Answer: A
Explanation:
A Gold (Au) atom has 79 protons and 79 electrons. A typical gold atom has 118 neutrons, though there are 18 other radioisotopes discovered so far. 79 is its charge (atomic number), which is both its proton number and electron number
The number of protons in the nucleus of the atom is equal to the atomic number. So the number of atomic number is equal to the number of protons. hope it helped (:
The answer is 200 g.
If the molar mass of CaCl2 is 110.98 g/mol, this means there are 110.98 g in 1 L of 1 M solution.
Let's find how many g of CaCl2 are present in 0.720 M.
110.98 g : 1 M = x : 0.720 M
x = 110.98 g * 0.720 M : 1 M
x = 79.90 g
So there are 79.90 g in 0.720 M. In other words, in 1 L of 0.720 M solution there will be 79.90 g.
Now, we need to prepare ten beakers with 250 mL of solutions:
10 * 250 mL = 2500 mL = 2.5 L
79.90 g : 1 L = x : 2.5 L
x = 79.90 g * 2.5 L : 1 L
x = 199.75 g ≈ 200 g
Answer:
pH = 9,32
Explanation:
The compound with 2 ionizable groups has the following equilibriums:
H₂M ⇄ HM⁻ + H⁺ pka = 6,2
HM⁻ ⇄ M²⁻ + H⁺ pka = 9,5
The reaction of M²⁻ with HCl is:
M²⁻ + HCl → HM⁻ + Cl⁻
The moles of M²⁻ are:
0,100L×1,0M = 0,1moles
And moles of HCl are:
0,060L×1,0M = 0,06moles
That means that moles of M²⁻ will be 0,1-0,06 = 0,04mol and moles of HM⁻ will be the same than HCl, 0,06mol
Using Henderson-Hasselbalch formula:
pH = pka + log₁₀ [M²⁻] / [HM⁻]
Replacing:
pH = 9,5 + log₁₀ [0,04] / [0,06]
<em>pH = 9,32</em>
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I hope it helps!