Answer:
pH of the final solution = 3.8
Explanation:
Concentration of NaF = 
molar
= 0.3 molar
NaF → Na⁺ + F⁻
HF ⇆ H⁺ + F⁻
- NaF is strong electrolyte so completely ionized but HF weak acid not completely ionized.
- Since F⁻ is common ion here
according to common ion effect dissociation of weak acid decreases.
Ka = ![\frac{[H]^{+}[F]^{-} }{[HF]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BH%5D%5E%7B%2B%7D%5BF%5D%5E%7B-%7D%20%20%7D%7B%5BHF%5D%7D)
⇒ [H⁺] = ![\frac{K_{a} [HF]}{[F]^{-} }](https://tex.z-dn.net/?f=%5Cfrac%7BK_%7Ba%7D%20%5BHF%5D%7D%7B%5BF%5D%5E%7B-%7D%20%7D)
...............(1)
{Ka of HF = 3.5 x 10⁻⁴} & Concentration of HF = 30 x 4 x 10⁻³ = 0.12 molar
from equation 1
⇒ [H⁺] = 
[Concentration of F⁻ ≡ Concentration of NaF]
⇒ [H⁺] = 0.00014
⇒pH = - log 0.00014 = 3.85
Answer:
Final temperature of water is 83.8°C
Explanation:
In 500.0mL of a 6.00M NaOH solution, there are:
0.5000L × (6.00mol NaOH/ L) = <em>3.00moles of NaOH</em>
As the heat involved in dissolution is 44.5 kJ/mol, when the solution is dissolved:
44.5kJ/mol × 3.00moles = 133.5kJ = 133500J
Using coffee-cup calorimeter equation:
q = m×C×ΔT
<em>Where q is heat, m is mass of water (500.0g), C is specific heat of water (4.186J/g°C) and ΔT is change in temperature</em>
<em />
133500J = 500.0g×4.186J/g°C×(X-20.0°C)
63.8 = (X-20.0°C)
83.8°C = X
<em>Final temperature of water is 83.8°C</em>
The spontaneous decay of an atom is called transmutation
Answer:
......... idk use a cheat and look up the answer just helping
Answer:
Various limitations of Mendeleev's periodic table are:-
Position of hydrogen - he couldn't assign a correct position to hydrogen as it showed properties of both alkali and halogens .
Position of isotopes - he considered that the properties of elements are a function of their atomic masses. Hence isotopes of a same element couldn't be placed.
In the d-block , elements with lower atomic number were placed before higher atomic number.
Explanation:
