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Lelechka [254]
2 years ago
5

The total number of the elements above with 2 valence electron is ____.

Chemistry
1 answer:
OverLord2011 [107]2 years ago
4 0

Answer:

four elements

Explanation:

He = 1s²

Be = 1s² 2s²

C = 1s² 2s² 2p²

Mg = 1s² 2s² 2p⁶ 3s²

Si = 1s² 2s² 2p⁶ 3s² 3p²

Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Valence electrons are those electrons which are present in outer most electronic shell.

He, Be, Mg, Ca these four elements have 2 valence electrons.

While Si and C have four valance electrons.

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Please answer asap! worth 35 points!
Gnesinka [82]

Answer:

The enthalpy of the solution is -35.9 kJ/mol

Explanation:

<u>Step 1:</u> Data given

Mass of lithiumchloride = 3.00 grams

Volume of water = 100 mL

Change in temperature = 6.09 °C

<u>Step 2:</u> Calculate mass of water

Mass of water = 1g/mL * 100 mL = 100 grams

<u>Step 3:</u> Calculate heat

q = m*c*ΔT

with m = the mass of water = 100 grams

with c = the heat capacity = 4.184 J/g°C

with ΔT = the chgange in temperature = 6.09 °C

q = 100 grams * 4.184 J/g°C * 6.09 °C

q =2548.1 J

<u>Step 4:</u> Calculate moles lithiumchloride

Moles LiCl = mass LiCl / Molar mass LiCl

Moles LiCl = 3 grams / 42.394 g/mol

Moles LiCl = 0.071 moles

<u>Step 5:</u> Calculate enthalpy of solution

ΔH = 2548.1 J /0.071 moles

ΔH = 35888.7 J/mol = 35.9 kJ/mol (negative because it's exothermic)

The enthalpy of the solution is -35.9 kJ/mol

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Given the balanced equation:
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