All categories

4 years ago

The ph of a solution that contains 0.818 m acetic acid (ka = 1.76 x 10-5) and 0.172 m sodium acetate is __________.

1 answer:

4 0

PH is calculated using <span>Handerson- Hasselbalch equation,

pH = pKa + log [conjugate base] / [acid]

Conjugate Base = Acetate (CH</span>₃COO⁻)
Acid = Acetic acid (CH₃COOH)
So,
pH = pKa + log [acetate] / [acetic acid]

We are having conc. of acid and acetate but missing with pKa,
pKa is calculated as,

pKa = -log Ka
Putting value of Ka,
pKa = -log 1.76 × 10⁻⁵

pKa = 4.75
Now,
Putting all values in eq. 1,

pH = 4.75 + log [0.172] / [0.818]

pH = 4.072

You might be interested in

Italian dressing contains olive oil and vinegar, which will separate out from each other if left to sit. This makes the dressing

OleMash [197]

Italian salad dressing would be a suspension

6 0

3 years ago

What mass of carbon monooxide must be burned to produce 175 kJ of heat under standard state condaitions?

Sphinxa [80]

Answer:

17.3124 grams

Explanation:

Given;

Amount of heat to be produced = 175 kJ

Molar mass of the carbon monoxide = 12 + 16 = 28 grams

Now,

The standard molar enthalpy of carbon monoxide = 283 kJ/mol

Thus,

To produce 175 kJ heat, number of moles of CO required will be

= Amount heat to be produced / standard molar enthalpy of CO

= 175 / 283

= 0.6183

Also,

number of moles = Mass / Molar mass

therefore,

0.6183 = Mass / 28

Mass of the CO required = 0.6183 × 28 = 17.3124 grams

7 0

4 years ago

Blood type is an example of a trait that's inherited by

maxonik [38]

The correct answer would be D) c<span>odominance, I believe.</span>

3 0

4 years ago

Consider the reaction: CO2(g) + CCl4(g) ⇌ 2 COCl2(g) ΔG° = 46.9 kJ Under the following conditions at 25 oC: LaTeX: P_{CO_2}P C O

Mamont248 [21]

Answer : The value of $\Delta G_{rxn}$ is, $-47.0kJ/mole$

Explanation :

The formula used for $\Delta G_{rxn}$ is:

$\Delta G_{rxn}=\Delta G^o+RT\ln K_p$ ............(1)

where,

$\Delta G_{rxn}$ = Gibbs free energy for the reaction

$\Delta G_^o$ = standard Gibbs free energy = 46.9 kJ

R = gas constant = 8.314 J/mole.K

T = temperature = $25^oC=273+25=298K$

$K_p$ = equilibrium constant

First we have to calculate the value of $K_p$ .

The given balanced chemical reaction is,

$CO_2(g)+CCl_4(g)\rightarrow 2COCl_2(g)$

The expression for reaction quotient will be :

$K_p=\frac{(p_{COCl_2})^2}{(p_{CO_2})\times (p_{CCl_4})}$

In this expression, only gaseous or aqueous states are includes and pure liquid or solid states are omitted.

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

$K_p=\frac{(0.653)^2}{(0.459)\times (0.984)}$

$K_p=0.944$

Now we have to calculate the value of $\Delta G_{rxn}$ by using relation (1).

$\Delta G_{rxn}=\Delta G^o+RT\ln K_p$

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

$\Delta G_{rxn}=-46.9kJ/mol+(8.314\times 10^{-3}kJ/mole.K)\times (298K)\ln (0.944)$

$\Delta G_{rxn}=-47.0kJ/mol$

Therefore, the value of $\Delta G_{rxn}$ is, $-47.0kJ/mole$

3 0

3 years ago

Pyridine, C5H5N, is a bad-smelling liquid that is a weak base in water. Its pKb is 8.77. What is the pH of a 0.20 M aqueous solu

kari74 [83]

Answer:

pH = 9.26

Explanation:

Let's make the reaction of this weak base:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻ Kb

We do not know the Kb, but we can discover it from pKb

Kb = 10^⁻pKb → 10⁻⁸'⁷⁷ = 1.70×10⁻⁹

So, let's make the expression for Kb

Kb = [OH⁻] . [C₅H₅NH⁺] / [C₅H₅N]

In the equilibrum, we would have 0.20 moles from the begining - x (react)

So we would proudce x moles of OH⁻ and x moles of C₅H₅NH⁺.

In conclussion:

1.70×10⁻⁹ = x . x / (0.20 - x)

To avoid the quadratic formula we can miss the x from the substraction

1.70×10⁻⁹ = x² / 0.20

1.70×10⁻⁹ . 0.20 = x²

We avoid the x from the (0.20-x), because the base is so concentrated, and Kb is very small.

x = √(1.70×10⁻⁹ . 0.20) → 1.84×10⁻⁵

That's the value of [OH⁻], so we can calculate pOH

- log [OH⁻] = pOH → - log 1.84×10⁻⁵ = 4.73

Then pH = 14 - pOH

14 - 4.73 = 9.26

4 0

4 years ago