Pete and Helen investigate the reaction between sodium carbonate, Na2CO3, and ethanoic acid, C2H4O2. Sodium ethanoate, C2H3O2Na, carbon dioxide and water are made. Pete and Helen measure the mass of carbon dioxide made every 30 seconds during the reaction. They do the experiment again. They use the same amount of acid and sodium carbonate. This time they use warm ethanoic acid instead of cold ethanoic acid. Look at the graph below. It shows their results. Look at the graph for the warm acid. How many minutes does it take for the reaction to finish?