On Monday, we did Zn + HCl Lab. But first we discussed the properties of gaseous substances, which were combustibility and flammability, which mean the same thing. For the lab we took the trough filled it with water, put a bell jar full of water over the hole and then had a flask of hydrochloric acid and we dropped zinc into it. Once the system was topped off with the cork, the bell jar captured the water. We wanted to find the mass, volume and density of the system before and after the we added the zinc. In my group though our stopper/cork was too small to close the system, so we did not get any measurements. On Tuesday, my group got a chance to redo the experiment and actually see the gas get collected and test if it was combustible. We found out that the gas made was combustible. Our observations from the experiment were that the hydrochloric acid looked like water, the flask got warm when we added zinc and after combustion the flask got colder. We then considered what the gas in the bell jar could be. We decided we had three options: hydrogen, chlorine, or zinc. We eliminated chlorine because it's a yellow color and a poison and we also eliminated zinc because it has a high boiling point. So, the gas made had to be hydrogen, because it was the last option left and H2 is combustible. But, as we tried to figure out our equation we noticed that a second compound was made ZnCl2. We also noticed that a third was mad that was H2O because the hydrogen combined with the oxygen in the air to create water. We know this because there was condensation inside the bell jar after combustion. The picture below shows the equation for this lab.
On Wednesday, I worked on the skills practice worksheet. I understood how to balance the equations, but other than that I wasn't sure how to complete the other things.
On Thursday, we talked about diatomic elements, they in pure element form and they come in pairs. We learned that when they join into other compounds the diatomic element become single atoms. We then talked about how H2O and H2O2 compared, we assumed that all their atoms were the same mass/size. So, we did an experiment to test our theory. We took Magnesium and set it on fire. But we measured the mass before and got .37g. After we combusted it we knew that it'd combine with the oxygen in the air to make 2mgO. So the mass after we combusted it was .45g. This proved that we can't assume atoms are the same size. Oxygen mass= 21% mass of mg.
On Friday, we had a snow day!!
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