass}{molar mass of 1 mole}

Putting the values in the equation:

n = \frac{67200}{70.96}               (atomic mass of chlorine gas = 70.96 grams/mole)

   = 947.01 moles

Fe is the limiting reagent so

2 moles of Fe gives 2 moles of FeCl3

0.52 moles of Fe will give

\frac{2}{2} = \frac{x}{0.52}

0.52 moles of FeCl3 is formed.

to convert it into grams:

mass = n X atomic mass

         = 0.52 x 162.2                   (atomic mass of FeCl3 is 162.2grams/mole)  

<h3>           = 84.34 grams         </h3>
3 0
2 years ago
Click the "draw structure" button to launch the drawing utility. Propane (CH3CH2CH3) has both 1° and 2° hydrogens. Draw the carb
OlgaM077 [116]

Answer:

a) find attached image 1

b) find attached image 2

Explanation :

The more stable radical is formed by a reaction with smaller bond dissociation energy.

since the bond dissociation for cleavage of the bond to form primary free radical is higher, more energy must be added to form it. This makes primary free radical higher in energy and therefore less stable than secondary free radical.

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A human hair is 75 um across. How many inches is this?
jonny [76]

Answer:

0.003in

Explanation:

75 what exactly

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2 years ago
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