Answer:
1.58x10⁻⁵
2.51x10⁻⁸
0.0126
63.10
Explanation:
Phenolphthalein acts like a weak acid, so in aqueous solution, it has an acid form HIn, and the conjugate base In-, and the pH of it can be calculated by the Handerson-Halsebach equation:
pH = pKa + log[In-]/[HIn]
pKa = -logKa, and Ka is the equilibrium constant of the dissociation of the acid. [X] is the concentrantion of X. Thus,
i) pH = 4.9
4.9 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = - 4.8
[In-]/[HIn] =
[In-]/[HIn] = 1.58x10⁻⁵
ii) pH = 2.1
2.1 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = -7.6
[In-]/[HIn] =
[In-]/[HIn] = 2.51x10⁻⁸
iii) pH = 7.8
7.8 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = -1.9
[In-]/[HIn] =
[In-]/[HIn] = 0.0126
iv) pH = 11.5
11.5 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = 1.8
[In-]/[HIn] =
[In-]/[HIn] = 63.10
Answer:
2)Both the salt dissolving and the evaporation of water are physical changes.
Explanation:
The two kinds of changes that has occurred are both physical changes.
Dissolution of a solute such as salt in water and evaporation of water from a solution are physical changes.
A physical change is one in which the physical property of matter is altered. Particularly the state and the form.
In many of these cases, the change is easily reversible.
Since this change is reversible in that we were able to collect the salt back, this is a physical change.
Answer is: the hydronium ion (H₃O⁺) concentration is greater than hydroxide ion (OH⁻)<span> concentration.
</span><span>Bases (more hydroxide ions than hydronium ions) turn red litmus paper blue and acids (more hydronium ions than hydroxide ions) turn blue
litmus paper red.
</span><span>Acids and bases have opposite properties and have the ability to
neutralize each other. Acids taste sour, give sharp stinging pain
in a wound and react with metals to produce hydrogen gas.</span>
C. pain reliever
ex. tylenol, aleve, etc.
Oxygen is a reactant in combustion and the concentration of oxygen is higher in pure oxygenthan it is in air.