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4 years ago

Which acid is the best choice to create a buffer with ph= 3.19?

1 answer:

5 0

The best choice is hypochlorous acid nitrous acid (HNO2) because it has the nearest value of pK to the desired pH.
pKa of nitrous acid is 3.34
If we know pKa and pH values, we can calculate the required ratio of conjugate base (NO2⁻) to acid (HNO2) from the following equation:
pH=pKa + log(conc. of base)/( conc. of acid)
3.19=3.34 + log c(NO2⁻)/c(HNO2)
3.19 - 3.34 = log c(NO2⁻)/c(HNO2)
-0.15 = log c(NO2⁻)/c(HNO2)
c(NO2⁻)/c(HNO2) = 10⁰¹⁵ = 1.41

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Wewaii [24]

A) Energy is released during the formation of the bond.

Explanation:

During the formation of a chemical bonds between two hydrogen atoms, energy is always released during the formation of this bond type.

Bond formation process is usually exothermic and energy is released during the formation of the bond.

Bond breaking process is an endothermic process in which energy is absorbed from the surrounding.
Whenever a bond is broken, the bond energy value is positive but when a bond is formed, the bond energy value is given a negative sign.

For a bond formation process in which hydrogen atoms are bonded covalently, energy is usually released.

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3 years ago

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neonofarm [45]

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3 years ago

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3 years ago

135 grams of sodium has ______ moles. (Enter just the number for this one.)

just olya [345]

Answer : 135 grams of sodium has 5.869 moles.

Solution : Given,

Mass of sodium = 135 grams

Molar mass of sodium = 23 g/mole

Formula used :

$\text{Moles of sodium}=\frac{\text{Mass of sodium}}{\text{Molar mass of sodium}}$

Now put all the given values in this formula, we get

$\text{Moles of sodium}=\frac{135g}{23g/mole}=5.869moles$

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3 years ago