Answer:
1.053×10²⁴ atoms of gold
Explanation:
Hello,
Gold nugget are usually the natural occurring gold and they contain 85% - 90% weight of pure gold.
In this question, we're required to find the number of atoms in 344.75g of a gold nugget.
We can use mole concept relationship between Avogadro's number and molar mass.
1 mole = molar mass
Molar mass of gold = 197 g/mol
1 mole = Avogadro's number = 6.022 × 10²³ atoms
Number of mole = mass / molar mass
Mass = number of mole × molar mass
Mass = 1 × 197
Mass = 197g
197g is present in 6.022×10²³ atoms
344.75g will contain x atoms
x = (344.75 × 6.022×10²³) / 197
X = 1.053×10²⁴ atoms
Therefore 344.75g of gold nugget will contain 1.053×10²⁴ atoms of gold
Answer:
pH = 12.7
Explanation:
First, we have to calculate the [Ca²⁺] in a solution of about 250 ppm CaCO₃.
Now, let's consider the dissolution of Ca(OH)₂ in water.
Ca(OH)₂(s) ⇄ Ca²⁺(aq) + 2 OH⁻(aq)
The solubility product Ksp is:
Ksp = [Ca²⁺] × [OH⁻]²
[OH⁻] = √(Ksp/[Ca²⁺]) = √(6.5 × 10⁻⁶/2.5 × 10⁻³) = 5.1 × 10⁻² M
Finally, we can calculate pOH and pH.
pOH = -log [OH⁻] = -log (5.1 × 10⁻²) = 1.3
pH + pOH = 14 ⇒ pH = 14 - pOH = 14 - 1.3 = 12.7
Answer:
Used for liquid extractions
Explanation:
Noble gases
also known as Inert gases