Answer:
Kₐ = 6.7 x 10⁻⁴
Explanation:
First lets write the equilibrium expression, Ka , for the dissociation of hydrofluoric acid:
HF + H₂O ⇄ H₃O⁺ + F⁻
Kₐ = [ H₃O⁺ ] [ F⁻ ] /[ [ HF ]
Since we are given the pH we can calculate the [ H₃O⁺ ] ( pH = - log [ H₃O⁺ ] , and because the acid dissociates into a 1: 1 relation , we will also have [F⁻ ]. The [ HF ] is given in the question so we have all the information that is needed to compute Kₐ.
pH = -log [ H₃O⁺ ]
1.68 = - log [ H₃O⁺ ]
Taking antilog to both sides of this equation:
10^-1.68 = [ H₃O⁺ ] ⇒ 2.1 X 10⁻² M= [ H₃O⁺ ]
[ F⁻ ] = 2.1 X 10⁻² M
Solving for Kₐ :
Kₐ = ( 2.1 X 10⁻² ) x ( 2.1 X 10⁻² ) / 0.65 = 6.7 x 10⁻⁴
(Rounded to two significant figures, the powers of 10 have infinite precision )
0.012moldm⁻³
Explanation:
Given parameters:
Mass of AgNO₃ = 1000mg
Volume of water = 500mL
Unknown:
Molarity of solution = ?
Solution:
The molarity of a solution is the number of moles of a solute dissolved in volume of solvent.
Molarity = 
Number of moles of AgNO₃ = ?
Number of moles = 
Molar mass of AgNO₃ = 108 + 14 + 3(16) = 170g/mol
convert mass to g;
1000mg = 1g
Number of moles = 
= 0.00588moles
convert the given volume to dm³;
1000mL = 1dm³;
500mL = 0.5dm³
Now solve;
Molarity = 
= 0.012moldm⁻³
learn more:
Molarity brainly.com/question/9324116
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Find the hydroxide ion concentration of a solution with a pOH of 5.90. To solve this, use a scientific calculator and enter 5.90 and use the +/- button to make it negative and then press the 10x key.
Answer:
8.6g/cm³ (BRASS)
Explanation:
Given the following :
Mass of object = 86g
Volume of object = 10cm³
The density of an object is calculated using the formula :
Density(g/cm³) = mass(g) / volume(cm³)
Inputting our values :
Density = 86g / 10cm³
Density = 8.6g/cm³
According to the table provided, the object which corresponds to having a density of 8.6g/cm³ is BRASS
