0.378 mL + 42.3 mL

A buffer solution contains 0.479 M NaHCO3 and 0.342 M Na2CO3. Determine the pH change when 0.091 mol HNO3 is added to 1.00 L of

pshichka [43]

Answer:

ΔpH = 0.20

Explanation:

The buffer of HCO₃⁻ + CO₃²⁻ has a pka of 10.2

HCO₃⁻ ⇄ H⁺ + CO₃²⁻

There are 0.479moles of NaHCO₃ and 0.342moles of Na₂CO₃.

Using Henderson-Hasselbalch formula:

pH = pka + log [Base] / [Acid]

pH = 10.2 + log 0.342mol / 0.479mol

pH = 10.05

NaOH reacts with HCO₃⁻ producing CO₃²⁻, thus:

NaOH + HCO₃⁻ → CO₃²⁻ + H₂O + Na⁺

0.091 moles of NaOH produce the same moles of CO₃²⁻ and consume HCO₃⁻. Moles of these species are:

CO₃²⁻: 0.342mol + 0.091mol: 0.433mol

HCO₃⁻: 0.479mol - 0.091 mol: 0.388mol

Using Henderson-Hasselbalch formula:

pH = pka + log [Base] / [Acid]

pH = 10.2 + log 0.433mol / 0.388mol

pH = 10.25

That means change of pH, ΔpH is:

ΔpH = 10.25 - 10.05 = 0.20

I hope it helps!

3 0

2 years ago

Gas laws describe and predict the behavior of gases without attempting to explain why they happen

Nutka1998 [239]

The gas laws describe and predict the behavior of gases with an explanation and experimental data

So the given statement is False.

2) The volume of gas can be calculated based on Avagadro's law

It states that the volume of a gas is directly proportional or varies with the moles of the gas. Higher the moles more the volume, condition is the pressure and temperature are constants in the two conditions

Thus as here the pressure and temperature of nitrogen gas is kept constant

V α moles

or

$\frac{V1}{n1}=\frac{V2}{n2}$

Where

V1 = 6 l

n1 = 0.50 mol

V2 = ?

n2 = 0.75 mol

On putting values

V2 = 6 X 0.75 / 0.5 = 9 L

so resulting volume of the gas will be 9L

5 0

3 years ago

Read 2 more answers

PLEASE HELP TEST density question EASY

AlexFokin [52]

it will float because it is not heavy enough

7 0

2 years ago

Read 2 more answers

Explain how scientists know the oxygen level in the atmosphere has changed because of plants. Could our atmosphere still be chan

alukav5142 [94]

Answer:

Kya hova be Tera question koi nahi btaye ga

4 0

3 years ago

What is the electron shielding effect? What is the trend for it? How and why does it happen?

andriy [413]

Answer:

See explanation

Explanation:

In an atom, the inner electrons may shield the outer electrons from the attractive force of the nucleus. We, refer to this phenomenon as the shielding effect, It is defined as a decrease in the magnitude of attraction between an electron and the nucleus of an atom having more than one electron shell (energy level).

Shielding effect increases down the group due to addition of more shells but decreases across the period due to the increase in the size of the nuclear charge.

As the magnitude of shielding increases down the group, ionization of electrons becomes easier and the first ionization energies of elements decreases as we move down the group. Since shielding effect decreases across the period, the first ionization energies of elements increases across the period.

6 0

2 years ago

0.378 mL + 42.3 mL - 1.5833 mL