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3 years ago

What is the pH of a sample with [OH-] = 2.5 x 10-11 M?

Chemistry

1 answer:

sveticcg [70]3 years ago

3 0

Answer:

The pH of the sample is 3,4.

Explanation:

We calculate the pOH from the formula pOH = -log (OH-). We know that for all aqueous solutions: pH + pOH = 14, and from there we clear pH:

pOH= -log (OH-)=10,60

pH + pOH = 14

pH + 10,60 = 14

pH=14 -10,60

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Given that ΔH = −571.6 kJ/mol for the reaction 2 H2(g) + O2(g) → 2 H2O(l), calculate ΔH for these reactions. (a) 2 H2O(l) → 2 H2

pashok25 [27]

Answer : The value of $\Delta H$ for the reaction is +571.6 kJ/mole.

Explanation :

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According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction is,

$2H_2(g)+O_2(g)\rightarrow 2H_2O(l)$ $\Delta H_1=-571.6kJ/mole$

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$2H_2O(l)\rightarrow 2H_2(g)+O_2(g)$ $\Delta H_2=?$

According to the Hess’s law, if we reverse the reaction then the sign of $\Delta H$ change.

So, the value $\Delta H_2$ for the reaction will be:

$\Delta H_2=-(-571.6kJ/mole)$

$\Delta H_2=+571.6kJ/mole$

Hence, the value of $\Delta H$ for the reaction is +571.6 kJ/mole.

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