We have to determine the formula of four compounds: beryllium sulphate, lead (II) nitrate, beryllium nitrate and lead (II) sulphate.
We have to find the formula for four ions:
Beryllium ion: Be²⁺ Sulphate ion: SO₄²⁻ Lead (II) ion: Pb²⁺ Nitrate ion: NO₃⁻
Then the formula on the compounds are:
Beryllium sulphate: BeSO₄ Lead (II) nitrate: Pb(NO₃)₂
Beryllium nitrate: Be(NO₃)₂ Lead (II) sulphate: PbSO₄
We are mixing beryllium sulphate with lead (Il) nitrate to produce beryllium nitrate and lead (II) sulphate. According to the problem they are all aqueous solutions except from lead (II) that is a solid.
BeSO₄ (aq) + Pb(NO₃)₂ (aq) ----> Be(NO₃)₂ (aq) + PbSO₄ (s)
Finally we have to determine if the equation is balanced. To do that we have to count the number of atoms of each element that we have on each side. To make it easier we can directly consider the ions.
BeSO₄ (aq) + Pb(NO₃)₂ (aq) ----> Be(NO₃)₂ (aq) + PbSO₄ (s)
Be: 1 Be: 1
SO₄: 1 SO₄: 1
Pb: 1 Pb: 1
NO₃: 2 NO₃: 2
Since we have the same number of atoms of each element on both sides, the equation is balanced. So the molecular equation is:
Answer: BeSO₄ (aq) + Pb(NO₃)₂ (aq) ----> Be(NO₃)₂ (aq) + PbSO₄ (s)