Explanation:
We have to predict the products of a double displacement reaction and then balance it. The reactants are:
CaCl₂ + H₂SO₄ ----> ?
Since it is a double replacement or displacement reaction, these reactants will "exchange" their ions to form two new products. Their ions are:
CaCl₂ ---> Ca²⁺ + 2 Cl⁻
H₂SO₄ ---> 2 H⁺ + SO₄²⁻
We have two exhange the ions to predict the products. We have to combine the cation calcium with the anion sulphate and the anion chloride with the protons.
That's how we get the formula of an ionic compound when we form it with two ions. We have to get a compound with 0 charge. Now that we have the products the unbalanced reaction will be:
CaCl₂ + H₂SO₄ ----> CaSO₄ + HCl
First, to balance this equation, we have to find the number of atoms of each element that we have on both sides of the equation.
CaCl₂ + H₂SO₄ ----> CaSO₄ + HCl
Ca: 1 Ca: 1
Cl: 2 Cl: 1
H: 2 H: 1
S: 1 S: 1
O: 4 O: 4
Ca is already balanced since we have one atom of it on each side of the equation. Cl is not balanced. We have two atoms of Cl on the left side and just one atom of Cl on the right side of the equation. We can change the coefficient for HCl and write a 2 in front of it.
CaCl₂ + H₂SO₄ ----> CaSO₄ + 2 HCl
Ca: 1 Ca: 1
Cl: 2 Cl: 2
H: 2 H: 2
S: 1 S: 1
O: 4 O: 4
We balanced the Cl and we also balanced the H. So now, the equation is balanced. Finally we have to determine the state of each compound. CaCl₂, H₂SO₄ and HCl are aqueous solutions. CaSO₄ is almost insoluble, its solubility is really low so we can consider it a solid.
Answer:
CaCl₂ (aq) + H₂SO₄ (aq) ----> CaSO₄ (s) + 2 HCl (aq)
