15. D is correct, exothermic reactions release heat
I am not sure about 16
Answer:
If anything but H2O were found, it would be evidence of a chemical change. Therefore, 4 is the only viable evidence that it was a physical change of H2O liquid to H2O gas.
D. Pentane. Pentane has 5 Carbon and 12 Hydrogen, like the molecule shown.
The balanced chemical reaction would be:
KHC8H4O4<span> (aq) + </span>NaOH<span> (aq) → NaKC8H4O4 (aq) + H2O.
The concentration of the NaOH is equal 0.1 M. We use this and the volume given above to determine the mass of KH</span>C8H4O4. We do as follows:
0.1 mol / L NaOH (.015 L) ( 1 mol KHC8H4O4 / 1 mol NaOH) (204 g / 1 mol) = 0.306 g KHC8H4O4
What is the empirical formula of a compound that contains 43.38% sodium, 11.33% carbon, and 45.29% oxygen?
Na2CO3
