Explanation:
He weighed silver, dissolved it in acid, and then recovered all the original silver by reacting the solution with copper. He also showed, by using iron to recover the copper, that this displacement of one metal from its salt by using a second metal was not because of transmutation, as many had held.
Answer;
-4. metallic, because the valance electrons are mobile
Explanation;
-Electrical conductivity in metals is a result of the movement of electrically charged particles.The atoms of metal elements are characterized by the presence of valence electrons (electrons in the outer shell of an atom) that are free to move about.
-Therefore; Metallic elements such as sodium and potassium conducts electricity in solid form due to the presence of delocalized valence electrons. These electrons can move freely within the structure of a metal when an electric current is applied.
Answer:
10°C
Explanation:
Heat gain by water = Heat lost by the slice of pizza
Thus,
<u>For water: </u>
Volume = 50.0 L
Density of water= 1 kg/L
So, mass of the water:
Mass of water = 50 kg
Specific heat of water = 1 kcal/kg°C
ΔT = ?
For slice of pizza:
Q = 500 kcal
So,
ΔT = 10°C
Increase in temperature = 10°C
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 )
