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3 years ago

Write the merits and demerits of Mendeleev periodic table in points and explain each of them in short

Chemistry

1 answer:

elena-14-01-66 [18.8K]3 years ago

6 0

Answer:

merits of mendeleev periodic table are:

it was first scientific and systamatic study of different element.
there were may gaps for in discovered elements.After their discovery the got their proper place in table.
with the help of mendeleev periodic table , properties of several elements were studied correctly.

demerits of mendeleev periodic table

it could not arrange hydrogen as it shows the property of both alkali and halogens.
it could not arrange isotopes because they have different atomic weight but same atomic number.
it could not arrange Lanthanides and Actinides.

hope these points helped you

need more points then comment it .

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Alenkinab [10]

Answer:

For a: The number of moles of air present in the RV is 0.047 moles

For b: The number of molecules of gas is $2.83\times 10^{22}$

Explanation:

For a:

To calculate the number of moles, we use the equation given by ideal gas follows:

$PV=nRT$

where,

P = pressure of the air = 1.00 atm

V = Volume of the air = 1200 mL = 1.2 L (Conversion factor: 1 L = 1000 mL)

T = Temperature of the air = $37^oC=[37+273]K=310K$

R = Gas constant = $0.0821\text{ L. atm }mol^{-1}K^{-1}$

n = number of moles of air = ?

Putting values in above equation, we get:

$1.00atm\times 1.2L=n_{air}\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 310K\\n_{air}=\frac{1.00\times 1.2}{0.0821\times 310}=0.047mol$

Hence, the number of moles of air present in the RV is 0.047 moles

For b:

According to mole concept:

1 mole of a compound contains $6.022\times 10^{23}$ number of molecules.

So, 0.047 moles of air will contain $(0.047\times 6.022\times 10^{23})=2.83\times 10^{22}$ number of gas molecules.

Hence, the number of molecules of gas is $2.83\times 10^{22}$

7 0

3 years ago

How do you convert from grams to moles?

ludmilkaskok [199]

Each element or compound has a molar mass, which is calculated by multiplying the atomic mass of each element by the amount of atoms of that element, and summing the results of each element. The molar mass is measured in g/mol. So you divide the mass in grams by the molar mass to get the amount of moles.

Example:

There are 5g of water.

Calculate the amount of moles.

The water's formula is H2O, so the molar mass of it is

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The amount of moles is:

5g ÷ 18g/mol ~ 0.28mol

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Use the information provided to determine ΔH°rxn for the following reaction: ΔH°f (kJ/mol) 3 Fe2O3(s) + CO(g) → 2 Fe3O4(s) + CO2

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Answer:

ΔH°rxn = -47 kJ

Explanation:

Using Hess´s law for the reaction:

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ΔH°rxn kJ = 2ΔHºf(Fe3O4) + ΔHºf(CO2) - ( 3ΔHºf(Fe2O3) + ΔHºf(CO) )

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3 years ago

Write the merits and demerits of Mendeleev periodic table in points and explain each of them in short​

Write the merits and demerits of Mendeleev periodic table in points and explain each of them in short