Answer:
a) 1.71 × 10⁻³ M
b) 8.00 × 10⁻⁵ M
Explanation:
In order to calculate the solubility (S) of Pb(SCN)₂ we will use an ICE chart. We identify 3 stages (Initial, Change, Equilibrium) and complete each row with the concentration or change in the concentration.
Pb(SCN)₂(s) ⇄ Pb²⁺(aq) + 2 SCN⁻(aq)
I 0 0
C +S +2S
E S 2S
The solubility product (Ksp) is:
Ksp = 2.00 × 10⁻⁵ = [Pb²⁺].[SCN⁻]² = S . (2S)² = 4S³
S = 1.71 × 10⁻³ M
<em>b) Calculate the molar solubility of lead thiocyanate in 0.500 M KSCN.</em>
KSCN is a strong electrolyte that dissociates to give 0.500 M K⁺ and 0.500M SCN⁻.
Pb(SCN)₂(s) ⇄ Pb²⁺(aq) + 2 SCN⁻(aq)
I 0 0.500
C +S +2S
E S 0.500 + 2S
Ksp = 2.00 × 10⁻⁵ = [Pb²⁺].[SCN⁻]² = S . (0.500 + 2S)²
In the term (0.500 + 2S)², 2S is negligible.
Ksp = 2.00 × 10⁻⁵ = S . (0.500)²
S = 8.00 × 10⁻⁵ M
1) If the arrangement is symmetrical and the arrows are of equal length the molecule is nonpolar
2) If the arrows are of different lengths and if they do not balance each other the molecule is polar
3) If the arrangement is asymmetrical the molecule is polar
Oxygen can combine with a metal to produce a compound
Density (kg/m³) = mass (kg) / Volume (m³)
d = m/V (1)
Ideal gas law,
PV = nRT (2)
<span>Where, P is the
pressure of the gas (Pa), V is the volume of the gas (m³), n is the number of moles of gas (mol), R is the
universal gas constant ( 8.314 J mol</span>⁻¹ K⁻<span>¹) and T is temperature in Kelvin.
</span>
n = m/M (3)
Where, n is number of moles, m is mass and M is molar mass.
From (2) and (3),
PV = (m/M) RT
By rearranging,
P = (m/VM)RT (4)
From (1) and (4)
P = (dRT) / M
P = standard pressure = 1 atm = 101325 pa
d = ?
R = 8.314 J mol⁻¹ K⁻¹
T = Standard temperature = 273 K
M = 44 g/mol = 44 x 10⁻³ kg/mol
By substitution,
101325 Pa = (d x 8.314 J mol⁻¹ K⁻¹ x 273 K) / 44 x 10⁻³ kg/mol
d = (101325 Pa x 44 x 10⁻³ kg/mol) / (8.314 J mol⁻¹ K⁻¹ x 273 K)
d = 1.96 kg m⁻³ = 1.96 g/L
Hence, the density of the CO₂ at STP is 1.96 g/L
Assumption made is "CO₂ gas has an ideal gas behavior".