How is wavelength measured (Select all that apply. from the trough (bottom) of one wave to the trough of the next wave
2 answers:
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Answer:
Ka = 6.02x10⁻⁶
Explanation:
The equilibrium that takes place is:
- HA ⇄ H⁺ + A⁻
- Ka = [H⁺][A⁻]/[HA]
We <u>calculate [H⁺] from the pH</u>:
- pH = -log[H⁺]
- [H⁺] =
- [H⁺] = 9.12x10⁻⁴ M
Keep in mind that [H⁺]=[A⁻].
As for [HA], we know the acid is 0.66% dissociated, in other words:
- [HA] * 0.66/100 = [H⁺]
We <u>calculate [HA]</u>:
- [HA] = 0.138 M
Finally we <u>calculate the Ka</u>:
- Ka =
= 6.02x10⁻⁶
Answer: -
3.151 M
Explanation: -
Let the volume of the solution be 1000 mL.
At 25.0 °C, Density = 1.260 g/ mL
Mass of the solution = Density x volume
= 1.260 g / mL x 1000 mL
= 1260 g
At 25.0 °C, the molarity = 3.179 M
Number of moles present per 1000 mL = 3.179 mol
Strength of the solution in g / mol
= 1260 g / 3.179 mol = 396.35 g / mol (at 25.0 °C)
Now at 50.0 °C
The density is 1.249 g/ mL
Mass of the solution = density x volume = 1.249 g / mL x 1000 mL
= 1249 g.
Number of moles present in 1249 g = Mass of the solution / Strength in g /mol
=
= 3.151 moles.
So 3.151 moles is present in 1000 mL at 50.0 °C
Molarity at 50.0 °C = 3.151 M