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anastassius [24]
3 years ago
15

How was the earth crust percentage determined ?

Chemistry
1 answer:
Troyanec [42]3 years ago
5 0
By how thick or slim it is
You might be interested in
1. Why is it necessary to equalize the pressure(i.e, have the water level the same in each tube) before taking a volume reading?
Anna11 [10]

Answer:

If you contact water with a gas at a certain temperature and (partial) pressure, the concentration of the gas in the water will reach an equilibrium ('saturation') according to Henry's law.

Explanation:

This means: if you increase the pressure (e.g. by keeping the vial closed), the CO2 concentration will increase. So it simply depends what concentration you need for your assay: 'CO2-saturated' water at low pressure or 'CO2-saturated' water at high pressure.

3 0
2 years ago
Taking advantage of their large differences in pKa values, describe how a mixture of phenol and benzoic acid in diethyl ether so
Marat540 [252]

Answer:

By adding bicarbonate.

Explanation:

The pka of the phenol (C₆H₅OH) is 10 and the pka of the benzoic acid (C₆H₅COOH) is 4, which means that the benzoic acid is a stronger acid than phenol, so if we want to separate phenol from benzoic acid in diethyl ether we need to first use a weak base that will react with benzoic acid and not with the phenol:  

C₆H₅-COOH + HCO₃⁻  ⇄  C₆H₅-COO⁻  +  H₂CO₃

C₆H₅-OH + HCO₃⁻  ⇄  no reaction

The reaction of the benzoic acid with bicarbonate will produce the benzoate ion that will be soluble in the aqueous layer, while the phenol will remain dissolved in the organic layer, so we can separate the two of them by the separation of the two immiscible layers.      

Having the two layers separated, the benzoic acid can be recovered from the aqueous layer by adding HCl:

C₆H₅-COO⁻ + HCl  ⇄  C₆H₅-COOH + Cl⁻

<u>This acid will precipitate from the aqueous solution, and the solid can be isolated by filtration</u>.  

The phenol in the organic layer can be dissolved into an aqueous layer by the adding of a strong base like NaOH:

C₆H₅-OH + OH⁻  ⇄  C₆H₅-O⁻ + H₂O

The phenoxide ion soluble in the aqueous layer can be recovered later by the adding of HCl, which will form the original phenol:

C₆H₅-O⁻ + HCl  ⇄  C₆H₅-OH + Cl⁻  

<u>The precipitated phenol can be isolated by filtration. </u>

This way we can separate a mixture of phenol and benzoic acid in diethyl ether solution.  

I hope it helps you!

6 0
3 years ago
Compare the type of change that occurs when an iron bar rusts and when a substance freezes.
Ivanshal [37]

Explanation:

when an iron bar rust is an example of a chemical change in which a new substance is formed and the change is not easily reversible.for iron to rust moisture and air must be present.while when a substance freezes,it can be easily reversed through melting and no new substance is formed.this change is termed a physical change.

5 0
2 years ago
25)
Taya2010 [7]

Answer:

The correct answer is B) electronegativities of the bonded atoms in a molecule of the compound .

Explanation:

When two atoms forming a bond differ in their electronegativities at that time bond polarity is generated

        In simple words a bond will be polar when the bonding electrons are not equally shared by two atoms.As a result the atom attract the bonding electron pair towards itself gain partial negative charge and the other atom gains partial positive charge.

       For HCl is a polar compound because H and Cl atom differ in their electronegativities,as a result the bonding electron pair is not shared equally by H and Cl atoms.

8 0
2 years ago
1. What pressure would be exerted by 46.0grams of hydrogen gas placed into a 3.00 L container at
dlinn [17]

Answer:

187.34 atm

Explanation:

From the question,

PV = nRT.................. Equation 1

Where P = Pressure, V = Volume, n = number of mole, R = molar gas constant, T = Temperature.

make P the subject of the equation

P = nRT/V.............. Equation 2

n = mass(m)/molar mass(m')

n = m/m'............... Equation 3

Substitute equation 3 into equation 2

P = (m/m')RT/V............ Equation 4

Given: m = 46 g, T = 25°C = (25+273) = 298 K, V = 3.00 L

Constant: m' = 2 g/mol, R = 0.082 atmL/K.mol

Substitute these values into equation 4

P = (46/2)(0.082×298)/3

P = (23×0.082×298)/3

P = 187.34 atm

3 0
2 years ago
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