Answer:
6.25×10⁻⁶ g / cm³
Explanation:
Density is the relation between mass and volume as this formula shows.
Density of a compound = Mass of the compound / Volume of compound
In the values, we were given:
0.0124 kg / 1983 mm³ = 6.25×10⁻⁶ kg/mm³
This number means that in a volume of 1 mm³ of compound, the mass of it occupies 6.25×10⁻⁶ kg. Let's make a rule of three:
1 cm³ = 1×10⁻³ mm³
In 1 mm³ we have 6.25×10⁻⁶ kg of compound
So in 1×10⁻³ mm³ we would have (1×10⁻³ mm³ . 6.25×10⁻⁶ kg) / 1 mm³ =
6.25×10⁻⁹ kg
Now let's convert the kg to g.
1 kg = 1000 g
6.25×10⁻⁹ kg . 1000 = 6.25×10⁻⁶ g
Finally density is : 6.25×10⁻⁶ g / cm³
Answer: 9.98
Explanation:
1) The equation for the dissociation of pyridine is:
C₅H₅N₅(aq )+ H₂O(l) ⇄ C₅H₅NH⁺(aq) + OH⁻(aq)
2) Kb equation:
Kb = [C₅H₅NH⁺(aq)] [OH⁻(aq)] / [C₅H₅N₅(aq )]
Where:
[C₅H₅NH⁺(aq)] = [OH⁻(aq)] ← from the equilibrium reaction
[C₅H₅N₅(aq )] = 4.8 M ← from the statement
⇒ 1.9 × 10 ⁻⁹ = x² / 4.8 ⇒ x² = 9.12 × 10⁻⁹
⇒ x = 9.55 × 10⁻⁵ = [OH⁻(aq)]
3) pOH
pOH = - log [OH⁻(aq)] = 4.02
4) pOH + pH = 14
⇒ pH = 14 - 4.02 = 9.98
Explanation:
When you rub a plastic ruler and bring it closer to a tissue, the piece of tissue is forced to attach to the ruler because of some electricity.
