Salt can dissolve in water because it is an ionic compound. The Na⁺ and Cl⁻ ions get solvated by the water molecules and leave the surface of the crystal;
The formula of ethanol is CH₃CH₂OH. Ethanol can dissolve in water because its OH group can form strong hydrogen bonds to the water molecules.
Answer:
1.2 × 10² J
Explanation:
Given data
- Initial temperature: 295 K
The amount of heat (Q) that a substance absorbs depends on its specific heat capacity (c), which is the amount of heat energy required to raise the temperature of a substance per unit of mass. It can be calculated through the following expression. <em>(cFe = 0.444 J/g.K)</em>
HNO₃(aq) + NaOH(aq) → NaNO₃(aq) + H₂O(l)
H⁺ + NO₃⁻ + Na⁺ + OH⁻ → Na⁺ + NO₃⁻ + H₂O
H⁺ + OH⁻ → H₂O (the net ionic equation)
Answer:
(C) arsenious acid, Ka = 6 x 10⁻¹⁰
Explanation:
A buffer is prepared by a weak acid and the conjugate base coming from its salt. Its function is to resist abrupt changes in pH when an acid or a base are added. The best working range of a buffer is in the range of pKa ± 1. Let's consider the 5 options and their pKa (pKa = -log Ka).
(A) phthalic acid, K1 = 1.3 x 10⁻³ (1st ionization) pKa = 2.9
(B) hydrogen phthalate, K2 = 3.9 x 10⁻⁵ pKa = 4.4
(C) arsenious acid, Ka = 6 x 10⁻¹⁰ pKa = 9
(D) formic acid, Ka = 1.8 x 10⁻⁵ pKa = 4.7
(E) phenol, Ka = 1.3 x 10⁻¹⁰ pKa = 9.8
The acid whose pKa is closer to the desired pH is arsenious acid. Its working range of pH is 8 - 10. In the second place, phenol could work as a buffer system since the working pH range is 8.8 - 10.8.
If my memory serves me well, each period in the periodic table corresponds to a principal energy level. I think it's correct because periods are the horizontal rows and when you go down you always add <span> one to the principal energy level. Hope it is clear. Good luck!</span>