This video tutorial is in the Education category which will show you how to understand chemistry and chemical change. The question here is 10g of Mg ribbon reacts with 0.15 mol decimeter cubed of hydrochloric acid at 25 degree Celsius. What is the balanced equation for this reaction? When magnesium reacts with hydrochloric acid, you will get magnesium chloride and hydrogen. So, the equation will be Mg + 2HCl = MgCl2 + H2. Mg is in group 2 of periodic table and has a valance of 2, whereas Cl is in group 7 and has valence of 1. Hence, magnesium chloride will be MgCl2. You can watch the video for more question answers.