If a<span> student used 10 mL water instead of 30 mL for extraction of salt water from mixture, the extraction of salt will be lesser than compared to using 30 mL since less solute will dissolve in 10 mL.</span>
Answer: No, boiling water is a physical change.
Explanation:
Physical change is a change in which there is no rearrangement of atoms and thus no new substance is formed. There is only change in physical state of the substance.
Boiling water is a physical change as liquid changes to gaseous state and no new substance is being formed.
Chemical change is a change in which there is rearrangement of atoms and thus new substance is formed. There may or may not be a change in physical state.
NH3(aq) + HCl(aq) ⇒ NH4Cl(aq) >>> (1)
∵ C = n/V; C= concentration, n= No. of moles, and V= volume (L)
∴ n = C*V, n(HCl) = 0.050*(50/1000) = 0.0025 moles
n(NH3) = 0.050*(50/1000) = 0.0025 moles
So, the limiting no. of moles is 0.0025 moles >>> (2)
∵ NH3 is weak base, and HCl is strong Acid (and have the same number of moles) >>> So, without any calculation we can notice that the formed salt (NH4Cl) is acidic salt and the pH is less than 7.
From (1) and (2), The no. of moles of NH4Cl is 0.0025 moles >>> (3)
∴ the concentration of [NH4Cl] = 0.0025 / (total volume per L)
= 0.0025 / ((50 + 50) / 1000) = 0.025 M
NH4+(aq) ⇔ NH3(aq) + H+(aq) >>> (4)
(0.025 - x) (x) (x) >>> (5)
∵ Ka = [NH3] [H+] / [NH4+] >>>> (6)
Ka = Kw / Kb, Kb = 1.8 * 10^-5 >>> (7)
∴ Ka = 10^-14 / 1.8*10^-5 = 5.56*10^-10 >>> (8)
From (4), (5), (7) and (8)
Ka = 5.56*10^-10 = (x * x) / (0.025-x) , we will assume that (0.025 - x) = 0.025
∴ x^2 = (5.56*10^-10)(0.025) = 139*10^-13
∴ x = 3.73*10^-6 = [H+]
∵ pH = - log [H+]
∴ pH = - log 3.73*10^-6 = 5.43
Answer:
2800 g de ácido nítrico
Explanation:
La ecuación por la oxidación de amoniaco es:
4NH₃ + 7O₂ → 4H₂O + 2HNO₂ + 2HNO₃
Si pensamos que el oxígeno es el reactivo limitante, trabajamos con el amoniaco. Convertimos su masa a moles:
1.36 kg = 1360 g
1360 g . 1mol /17g = 80 moles
Si 4 moles de amoniaco pueden producir 2 moles de acido nítrico
80 moles producirán, (80 . 2)/4 = 40 moles.
Convertimos los moles a gramos:
40 mol . 63g /mol = 2520 g
Si le aplicamos la pureza
2520 g . 100/90 = 2800 g
Ans:
from the product / reactant solution
from the environment when no solution is involved
Endothermic reactions are those reactions that proceed with the absorption of heat energy. In this case, the enthalpy of the reactants i.e. the initial energy is lower than that of the products. Therefore, energy needs to be supplied in order to break the bonds in the reactants and allow the reaction to proceed. This energy can be absorbed either from the environment when no solution is involved or from the product reactant solution.
For example, electrolysis of water which produces H2 and O2 is an endothermic reaction. Here, energy is absorbed by water in the form of electricity (current) to split it into corresponding products.