Answer:
Explanation:
1) How much would 1.34 moles of carbon weigh?
Given data:
Moles of carbon = 1.34 mol
Mass of carbon = ?
Solution:
Formula:
Molar mass of carbon = 12 g/mol
Number of moles = mass/molar mass
Mass = moles × molar mass
Mass = 1.34 mol × 12 g/mol
Mass = 16.08 g
So 1.34 moles of carbon have 16.08 g mass.
2) How many moles of magnesium in 24.32 g?
Given data:
Mass of magnesium = 24.32 g
Moles of magnesium = ?
Solution:
Molar mass of magnesium = 24.305 g/mol
Number of moles = mass/molar mass
Number of moles = 24.32 g/24.305 g/mol
Number of moles = 1 mol
Thus 24.32 g of magnesium have one mole of Mg.
3) How many atoms of lithium in 4.00 g of lithium?
Given data:
Mass of lithium = 4 g
Atoms of lithium = ?
Solution:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
Moles of lithium:
Number of moles = mass/molar mass
Number of moles = 4 g / 6.9 g/mol
Number of moles = 0.6 mol
1 mole = 6.022 × 10²³ atoms
0.6 mol × 6.022 × 10²³ atoms / 1 mol = 3.6 × 10²³ atoms
4) How much would 4.45 ×10²² atoms of U weigh?
Given data:
Number of atoms of uranium = 4.45 ×10²² atoms
Mass of uranium = ?
Solution:
one mole = 6.022 × 10²³ atoms
4.45 ×10²² atoms × 1 mol / 6.022 × 10²³ atoms
0.74 ×10⁻¹ mol
0.074 mol
Mass of uranium:
Mass = number of moles × molar mass
Mass = 0.074 mol × 238 g/mol
Mass = 17.6 g
