Label the liquids from least to most dense, Vegetable oil, water, Dish soap, Corn syrup, Honey

The value of Ka for nitrous acid (HNO2) at 25 ∘C is 4.5×10−4 .a. Write the chemical equation for the equilibrium that correspond

kvv77 [185]

Answers and Explanation:

a)- The chemical equation for the corresponden equilibrium of Ka1 is:

2. HNO2(aq)⇌H+(aq)+NO−2

Because Ka1 correspond to a dissociation equilibrium. Nitrous acid (HNO₂) losses a proton (H⁺) and gives the monovalent anion NO₂⁻.

b)- The relation between Ka and the free energy change (ΔG) is given by the following equation:

ΔG= ΔGº + RT ln Q

Where T is the temperature (T= 25ºc= 298 K) and R is the gases constant (8.314 J/K.mol)

At the equilibrium: ΔG=0 and Q= Ka. So, we can calculate ΔGº by introducing the value of Ka:

⇒ 0 = ΔGº + RT ln Ka

ΔGº= - RT ln Ka

ΔGº= -8.314 J/K.mol x 298 K x ln (4.5 10⁻⁴)

ΔGº= 19092.8 J/mol

c)- According to the previous demonstation, at equilibrium ΔG= 0.

d)- In a non-equilibrium condition, we have Q which is calculated with the concentrations of products and reactions in a non equilibrium state:

ΔG= ΔGº + RT ln Q

Q= ((H⁺) (NO₂⁻))/(HNO₂)

Q= ( (5.9 10⁻² M) x (6.7 10⁻⁴ M) ) / (0.21 M)

Q= 1.88 10⁻⁴

We know that ΔGº= 19092.8 J/mol, so:

ΔG= ΔGº + RT ln Q

ΔG= 19092.8 J/mol + (8.314 J/K.mol x 298 K x ln (1.88 10⁻⁴)

ΔG= -2162.4 J/mol

Notice that ΔG<0, so the process is spontaneous in that direction.

6 0

3 years ago

Help!

almond37 [142]

D. How the pull of gravity has changed.

4 0

3 years ago

Hydrocyanic acid, HCN, is a weak acid. (a) Write the chemical equation for the dissociation of HCN in water. (b) Identify the Br

12345 [234]

Answer: a) $HCN(aq.)+H_2O\rightleftharoons H_3O^+(aq.)+CN^-(aq.)$

b) $HCN$ : acid $CN^-$ :conjugate base.

And, $H_2O$ : base $H_3O^+$ : conjugate acid.

c) $HCN(aq.)+NaOH(aq)\rightleftharoons NaCN(aq.)+H_2O(l)$

d) $NaCN(aq)\rightarrow Na^+(aq.)+CN^-(aq)$

e) $NaCN(aq)+HCl(aq)\rightarrow NaCl(aq.)+HCN(aq)$

Explanation:

a) Weak acid is defined as the acid which does not completely dissociates when dissolved in water. They have high pH. These releases $H^+$ ions in their aqueous states.

The equation for the dissociation of $HCN$ acid is given by:

$HCN(aq.)+H_2O\rightleftharoons H_3O^+(aq.)+CN^-(aq.)$

b) According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

For the given chemical equation:

$HCN$ is loosing a proton, thus it is considered as an acid and after losing a proton, it forms $CN^-$ which is a conjugate base.

And, $H_2O$ is gaining a proton, thus it is considered as a base and after gaining a proton, it forms $H_3O^+$ which is a conjugate acid.

c) Neutralization reaction is a reaction in which an acid reacts with base to produce salt and water.

$HCN(aq.)+NaOH(aq)\rightarrow NaCN(aq.)+H_2O(l)$