(a) Interpretation: The number of moles of platinum in the cone should be calculated. Concept introduction: The number of moles of a substance is related to molar mass of the substance as follows: n = m M Here, m is mass and M is molar mass. In 1 mol of a substance there are 6.023 × 10 23 units of that substance. Also, density of a substance is related to mass and volume as follows: d = m V Here, m is mass and V is volume of the substance.
(a) Interpretation: The number of moles of platinum in the cone should be calculated. Concept introduction: The number of moles of a substance is related to molar mass of the substance as follows: n = m M Here, m is mass and M is molar mass. In 1 mol of a substance there are 6.023 × 10 23 units of that substance. Also, density of a substance is related to mass and volume as follows: d = m V Here, m is mass and V is volume of the substance.
Definition Definition Number of atoms/molecules present in one mole of any substance. Avogadro's number is a constant. Its value is 6.02214076 × 10 23 per mole.
Chapter 3, Problem 6QAP
Interpretation Introduction
(a)
Interpretation:
The number of moles of platinum in the cone should be calculated.
Concept introduction:
The number of moles of a substance is related to molar mass of the substance as follows:
n=mM
Here, m is mass and M is molar mass.
In 1 mol of a substance there are 6.023×1023 units of that substance.
Also, density of a substance is related to mass and volume as follows:
d=mV
Here, m is mass and V is volume of the substance.
Interpretation Introduction
(b)
Interpretation:
The number of electrons in there in the cone should be calculated.
Concept introduction:
The number of moles of a substance is related to molar mass of the substance as follows:
n=mM
Here, m is mass and M is molar mass.
According to Avogadro’s law, in 1 mol of a substance there are 6.023×1023 units of that substance.
6. A solid circular cone made of pure platinum (d =
21.45 g/cm³) has a diameter of 2.75 cm and a height of
%3D
3.00 inches.
(a) How many moles of platinum are there in the cone?
(b) How many electrons are there in the cone?
2.43 g magnesium was completely burnt in oxygen to give magnesium oxide. 2 Mg(s) + O2(g) → 2 MgO(s)
(Relative atomic masses: O = 16.0, Mg = 24.3)
(a) Draw the electronic diagrams of O2 and MgO, showing electrons in the outermost shell only.
(b) (i) How many mole of magnesium was present? (ii) How many mole of oxygen was required to completely react with the amount of magnesium in (i)?
(iii) Hence, calculate the amount of oxygen required to completely react with the magnesium.
(c) Similarly, calculate the amount of MgO formed.
Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe.
(a) The radius of a helium atom is 3.1x10-11 m; the radius of its nucleus is 2.5x10-15 m. What fraction of the spherical atomic volume is occupied by the nucleus (V of a sphere 5 4/ 3πr3)?
(b) The mass of a helium-4 atom is 6.64648x10-24 g, and each of its two electrons has a mass of 9.10939x10-28 g.
What fraction of this atom’s mass is contributed by its nucleus?