Question

Write a balanced formation equation at standard conditions for the compound HI.

Answer 1

The compound HI (hydrogen iodide) is formed from the reaction of hydrogen (H2) with iodine (I2). The subscript 2 in hydrogen and iodine means that they exist as biatomic molecules. The reaction is therefore,
                                        H2 + I2 ---> HI
Balancing,
                                         H2 + I2 ---> 2HI