On combustion of 0.7 g of a monovalent metal in oxygen, 1.5 g of its oxide was formed
June 12, 2021 | education
| On combustion of 0.7 g of a monovalent metal in oxygen, 1.5 g of its oxide was formed. Define the period, group and subgroup of this element.
The molar mass of the metal is denoted by x. Let’s make a proportion.
4 Ме + O2 = 2 Ме2O.
4 x g / mol 2 (2x + 16)
4 x x 1.5 g = 0.7 x 2 (2 x + 16),
6 x = 0.7 × (4 x + 32)
6 x = 2.8 x + 22.4,
6 x – 2.8 x = 22.4
3.2 x = 22.4,
x = 22.4: 3.2,
x = 7.
M (Li) = 7 g / mol.
Answer: the metal is lithium.
It is in the II period, I – A – group (main subgroup).
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