Mass of Co(NO₃)₂ = 1.95 g
V KOH = 0.350 L
[KOH] = 0.220 M
Kf = 5.0 x 10⁹
molar mass of Co(NO₃)₂ = 182.943 g/mol
so [Co(NO₃)₂] = 1.95 / (0.350 * 182.943) = 0.03045 M
[Co²⁺] = 0.03045 M
[OH⁻] = 0.22 M
chemical reaction:
Co²⁺(aq) + 4 OH⁻ ⇄ Co(OH)₄²⁻
I (M) 0.03045 0.22 0
C (M) - 0.03045 - 4 (0.03045) 0.03045
E (M) - x 0.22 - 4(0.03045) 0.03045
= 0.0982
Kf = [Co(OH)₄²⁻] / [Co⁺²][OH⁻]⁴
5.0 x 10⁹ = (0.03045) / x (0.0982)⁴
x = 6.5489 x 10⁻⁸
at equilibrium:
[Co²⁺] = 6.54 x 10⁻⁸
[OH⁻] = 0.0982 M
[Co(OH)₄²⁻] = 0.03045 M
Answer: The pH of the solution is 11.2
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

where,
n = moles of solute
= volume of solution in ml
moles of
=
(1g=1000mg)
Now put all the given values in the formula of molality, we get


pH or pOH is the measure of acidity or alkalinity of a solution.
pH is calculated by taking negative logarithm of hydrogen ion concentration.
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)

According to stoichiometry,
1 mole of
gives 2 mole of
Thus 0.0298 moles of
gives =
moles of
Putting in the values:
![pOH=-\log[0.0596]=2.82](https://tex.z-dn.net/?f=pOH%3D-%5Clog%5B0.0596%5D%3D2.82)



Thus the pH of the solution is 11.2
<h3>
Answer:</h3>
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
<h3>
Explanation:</h3>
- The equation for the reaction shown represents the combustion of ethane.
C₂H₆ + O₂ → CO₂ + H₂O
- To balance the equation we put the coefficients, 2, 7, 4, and 6 on the reactants and products.
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
- Balancing chemical equations makes the number of atoms of each element equal on both side of the equation.
- It ensures that chemical equations obey the law of conservation of mass in chemical reactions.
Answer: -
The experiment Niven is doing is burning of Mg.
The first step would be finding the molar mass of MgO
Atomic mass of Mg = 24 g
Atomic mass of Oxygen = 16 g
Molar mass of MgO = 24 x 1 + 16 x 1 = 40 g
The balanced chemical equation for this reaction is
2 Mg + O2 -- > 2MgO
From the balanced equation we see that
2 Mg gives 2 MgO
2 x24 g of Mg O gives 2 x 40 g of MgO.
28g of MgO gives

= 46.66 g of MgO.
The integrated rate law for a second-order reaction is given by:
![\frac{1}{[A]t} = \frac{1}{[A]0} + kt](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B%5BA%5Dt%7D%20%3D%20%20%20%5Cfrac%7B1%7D%7B%5BA%5D0%7D%20%2B%20kt%20)
where, [A]t= the concentration of A at time t,
[A]0= the concentration of A at time t=0
<span>k =</span> the rate constant for the reaction
<u>Given</u>: [A]0= 4 M, k = 0.0265 m–1min–1 and t = 180.0 min
Hence, ![\frac{1}{[A]t} = \frac{1}{4} + (0.0265 X 180)](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B%5BA%5Dt%7D%20%3D%20%5Cfrac%7B1%7D%7B4%7D%20%2B%20%280.0265%20X%20180%29%20)
<span> = 4.858</span>
<span><span><span>Therefore, [A]</span>t</span>= 0.2058 M.</span>
<span>
</span>
<span>Answer: C</span>oncentration of A, after 180 min, is 0.2058 M