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ratelena [41]
4 years ago
5

What was Johann Dobereiner’s contribution to the development of the periodic table?

Chemistry
2 answers:
sp2606 [1]4 years ago
5 0

Answer:

He identified triads of elements that had similar properties.

Explanation:

He identified a group of there elements that have relatable physical properties such their atomic weight and density. For example in alkali metals such as lithium, sodium and potassium, the atomic weight of sodium is the arithmetic mean of the first and the third element. The same trend was observed with alkaline earth metals (calcium, strontium and barium), halogen (chlorine, bromine and iodine) and chalcogens (sulphur, selenium and tellurium).

PIT_PIT [208]4 years ago
3 0

He discovered what became known as Dobereiner's triads.  For example he noticed that the average of the atomic mass of lithium and potassium was close to the atomic mass of sodium and they had similar properties.

The third choice is the correct one.


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a glass container was initially charged with 1.50 mol of a gas sample at 3.75 atm and 21.7C. some of the gas was release as the
butalik [34]

Answer:

0.39 mol

Explanation:

Considering the ideal gas equation as:

PV=nRT

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 0.0821 L.atm/K.mol

At same volume, for two situations, the above equation can be written as:-

\frac {{n_1}\times {T_1}}{P_1}=\frac {{n_2}\times {T_2}}{P_2}

Given ,  

n₁ = 1.50 mol

n₂ = ?

P₁ = 3.75 atm

P₂ = 0.998 atm

T₁ = 21.7  ºC

T₂ = 28.1 ºC

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T₁ = (21.7 + 273.15) K = 294.85 K  

T₂ = (28.1 + 273.15) K = 301.25 K  

Using above equation as:

\frac{{n_1}\times {T_1}}{P_1}=\frac{{n_2}\times {T_2}}{P_2}

\frac{{1.50\ mol}\times {294.85\ K }}{3.75\ atm}=\frac{{n_2}\times {301.25\ K  }}{0.998\ atm}

n_2=\frac{{1.50}\times {294.85}\times 0.998}{3.75\times 301.25}\ mol

Solving for n₂ , we get:

n₂ = 0.39 mol

7 0
4 years ago
SCIENCE LESSON:
Sergio039 [100]
<h3>Answer:</h3>

D: All objects fall at the same rate of acceleration regardless of their individual mass.

<h3>Explanation:</h3>
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  • An object with more mass will have less acceleration while a lighter object will  have greater acceleration.
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4 years ago
Explain the relationship between forward and reverse reactions at equilibrium
faust18 [17]

Answer:

In a chemical reaction, chemical equilibrium is the state in which the forward reaction rate and the reverse reaction rate are equal. The result of this equilibrium is that the concentrations of the reactants and the products do not change.

Explanation:

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Answer:

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