This is an **acid-base** reaction (*neutralization*): *HI* is an **acid**, *KOH* is a **base**.

### Word equation

* hydrogen iodide + potassium hydroxide → potassium iodide + water*

### Input interpretation

* HI + KOH → KI + H2O*

** Hydrogen iodide potassium hydroxide potassium iodide water**

### Balanced equation

Balance the chemical equation algebraically:

* HI + KOH → KI + H2O*

Add stoichiometric coefficients, c,, to the reactants and products:

* c1 HI + c2 KOH → c3 KI + c4 H2O*

Set the number of atoms in the reactants equal to the number of atoms in the products for** H, I, K **and **O:**

*H: c1 + c2 = 2c4*

*I: c1 = c3*

*K: c2 = c3*

*O: c2 = c4*

Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set **c1 = 1** and solve the system of equations for the remaining coefficients:

* c1 = 1 c2=1*

* c3 = 1 c4=1*

Substitute the coefficients into the chemical reaction to obtain the balanced equation:

**Answer:**

* HI + KOH → KI + H2O*

### Word equation

* hydrogen iodide + potassium hydroxide → potassium iodide + water*