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3 years ago

Write the symbol for the ion formed when each element gains electrons and attains a noble-gas electron configuration. Br, H, Se.

Chemistry

2 answers:

Bad White [126]3 years ago

8 0

Br^-
H^-
Se^2-

(^ - superscript)

Aneli [31]3 years ago

5 0

Explanation:

When an atom gain electrons then it acquires a negative charge whereas when an atom loses electrons then it acquires a positive charge.

For example, atomic number of bromine is 35 and its electronic distribution is 2, 8, 18, 7. So, in order to gain stability bromine accepts one electrons and thus it acquires a negative charge as $Br^{-}$ .

Therefore, the symbol for the ion formed when each given element gains electrons and attains a noble-gas electron configuration are as follows.

Br changes into $Br^{-}$ .

H changes into $H^{-}$ .

Se changes into $Se^{2-}$ .

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The energy produced by burning : -32.92 kJ

<h3>Further explanation</h3>

Delta H reaction (ΔH) is the amount of heat change between the system and its environment

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Answer:

The percent yield would be 73%

Explanation:

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Salicylic acid + acetic anhydride → acetylsalicylic acid + acetic acid

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According to the reaction, 1 mol of salicylic acid reacts with 1 mol of acetic anhydride to give 1 mol of acetylsalicylic acid (aspirin) and 1 mol of acetic acid.

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2.0 g salicylic acid

acetic anhydride = 5.0 mL x 1.08 g/mL = 5.4 g

The reactants ratio is = 2.0 g salicylic acid/5.4 g acetic anhydride = 0.37

0.37 < 1.35 , therefore <em>salicylic acid is the limiting reactant</em>.

Now, we use the amount of salicylic acid to calculate the theoretical amount of aspirin. For this, we know that 1 mol of aspirin (180 g) is obtained from 1 mol of salycilic acid (138 g):

theoretical yield= 180 g aspirin/138 g salycilic acid x 2.0 g salycilic acid = 2.61 g aspirin

actual yield = 1.9 g

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