Answer:
The pH of the buffer is 7.0 and this pH is not useful to pH 7.0
Explanation:
The pH of a buffer is obtained by using H-H equation:
pH = pKa + log [A⁻] / [HA]
<em>Where pH is the pH of the buffer</em>
<em>The pKa of acetic acid is 4.74.</em>
<em>[A⁻] could be taken as moles of sodium acetate (14.59g * (1mol / 82g) = 0.1779 moles</em>
<em>[HA] are the moles of acetic acid (0.060g * (1mol / 60g) = 0.001moles</em>
<em />
Replacing:
pH = 4.74 + log [0.1779mol] / [0.001mol]
<em>pH = 6.99 ≈ 7.0</em>
<em />
The pH of the buffer is 7.0
But the buffer is not useful to pH = 7.0 because a buffer works between pKa±1 (For acetic acid: 3.74 - 5.74). As pH 7.0 is out of this interval,
this pH is not useful to pH 7.0
<em />
Answer:
one in a 2s orbital
Explanation:
Because of the peak near the nucleus in the 2s curve there is a higher probability of finding a 2s within 4 Å of the nucleus. In a multi-electron atom an electron in a 2s orbital will have a lower energy than one in a 2p orbital
Answer:
A scientific question to be asked is; <em>What is the average speed of the toy car?</em>
Explanation:
A scientific question is a question which is well defined, the values in the question can be measured, and the inputs and outputs related to the question are controllable
The parameters measured in the experiment are;
The time elapsed during the movement of the car, <em>Δt</em>
The distance the car moves, <em>d</em>
From the obtained measurements, the value can be calculated is the average speed of the toy car as follows;
Therefore, a scientific question to be asked that will be answered by doing the experiment is; What is the average speed of the toy car?
Answer:
The vinegar is not enough to neutralize the pool.
Explanation:
The [OH⁻] in the pool is 1.0x10⁻¹mol / L. To know how many moles of OH⁻ are in the solution, you must calculate volume of the pool thus:
V(pool) = πr²h
<em>Where r, radius is d/2 = 12m/2 = 6m and h is deep of the pool = 10m
</em>
V(pool) = π(6m)²*10
V(pool) = 1131m³
As 1m³ = 1000L:
1131m³ × (1000L / 1m³) = 1131000L in the pool.
And moles of OH⁻ are:
1.0x10⁻¹mol / L ₓ 1131000L = 131100 moles of OH⁻ are in the pool
The neutralization of OH⁻ with H⁺ is:
OH⁻ + H⁺ → H₂O
<em>That means to neutralize the pool you must add 131100 moles of H⁺.
</em>
The H⁺ concentration in a vinegar pH = 2 is:
pH = -log [H⁺]
2 = -log [H⁺]
1x10⁻²M = [H⁺]
4L are just 4x10⁻² moles of [H⁺]. As you need 131100 moles of H⁺:
<h3>The vinegar is not enough to neutralize the pool.</h3>
<h2>The number of moles of formaldehyde can be produced by reacting 4.0 moles of methanol with 4.0 moles of oxygen gas is
<u>
8 moles</u></h2>
<u> explanation</u>
write a balanced chemical reaction
that is 2 CH3OH (l) + O2 (g) → 2HCOH (l)+ 2H2O (l)
from the reaction above 2 moles of CH3OH reacted with 1 moles of O2 to form 2 moles of HCOH and two moles of H2O
This imply that O2 is the limiting reagent ,therefore by use of mole ratio between O2 : HCOH which is 1 :2 the moles of HCOH= 2 x4 = 8 moles
