Answer:
d. 99.63% and 0.364%, respectively
Explanation:
The average mass of a nitrogen atom is 14.006 amu
14N-14.00307 amu with 0.9963 fractional abundance
1SN- 15.000108 amu with 0.00364 fractional abundance.
The relative abundance definition in chemistry is the percentage of a particular isotope that occurs in nature. The atomic mass listed for an element on the periodic table is an average mass of all known isotopes of that element.
In this problem, the fractional abundance has areaady been given. All we need to do now is convert them to percentage abundance.
14N-14.00307 = 0.9963* 100% = 99.63%
1SN- 15.000108 = 0.00364 * 100% = 0.364%
Answer:
65.0 g NH3 x
mol NH3
17.04 g NH3
x
6.02x1023 NH3 molecules
mol NH3
= 2.30x1024 NH3 molecules
(have uh good day)
HBr and HF are both monoprotic Arrhenius acids—that is, in aqueous solution, they dissociate and ionize to give hydrogen ions. A strong acid ionizes completely; a weak acid ionizes partially.
In this case, HBr, being a strong acid, would ionize completely in water to yield H+ and Br- ions. However, HF, being a weak acid, would ionize only to a limited extent: some of the HF molecules will ionize into H+ and F- ions, but most of the HF will remain undissociated.
pH is, by definition, a measurement of the concentration of hydrogen ions in solution (pH = -log[H+]). A higher concentration of hydrogen ions gives a lower pH, while a lower concentration of hydrogen ions gives a higher pH. At 25 °C, a pH of 7 indicates a neutral solution; a pH less than 7 indicates an acidic solution; and a pH greater than 7 indicates a basic solution.
If we have equal concentrations of HBr and HF, then the HBr solution will have a greater concentration of hydrogen ions in solution than the HF solution. Consequently, the pH of the HBr solution will be less than the pH of the HF solution.
Choice A is incorrect: Strong acids like HBr dissociate completely, not partially.
Choice B is incorrect: While the initial concentration of HBr and HF are the same, the H+ concentration in the HBr solution is greater. Since pH is a function of H+ concentration, the pH of the two solutions cannot be the same.
Choice C is correct: A greater H+ concentration gives a lower pH value. The HBr solution has the greater H+ concentration. Thus, the pH of the HBr solution would be less than that of the HF solution.
Choice D is incorrect for the reason why choice C is correct.
