Answer to Question #133989 in Physics for Divine

Question

The sulphuric acid in Ql. Above was poured into a beaker and 0.12g of magnesium was added. The magnesium reacted with sulphuric acid and hydrogen was produced.
(a) How many moles of magnesium were added
(b) Write the equation for the reaction between magnesium and sulphuric acid
(c) Using your answer to lc, 2a, and 2b, suggest which reagent was in excess, and explain.

Answer 1

(a) How many moles of magnesium were added:

$$n=\frac{m}{\Mu}=\frac{0.12}{24}=0.005\text{ mol}.$$

(b) The reaction was

$$\text{H}_2\text{SO}_4+\text{Mg}\rightarrow\text{MgSO}_4+\text{H}_2\uparrow.$$

(c) The reagent that was in excess is the one that was not used up in the reaction.