[EX5TASY]

Hey all, I have these 2 questions that have really been bugging me.


1.) Upon strong heating, Cu₂(CO₃)(OH)₂ or Cu₃(CO₃)₂(OH)₂ decomposes to leave CuO(s) in the heating crucible. Upon heating of 1.104 g of sample, 0.796 g remains. Calculate the %Cu in the sample.


The first one, I got the right answer to be: 57.6% Cu, but that was mostly by luck and out of frustration guessed. Since it is 57.6%, it shows that it we are talking about the first compound, but I am confused on how we differentiate which compound it is, and how to use the before and after masses to find that out. I tried using a ratio of 1.104/0.796 = (Molar mass of compound) / (Molar masses of C and H), because it says the Carbon and Hydrogen decomposed. But using that way of thinking, i wasn't able to get the right answer.


2.) The Environmental Protection Agency (EPA) has proposed a new standard for microparticulates in air: For particles up to 2.5 µm in diameter, the maximum allowable amount is 50. µg/m³. If your 11.3 ft x 7.75 ft x 12.3 ft dorm room just meets the new EPA standard, how many of these particles are in your room? How many of these particles are in each 0.500 L breath you take? (Assume the particles are spheres of 2.5 µm diameter and made primarily of soot, a form of carbon with a density of 2.5 g/cm³.)

This question I know is basic, but I'm really confused because there are so many different components to use.


Any help is greatly appreciated 

[chiralic]

For your Question #1:

Hint: What compound (or substance) remain after strong heating into a crucible?