Which item in the photo is a good thermal insulator and why A. the plastic handle because it’s electrons don’t move freely
B. the cut vegetables because they contain a lot of water
C. The metal pan, because it’s electrons move quite freely
D. Human skin because it is made up mostly of water

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante