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Mumz [18]
3 years ago
7

Will make brainliest if answer correctly.

Chemistry
1 answer:
Sonja [21]3 years ago
6 0

Answer:

They are in same group/family.

Explanation:

Alkaline earth metals are present in group 2 of periodic table. There are six elements in second group. Beryllium, magnesium, calcium, strontium, barium and radium.

All have two valance electrons but in different energy levels. Thus they have similar chemical properties.

Electronic configuration of calcium.

Ca = [Ar] 4s²

Electronic configuration of strontium.

Sr = [Kr] 5s²

They are present in group two and have same number of valance electrons (two valance electrons) and show oxidation state +2 by loosing two valance electrons. They also show similar reactivity.

They react with oxygen and form oxide.

2Sr  +   O₂   →    2SrO

2Ca +   O₂   →    2CaO

this oxide form hydroxide when react with water,

SrO  + H₂O   →  Sr(OH)₂

CaO  + H₂O   →  Ca(OH)₂

With sulfur,

Sr + S   →  SrS

Ca + S   →  CaS

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Answer:

B.Michanine

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A block of wood has a volume of 55 cm3 and a mass of 550 g. What would be its density? Answer in units of g/cm3.
VLD [36.1K]

given,

volume (V)=55cm3

mass(m)=550g

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3 years ago
B. For the following questions, use the reaction NO2(g) N2(g) + O2(g), with ΔH = –33.1 kJ/mol and ΔS= 63.02 J/(mol·K).
Troyanec [42]

Answer:

I. Kindly, see the attached image.

II. The reaction is exothermic.

III. - 51.88 kJ/mol.

IV. The reaction is spontaneous.

Explanation:

I. Draw a possible potential energy diagram of the reaction. Label the enthalpy of the reaction.

  • Since the sign of ΔH is negative, the reaction is exothermic reaction.

In an exothermic reaction, the energy of the reactants is higher than that of the products.

<u><em>Kindly see the attached image to show you the potential energy diagram of the reaction.</em></u>

     

<em>II. Is the reaction endothermic or exothermic? Explain your answer.</em>

  • The reaction is exothermic reaction.
  • The sign of ΔH indicates wither the reaction is endothermic or exothermic one:

If the sign is positive, the reaction is endothermic.

If the sign is negative, the reaction is exothermic.

Herein, <em>ΔH = - 33.1 kJ/mol, </em>so the reaction is exothermic.

<em>III. What is the Gibbs free energy of the reaction at 25°C? </em>

∵ ΔG = ΔH - TΔS.

Where, ΔG is the Gibbs free energy change (J/mol).

ΔH is the enthalpy change (ΔH = - 33.1 kJ/mol).

T is the temperature (T = 25°C + 273 = 298 K).

ΔS is the entorpy change (ΔS = 63.02 J/mol.K = 0.06302 J/mol.K).

<em>∴ ΔG = ΔH - TΔS</em> = (- 33.1 kJ/mol) - (298 K)(0.06302 J/mol.K) = <em>- 51.88 kJ/mol.</em>

IV. Is the reaction spontaneous or nonspontaneous at 25°C?

The sign of ΔG indicates the spontaneity of the reaction:

If ΔG < 0, the reaction is spontaneous.

If ΔG = 0, the reaction is at equilibrium.

If ΔG > 0, the reaction is nonspontaneous.

Herein, <em>ΔG = - 51.88 kJ/mol, </em>so the reaction is spontaneous.

7 0
3 years ago
How to find the number of protons in an element?​
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Locate the element’s atomic number. The atomic number is located above the element symbol, in the upper left-hand corner of the square. The atomic number will tell you how many protons make up a single atom of an element.

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