Question

A group 2 metal carbonate has a mass of 84 g/mol. Identify the group 2 metal X using its chemical formula.

Please show your working out. number of moles in 0.3g of calcium carbonate.

Answer 1

Magnesium

0.003mole

Step-by-step explanation:

The problem here entails we find the metal in the carbonate.

For group 2 member, let the metal = X;

The carbonate is XCO₃;

If we sum the atomic mass of the elements in the metal carbonate, we should arrive at 84g/mol

Atomic mass of C = 12g/mol

O = 16g/mol

Atomic mass of X + 12 + 3(16) = 84

Atomic mass of X = 84 - 60 = 24g/mol

The element with atomic mass of 24g is Magnesium

B.

Number of moles in 0.3g of CaCO₃:

Molar mass of CaCO₃ = 40 + 12 + 3(16) = 100g/mol

Number of moles =
`(mass)/(molar mass)`

Number of moles =
`(0.3)/(100)` = 0.003mole