Whats the difference between these experiments

1.milk of magnesia, a suspension of mg(oh)2in water, reacts with stomach acid (hcl) in a neutralization reaction. mg(oh)2(s) + 2 hcl(aq) −→ 2 h2o(l) + mgcl2(aq) what mass of mgcl2 will be produced if 5.49 g of mg(oh)2 reacts? answer in units of g. 2.what mass of hcl is required to completely react with 5.49 g of mg(oh)2? answer in units of g.

What is the correct term for living the most sustainable life you can within your current circumstances?

Why does his teacher ask him to balance the equation by including the correct coefficient