(1) The melting of a crystalline solid is best depicted by the second graph. This is because, the second graph shows a horizontal line which means that for a while there was no change in temperature. This zone is the latent heat of fusion.
(2) The first graph shows the graph of a solid that is just heated but does not experience phase change. However, the second graph shows a solid that changes phase (from crystal/solid to liquid).
Children might not be able to take on the responsibility of it.
Answer:
The mass of the products left in the test tube will be less than that of the original reactants.
Explanation
The equation for the reaction is
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
1.0 3.0 3.9 0.1
Assume you started with 1.0 g of Mg.
It will react with 3.0 g of HCl to form 3.9 g of MgCl2 and 0.1 g of H2
.
Mass of reactants = mass of products
1.0 g + 3.0 g = 3.9 g + 0.1 g
4.0 g = 4.0 g
The Law of Conservation of Mass is obeyed.
However, your test tube and its contents will weigh 0.1 g less than it did before the reaction.
Does that contradict the Law of Conservation of Mass? It does not.
One of the products was the gas, hydrogen, and it escaped from the test tube. You weren't measuring all the products, so test tube and its contents weighed less than before.
