Purpose: The purpose of this lab is to create an experiment where zinc reacts with hydrochloric acid in order to find out the number of moles and atoms of zinc reacted. This can be accomplished by weighing the sample before and after the reaction with hydrochloric acid.
Mass in grams (g)
Initial mass of dry beaker
Initial mass of dry beaker + zinc
Initial mass of zinc
Final mass of beaker + zinc
Final mass of dry beaker
Final mass of zinc
Observation: We placed the zinc inside the beaker and slowly poured the hydrochloric acid into the beaker. As soon as the acid entered the beaker, there was a sizzling sound and bubbles started to form as we add more of the substance in. When the bubbles were forming, we could see a steam of gas coming out of the beaker. After 10 minutes, we noticed bits of zinc were floating on top of the hydrochloric acid and lining the beaker. I lifted the beaker and felt the bottom and it felt warm, which meant the reaction was still happening. After 20 minutes, we added water into the zinc and hydrochloric acid to stop the reaction and we observed a slight cloudy colour (still clear) forming as we slowly pour the water in the beaker.
Calculations and Analysis:
4) Difference in answer could be the different initial masses of zinc, how accurate on measuring the hydrochloric acid, and calculation errors.
1) The reason why the reaction started very slowly then increased after a few minutes is because the hydrochloric acid has to first dissolve the protective layer that coats zinc. As the layer dissolves, more metal is exposed to the acid, therefore it begins to react.
2) If twice the mass of zinc were used in this experiment, the reaction is faster and the mass of zinc that reacted would increase. This occurs because of the larger surface