Barium's ionic charge is 2+ and chlorine's is 1-, meaning you need 2 chlorine ions for each barium ion in barium chloride. The polyatomic ion hydroxide has a 1- charge, and sodium's is 1+, so you need no subscripts for sodium hydroxide.
The reaction between BaCl2 and NaOH is a double replacement reaction because there are two polyatomic compounds, both with metal ions, reacting. The barium and sodium ions will literally swap places with each other to form barium hydroxide and sodium chloride.
BaCl2 + NaOH → Ba(OH)2 + NaCl
Notice that the equation isn't balanced because there are more chlorine ions and less hydroxide ions on the left than there are on the right, so the first step in balancing the equation is to add coefficients to one of the compounds, in this case a 2 to NaOH to get the required 2 hydroxide ions on the right:
BaCl2 + 2NaOH → Ba(OH)2 + NaCl
Now we must balance the sodium ions AND the chlorine ions because adding a 2 to NaOH upset the balance of sodium ions. Adding another 2 to NaCl gives us the required number of sodium and chlorine ions, so the balanced chemical equation of barium chloride and sodium hydroxide is:
BaCl2 + 2NaOH → Ba(OH)2 + 2NaCl
The reaction between BaCl2 and NaOH is a double replacement reaction because there are two polyatomic compounds, both with metal ions, reacting. The barium and sodium ions will literally swap places with each other to form barium hydroxide and sodium chloride.
BaCl2 + NaOH → Ba(OH)2 + NaCl
Notice that the equation isn't balanced because there are more chlorine ions and less hydroxide ions on the left than there are on the right, so the first step in balancing the equation is to add coefficients to one of the compounds, in this case a 2 to NaOH to get the required 2 hydroxide ions on the right:
BaCl2 + 2NaOH → Ba(OH)2 + NaCl
Now we must balance the sodium ions AND the chlorine ions because adding a 2 to NaOH upset the balance of sodium ions. Adding another 2 to NaCl gives us the required number of sodium and chlorine ions, so the balanced chemical equation of barium chloride and sodium hydroxide is:
BaCl2 + 2NaOH → Ba(OH)2 + 2NaCl
