Hey there!:
is the solution <span>saturated , ie :
</span>They are the ones that have reached the exact solubility coefficient.<span>If we mix 64.4 g of KCl at 200.0 g of water at 20 º C, we'll see that the 32.2 g will dissolve and the remainder (32.2 g) will precipitate, forming the bottom body. In this case we will then have a solution saturated with background. However, if we want only the saturated solution, simply perform a simple filtration to separate the precipitate from the saturated solution.
hope this helps!</span>
Answer:
pH = 8.24
Explanation:
Nitrous acid (HNO₂) reacts with KOH, thus:
HNO₂ + KOH → KNO₂ + H₂O
Moles of HNO₂ are:
0.0257mL ₓ (0.370mol / L) = 0.00951moles.
In equivalence point, the complete moles of nitrous acid reacts with KOH producing potassium nitrite. There are needed:
0.00951mol ₓ (1L / 0.491mol) = 0.01937L ≡ 19.4mL of 0.491M KOH to reach equivalence point.
Total volume in equivalence point is: 19.4mL + 25.7mL = <em>45.1mL</em>
Potassium nitrite is in equilibrium with water, thus:
NO₂⁻ + H₂O ⇄ HNO₂ + OH⁻
Where equilibrium constant, Kb, is defined as:
Kb = 1.41x10⁻¹¹ = ![\frac{[OH^-][HNO_2]}{[NO_2]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BOH%5E-%5D%5BHNO_2%5D%7D%7B%5BNO_2%5D%7D)
In equilibrium, molarity of each compound are:
[NO₂⁻]: 0.00951mol/0.00451L - X = 0.211M - X
[HNO₂]: X
[OH⁻]: X
<em>Where X is reaction coordinate</em>
Replacing in Kb:
1.41x10⁻¹¹ = ![\frac{[X][X]}{[0.211 -X]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BX%5D%5BX%5D%7D%7B%5B0.211%20-X%5D%7D)
0 = X² + 1.41x10⁻¹¹X - 2.97x10⁻¹²
Solving for X:
X = -1.72x10⁻⁶ <em>FALSE ANSWER. There is no negative concentrations.</em>
X = 1.72x10⁻⁶. <em>Right answer.</em>
That means:
[OH⁻]: 1.72x10⁻⁶M
As pOH is -log [OH⁻] and pH = 14-pOH:
pOH = 5.76; <em>pH = 8.24</em>
Answer:
900 J/mol
Explanation:
Data provided:
Enthalpy of the pure liquid at 75° C = 100 J/mol
Enthalpy of the pure vapor at 75° C = 1000 J/mol
Now,
the heat of vaporization is the the change in enthalpy from the liquid state to the vapor stage.
Thus, mathematically,
The heat of vaporization at 75° C
= Enthalpy of the pure vapor at 75° C - Enthalpy of the pure liquid at 75° C
on substituting the values, we get
The heat of vaporization at 75° C = 1000 J/mol - 100 J/mol
or
The heat of vaporization at 75° C = 900 J/mol
Slime flows like a liquid, but unlike familiar liquids (e.g., oil, water), its ability to flow, or viscosity, is not constant. So it's a fluid, but not a regular liquid. Scientists call a material that changes viscosity a non-Newtonian fluid. The technical explanation is that slime is a fluid that changes its ability to resist deformation according to shear or tensile stress.
What this means is, when you pour slime or let it ooze through your fingers, it has a low viscosity and flows like a thick liquid. When you squeeze a non-Newtonian slime, like oobleck, or pound it with your fist, it feels hard, like a wet solid. This is because applying stress squeezes the particles in the slime together, making it hard for them to slide against each other.
Most types of slime are also examples of polymers. Polymers are molecules made by linking together chains of subunits.
The specifics of how a type of slime works depends on its chemical composition, but the basic explanation is that chemicals are mixed to form polymers. The polymers act as a net, with molecules sliding against each other.
Two solutions are combined to make classic slime. One is diluted school glue, or polyvinyl alcohol in water. The other solution is borax (Na2B4O7.10H2O) in water.
Borax dissolves in water into sodium ions, Na+, and tetraborate ions.
The tetraborate ions react with water to produce the OH- ion and boric acid:
B4O72-(aq) + 7 H2O <—> 4 H3BO3(aq) + 2 OH-(aq)
Boric acid reacts with water to form borate ions:
H3BO3(aq) + 2 H2O <— > B(OH)4-(aq) + H3O+(aq)
Hydrogen bonds form between the borate ion and the OH groups of the polyvinyl alcohol molecules from the glue, linking them together to form a new polymer: slime.
Answer
A. It changes the rate, R
Explanation
When we change the concentration of the reactants in a chemical reaction, it affects the rate of reaction that happens in the process. Typically, the rate of reaction will decrease with time if the concentration of the reactants decreases because the reactants will be converted to products. Similarly, the rate of reaction will increase when the concentration of reactants are increased.
