(3) the mass of neutrons in grams
(4) the number of neutrons in grams
Answer: option (1) the atomic mass in grams.
Explanation:
1) The atomic mass is the mass in grams of one mole of atoms.
2) Hence, it is always the atomic mass of an element equal to the mass of one mole of atoms of such element. Therefore, the atomic mass of Au is the mass of one moles of atoms of Au.
3) Here are some examples:
i) Atomic mass of gold: 196.67 g/atoms, means that 196.97 grams of Au is one mole of Au.
ii) Atomic mass of hydrogen: 1.008 g/mol, means that 1.008 grams of H is one mole of H.
iii) Atomic mass of oxygen: 15.999 g/mol, means that 15.999 grams of O is one mole of O.
iv) Atomic mass of lead: 207.2 g/mol, means that 207.2 grams of Pb is one mole of Pb.
Now you see it, the atomic mass in grams of an element is equal to one mole of the element.
An atom is electrically neutral when it has an equivalent number of protons and electrons. Therefore, an atom with 35 protons in the nucleus will also have 35 electrons orbiting the nucleus.
In atomic theory, an atom is neutral when the number of protons present in the nucleus is equal to the number of electrons orbiting the nucleus. For example, hydrogen atoms all have one proton in the nucleus and one electron orbiting the nucleus. Therefore, if an atom has 35 protons in the nucleus, it will also have 35 electrons orbiting the nucleus. This is due to the characteristic of atomic structure that aims for neutrality by maintaining an equal number of positive protons and negative electrons.
#SPJ12
Answer: The pH of the solution is 13.
Explanation:
pOH is defined as the negative logarithm of hydroxide ion concentration present in the solution.
We are given:
Concentration of (Conversion factor: )
1 mole of calcium hydroxide produces 1 mole of calcium ions and 2 moles of hydroxide ions
Concentration of
Putting values in above equation, we get:
We know:
Hence, the pH of the solution is 13.
a. What is the pKa of X-281? Express your answer numerically.
At 25∘C, for any conjugate acid-base pair
pKa + pKb = 14.00
b. What is pKb of the conjugate base of X-281? (Assume 25 ∘C.) Express your answer numerically.
Answer:
a. pka = 3,73.
b. pkb = 10,27.
Explanation:
a. Supposing the chemical formula of X-281 is HX, the dissociation in water is:
HX + H₂O ⇄ H₃O⁺ + X⁻
Where ka is defined as:
In equilibrium, molar concentrations are:
[HX] = 0,089M - x
[H₃O⁺] = x
[X⁻] = x
pH is defined as -log[H₃O⁺]], thus, [H₃O⁺] is:
[H₃O⁺] = 0,004M
Thus:
[X⁻] = 0,004M
And:
[HX] = 0,089M - 0,004M = 0,085M
ka = 1,88x10⁻⁴
And pka = 3,73
b. As pka + pkb = 14,00
pkb = 14,00 - 3,73
pkb = 10,27
I hope it helps!