A chemist measures the energy change ?H during the following reaction: 2HgO (s) ?2Hg (l) +O2 (g) =?H182.kJ Use the information t
1 answer:
Answer:
A. endothermic.
A. Yes, absorbed.
Explanation:
Let's consider the following thermochemical equation.
2 HgO(s) ⇒ 2 Hg(l) + O₂(g) ΔH = 182 kJ
The enthalpy of the reaction is positive (ΔH > 0), which means that the reaction is endothermic.
182 kJ are absorbed when 2 moles of HgO react (molar mass 216.59 g/mol). The heat absorbed when 72.8 g of HgO react is:
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The concentration after dilution is 1.4%.
We are aware that concentration and volume are related to each other by the formula -
=
, where we have initial concentration and volume on Left Hand Side and final concentration and volume on Right Hand Side.
Keep the values to calculate final concentration.
= (53.5 × 5.4)/205.0
Performing multiplication on Right and Side
= 288.9/205.0
Performing division on Right Hand Side
= 1.4%
Hence, the final concentration is 1.4%.
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The complete question is -
A 53.5 mL sample of an 5.4 % (m/v) KBr solution is diluted with water so that the final volume is 205.0 mL.
Calculate the final concentration and express your answer to two significant figures and include the appropriate units.
The concentration of hydroxide ion is 5 10^
−
14 M.
<u>Explanation:</u>
Consider the equilibrium of this acid's dissociation,
H C l O 4 ⇌ H + + C l O 4 -
Moreover, let's assume that H C l O 4 is a strong acid and will fully dissociate.
Hence,
[ H + ] = 0.20 M
Now, recall,
K
w = [
H
+
]
[
O
H
−
] = 1.0 10
^−
14
Hence,
⇒
[
O
H
−
] = K
w / [
H
+
] = 5 10^
−
14 M.